GREENLAND – Gentle remediation of trace element

contaminated land

BEST PRACTICE GUIDANCE FOR PRACTICAL

APPLICATION OF GENTLE REMEDIATION

OPTIONS (GRO):

APPENDICES/TECHNICAL REFERENCE SHEETS

December 2014.

GREENLAND: consortium lead scientists and contact points

Markus Puschenreiter, University of Natural Resources and Life Sciences, Vienna (co-ordinator)

Jaco Vangronsveld, Universiteit Hasselt

Jurate Kumpiene, Luleå tekniska universitet

Michel Mench, Institut National de la Recherche Agronomique

Valerie Bert, Institut National de l’Environnement industriel et des Risques

Andrew Cundy, University of Brighton

Petra Kidd, Consejo Superior de Investigaciones Cientificas

Giancarlo Renella, University of Florence

Wolfgang Friesl-Hanl, Austrian Institute of Technology

Grzegorz Siebielec, Instytut Uprawy Nawozenia I Glebooznawstwa – Panstwowy

Rolf Herzig, Phytotech-Foundation

Ingo Müller, Sächsisches Landesamt für Umwelt, Landwirtschaft und Geologie

Jannis Dimitriou, Sveriges lantbruksuniversitet

Xose Quiroga Troncosco, Tratamientos Ecológicos del Noroeste SL

Patrick Lemaitre, Innoveox

Anne Serani Loppinet, CNRS-ICMCB

Other contributors: Paul Bardos, Andrew Church, Jolien Janssen, Silke Neu, Nele Weyens, Nele Witters, Angela

Sessitsch, Rodolphe Gaucher.

The views expressed in this guidance are those of the authors, and do not necessarily reflect the views or policy of their employers, or of the European Commission. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. The property rights of the content belong to the GREENLAND consortium. While every effort has been made to ensure the accuracy and validity of the content, the authors do not make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights.

The GREENLAND project is financially supported by the European Commission under the Seventh

Framework Programmes for Research (FP7-KBBE-266124, Greenland).

Appendix 1: Design and implementation of GRO: technical guidance notes.

Michel Mench, Jaco Vangronsveld

?

Stage 1: Initial risk

assessment

Stage 3: Implementation of the

phytoremediation option in situ

Stage 4:● Biomass production● Biomass quality● Local conversion chains● Life cycle analysis● Ecosystem services

Stage 2: Option

appraisal

Decision support tool

From Phytoremediation to Phytomanagement of contaminated soils

Figure 1: Phytomanagement schematic. Phytomanagement Epistemology: Initially coined by Robinson et al (2007), the phytomanagement concept was developed in Dominguez et al (2008) and Fässler et al (2010). Zalesny et al (2008) extended the concept to an emerging paradigm including provisioning, ecological and social services. Long-term operations are included under the umbrella term of “phytomanagement”, where the phytoextraction of TEs for soil remediation is relatively unimportant compared to the goal of producing a profit from contaminated land, while mitigating environmental risk (Robinson et al., 2009). Time-scale: To distinguish phytoextraction from phytomanagement, Robinson et al define “reasonable” as one human generation of <25 years.

Greenland definition: the long term combination of profitable crop production with gentle remediation options (GRO) leading gradually to the reduction of pollutant linkages due to metal(loid) excess and the restoration of ecosystem services. The broadest term, ‘phytomanagement’, encompasses a range of land management activities. Implementation The implementation of GRO is related to the stage 3 of the management procedure (implementation of the remedy strategy), but various information must be collected during stages 2 and 3 (Fig. 1). When implementation must be considered? ● the decision to implement GRO is supported by use of appropriate decision support tools (DST) ● delimit the areas concerned: in stage 1 of the management procedure, the investigated area(s) concerned by the initial risk assessment must be defined and delimited. Notice that these areas can be divided into various clusters according to the initial risk assessment, identified pollutant linkages, and current/future land use. The main outcomes of stage 1 (Fig. 1) are to identify and quantify the pollutant linkages and the risk probabilities for either the current or planned land uses, in line with biological receptors involved, for each cluster identified for the area(s) under investigation. At this stage, for the topsoil and subsoil, and eventually groundwater (and surface water), it is crucial to have relevant datasets quantifying the 3D-spatial variability of parameters driving the choice of feasible (phyto)management and GRO according to the current/future land uses (for each cluster) and the related target/trigger values (i.e. all parameters/indicators of the exposure pathways) and other drivers (land value, time constraints, etc). These parameters are (in a non-exhaustive list): total and labile pool for each contaminant (when possible, including the chemical speciation of contaminants) in the soil and soil pore water (if possible in the soil profile), capacity to buffer/resupply the soil solution, leachability, basic physico-chemical properties, texture/composition (define the soil type), and ecotoxicity of the (solid/liquid) matrices, climatic conditions including water supply and its distribution, etc. ● account for any specific requirements related to the selected feasible GRO (e.g. water requirement vs. water supply) and the best conventional option (to be compared). Spatial variability of pollutant linkages: a pivotal parameter ● gain information: Before implementing field plots for testing of selected feasible GRO (and best conventional option(s) for the purpose of comparison) pay attention to the plant communities already colonizing the site/clusters (if any). Watch also for the presence and habitats of animals (including insects, soil mesofauna, etc.), the slope and the terrain relief in general (you may have to create some terraces). You will gain information on the spatial variability of pollutant linkages, plant candidates for GRO, and eventually specific (native) plant populations and associated microbes (which can be used directly or selected to obtain efficient partnerships). Define sub-site(s) allowing to statistically exploit the field plots. It is important to obtain a representative assessment of the spatial variability of soil (or other matrices) ecotoxicity for each cluster (at least a plant test with a sensitive plant species such as dwarf bean and an exposome indicator such as the NH4NO3-extractable soil fraction).

● in stage 2, option appraisal must consider if the relevant options can be really implemented at field scale (try to identify the bottlenecks?). Thereafter implementation is of concern (for each identified cluster, its pollutant linkages and current/future land use): ● select sub-site(s) for testing GROs vs. best conventional option(s): it is recommended to compare the best conventional technology(ies) in parallel with the selected feasible GRO (emerging from stage 2): why? In case of failure of the GRO’s, the conventional technology will be an alternative, and to better assess the benefits/limits of the GRO’s it is better to compare with the best conventional technology to provide relevant information to the landowner and the stakeholder core. ● don’t upscale directly from ‘pot experiments’ to ‘full-scale’ (in situ) of the cluster without the return skill of biomonitoring for several years For each cluster, according to the spatial variability of the parameters listed above: - select sub-sites (sufficiently large to be representative) to test for several years the selected options emerging from the stage 2; this especially offers the opportunity to address (and optimize) some aspects which cannot be investigated in stage 2 (variability of climatic conditions, colonization by animal communities, pests, ageing of soil amendments, extension of the root systems, etc.). In case of tree management, allow enough space between the plots (e.g. root system can extend horizontally more than 10 m for poplars as well as the shading effect). ● lysimeters As far as vertical migration to the subsoil and groundwater is of concern, try to establish an in situ lysimeter system (even a basic one with containers) to assess the quality and the ecotoxicity of the leachates. Horizontal migration of the contaminants through wind erosion and other natural agents (water run off), in particular to inland water and allotments, must be considered too (basic or sophisticated systems for trapping dust and run-off particles can be implemented) ● fences: A single fence around the whole site may be necessary (notably to restrict the entrance) but it is generally not sufficient to prevent damage caused by mammal herbivores (i.e. rabbits, field rats, deers, etc.). It should be complemented by fences around small clusters (especially at the start of the phytomanagement, to protect the trees and other attractive plant species; individual fences around trees are less time-consuming but their efficiency is lower). ● sizes - define reasonable size of the plots for avoiding edge effects and permitting a long-term (at least 5 years) monitoring (notably soil and plant samplings). - implement the experimental design (field plots) according to the spatial variability of the parameters listed above; pay attention to allow sufficient space between the various options (if two or more options have been selected from stage 2); always remember that the tree roots (and associated hyphosphere) will effectively integrate soil and groundwater conditions over more than 10-15 m; pay attention to the shading effect which may occur with the canopy development. Pay attention to the slope: if there is one; use the common technique of terraces to overcome this factor; use the option of fiber nets to counteract the soil run-off till the establishment of the vegetation cover (see the technology developed to vegetate ski tracks) - prepare the implementation in line with the monitoring programme (i.e. monitoring of labile contaminant pools, pollutant linkages, colonization by the plant and animal communities) If there is a local planning to apply a specific future land use on the whole surface of the cluster (or if you want to avoid wind erosion and foliar exposure) you may implement a temporary, reversible

(phyto)management option, that can be modified/improved later based on the feedback of the phytomanaged clusters. ● don’t forget to monitor the foliar exposure Place some pots (in or around the plots) with uncontaminated soil to grow grassy crops and small trees for assessing the foliar exposure (in comparison with potted contaminated soils under remediation; such pots with contaminated soil can be placed also at another uncontaminated site to avoid the foliar exposure if one is suspected (this will help to determine changes in pollutant linkages and calculation of the mass-balance). Soil conditioners - compost: composts are frequently present in amendment combinations promoting crop production. The quality of the compost (and especially its C/N ratio, seed bank, labile P pool, etc.) is pivotal. Caution must be used in the case of a labile pool of Cu, Pb, As, Mo, Cr, Sb, and Sn as dissolved organic matter (DOM) may transiently increase the soluble complexed (for metals) or free anions (for metalloids) concentrations. Generally, notably in case of phytoextraction with annual crops, maintenance and additional compost dressing will be necessary after the initial application (the duration period of each dressing depends on the compost quality)

- alkaline materials: their effect on soil pH has major influence on physico-chemical and biological reactions in the contaminated soil, with consequences on the chemical speciation, location and mobility of trace elements. Consider also that over-liming may induce nutrient deficiency and mobilize trace elements in oxyanionic forms. - other soil conditioners: For iron grit (and similar material) it is recommended to split their incorporation into the soil over at least two applications (to avoid the pepite formation and to better homogenize the amended soil) - Fertilization: it must be appropriate to the choice of initial plant assemblages. It is pivotal in case of bioavailable contaminant stripping to promote the biomass production. With long-term phytomanagement, even (micro)nutrient deficiencies may occur and all agricultural recommendations can be applied. Implementation of plant species In the case of phytomanagement, the choice of the initial plant/microbe partnerships must be made according to the local conversion chains for biomass (generally the biomass production on the site is not enough to financially support a dedicated local conversion chain; this biomass must be commonly merge with similar ones from other sites (forest, SRC, agricultural field, greenwaste, etc) ● grassy crops: - for the same plant species, some ecotypes/cultivars are more tolerant to the contaminant exposure and other stresses (frost, drought, low fertility, herbivory, pest, etc.). Such (native) tolerant populations (and their associated rhizosphere and endophytic bacteria/fungi) are often already present at the site under investigation (or a similar one, in the same area). - all common agronomic practices can be used (especially in Europe), to take advantage of autumn to implement the grassy crops; sometime it may be an advantage to transplant some patches of grasses to speed up the colonization or when a diversity is required. Trapping and germination of seeds can be enhanced by the use of mulch or nets (see the technology to restore ski slopes)

Starting from seeds, some light mulch (with straw, fern fronds, bark chips, coconut nets, etc.) to trap the seeds (and avoid migration with natural agents or bird predation) can be necessary. This point can be pivotal in case of slopes. Some Fabaceae can be included in the seed mixture to promote the fixation of atmospheric nitrogen. Perennial grasses Water and nitrogen supply as well as weed competition may be limiting factors, especially at sites with sandy soils in the southern part of Europe. So, irrigation and fertilization may be required depending on the site-specific conditions. ● Short rotation coppicing (SRC): - Generally there is a competition between young trees and the herbaceous plant community (notably grassy crops) that can be adverse for tree development. Therefore, try to implement the young trees before implementing the grassy crops (for later increasing the vegetation cover and reducing the contaminant migration through natural agents - It is pivotal to apply irrigation of the trees in year 1 (and sometime year 2) during dry periods to increase the survival rate and promote the development of their root systems (of course it depends of soil type, climatic conditions, etc.) - pay attention also to the slope, potential soil erosion and/or flooding Mycorrhiza: From the GREENLAND network, transplantation of mycorrhizal trees is more successful than that of non-mycorrhizal trees and the on-site mycorrhization of tree cuttings (usually implemented during the winter time, notably for Cu-contaminated soils). If possible produce the mycorrhizal trees with native metal(loid) tolerant fungi which can effectively initiate a fungal succession (Hebeloma, Paxillus, Lactarius, Suillus spp., etc.) Management of biodiversity - establish natural or passive habitats to take advantage of the biological auxiliaries (notably beneficial insects); such habitats must be designed to host and/or promote the reproduction of the biological auxiliaries. Think about the connection of the clusters with the other ones or the neighboring areas. - use corridors allowing the predators (fox, raptors, etc.) to hunt; these corridors can be combined with the access required by the harvest machines. - avoid monocultures to avoid the selection of pest populations (use diverse clones/genotypes for trees in the clusters); - use a crop rotation in case of annual plants

Appendix 2: Selection of plant species, cultivars and soil amendments for

application in gentle remediation approaches (GROs).

Petra Kidd, Grzegorz Siebielec, Michel Mench

Selection of adequate plant species for implementation of GROs Phytotoxicity and other stress factors can severely limit the performance and establishment of the plant

species used in the remediation process. The selection of plant species and optimization of growth are

therefore pivotal in successful phytomanagement of trace element (TE)-contaminated soils under different

pedo-climatic conditions. Decades of research have been dedicated to the screening and selection of TE-

tolerant plant species or genotypes. However, plants must not only show tolerance to the contaminant(s)

present but at the same time they may also require tolerance to numerous additional abiotic and biotic

factors, such as water stress, soil acidity or salinity, nutrient deficiency, frost, soil erosion or compaction,

herbivory, pests, etc. Success also depends upon the careful implementation of effective agronomic

practices such as crop rotations, intercropping, planting density, fertilization, irrigation schemes, weed, pest

and herbivory management etc. Conventional agricultural methods can be modified so as to suit both the

characteristics of contaminated soils, and to meet the requirements of effective phytoremediating crops.

The selected plant species or genotype will depend on the remediation option to be implemented, the

contaminant location, and pollutant linkages. For example, for phytoextraction the plants must be able to

accumulate and tolerate high TE concentration in their harvestable parts (e.g. shoots) and have a reasonably

high biomass production. One option is using TE-hyperaccumulators (such as Noccaea caerulescens, Alyssum

murale and A. corsicum) which are able to accumulate extreme concentrations of metal(loid)s (e.g. Cd, Ni,

Zn, Se, and As) in their above-ground biomass (often endemic to metal-enriched substrates, such as

ultramafic or calamine soils) and at the same time possess some economic added value (renewable biomass

for bio-economy and/or bio-ores (van der Ent et al. 2013a, b; Chaney et al. 2007). An argument in favour of

hyperaccumulators is the possible recuperation of TE from TE-rich biomass, but effective recycling of TE from

TE-loaded plants has not yet been proven, and without this the potential role of hyperaccumulators may be

overestimated. Moreover, the price of Zn in the world market is at present too low to make “Zn-recycling”

from trace element contaminated soil economically feasible (Vangronsveld et al., 2009). However, Ni

phytomining was proven to be economically feasible in the USA (Chaney et al. 2007) and in Europe (Albania)

(Bani et al. 2007). In East Asia, Sedum alfredii was identified as a dominant colonizer of Pb/Zn spoils and

Zn/Cd hyperaccumulator. Nonetheless, the main bottleneck limiting the practical application of

hyperaccumulators is the low biomass production of most of these species (except some of the Ni-

hyperaccumulators) and the high number of cropping cycles required for clean-up (if the objective is to

reduce total TE concentrations in soils). Additional limiting factors include the absence of commercially

available seeds/seedlings, their sensibility to the presence of contaminants other than the

hyperaccumulated TE, a lack of knowledge related to their cultivation, climate needs or competition with

other TE-tolerant plants.

As a result, high-biomass crops (annuals or perennials) and woody plants are recognized as viable

alternatives to hyperaccumulators for phytoextraction of TEs (particularly Cd, Se and Zn) if they also show

relevant shoot TE removals (i.e. moderate-high bioconcentration factor (BCF) and high shoot yield). Over the

last two decades, both high yielding crop species, such as tobacco (Nicotiana tabacum) and sunflower

(Helianthus annuus), and specific clones of several members of the Salicaceae family have been assessed in

Europe for their suitability within GRO. Examples of high-biomass crops and woody plants which have been

evaluated for their potential application in distinct GRO are given in Table 1.

Tobacco is a well-known and efficient accumulator of trace elements, especially for Cd. In vitro breeding and

chemical mutagenesis can improve the metal tolerance and phytoextraction capacity of these high-yielding

annual crops (Nehnevajova et al. 2007, 2009). Such non-genetically modified plants can be directly tested for

their metal extraction potential under real field conditions without any legal restrictions (Herzig et al. 2014).

Field trials within the EU FP5 project PHYTAC (2005) confirmed enhanced shoot metal removals of up to 1.8-

(Cd), 3.2- (Zn) and 2.0-fold (Pb) higher than that of mother lines at the Swiss Rafz site (soil contaminated by

industrial sewage sludge). Commercial sunflower cultivars accumulate only moderate metal concentrations,

but their high biomass production makes them interesting for phytoextraction (Madejón et al. 2003; Kolbas

et al. 2011). Some oleic cultivars, combined with efficient soil amendments, can provide both relevant

oilseed yield and shoot Cu removal (Kolbas et al. 2011, 2012). Chemical mutagenesis (EMS) was also used to

improve shoot metal concentrations and biomass production of a sunflower inbred line IBL04 (Nehnevajova

et al. 2007, 2009). At the Rafz site (Switzerland), using the second mutant generation of sunflowers (F2) with

improved metal extraction, shoot metal removals were up to 7.5-, 9.2- and 8.2-fold higher for Cd, Zn and Pb

than the inbred line, respectively (Nehnevajova et al. 2009). Rice (Oryza sativa ssp.) has been shown to be an

efficient Cd-phytoextracting plant for paddy fields in Japan. Some indica rice varieties can accumulate

relatively high Cd concentrations in their shoots (e.g. IR8, Chokoukoku) (Ibaraki et al. 2014).

A large number of Salix and Populus clones have been screened, and show great variation in biomass

production, TE tolerance and accumulation patterns in roots and leaves between clones (Landberg and

Greger 1994; Pulford et al. 2002; Migeon et al. 2009; Gaudet et al. 2011; Ruttens et al. 2011; Van Slycken et

al. 2013). These woody species show the ability to re-sprout from the stumps after harvests which are

performed at short time intervals (i.e. 2 – 6 years) (Dimitriou et al. 2012). It is possible to select the best-

performing clones based on their TE tolerance, uptake efficiency (accumulating clones for phytoextraction

vs. excluding clones for phytostabilisation), TE translocation from roots to shoots, and biomass production

(Pulford and Dickinson 2005; Unterbrunner et al. 2007; Wieshammer et al. 2007; Pourrut et al. 2011). Clones

can also be selected for their ability to accumulate selected TEs (e.g. Cd and Zn) while at the same time

immobilizing elements such as Cu or Pb. Additional factors influencing clone selection include their tolerance

to abiotic and biotic factors other than soil contaminants, such as fungal and insect infection (e.g. leaf rust

(Melampsora sp.) and lace bug (Monosteira unicostata)), cold and drought adaptation (Fernandez-Martinez

et al. 2013). Phytostabilisation can be combined with excluder-based SRC for bioenergy purposes. In this

case the selection of genotypes can also be based on their characteristics in relation to conversion processes,

e.g. calorific value, bulk density, moisture content, ash and extractive content (Demirbas and Demirbas 2009;

Chalot et al. 2012). However, willows have high irrigation requirements for successful establishment and

productivity, and under water stress conditions, do not maintain the same level of biomass production. For

example, in Australia using proven metal accumulators like willows and poplar is not feasible and the

selection of native woody species (such as Grevillea robusta, Acacia mearnsii, Eucalyptus sp.) with

characteristics suitable for GRO over non-natives is considered less ecologically disruptive.

In cases of extremely contaminated sites (e.g. smelter wastelands) the goal is to revegetate in order to

reduce TE dispersion in the local environment. Certain grass species have been proved to be effective in

establishing long-term plant cover, namely Poa pratensis, Agrostis capilaris, Festuca arundinacea, Festuca

rubra, Festuca ovina (Stuczynski et al., 2007).

Perennial herbaceous crops, such as switchgrass (Panicum virgatum), miscanthus (Miscanthus spp.) and

giant reed (Arundo donax) are good examples of grass crops which are being adopted as bioenergy crops in

Europe and North America (Zegada-Lizarazu et al. 2010; Nsanganwimana et al. 2013). The attraction lies in

their wide climatic adaptability, low production costs, suitability to marginal lands, relatively low water

requirements, low nutrient and agrochemical needs, and possible environmental benefits such as the

potential for C storage through their deep and well-developed root system (Zegada-Lizarazu et al. 2010). The

low metal(loid) uptake and transfer from soil to shoots, combined with a potential use in bioenergy, make

these species attractive candidates for phytostabilisation options.

Major staple crops have been screened for their TE phytoexclusion ability: including, wheat, barley, rice,

potato and maize. Cd is one element of most concern regarding metal uptake into the food chain (Grant

1999; Grant et al. 2008). The use of TE-excluding cultivars of annual crops can be an effective option for

mitigating soil contamination on agricultural land: some recommended Cd-excluding cultivars are given in

Table 1.

Biotechnological approaches have been developed to improve plant growth and performance in the

presence of contaminants. Inoculation with mycorrhizal fungi and plant-associated bacteria (rhizobacteria

and endophytes) have been reported to not only improve plant growth but also to modify soil TE mobility

and uptake/translocation by woody crops.

Selection of soil amendments for application in GROs Soil amendments including liming agents (calcite, burnt lime, slaked lime, dolomitic limestone), phosphates

and apatites, Fe, Al and Mn oxyhydroxides, organic amendments, and industrial waste products have been

widely used in phytostabilisation and some (aided) phytoextraction experiments. The formation of insoluble

TE chemical species reduces leaching through the soil profile and the labile metal pool in the soil

(Vangronsveld et al. 1995, 1996; Mench et al. 2000, 2003; Lagomarsino et al. 2011; Bert et al. 2012). Several

case studies have illustrated the successful use of soil amendments to support the establishment of a

persistent plant cover, reduce bioavailability and mobility of TEs, and induce the accumulation of organic

carbon and nutrients needed to support persistent vegetation (Clemente et al., 2005, Stuczynski et al.,

2005). Examples of both inorganic and organic materials which have been incorporated into in situ

immobilisation techniques (including (aided) phytostabilisation and in situ stabilisation and phytoexclusion)

can be found in Table 2. The most important processes involved in this immobilization are the

transformation of metals in soils, through precipitation–dissolution, adsorption–desorption, complexation

processes and ion exchange. In addition to reducing TE bioavailability the incorporation of effective

amendments restores soil quality by balancing pH, adding organic matter, increasing water holding capacity,

re-establishing microbial communities, and alleviating compaction. As such, the use of soil amendments

potentially enables site remediation, revegetation and revitalization, and finally sustainable reuse. Alkaline

materials can effectively induce metal hydrolysis reactions and/or co-precipitation with carbonates or act as

a precipitating agent for metals in the soil solution (Bes and Mench, 2008). Soils amended with Fe-

(hydr)oxides or by-products, rich in Fe-oxides, usually reveal a decrease in the most labile TE fractions (i.e.

soluble and exchangeable) and increase in the reducible fraction (i.e. oxide-bound) (Komárek et al., 2013).

Organic residues are able to improve soil physical, chemical and biological properties by modifying organic

matter content, increasing water holding capacity and modifying TE mobility (Alvarenga et al., 2009).

However, in some cases they can generate soil pH decrease due to mineralisation processes, and they should

therefore be combined with liming agents.

Metal immobilisation, and in particular Pb immobilisation, has been studied using a range of high phosphate

materials, such as synthetic and natural apatites and hydroxyapatites (HA), phosphate rock (PR), phosphate-

based salts (PBS), diammonium phosphate (DAP), phosphoric acid (PA) and their combinations (Kumpiene et

al. 2008; Chen et al. 2007, Cao et al. 2003; Gebeelen et al., 2003). Phosphorus fertilizers (such as single and

triple superphosphates, diammonium phosphate) are acidic phosphate compounds (Bolan et al. 2003) which

lead to a decrease in soil pH and consequent dissolution of both P and Pb, and subsequent precipitation of

lead phosphate compounds. Precipitation as metal phosphates has been proven to be one of the main

mechanisms for the immobilisation of metals, such as Pb and Zn in soils (McGowen et al. 2001). In general,

high-phosphate materials are considered to be more effective for Pb immobilisation than for Zn, Cu, and Cd.

Among all the lead phosphate minerals, chloropyromorphite has the lowest solubility, thus, it is most stable

under favourable environmental conditions. The formation of insoluble pyromorphite-like minerals was

responsible for Pb immobilization, whereas Zn, Cu, and Cd immobilization was attributed to co-precipitation

and surface complexation mechanisms (Miretzky and Cirelli 2008). Some risks associated with the use of

phosphate materials have been identified. For example, in cases of soils co-contaminated with Pb and As, P

addition can effectively reduce Pb availability but inadvertently solubilize As.

Many case studies have shown the stabilisation process to be more effective when several amendments are

used in combination. Amendments rich in metal oxides combined with compost, fertilisers, beringite,

cyclonic ashes or lime enhanced plant growth (Bes and Mench, 2008; Vangronsveld et al., 2009). A

combination of iron grit and OM improved shoot DW yield of bean cultivated in Cu-contaminated soils,

compared to OM application without iron grit (Bes and Mench, 2008). Additionally, the combination of iron

grit with lime and compost was more effective in reducing Cu concentrations in soil pore water than

individual amendments.

One key point is the sustainability and (self)-maintenance of the GROs (Hartley et al. 2012; Kumpiene et al.

2012). Too few long-term field trials consider this point. Ageing of the added and newly-formed minerals,

litterfall build-up, plant and animal colonists, pests, etc. can really challenge the GRO efficiency. After 5

years, a second dressing of compost highly promoted the shoot DW yield of tobacco and sunflower, and

their shoot Cu removals compared to a single compost incorporation into the soil in the case of bioavailable

Cu stripping (Mench et al Greenland WP1 report).

Table 2. Soil amendments commonly used for in situ stabilisation and (aided) phytostabilisation

Inorganic amendments Organic amendments

Rock phosphate (a major source of P fertilizers)

Manures

Thomas basic slag (a by-product of the iron industries)

Biosolids (sewage sludge), Composted biosolids

Wood ashes Green waste composts

Cyclonic ashes

Zerovalent iron grit

Linz-Donawitz slag

Siderite

Gravel sludge

Red mud

Drinking water residues

Key references and further reading

Alvarenga, P., Palma, P., Gonçalves, A.P., Fernandes, R.M., de Varennes, A., Vallini, G., Duarte, E., Cunha-Queda, A.C. 2009. Organic residues as immobilizing agents in aided phytostabilization: (II) Effects on soil biochemical and ecotoxicological characteristics. Chemosphere 74: 1301-1308. Bani A, Echevarria G, Sulçe S, Morel JL. 2014. Improving the agronomy of Alyssum murale for extensive phytomining: A five-year field study. Int J Phytoremediat, 10.1080/15226514.2013.862204null-null. Bert V, Lors C, Ponge JF, Caron L, Biaz A, Dazy M, Masfaraud JF. 2012. Metal immobilization and soil amendment efficiency at a contaminated sediment landfill site: A field study focusing on plants, springtails, and bacteria. Environ Pollut 169:1-11. Bes, C., Mench, M. 2008. Remediation of copper-contaminated topsoils from a wood treatment facility using in situ stabilisation. Environ Pollut 156:1128-1138 Bolan, N., C. Domy, A. Naidu, R. Naidu. 2003. Role of Phosphorus in (Im)mobilization and Bioavailability of Heavy metals in the Soil-Plant System. Reviews of Environmental Contamination and Toxicology 177: 1-44. Cao, R., L. Ma, M. Chen, P. Singh, W. Harris. 2003. Phosphate-induced metal immobilization in a contaminated site. Environmental Pollution 122:19–28. Chalot M, Blaudez D, Rogaume Y, Provent A-S, Pascual C. 2012. Fate of trace elements during the combustion of phytoremediation wood. Environ Sci Technol 46:13361−13369. Chaney RL, Angle JS, Broadhurst CL, Peters CA, Tappero RV, Sparks DL. 2007. Improved undestanding of hyperaccumulation yields commercial phytoextraction and phytomining technologies. J Environ Qual 36:1592-1443. Chen, S., M. Xu, Y. Ma, J. Yang. 2007. Evaluation of different phosphate amendments on availability of metals in contaminated soil. Ecotoxicology and Environmental Safety 67:278–285. Clemente, R, Walker DJ, and Pilar Bernal M. 2005. Uptake of heavy metals and As by Brassica juncea grown in a contaminated soil in Aznalcollar (Spain): The effect of soil amendments. Environ. Pollut. 138:46–58 Demirbas T, Demirbas C. 2009. Fuel properties of wood species. Energy Sources Part A-Recovery Util Environ Eff 31:1464-1472. Fernandez-Martinez J, Zacchini M, Elena G, Fernandez-Marin B, Fleck I. 2013. Effect of environmental stress factors on ecophysiological traits and susceptibility to pathogens of five Populus clones throughout the growing season. Tree Physiol 33:618-627. Gaudet M, Pietrini F, Beritognolo I, Iori V, Zacchini M, Massacci A, Mugnozza GS, Sabatti M. 2011. Intraspecific variation of physiological and molecular response to cadmium stress in Populus nigra L. Tree Physiol 31:1309-1318. Geebelen W, Adriano DC, van der Lelie D, Mench M, Carleer R, Clijsters H, Vangronsveld J. 2003. Selected bioavailability assays to test the efficacy of amendment-induced immobilization of lead in soils. Plant Soil 249:217-228. Grant CA. 1999. Management factors which influence cadmium concentration in crops. In: McLaughlin MJ and Singh BR, Eds. Cadmium in Soils and Plants. The Netherlands, Springer. p. 151-198. Grant CA, Clarke JM, Duguid S, Chaney RL. 2008. Selection and breeding of plant cultivars to minimize cadmium accumulation. Sci Total Environ 390:301-310. Hartley W, Dickinson NM, Riby P, Shutes B. 2012. Sustainable ecological restoration of brownfield sites through engineering or managed natural attenuation? A case study from Northwest England. Ecological Engineering 40: 70-79. Herzig R, Nehnevajova E, Pfistner CS, J-P. Ricci, A., Keller C. 2014. Feasibility of labile Zn phytoextraction using enhanced tobacco and sunflower: Results of five- and one-year field-scale experiments in Switzerland. Int J Phytoremediat 16:735-754. Ibaraki T, Fujitomi S, Ishitsuka A, Yanaka M. 2014. Phytoextraction by high-Cd-accumulating rice to reduce Cd in wheat grains grown in Cd-polluted fields. Soil Science and Plant Nutrition 60: 266–275. Kolbas A. 2012. Phenotypic traits and development of plants exposed to trace elements; use for phytoremediation and biomonitoring. PhD University of Bordeaux, France.

Kolbas A, Mench M, Herzig R, Nehnevajova E, Bes CM. 2011. Copper phytoextraction in tandem with oilseed production using commercial cultivars and mutant lines of sunflower. Int J Phytoremediat 13:55-76. Komárek M, Vaněk A, Ettler V. 2013. Chemical stabilization of metals and arsenic in contaminated soils using oxides - A review. Environ Pollut 172:9-22. Kumpiene J, Lagerkvist A, Maurice C. 2008. Stabilization of As, Cr, Cu, Pb and Zn in soil using amendments – A review. Waste Management 28:215–225. Kumpiene J, Fitts JP, Mench M 2012. Arsenic fractionation in mine spoils 10 years after aided phytostabilization. Environmental Pollution 166, 82-88, doi:10.1016/j.envpol.2012.02.016. Lagomarsino A, Mench M, Marabottini R, Pignataro A, Grego S, Renella G, Stazi SR. 2011. Copper distribution and hydrolase activities in a contaminated soil amended with dolomitic limestone and compost. Ecotoxicol Environ Saf 74:2013-2019. Landberg T, Greger M. 1994. Can heavy metal tolerant clones of Salix be used as vegetation filters on heavy metal contaminated land? Willow vegetation filters for municipal wastewaters and sludges: a biological purification system. Study tour, conference and workshop in Sweden, 5–10 June 1994, Report No 50, Uppsala, p. 133–144. McGowen, S., N. Basta, G. Brown. 2001. Use of diammonium phosphate to reduce heavy metal solubility and transport in smelter contaminated soil. Journal of Environmental Quality 30:493–500. Madejón P, Murillo JM, Marañón T, Cabrera F, Soriano MA. 2003. Trace element and nutrient accumulation in sunflower plants two years after the Aznalcóllar mine spill. The Science of the Total Environment 307:239-257. Mench M, Vangronsveld J, Clijsters H, Lepp NW, Edwards R. 2000. In situ metal immobilization and phytostabilization of contaminated soils. Boca Raton, Lewis Publishers Inc. Mench M, Bussiere S, Boisson J, Castaing E, Vangronsveld J, Ruttens A, De Koe T, Bleeker P, Assuncao A, Manceau A. 2003. Progress in remediation and revegetation of the barren Jales gold mine spoil after in situ treatments. Plant Soil 249:187-202. Migeon A, Richaud P, Guinet F, Chalot M, Blaudez D. 2009. Metal accumulation by woody species on contaminated sites in the north of France. Water Air Soil Pollut 204:89-101. Miretzky, P., A. Cirelli 2008. Phosphates for Pb immobilization in soils: a review. Environmental Chemistry Letters 6:121-133. Nehnevajova E, Herzig R, Federer G, Erismann KH, Schwitzguebel JP. 2007. Chemical mutagenesis - A promising technique to increase metal concentration and extraction in sunflowers. Int J Phytoremediat 9:149-165. Nehnevajova E, Herzig R, Bourigault C, Bangerter S, Schwitzguebel JP. 2009. Stability of enhanced yield and metal uptake by sunflowers mutants for improved phytoremediation. Int J Phytoremediat 11:329-346. Nsanganwimana F, Marchand L, Douay F, Mench M. 2013. Arundo donax L., a candidate for phytomanaging water and soils contaminated by trace elements and producing plant-based feedstock. A review. Int J Phytoremediat, 16: 982-1017. PHYTAC Final Report 2005. Development of Systems to Improve Phytoremediation of Metal Contaminated Soils through Improved Phytoaccumulation (QLRT-2001-00429). Pourrut B, Lopareva-Pohu A, Pruvot C, Garcon G, Verdin A, Waterlot C, Bidar G, Shirali P, Douay F. 2011. Assessment of fly ash-aided phytostabilisation of highly contaminated soils after an 8-year field trial Part 2. Influence on plants. Sci Total Environ 409:4504-4510. Pulford ID, Dickinson NM. 2005. Phytoremediation technologies using trees. In: M. N. V. Prasad, K. S. Sajwan and R. Naidu. Trace Elements in the Environment. Boca Raton, Lewis. p. 375-395. Pulford ID, Riddell-Black D, Stewart C. 2002. Heavy metal uptake by willow clones from sewage sludge-treated soil: The potential for phytoremediation. Int J Phytoremediat 4:59-72. Ruttens A, Boulet J, Weyens N, Smeets K, Adriaensen K, Meers E, van Slycken S, Tack F, Meiresonne L, Thewys T, Witters N, Carleer R, Dupae J, Vangronsveld J. 2011. Short rotation coppice culture of willows and poplars as energy crops on metal contaminated agricultural soils. Int J Phytoremediat 13:194-207. Stuczynski T, Siebielec G, Daniels W, McCarty G, Chaney R. 2007. Biological aspects of metal waste reclamation with biosolids. Journal of Environmental Quality, 36: 1154-1162

Unterbrunner R, Puschenreiter M, Sommer P, Wieshammer G, Tlustos P, Zupan M, Wenzel WW. 2007. Heavy metal accumulation in trees growing on contaminated sites in Central Europe. Environ Pollut 148:107-114. van der Ent A, Baker AJM, Reeves RD, Pollard AJ, Schat H. 2013a. Hyperaccumulators of metal and metalloid trace elements: Facts and fiction. Plant Soil 362:319-334. van der Ent A, Baker AJM, van Balgooy MMJ, Tjoa A. 2013b. Ultramafic nickel laterites in Indonesia (Sulawesi, Halmahera): Mining, nickel hyperaccumulators and opportunities for phytomining. J Geochem Explor 128:72-79. Van Slycken S, Witters N, Meiresonne L, Meers E, Ruttens A, Van Peteghem P, Weyens N, Tack FMG, Vangronsveld J. 2013. Field evaluation of willow under short rotation coppice for phytomanagement of metal-polluted agricultural soils. Int J Phytoremediat 15:677-689. Vangronsveld J, Colpaert JV, Van Tichelen KK. 1996. Reclamation of a bare industrial area contaminated by non-ferrous metals: physico-chemical and biological evaluation of the durability of soil treatment and revegetation. Environ Pollut 94:131-140. Vangronsveld J, Herzig R, Weyens N, Boulet J, Adriaensen K, Ruttens A, Thewys T, Vassilev A, Meers E, Nehnevajova E, van der Lelie D, Mench M. 2009. Phytoremediation of contaminated soils and groundwater: lessons from the field. Environ Sci Pollut Res 16:765-794. Vangronsveld J, Sterckx J, Van Assche F, Clijsters H. 1995. Rehabilitation studies on an old non-ferrous waste dumping ground: effects of revegetation and metal immobilization by beringite. J Geochem Explor 52:221-229. Wieshammer G, Unterbrunner R, Garcia TB, Zivkovic MF, Puschenreiter M, Wenzel WW. 2007. Phytoextraction of Cd and Zn from agricultural soils by Salix ssp and intercropping of Salix caprea and Arabidopsis halleri. Plant Soil 298:255-264. Zegada-Lizarazu W, Monti A. 2011. Energy crops in rotation. A review. Biomass Bioenerg 35:12-25.

Table 1. Examples of high-biomass crops and woody plants which have been evaluated for their potential application in different GROs.

Plant Woody crops High-biomass annual crops Perennial herbaceous crops Cd-excluding agricultural crop cultivars*

GROs Phytostabilisation/phytoextraction Phytoextraction Phytostabilisation/(Bioenergy crops)

In situ stabilisation and phytoexclusion

Salix Salix alba var. alba (Belders) Salix atrocinerea Salix caprea x cineria x viminalis (Calodendron) Salix dasyclados (Loden) Salix fragilis (Belgisch Rood) Salix smithiana (Salix caprea x viminalis) Salix triandra x viminalis (Inger) Salix viminalis (clones Jorum, Christina, Jorr, Jorunn, Orm,) Salix viminalis x schwerinii (clones Tora, Björn)

Sunflower (Helianthus annus) Tobacco (Nicotianna tabacum) Maize Alfalfa Sorghum

Switchgrass (Panicum virgatum) Miscanthus (Miscanthus spp.) Giant reed (Arundo donax) Biomass sorghum (Sorghum spp.) Fibre hemp (Cannabis sativa) Vetiver (Vetiveria zizanioïdes) Bamboo Phragmites australis

Maize1 cv. Fuxxol cv. Morisat cv. Acces cv. Die Samanta cv. Antonio cv. Atletico cv. Fransisco cv. LaFortuna

Populus Populus alba Populus deltoides x nigra (Ghoy) Populus nigra Populus tremula Populus trichocarpa (clones Columbia River, Fritzi Pauley, Trichobel) Populus trichocarpa x deltoides (clones Beaupre,

Grassy species: Agrostis sp., Festuca sp.

Spring barley2,3,4,5

cv. Streif cv. Sebastian cv. Sunshine cv. Auriga cv. Bodega cv. Ursa cv. Pasadena cv. Xanadu cv. Hanka cv. Felicitas

Hazendans, Hoogvorst, Raspalje, Unal)

cv. Messina

Alnus Alnus cordata (clone Lois) Alnus glutinosa Alnus incana

Spring durum5,6

cv. Astradur cv. Rosadur cv. Floradur cv. Helidur

Paulownia Paulownia tomentosa Winter durum5

cv. inerdur cv. Prowidur cv. Aradur cv. Superdur

Betula Betula pendula Winter rey5 cv. Agronom cv. Ero cv. Kier cv. Picasso cv. Nikita

Winter wheat3,4,5,6,7

cv. Batis cv. Skagen cv. Türkis cv. Orkas cv. Esket cv. Julius cv. Xenos cv. Josef cv. Fridolin cv. Tommi

Potato5 cv. Ditta cv. Nicola

*, the commercially available range of cultivar seed changes yearly, e.g. some cultivars disappear and others enter the market. 1Friesl-Hanl et al. 2011; 2Friesl-Hanl et al. 2009; 3LfL 2006; 4BfUL/LfL 2002-2011; 5Spiegel et al. 2009; 6Wenzel et al. 1996; 7Klose 2011

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Appendix 3: Safe biomass usage Valérie Bert, Jolien Janssen, Rodolphe Gaucher

As a result of plant and culture management, Gentle Remediation Options (GRO) produce plant biomass (herbs or woody biomass). Depending on the GRO set up on the polluted site and the type of plant used, harvested plant parts may contain concentrations of TE that may be higher than those found in similar vegetation grown on uncontaminated soils. This is, in particular, the case with phytoextraction which leads to metal-enriched plant biomass. These plants may enter valuation pathways if (i) TE do not disturb the functioning and the performance of the process, (ii) if the TE transfer is controlled and (iii) if such plant use complies with current regulations. To our knowledge, thus far, plant biomass on contaminated lands was only produced for scientific purposes to be used in demonstration projects such as GREENLAND. As a potential advantage, these plants will not compete with plants grown on agricultural lands as contaminated lands are not suitable for food production. On contaminated lands, plants may serve to provide feedstocks and non-food products for bioenergy and, thus, may contribute to achieve the EU aim by 2020 of obtaining 20% of energy from renewable sources. In GREENLAND, our approach was to select routine pathways for plant biomass as a basis to discuss the possible advantages and potential limitations, regarding technical, social and regulatory aspects, of using plant biomass produced from TE contaminated soil into these pathways. In addition, two emerging processing pathways were selected and discussed based on existing knowledge. Thus, combustion and anaerobic digestion were selected as established pathways whereas solvolysis and flash pyrolysis were selected as emerging technologies. Technical assessment was based on assays. They were performed with plants cultivated for the purpose of phytoextraction leading to metal-enriched biomass. All plants used in assays were provided by GREENLAND partners who owned field sites. Assays were performed using equipment owned by GREENLAND partners. Table 1 details processes and plants used in assays.

Table 1: Type of process and plant used in assays.

Process Test scale Plant Targeted metal

Combustion Pilot (40kW) Willow ‘Tora’ Zn, Cd Poplar ‘Max3’ Zn, Cd Mix willow, poplar Zn, Cd

Anaerobic digestion Laboratory (5L reactor)

Sunflower Zn

Solvolysis Laboratory (110cm3 reactor)

Tobacco Zn, Cd Cu

Flash pyrolysis Laboratory (100g reactor)

Willow Sunflower

Zn, Cd Zn

Tobacco Zn, Cd Cu

Acceptance and feasibility assessments were realized for combustion and anaerobic digestion based on interviews with installation operators in several European countries (France, Austria, Germany, Sweden). Regarding regulatory aspects, the assessment consisted of a review of current European regulation and examples of national regulations related to combustion and anaerobic digestion focused on plant biomass utilization. This review was used as a basis to discuss possibilities to use plant biomass produced on TE contaminated lands in these processes.

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KEY RESULTS

A) Assays

The main objective of the assays was to determine the fate of the TE in the resulting products of each conversion process. A-1: Combustion, defined as thermochemical conversion of biomass, occurs in combustion plants or boilers, i.e. technical apparatus in which fuels are oxidized in order to use the heat generated. Contrary to incinerators, used primarily for waste destruction, boilers are used primarily for energy production. The fuels can be solid, liquid or gaseous combustible materials. The combustion process results in bottom ashes and flue gases (gaseous fraction and fly ashes). Combustion is the most important energy conversion route for biomass. Biomass means products consisting of any whole or part of a vegetable matter from agriculture or forestry which can be used as a fuel for the purpose of recovering its energy content and wastes used as a fuel (IED 2010/75/UE). Forest and wood-based industries produce wood, which is the largest source of solid biomass used as fuels (logs, bark, chips, sawdust, pellets). Depending on its quality and national legal framework, ashes (bottom ashes and fly ashes) can be used on agricultural land and forest. For assays, wood chips of Zn and Cd-enriched willows and poplars were used as fuels (Table 2) in a biomass boiler of 40 kW (Picture 1). Commercial willows and poplars bought in wood nurseries were tested for comparison (Table 2). Picture 1. Boiler design used for combustion assays.

Table 2. Zn and Cd concentrations (mg kg-1 DW) in willow and poplar wood chips used as fuel in combustion assays (mean ± (SD)).

Assay 1 Assay 2 Assay 3

CSalix ‘Tora’ Phytoextr. CPopulus

‘Max3’ Phytoextr. CSalix alba CPopulus

trichocarpa Phytoextr.

Zn 53 (8) 91 (18) 91 (2) 102 (0,8) 20 (3) 103 (7) 929 (236)

Cd 1,9 (0,2) 2 (0,4) 2,2 (0,0) 3,9 (0,1) 0,2 (0,0) 2,1 (0,1) 39 (9)

Figure 1 shows the distribution of Zn in the emissions, i.e. bottom ashes, particulate fraction (fly ashes) and gaseous fraction of the flue gases, as a result of combustion assays performed on willows and poplars cultivated for phytoextraction purposes and the comparison with corresponding virgin wood (Control). For all assays, Zn occurred mainly (> 50%) in the fly ashes. The bottom ashes represented the second

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compartment for the occurrence of Zn whereas the gaseous fraction of the flue gases represented a minor compartment for Zn emissions. The distribution was not dependent on the initial burnt wood, i.e. virgin wood (control) or Zn enriched wood (phytoextraction). Similar results have been found for Cd.

Figure 1: Distribution (%) of Zn in bottom ash and flue gas (fly ash and gaseous fraction).

Independently of regulatory issues, the assays allowed to conclude that the burning of plant biomass naturally enriched with metals in industrial or collective boilers could be possible, as these boilers are normally equipped with efficient systems to reduce dust emissions. Depending on the TE concentration in bottom ashes and national legal framework, bottom ashes could be re-used by land spreading. Concerning fly ashes, the results invite to perform further in-depth analysis of current practices regarding separation of ashes and valorisation pathways.

A-2: Anaerobic digestion is a biological process performed by the combined action of several types of micro-organisms in the absence of oxygen. This process culminates in the partial degradation of organic matter and leads to formation of biogas and digestate. The volume of the digestate is around 50% of what was put into the digester. Typical feedstocks are organic waste such as sewage, manure, food waste, landfill, crops grown specifically for anaerobic digestion, crop residues, etc. Amongst crops, maize, sunflower, grass silage, cereals and rape meal give high biogas yields. Biogas is a mixture of biomethane CH4 (55-70%) and carbon dioxide CO2 (30-35%) and small amounts of other gases. biogas can be used in combustion plants to produce heat and electricity. After removal of contaminants and CO2, it becomes biomethane which has comparable characteristics with natural gas. It thus can be injected into the natural gas distribution network, used as a transport fuel in the form of Liquid Natural Gas (LNG) or Compressed Natural Gas (CNG). Depending on its quality and the local legal framework, the solid part of the digestate can be used on agricultural land.

For assays, Zn enriched leaves of sunflower were used as feedstocks in a 5L batch reactor (Picture 2). Zn concentrations in the sunflowers were 687 ± 29 (high Zn-enriched sunflower) and 247 ± 2 (medium Zn-enriched sunflower) mg kg-1 DW. Normal range of Zn values usually measured in sunflower grown on uncontaminated soil is 30-80 mg kg-1 DW. Biogas composition was monitored (Figure 2) and digestate was analysed for Zn.

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Picture 2. Batch reactor for anaerobic digestion assays and monitoring equipment.

Figure 2. Biogas composition (left axis in %; right axis in ppm) of medium Zn-enriched sunflower.

Medium Zn-enriched sunflower showed similar biogas composition as typical biogas (CH4: 50-75%; CO2: 25-45%; O2: <2%; H2S: <1%). This result evidenced that the presence of Zn in sunflower did not modify the composition of biogas. Results also showed that Zn did not inhibit biogas production. Due to technical problems, the assay performed on high Zn-enriched sunflower was not conclusive. Nevertheless, during the biogas monitoring which lasted 10 days, we could observe that biogas production was not inhibited. As expected, Zn was measured in digestates. Indeed, at 55°C, the temperature of the anaerobic digestion, no Zn volatilization can occur. Depending on TE concentration in digestates and the local legal framework, digestates could be re-used by land spreading or by composting. A-3: Solvolysis is the chemical decomposition of biomass with a solvent under pressure. This innovative technology aimed at investigating metal behaviour in biomass converted at sub- and supercritical conditions. As a reduction of the initial volume of biomass was expected, solvolysis was tested as a pre-treatment, resulting in a metal free liquid phase, where organic molecules of interest for green chemistry could be found, and a metal enriched solid residue. Regarding its metal concentrations and its properties, possibilities of valuation were discussed. Solvolysis of two tobaccos enriched in either Cu or Zn-Cd (Table 3) was carried out in a semi-continuous reactor in sub- and supercritical conditions (Picture 3). Temperatures ranged from 50, 150, 250, 350 to 400 °C, at a pressure of 25 MPa. In the assays, the solvent was water.

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Table 3. Metal concentrations in Cu and Zn-Cd enriched tobaccos used in solvolysis assays.

(mg kg -1 DW) Cu Zn Cd

Cu-tobacco 16 34 - Zn-Cd tobacco 14 847 9 Picture 3. Semi-continuous reactor used in solvolysis assays.

As shown in Figure 3, Cu was mainly found in the liquid phase during the heating step or in the residual solid, depending on the temperature. Zn was mainly found in the liquid phase during the heating step whereas Cd was mainly found in the residual solid. Carbon is almost exclusively found in the residual solid (> 99%). Some molecules of interest were found in the liquid phase but in very small amounts which did not permit quantification. Figure 3. Copper (a) and Zn-Cd (b) recovered in the different phases. C= carbon. Metal and C are expressed as percentages.

In the solid residues, Cu ranged from 180 to 764, Zn ranged from 94 to 905 and Cd ranged from 3 to 79 mg kg-1 DW, depending on the plant used and temperature. These concentrations were too high to consider the usage of the solid residue as an organic amendment. The idea was then to use the solid phase enriched with metals as a raw material to produce polymetallic catalysts which could be used in industrial biotechnologies and chemocatalytic processes. Preliminary assays showed that the metal concentrations were too low to evidence a catalytic activity of these residues.

A-4: Flash pyrolysis. Pyrolysis is the thermochemical decomposition of (biomass) material at moderate temperature and in oxygen deficient conditions resulting in 3 end products: char, oil and gas. Flash pyrolysis typically uses moderate temperatures (450 – 600°C), a very high heating rate and a very short vapor residence time (< 1.5 s). Flash pyrolysis targets the pyrolysis liquid as an end product.

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For the assays, metal enriched willow, tobacco and sunflower were used as feedstocks (Table 4) in a 100g

biomass semi-continuous reactor (Figure 4).

Figure 4. Scheme of flash pyrolysis reactor.

Table 4: Cd, Zn and Cu concentrations in biomass used for flash pyrolysis. Mean (SD).

Biomass sample Target metals (mg kg-1

dry weight)

Origin Species Cd Zn Cu

Cd/Zn phytoextraction Willow 1 high Cd/Zn 14.2 (1.0) 508 (26) < 10.0

Willow 2 high Cd/Zn 8.3 (0.1) 396 (8) < 10.0

Cd/Zn phytoextraction Tobacco low Cd/Zn < 1.1 121 (17) 18 (2)

(moderate and low Tobacco mod. Cd/Zn 1.5 (0.1) 390 (28) 23 (3)

metal level) Sunflower low Cd/Zn < 1.1 112 (5) 18 (1)

Sunflower mod. Cd/Zn < 1.1 463 (24) 17 (1)

Cu phytoextraction Tobacco Cu < 1.1 25 (5) 36 (4)

Sunflower Cu < 1.1 51 (2) 22 (1)

The pyrolysis liquid was a dark brown single-phased aqueous liquid in case of the willow samples (Table 5). The pyrolysis liquid of the tobacco and sunflower samples was two-phased, consisting of a tar and an aqueous fraction. The Cd concentrations in the aqueous fractions were, in this study, never higher than 12.3% of the %wt of Cd present in the original biomass. The recovery of Zn in the aqueous fraction is much lower and did not exceed 2.8% of the %wt of Zn present in the biomass. Also the Cu content in the aqueous pyrolysis oil after flash pyrolysis of the Cu-rich biomass was relatively low. The tar fractions of tobacco and sunflower contained in all cases more target metals than the corresponding aqueous fractions (Table 5).

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Table 5. Cd, Zn and Cu concentrations in the pyrolysis liquid after flash pyrolysis of the different biomass.

Mean (Recovery of metals in pyrolysis liquid, expressed as %wt of the metals present in the original

biomass).

Aqueous fraction Tar fraction

Biomass sample Target metals (mg kg-1 dry weight) Target metals (mg kg-1 dry weight)

Cd Zn Cu Cd Zn Cu

Willow 1 high Cd/Zn 2.22 (7.2%) 12.8 (1.2%) 12.8 (-) / / /

Willow 2 high Cd/Zn 1.31 (6.7%) 11.3 (1.2%) 9.1 (-) / / /

Tobacco low Cd/Zn < 0.5 (-) 12.6 (2.8%) 7.2 (10.7%) < 0.6 (-) 26.1 (2.8%) 15.1 (10.9%)

Tobacco mod. Cd/Zn 0.75 (12.3%) 10.2 (0.7%) 6.1 (6.8%) 1.2 (11.6%) 73.0 (2.8%) 7.0 (4.6%)

Sunflower low Cd/Zn < 0.5 (-) 6.5 (1.4%) 3.8 (5.1%) < 0.6 (-) 42.8 (4.9%) 6.9 (5.0%)

Sunflower mod. Cd/Zn < 0.5 (-) 14.3 (0.7%) 3.4 (4.3%) 0.62 (-) 152 (4.5%) 10.6 (8.3%)

Tobacco Cu < 0.5 (-) 4.9 (4.6%) 4.5 (2.9%) < 0.7 (-) 14.3 (6.3%) 25.0 (7.5%)

Sunflower Cu < 0.6 (-) 9.3 (3.1%) 3.1 (2.4%) < 0.8 (-) 16.9 (3.7%) 7.9 (4.0%)

A-5: Preliminary conclusions concerning emerging valorisation processes (solvolysis, flash pyrolysis)

The usage of metal-enriched plant biomass as a feedstock depends on multiple factors : the desired end product (e.g. liquid or solid phase), the amount and quality of this end product (e.g. energy content), the threshold concentrations of contaminants in this end product, regulation and standards (when existing). Concerning flash pyrolysis, the assays showed that ‘phytoextracting’ crops may be used for flash pyrolysis resulting in a liquid oil with a similar or higher energy content (not shown) to the initial biomass, but containing metals. To be used as a renewable fuel, the physicochemical properties of the liquid must be investigated as well as the potential impact and constraints associated with the presence of the metals for this usage. Further research efforts are needed to investigate these points. Concerning solvolysis, the distribution of TE between the liquid and solid phases depends on the element and the temperature of the treatment. Solvolysis can be used as a pre-treatment leading to a significantly reduced biomass and a liquid. From the view-point of industrial application, it would be preferable to obtain a metal free liquid phase. Preliminary investigations supported the idea that metal-enriched solid residue could serve as a raw material to produce bio-catalysts. Further research will investigate this possibility.

B) Interviews Operators of anaerobic digestion (AD) platforms and actors of the wood bioenergy sector were interviewed to assess the potential acceptance of using plant biomass produced by GRO on metal contaminated lands in their installations and network. The reasons of acceptance or refusal were investigated by separating phytostabilisation from phytoextraction. Selection of AD platforms and boiler operators/owners was based on countries among those represented in GREENLAND which used wood and energy crops as fuel/feedstocks at a significant rate in combustion and AD. As a result, 8 actors of the wood energy sector from France, Germany and Sweden, and 11 AD platforms operators from France, Germany and Austria were interviewed. The questionnaire interrogated installation characteristics, plant characteristics, performed analyses and phytotechnologies. Concerning AD, plants were used either for making digestate or as a structuring matter to make compost. Eight out of 11 operators did not know of phytotechnologies. All can accept plants from phytotechnologies under certain conditions. Differences in plant acceptance were related to phytotechnology type (phytostabilisation versus phytoextraction). Based on their own experience, operators thought that they could accept 10 to 50% of phytostabilising plants, i.e. these plants would not have increased TE concentrations compared to similar plants grown on uncontaminated soils. Phytostabilising plants would be

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accepted after careful checking (i) of their TE concentrations, (ii) that metals would not negatively impact equipment, microorganism activity and process performance (gas yield), and (iii) if there was an economical interest. In contrast, 2 out of 11 operators would not accept plants issued from phytoextraction whereas 9 would accept them with caution. The conditions for acceptance of metal-enriched plants were quite similar to those listed for the phytostabilising plants (after extensive TE analyses to validate the use of digestate and compost, economic interest, no negative effect observed on equipment and AD biology and performance) even if the potential use of these plants in AD installations seemed more risky to operators. Based on their own experience, they thought that they would only accept 10 to 35% of metal-enriched plants. The operator point of view highlighted that the use of biomass cultivated on contaminated lands could be more disadvantageous than advantageous, in particular when metal-enriched plants were produced, leading to additional controls, installation modifications and waste treatment assimilation. Diversification of providing sources and no land competition for food were advantages pointed out by operators. Concerning combustion interviews, 4 actors out of 8 did not know of phytotechnologies. Interviewed actors were boiler operators, boiler owners and wood suppliers. Boilers used primarily wood chips as fuel, wood often coming from the boiler vicinity. Six out of 7 interviewees would consider wood cultivated on contaminated soil with metal concentrations similar to those measured in forest as biomass, not waste. This choice was motivated by taking into consideration wood characteristics rather than the place where trees were grown. In contrast, 5 out of 7 considered metal enriched wood produced by phytoextraction as waste rather than biomass. The reasons which motivated this choice were related to the fact that ashes could not be re-used by land spreading or co-composted and that metals could negatively impact boiler equipment. As for AD, main advantages of using wood cultivated on metal contaminated soil were diversification of providing sources and no competition with agricultural land. In addition, interviewed actors thought phytotechnologies were in agreement with the principles of sustainable development. They also thought that wood cultivated on metal contaminated soil will be less expensive than virgin wood, leading to economical interest. As the main disadvantages, interviewed actors cited the potential need of additional controls, installation modifications and waste treatment assimilation. Results from questionnaires suggested that plant biomass from phytotechnologies could be used in AD and combustion, under certain conditions. From the view-point of interviewed actors, the main limitations related to additional controls in process end-products and installations that might generate additionnal costs. In most cases, price of phytotechnologies biomass was mentioned as a driver to potentialy use plants from metal contaminated soils. It should be similar to the market price for feedstocks and fuels, less expensive or free. Plants used in phytostabilisation or phytoexclusion were thought to be less risky and, consequently, benefited from a better theoritical acceptance than those issued from phytoextraction.

C) Regulation Status of biomass The classification of the plant biomass produced on contaminated land (biomass or waste?) is essential to choose the appropriate valuation pathway, and thus, assess the profitability or the cost from gentle remediation options. Thus far, this question is solved neither at the European level nor at the local/national level. Amongst the aspects that should be considered, we can cite: waste definition and discard notion (as for biomass on uncontaminated soils, the question is: is the first aim of phytotechnologies to produce biomass on contaminated soil or is harvested biomass an unwanted result of the remediation activities?), the fact that biomass is produced on contaminated land and the absence of a common European definition of such land, regulation concerning valuation processes such as combustion and definition of biomass in this context, the renewable energy Directive and national incentives, and end of waste criteria. From the definition of biomass taken in the Industrial Emission Directive (IED 2010/75/EU), plant biomass cultivated on contaminated soil for GRO could be classified as (a) products consisting of any vegetable matter from agriculture or forestry which can be used as a fuel for the purpose of recovering its energy content or (b) wastes such as (i) vegetable waste from agriculture and forestry or (v) wood waste.

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To know how European regulators would consider biomass produced on contaminated soils by phytotechnologies, we asked some of them through the advisory board of GREENLAND. A first comment from German, Italian, Austrian and Swedish regulators related to the fact that this point was never discussed yet. One reason could be that the amount of plants produced on contaminated sites for remediation purposes or for bioenergy production is so far not significant, as it is only produced for scientific purposes. With the exception of the Austrian regulator who had the feeling that this biomass could be classified as an agricultural product, other regulators had the tendency to classify the biomass from phytotechnologies as waste. These answers could be related to the way in which the questions were formulated that could have orientated the regulator answers. Nevertheless, these answers highlighted the fact that it is necessary to evidence harmlessness of metal-enriched biomass, bring information on TE transfer control to regulators and clarify product vs waste consideration. Valuation pathway regulation A state of the art review on European and national regulations was performed related to combustion aspects, as this valuation pathway is the most important energy conversion route for biomass produced on uncontaminated soils, and anaerobic digestion aspects, highlighting metal emission limit values or metal input fuel concentrations. To illustrate the work done on these aspects, we took the example of combustion in the French context. In 2013, French regulation regarding combustion plants changed. Now, it depends on the total rated thermal input and the type of fuels used. These requirements led to 3 categories of boilers, those submitted to specific procedures named “declaration” (for the smallest installations), “registration” and “authorization” (permit required for the biggest installations, including IED installations). Declaration and authorization categories are allowed to accept fuels among which (a), b(i) and some biomass classified as b(v) whereas registration category accepts other biomass classified as b(v). Depending on the boiler category, requirements regarding metals differ. For instance, in the declaration and the registration categories, maximal metal concentrations in bottom ashes and metal load over 10 years have been set and cannot be exceeded, when land spreading is considered. In the registration category, additional limits have been set such as metal concentrations in fly ashes, air emission limit values (ELV) on metals and maximal metal concentration in b(v) biomass. In the authorization category, ELV on metals are set as well as measurement of maximal metal concentrations in fuels authorized in the permit. Limit values which are considered in regulation are reported in Table 6. Metal concentrations obtained in our combustion assays were used for comparison with these values (Table 6).

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Table 6. Maximal concentrations established in the French combustion regulation for fuels (b(v) biomass; registration category), fly ashes (registration category) and bottom ashes if land spreading is considered (declaration and registration categories) and concentrations measured in wood used for phytoextraction and corresponding fly ashes and bottom ashes. TE (mg kg-1 DW) Cd Zn

Limit values in fuel 5 200 Willow 2 91 Poplar 4 102 Mix willow/poplar 39 929

Limit values in fly ashes 130 15000 Willow 759 38476 Poplar 436 12154 Mix willow/poplar 6279 247868

Limit values in bottom ashes 10 3000 Willow 12 946 Poplar 18 766 Mix willow/poplar 42 2608 If the biomass from phytotechnologies is considered as (a) biomass, i.e. products consisting of any vegetable matter from agriculture or forestry which can be used as a fuel for the purpose of recovering its energy content, in any case or in some situation, the comparison with limit values given in Table 6 is not relevant. On the contrary, if biomass is considered as b(v) biomass, some preliminary interpretation can be drawn (Table 6). Based on measured concentrations in wood, willow and poplar fitted with legal values whereas the mixture did not. Regarding fly ashes and bottom ashes obtained after combustion of wood used in phytoextraction, measured concentrations were all higher, at least for one metal, than legal limit values, which would forbid, in these specific cases, the land spreading of bottom ashes and fly ashes.

Finally, plant biomass from phytotechnologies is not specifically addressed in regulation (French and European level). From the current French regulation, three options could be possible to classify such plant biomass. So far, these are only hypotheses. Consequently, constraints or limitations related to their usage in combustion are not clearly stated. Results of the regulation study and the combustion assays performed on plant biomass used in phytoextraction highlighted the need to separate fly ashes from bottom ashes (in countries where it is not already done) to re-use bottom ashes more easily and to manage fly ashes accordingly to their TE content. In this study, we worked on wood produced for phytoextraction purposes. Results and regulation interpretation with less metal enriched plant biomass; i.e. phytostabilising or phytoexclusing plants, could obviously be different. To be processed in combustion installations in France without limitations, concentrations in plants should not exceed 5 and 200 mg kg-1 DW Cd and Zn, respectively. Plants that typically show lowest concentrations are phytostabilising and phytoexcluding plants. As Zn and Cd are mostly recovered in fly ashes rather than in bottom ashes, it should be possible to land spread bottom ashes more easily than fly ashes. Nevertheless, as shown with willow in our study, a low concentration in plant biomass does not necessarily imply that ashes resulting from this plant can be spread on land. Further research might focus on combustion assays with phytostabilising plants to answer more precisely this point.

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Key references and further reading Carleer R, Vangronsveld J. Phytoremediation, a sustainable remediation technology? Conclusions from a case study: I: energy production and carbon dioxide abatement. Biomass Bioenerg 2012; 39: 454-69. Carrier M, Loppinet-Serani A, Absalon C, Marias F, Aymonie C, Mench M 2011 Conversion of fern (Pteris vittata L.) biomass from a phytoremediation trial in sub- and supercritical water conditions. Biomass and Bioenergy 35, 872-883. Chalot M, Blaudez D, Rogaume Y, Provent AS, Pascual Ch. Fate of trace elements during the combustion of phytoremediation wood. Environ Sci Technol 2012; 46(24), 13361-9. Chen Y, Cheng JJ, Creamer KS. Inhibition of anaerobic digestion process: a review. Bioresource Technol 2008; 99: 4044-64. Czernik, S. and Bridgwater, A.V. Overview of applications of biomass fast pyrolysis oil. Energy & Fuels, 2004. 18(2): 590-598. Delplanque M, Collet S, Del Gratta F, Schnuriger B, Gaucher R, Robinson B, Bert V. Combustion of Salix used for phytoextraction: the fate of metals and viability of the processes. Biomass Bioenerg 49: 160-170. Hansen HK, Pedersen AJ, Ottosen LM, Villumsen A. Speciation and mobility of cadmium in straw and wood combustion flyash. Chemosphere 2001; 45: 123-8. Keller C, Ludwig C, Davoli F, Wochele J. Thermal treatment of metal-enriched biomass produced from heavy metal phytoextraction. Environ Sci Technol 2005; 39(9), 3359−67. Lievens, C., Yperman, J., Cornelissen, T., and Carleer, R. Study of the potential valorisation of heavy metal contaminated biomass via phytoremediation by fast pyrolysis: Part II: Characterisation of the liquid and gaseous fraction as a function of the temperature. Fuel, 2008. 87(10-11): 1906-1916. Lievens, C., Yperman, J., Vangronsveld, J., and Carleer, R. Study of the potential valorisation of heavy metal contaminated biomass via phytoremediation by fast pyrolysis: Part I. Influence of temperature, biomass species and solid heat carrier on the behaviour of heavy metals. Fuel, 2008. 87(10-11): 1894-1905. Lievens, C., Carleer, R., Cornelissen, T., and Yperman, J. Fast pyrolysis of heavy metal contaminated willow: Influence of the plant part. Fuel, 2009. 88(8): 1417-1425. Lind T, Valmari T, Kauppinen EI, Sfiris G, Nilsson K, Maenhaut W. Volatilization of the heavy metals during circulating fluidized bed combustion of forest residue. Environ Sci Technol 1999; 33(3):496-502. Ljung A, Nordin A. Theoretical feasibility for ecological biomass ash recirculation: chemical equilibrium behaviour of nutrient elements and heavy metals during combustion. Environ Sci Technol 1997;31(9):2499-2503. Lundholm K, Nordin A, Backman R. Trace element speciation in combustion processes – review and compilations of thermodynamic data. Fuel Process Technol 2007; 88: 1061-1070. Naja GM, Alary R, Bajeat Ph, Bellenfant G, Godon JJ, Jaeg JPh et al. Assessment of biogas potential hazards. Renewable energy 2011; 36: 3445-51. Narodoslawsky M, Obernberger I. From waste to raw material – the route from biomass to wood ash for cadmium and other heavy metals. J Hazard Materials 1996; 50: 157-68. Oasmaa, A. and Peacocke, C. A guide to physical property characterisation of biomass-derived fast pyrolysis liquids, ed. Finland, T.r.c.o. Vol. 450. 2001, Technical research centre of Finland, Espoo, Finland: VTT Publications. Obernberger I, Biedermann F, Widmann W, Riedl R. Concentrations in inorganic elements in biomass fuels and recovery in the different ash fractions. Biomass Bioenerg 1997: 12(3): 211-24. Obernberger I. Decentralized biomass combustion: state of the art and future development. Biomass Bioenerg 1998; 14(1): 33-56; Pahl O, Firth A, MacLeod I, Baird J. Anaerobic co-digestion of mechanically biologically treated municipal waste with primary sewage sludge – a feasibility study. Bioresource Technol 2008; 99:3354-64. Stals, M., Thijssen, E., Vangronsveld, J., Carleer, R., Schreurs, S., and Yperman, J. Flash pyrolysis of heavy metal contaminated biomass from phytoremediation: Influence of temperature, entrained flow and wood/leaves blended pyrolysis on the behaviour of heavy metals. Journal of Analytical and Applied Pyrolysis, 2010. 87(1): 1-7. Stals, M., Carleer, R., Reggers, G., Schreurs, S., and Yperman, J. Flash pyrolysis of heavy metal contaminated hardwoods from phytoremediation: Characterisation of biomass, pyrolysis oil and char/ash fraction. Journal of Analytical and Applied Pyrolysis, 2010. 89(1): 22-29. Syc M, Pohorely M, Kamenikova P, Habart J, Svoboda K, Puncochar M. Willow trees from heavy metals phytoextraction as energy crops. Biomass Bioenerg 2012; 37:106-113. Thewys T, Witters N, Van Slycken SV, Ruttens A, Meers E, Tack FMG, Vangronsveld J. Economic viability of phytoremediation of a cadmium contaminated agricultural area using energy maize. Part I: effect on the farmer’s income. International J Phytoremediation 2010; 12: 650-62. Thewys T, Witters N, Meers E, Vangronsveld J. Economic viability of phytoremediation of a cadmium contaminated agricultural area using energy maize. Part II: economics of anaerobic digestion of metal contaminated maize in Belgium. International J Phytoremediation 2010; 12: 663-79. Verma VK, Singh YP, Rai JPN. Biogas production from plant biomass used for phytoremediation of industrial wastes. Bioressource Biotechnol 2007; 98: 1664-9. Witters N, Mendelsohn RO, Van Slycken SV, Weyens N, Schreurs E, Meers E, Tack F, Wong MH, Cheung YH. Gas production and digestion efficiency of sewage sludge containing elevated toxic metals. Bioresource Biotechnol 1995; 54: 261-8.

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Appendix 4: Indicators of success and methods

Jurate Kumpiene, Giancarlo Renella, Petra Kidd

Background Risk management of contaminated soil using GROs focuses on breaking the contaminant linkage, mainly by either

1. controlling the source (e.g. removing or (bio)degrading the contamination), or 2. managing the pathway(s) (e.g. preventing labile contaminant pools and migration of contamination

through immobilization).

Since soil in both cases is left on site (i.e. the GROs are mainly in situ methods), the soil productivity and functionality should be improved in addition to the decreased risk for contaminant exposure. Such risk-based management requires the use of multiple tools (Posthuma et al., 2008; Asensio et al., 2013, Foucault et al., 2013) that can help us to monitor soil health and contaminant spreading.

Traditionally, the main physico-chemical soil properties such as organic matter (SOM) content, soil profile development, water infiltration, soil aggregation, pH and electrical conductivity values have been used as indicators of soil quality and restoration. While being fundamental soil attributes, these main soil parameters change very slowly. Further, they may not indicate the actual health status of contaminated soils and the direction of the dominant ecological processes. For example, SOM content is typical of fertile soils, but it can accumulate in TE contaminated soils due to the reduced decomposition activity. Therefore, the main physico-chemical soil properties are not useful for making decisions on the potential management options and monitoring of remediation actions of TE contaminated soils. Determination of the total contaminant concentration in soil is also not sufficient to assess the actual environmental risks. Multiple studies worldwide demonstrate that the risks for human health and ecosystems at TE-contaminated sites are often poorly predicted by the total TE concentrations in soil (e.g. McLaughlin et al., 2000). Soil properties, such as organic matter and clay content, cation exchange capacity and soil pH can substantially modify TE mobility in soil and their availability for uptake by soil organisms (bioavailability). This is actually the main principle of the second of the above listed GRO-approaches, where TE mobility and bioavailability (and hence risks) are decreased by various soil amendments, although total TE concentrations may remain unchanged. The challenge here is to estimate bioavailability of TE in soil. Two general options are commonly used: (1) chemical methods for assessing the TE solubility and mobility in soil, which represent the potential bioavailable fraction (Dean, 2010), and (2) bioassays for determining the actual TE uptake by living organisms (Thakali et al., 2006). To make a distinction between the bioavailability inside a cell and that assessed by chemical methods, the term bioaccessibility is applied in the latter case. When chemical methods are used, it is assumed that the potential TE bioavailability correlates to its solubility/chemical speciation and mobility, estimated by leaching tests and chemical extractions (Prueβ, 1992; Lebourg et al., 1998; McBride et al., 2009; Soriano-Disla et al., 2010). Some chemical methods have been standardized and are currently used in the legislation of several Countries, like protocols for quantifying soluble and exchangeable TE fraction using 0.1 M NaNO3 in Switzerland (Osol, 1998) and TE extraction using 1 M NH4NO3 in Germany (DIN ISO 19730, 2008; Prueß, 1998). Adoption of the latter protocol by other EU countries has been proposed (Anderson et al., 1994) and is also used in Austria (Austrian Standard L 1094-1).

Since the impact of TE on soil organisms is complex and difficult to predict with only knowing extractable TE concentrations, ecotoxicological tests are applied as a direct tool for estimating soil toxicity (Boluda et al., 2011; Mayfield and Fairbrother, 2013). For testing contaminated soils, three main groups of ecotoxicological

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tests are available: (1) microbial tests (including cellular biosensors), (2) plant tests, and (3) invertebrate tests.

The measurement of the soil microbiological and biochemical endpoints can be used to assess the actual status and the efficiency of the remediation actions, especially in combination to the measurement of the main soil physico-chemical properties. An early indication of the dynamics triggered by the remediation actions can be achieved by studying the rate of main ecological functions. They can also indicate the long term direction of main soil ecological processes. Several studies based on the use of soil biochemical and bio-molecular methods for determining the microbial diversity and functional activity have demonstrated the positive effects of GROs on the ecological functions, also called soil ecological services. Such studies also clarified the biological mechanisms that are triggered by the plant colonization of TE contaminated soils, as well as their relation with the TE mobility and bioavailability. Literature reports on the positive effects of man-established or spontaneous vegetation (volunteer plants) date back to the mid 1900’s, and unequivocally show that size, composition and activity of the soil microbial communities allows the distinction between vegetated and bare soils, and also the effects of soil management.

Plants can be used to assess phytotoxicity of contaminated soil through the evaluation of several endpoints, e.g. seed germination, root elongation, shoot yield, leaf asymmetry and area, photosynthetic pigments, chlorophyll fluorescence, and activity of stress related enzymes (Kolbas et al., 2013; Meers et al., 2007). Phytotoxicity occurs from the interference of TEs taken up through the roots, with metabolic processes, leading to specific toxicity symptoms such as chlorosis and high activity of detoxification enzymes, or general toxicity symptoms such as reduced leaf area and stunted growth (Vangronsveld and Clijsters, 1994; Meers et al., 2006; 2007). Survival and reproduction of soil dwelling invertebrates, such as nematodes, earthworms, potworms, springtails and snails are also used to determine acute and chronic soil toxicity (e.g. de Vaufleury et al. 2006), for risk assessment (Höss et al., 2009) and estimation of TE exposure in soils (Boyd and Williams, 2003). The list of the available methods is rather extensive. The selection of the evaluation tests is made depending on the experience of the evaluators, access to the facilities and equipment, etc. But to evaluate the success of GRO techniques for TE-contaminated soils in a time and cost-efficient way, the selection of the minimum test battery to assess the initial and residual risks is needed.

Assessing success of GRO-managed TE-contaminated soils

In the GREENLAND project, two test batteries were pre-selected; a chemical one for quantifying TE exposure in untreated soils and GRO-managed soils and a biological one for characterizing soil ecotoxicity and functionality (Table 1). Soil samples from field studies representing one of the main GROs (phytoextraction in Belgium, Sweden, Germany and Switzerland, aided phytoextraction in France, and aided phytostabilisation or in situ stabilization/phytoexclusion in Poland, France and Austria) were collected and assessed using the selected test batteries.

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Table 1 Chemical and biological tests applied in Greenland project for the selection of test battery for identification and monitoring of GROs success

Test Description Purpose Reference

CHEMICAL TESTS Quantification of TE exposure in soil

Aqua regia (HNO3: HCl 1:3 v/v) 0.5 g soil, microwave digester at 160°C, 25 min ramp

time and 20 min hold time (Pseudo)total TE concentrations

Ethylenediaminetetraacetic acid disodium-dihydrate (EDTA)

10 g soil in 100 mL of 0.05 M EDTA solution, for 2 h The amount of TE (originally for Cu, Zn, Fe, Mn) which might be plant available on the long run

ÖNORM L 1089, 2005

Ammonium nitrate (NH4NO3) Soil at liquid-to-solid ratio (L/S) of 2.5 L kg-1

for 120 min in 1 M NH4NO3

The amount of TE which are plant available and labile DIN ISO 19730:2008(E)

Sodium nitrate (NaNO3) 20 g soil in 50 mL of 0.1 M NaNO3-solution for 2 h The amount of TE which are easily plant available and exchangeable.

Osol, 1998

Water extractable Soil at L/S of 2 L kg-1

, for 24 h The amount of TE which are easily plant available and easily leachable

ISO/TS 21268-1

BIOLOGICAL TESTS Characterization of soil ecotoxicity and functionality Plantox Measured morphological parameters

Lettuce (Lactuca sativa L.) Root and shoot fresh and dry weight yield Indication of soil phytotoxicity ISO 17126:2005 Dwarf beans (Phaseolus vulgaris) Shoot length, fresh root, shoot and primary leaf weight Indication of soil phytotoxicity Vangronsveld and

Clijsters, 1992 Turnip (Brassica rapa) Emergence and growth, shoot dry weight Indication of soil phytotoxicity ISO 11269-2:2012

Plant stress enzymes:

guaiacol peroxidase (GPOD) malic enzyme (ME) glutamate dehydrogenase (GlDH) iso-citrate dehydrogenase (ICDH)

Capacity, i.e. the potential activity measured in vitro under non-limiting conditions of substrate and coenzyme

Detection of general toxicity symptoms in plants under stress conditions

Vangronsveld and Clijsters, 1992

Soil invertebrates Earthworms (Eisenia andrei)

Avoidance Estimation of the soil quality through effects of chemicals on behaviour (avoidance) of worms

ISO 17512-1, 2008

Nematodes (Caenorhabditis elegans)

Growth and reproduction Estimation of the toxic effect of soil samples on growth, fertility and reproduction of nematodes.

ISO 10872, 2010

Soil respiration (CO2-C evolution)

Integrated determination of microbial activity in soil Indication of biological activity of soil (mainly microbial activity)

Blackmer and Bremner, 1977

Soil microbial biomass Adenosine triphosphate (ATP) content

Determination of total soil microbial biomass Indication of microbial abundance in soil and respiratory activity, which is related e.g. with nutrient (N) mineralization.

Aleph and Nannipieri, 1998.

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Specific soil biochemical functions phosphatase, glycosidase, sulfatase, arylesterase, urease, protease, nitrification and ammonification potentials

Determination of the potential rate of specific biochemical activities

Early detection of changes in soil quality, indication of organic matter decomposition, nutrient cycling and mineralization to plant available forms.

Aleph and Nannipieri, 1998.

Total organic C, N and P, inorganic N (NH4

+-N, NO3

--N), available and

soluble P

Integrated chemical parameters of soil quality Indication of availability of nutrients in soil American Society of Agronomy

Microbial Functional diversity

GeoChip microarray (v4.2) technology Analysis of diversity of functional genes belonging to microbial groups involved in key soil functions such as nutrient cycling, metal resistance, and degradation of organic contaminants and ecological interactions

Tu et al., 2014

Microbial community structure Real-time quantitative PCR (qPCR) Denaturing gradient gel electrophoresis (DGGE) technique focusing on the total Eubacterial community, Alpha- and Beta-Proteobacteria, Actinobacteria and Streptomycetaceae

Evaluation of the presence of genes involved in key processes of the N cycle (ammonia oxidation and denitrification) in the soil

Braker et al., 1998, Mao et al., 2011 Muyzer et al., 1998

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Results

Extractable TE concentrations generally decreased more significantly in soils managed by in situ stabilisation combined with phytoexclusion, phytostabilisation or phytoextraction than in soils only managed with phytoextraction. Pseudo-total TE concentrations did not significantly change in the phytomanaged sites, except for one case attributed to the dilution by the amendments. Among the chemical extractions, the NH4NO3 and EDTA-extractions showed the most frequent differences in the extracted TE concentrations between the treated and untreated soils, while the most frequent correlations with the biological responses occurred for NH4NO3, followed by NaNO3-extractable TE pools. Pseudo-total (aqua regia extractable) concentrations showed no significant correlation with the biological responses.

Among the bioindicators (plants, earthworms, and nematodes), dwarf beans, especially through root mass, followed by shoot length, and stress enzyme activities, were the most responsive indicators to the soil treatments. Even though the selective chemical extractions did not always show statistically significant changes in TE extractability, dwarf beans and stress enzymes developed a stronger response to the tested GRO options. Generally, the plant growth decreased with higher extractable TE concentrations in soil, while bean stress enzymes reacted in the opposite way, i.e. increased with increasing TE extractability.

Soil N and P significantly changed only in soils where organic amendments were used. The soil biochemical properties positively responded to the different phytoremediation options, with arylesterase, urease and protease enzymatic activities, nitrification and ammonification potentials responding in all studied cases. The β-glucosidase activity only responded in sites where organic amendments were used. The measured microbiological and biochemical endpoints indicated significant improvement of soil functionality in soils with the heaviest contamination and where organic amendments were used such as in the French, German and Swiss sites. In soils with moderate contamination such as those of Belgian and Swedish sites, only some of the microbiological and biochemical endpoints were improved by the adopted phytomanagement. Among the microbiological endpoints, the most responsive were nitrification and ammonification potentials > soil enzymatic activities ≥ soil respiration > microbial biomass. These microbiological and biochemical endpoints are in a good agreement with soil toxicity data and TE solubility and mobility estimated by chemical extractions, and therefore are robust indicators on which management decisions can be based on. It is expected that soil microbial biomass and functional activity increases during the early stages of TECS phytomanagement up to typical levels because soils, like any other ecosystem, have an own maximum carrying capacity, which is site specific depending on the pedo-climatic conditions, vegetation and site management. Functional gene diversity of the soil microbial communities that was measured in soils managed by phytoextraction using willow short-rotation coppice (SRC) showed no significant changes. The functional diversity of the soil significantly increased only in soil where amendment with a mixture of organic matter and dolomitic limestone were used in addition to the willows, indicating that microbial communities responded to SRC-based GRO by enriching carbon degradation, nutrient cycling (nitrogen and phosphorous) and metal resistance response gene families. The analysis of the microbial community structure by the clustering of DGGE profiles showed clear differences between the treated and the untreated soils (at both the total community and phylogenetic group level), while the qPCR technique showed differences in the number of gene copies (nirK, nirS, nosZ, amoA), demonstrating that GRO implementation can lead to a shift in bacterial community and diversity. Shifts in community structure were more pronounced in soils where phytoexclusion or phytostabilisation had been implemented.

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Recommendations

Based on the obtained results with the selected evaluation methods, it is suggested that a minimum risk assessment battery to compare or monitor the sites phytomanaged by GROs might consist of the 1M NH4NO3 extraction and the dwarf bean Plantox test including the plant stress enzyme activities.

Soil microbiological and biochemical endpoints provide early indications on the effectiveness of the phytomanagement and, if regularly monitored, indicate the direction of the ecosystem recovery. Measurement of nitrification and ammonification potentials, soil enzymatic activity, soil microbial biomass and respiration is highly recommended in addition to the above methods, because such biochemical endpoints can be measured with standardized ISO protocols (visit http://www.iso.org/iso/home/store/catalogue_tc/), can be easily evaluated and consistently compared between case studies and over time in monitoring campaigns. They can be performed with low costs in general analytical laboratories with no need of specific expertise. Current methodologies for measuring soil microbiological and biochemical endpoints are relatively simple, standardized, robust and cheap. Although the microbial community structure showed clear differences between the treated and the untreated soils, these methods are costly and labour intensive. These methods use non-routine approaches, requiring specialized laboratories and bioinformatic expertise. It would be difficult to include them as routine measurements for monitoring of the GROs success. Nevertheless, the bio-molecular analysis of microbial community diversity and functional gene diversity at phytomanaged sites can be useful to explain the main trends in microbial community composition and specific microbially driven ecological functions such as TE resistance, microbial-plant beneficial activities and redundancy of key ecosystem functions. This high resolution level of analysis can be useful to optimize specific phytomanagement approaches of microbe-assisted phytoremediation by monitoring selected natural or inoculated microbial species.

Soil microbiological and biochemical endpoints also respond to several environmental co-variates such as soil organic matter, nutrient content and availability, pH value, water holding capacity, plant and litter cover and management. It is therefore recommended to include several biochemical analyses into test batteries, and to not rely on single or a few endpoints, especially in soils where organic amendments and pH conditioners are used.

Table 2. Recommended minimum test battery to evaluate success of remediation by GROs

Test Purpose Reference 1M NH4NO3-extraction Plant available TE DIN ISO 19730:2008(E)

Dwarf bean Plantox test Soil phytotoxicity Vangronsveld and Clijsters, 1992 ISO 15685 protocols

Plant stress enzyme activities Soil phytotoxicity Vangronsveld and Clijsters, 1992

Additional recommended tests

Nitrification and ammonification potentials

Soil toxicity ISO 14238, ISO 15685 protocols

Soil microbial biomass and respiration Soil microbial stress ISO 14240-1, ISO 16072 protocols Soil enzymes Soil toxicity 23753-1; ISO/TS 22939 protocols

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Specific aspects to consider

Soil properties and analytical methodologies

Knowledge of the background concentration of TE in the soils of the intervention area and evaluation of changes in total and extractable TE pools is the first step to take at sites managed both by phytoextraction and phytostabilisation/immobilisation. The use of standard protocols for soil sampling and analysis increased the transparency of the soil analysis to TECS managers. However, the TE-extraction results in phytostabilised/immobilised soils are only indicative and should be interpreted in combination with ecotoxicological indicators. Incorrectly selected soil amendments or their doses may increase toxicity to soil biota, regardless of their TE-immobilisation performance. High TE immobilisation efficiency of soil amendments may also cause deficiency of essential nutrients (e.g. phosphorus), thus diminishing plant growth.

Soil amendments strongly modifying soil properties, such as texture and organic matter content (e.g. compost, organic sludge), can create favourable conditions for soil dwelling organisms such as earthworms. Earthworms might thrive better in soils rich in organic matter despite high extractable TE-concentrations, yielding false positive indication of remediation success in soils remediated by using organic matter amendments if used as sole indicators.

Soil salinity, soil structure and nutrient levels are important factors that may affect the response of ecotoxicological tests, such as plant biomass, plant stress enzymes activities and invertebrate colonization. At similar extractable TE-concentrations in soil, higher soil salinity might cause weaker responses of the above mentioned indicators.

Time aspect

Recovery of soil functions might take a variable time to stabilize to new levels, depending on the pedo-climatic conditions and implemented GRO. Generally, soil biochemical activity increases shortly after the beginning of the remediation operations, but monitoring is necessary to assess the fluctuation and trend towards new levels. Plant and animal indicators may take longer times (e.g. 5-10 years), as their responses also depend on important co-variates such as nutrient levels, soil porosity, and plant species (Appendix 2).

35

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Aleph K., Nannipieri, P. (Eds), Methods in Applied Soil Microbiology and Biochemistry, Academic Press, London, UK, 1998. American Society of Agronomy. https://www.agronomy.org/publications Anderson STG, Robert RVD, Farrer HN. Determination of total and leachable arsenic and selenium in soils by continuous hydride generation inductively coupled plasma mass spectrometry. J Anal At Spectrom 1994;9:1107–10 Asensio V, Rodriguez-Ruiz A, Garmendia L, Andre J, Kille P, Morgan AJ, et al. Towards an integrative soil health assessment strategy: A three tier (integrative biomarker response) approach with Eisenia fetida applied to soils subjected to chronic metal pollution. Sci Total Environ 2013;442:344-65 Austrian Standard L 1094-1 Austrian Standard. Chemical analyses of soils – Extraction of trace elements with ammonium nitrate solution. ÖNORM L 1094-1, 1999 Blackmer AM, Bremner JM. Gas chromatographic analysis of soil atmospheres. Soil Sci Soc Am J 1977;41:908–912 Boluda R, Roca-Pérez L, Marimón L. Soil plate bioassay: an effective method to determine ecotoxicological risks. Chemosphere 2011;84:1-8 Boyd WA, Williams PL. Availability of metals to the nematode Caenorhabditis elegans: toxicity based on total concentrations in soil and extracted fractions. Environ Toxicol Chem 2003;22:1100–6. Braker G, Fesefeldt A, Witzel K-P. Development of PCR Primer Systems for Amplification of Nitrite Reductase Genes (nirK and nirS) To Detect Denitrifying Bacteria in Environmental Samples. Applied and Environmental Microbiology 1998;64:3769–3775. De Vaufleury A, Coeurdassier M, Pandard P, Scheifler R, Lovy C, Crini N, et al. How terrestrial snails can be used in risk assessment of soils. Environ Toxicol Chem 2006;25:797-806 Dean JR. Heavy metal bioavailability and bioaccessibility in soil. In: Cummings SP, editor. Bioremediation: Methods and protocols. Humana Press; 2010. P. 15-36 DIN ISO 19730:2008. Extraktion von Spurenelementen mit Ammoniumnitratlösung. Deutsches Institut für Normung Hrsg, Berlin. Foucault Y, Durand MJ, Tack K, Schreck E, Geret F, Leveque T, et al. Use of ecotoxicity test and ecoscores to improve the management of polluted soils: case of a secondary lead smelter plant. J Hazard Mater 2013;246:291-9 Höss S, Jänsch S, Moser T, Junker T, Römbke J. Assessing the toxicity of contaminated soils using the nematode Caenorhabditis elegans as test organism. Ecotox Environ Safe 2009;72:1811-8 ISO/TS 21268-1:2002. International Standardisation Organisation. Soil quality. Leaching procedures for subsequent chemical and ecotoxicological testing of soil and soil materials. Part 1: Batch test using a liquid to solid ratio of 2 l/kg dry matter. Geneva, Switzerland. ISO 16072:2002. International Organization for Standardization. Soil quality -- Laboratory methods for determination of microbial soil respiration. Geneva, Switzerland. ISO 17126:2005. International Organization for Standardization. Soil quality - Determination of the effects of pollutants on soil flora. Screening test for emergence of lettuce seedlings (Lactuca sativa L.). Geneva, Switzerland. ISO 23753-1:2005. International Organization for Standardization. Soil quality -- Determination of dehydrogenase activity in soils -- Part 1: Method using triphenyltetrazolium chloride (TTC). Geneva, Switzerland. ISO 17512-1, 2008. International Organization for Standardization . Soil quality - Avoidance test for testing the quality of soils and the toxicity of chemicals. Test with earthworms (Eisenia fetida). Geneva, Switzerland. ISO 10872, 2010-06(E). International Standardisation Organisation. Water quality - Determination of the toxic effect of sediment and soil samples on growth, fertility and reproduction of Caenorhabditis elegans (Nematoda). Geneva, Switzerland. ISO/TS 22939:2010. International Organization for Standardization. Soil quality -- Measurement of enzyme activity patterns in soil samples using fluorogenic substrates in micro-well plates. Geneva, Switzerland. ISO 14240-1:2011. International Organization for Standardization. Soil quality -- Determination of soil microbial biomass -- Part 1: Substrate-induced respiration method. Geneva, Switzerland. ISO 11269-2:2012. International Organization for Standardization. Soil quality - Determination of the effects of pollutants on soil flora, Part 2: Effects of chemicals on the emergence and growth of higher plants. Geneva, Switzerland. ISO 14238:2012. International Organization for Standardization. Soil quality -- Biological methods -- Determination of nitrogen mineralization and nitrification in soils and the influence of chemicals on these processes. Geneva, Switzerland. ISO 15685-2012. International Organization for Standardization. Soil quality -- determination of potential nitrification and inhibition of nitrification -- rapid test by ammonium oxidation. Geneva, Switzerland. Kolbas A, Mench M, Marchand L, Herzig R, Nehnevajova E. Phenotypic seedling responses of a metal-tolerant mutant line of sunflower growing on a Cu-contaminated soil series. Plant Soil 2013 DOI: 10.1007/s11104-013-1974-8 Lebourg A, Sterckeman T, Ciesielski H, Proix N. Trace metal speciation in three unbuffered salt solutions used to assess their bioavailability in soil. J Environ Qual 1998;27:584-590 Mao, Y, Yannarell, AC, Mackie RI. Changes in N-Transforming archaea and bacteria in soil during the establishment of bioenergy crops. PLoS ONE 2011;6. Mayfield DB, Fairbrother A. Efforts to standardize wildlife toxicity values remain unrealized. Integrated Environ Assess Manag 2013;9:114-23 McBride MB, Pitiranggon M, Kim B. A comparison of tests for extractable copper and zinc in metal-spiked and field-contaminated soil. Soil Science 2009;174:439-44 McLaughlin MJ, Zarcinas BA, Stevens DP, Cooka N. Soil testing for heavy metals. Commun Soil Sci Plan 2000;31:1661-700 Meers E, Geebelen W, Ruttens A, Vangronsveld J, Samson R, Vanbroekhoven K, et al. Potential use of the plant antioxidant network for environmental exposure assessment of heavy metals in soils. Environ Monit Assess 2006;120:243-67

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Meers E, Samson R, Tack FMG, Ruttens A, Vangronsveld J, Verloo M. Phytoavailability assessment of heavy metals in soils by single extractions and accumulation by Phaseolus vulgaris. Environ Exp Bot 2007;60:385-96 Muyzer G, Brinkhoff T, Nübel U, Santegoeds C, Schafer H, Wawer C. 1998. Application of denaturing gradient gel electrophoresis in microbial ecology. Molecular Microbial ecology manual 3.4.4/1-27. Osol (Ordonnance sur les atteintes portées aux sols). Valeurs indicatives, seuils d’investigation et valeurs d’assainissement pour les métaux lourds et le fluor dans les sols Available at http://www.admin.ch/ch/f/rs/814_12/index.html and Annexe 1 at: http://www.admin.ch/ch/f/rs/814_12/app1.html, 1998 Posthuma L, Eijsacker HJP, Koelmans AA, Vijver, MG. Ecological effects of diffuse mixed pollution are site-specific and require higher-tier risk assessment to improve site management decisions: A discussion paper. Sci Total Environ 2008;406:SI503-17 Prueβ A. Vorsorgewerte und Prüfwerte für mobile und mobilisierbare, potentiell okotoxische Spurenelemente im Boden. Verlag Ulrich E. Graner, Wendlingen; 1992 Prueß A. Action values for mobile (NH4NO3-extractable) trace elements in soils based on the German national standard DIN 19730. In: Proceedings of the Third International Conference on Biogeochemistry of Trace Elements, 1995, Paris; 1998 Soriano-Disla JM, Gomez I, Navarro-Pedreno J, Lag-Brotons A. Evaluation of single chemical extractants for the prediction of heavy metal uptake by barley in soils amended with polluted sewage sludge. Plant Soil 2010;327:303-14 Thakali S, Allen HE, Di Toro DM, Ponizovsky AA, Rooney CP, Zhao FJ, et al. Terrestrial biotic ligand model. 2. Application to Ni and Cu toxicities to plants, invertebrates, and microbes in soil. Environ Sci Technol 2006;40:7094-100 Tu Q, Yu H, He Z, Deng Y, Wu L, Van Nostrand JD, Zhou A, Voordeckers J, Lee Y-J, Qin Y, Hemme C, Shi Z, Xue K, Yuan T, Wang A, Zhou J-Z. GeoChip 4: a functional gene arrays-based high throughput environmental technology for microbial community analysis. Mol Ecol Resource 2014;14(5):914-928 Vangronsveld J, Clijsters H. A biological test system for the evaluation of metal phytotoxicity and immobilization by additives in metal-contaminated soils. In: Merian E, Haerdi W editors. Metal Compounds in Environment and Life, 4 (Interrelation Between Chemistry and Biology), Science and Technology Letters, Northwood; 1992. p. 117–25 Vangronsveld J, Clijsters H. Toxic effects of metals. In: Farago M. editor. Plants and the chemical elements. Weinheim: VCH Verlagsgesellshaft; 1994. p. 149-77 ÖNORM L 1089. Chemical analysis of soils – EDTA-extract for the determination of heavy metals. Austrian standard, 2005

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Appendix 5: The GREENLAND Decision Support Tool (DST) and Cost-calculator.

Andy Cundy, Nele Witters

Introduction

Gentle remediation options (GROs) offer strong benefits in terms of risk management, deployment costs and

sustainability for a range of site problems, however, awareness and take up is low, at least in a European

context. Practical, well disseminated decision support tools (DST) which incorporate GRO could help in this

respect, but the take up and acceptance of bespoke systems, such as specialist softwares, by stakeholders is

low. Previous work under the EU SNOWMAN SUMATECS project published by Onwubuya et al (2009)

reviewed available decision support tools and systems, and stakeholder perceptions of the fitness for

purpose of these systems, and argued that a simple, tiered DST model, which linked to well-established

national decision frameworks, and provided links to more detailed information to support practical GRO

implementation, was the most effective format to promote wider use and uptake both of GRO and of GRO-

based decision support. GREENLAND has adopted and expanded on these recommendations to produce a

transparent and simple framework for promoting the appropriate use of gentle remediation options and

encouraging participation of stakeholders, supplemented by a set of specific design aids for use when GROs

appear to be a viable option. The decision support tool produced is a phased or tiered model (figure 1

below), designed to inform decision-making and options appraisal during the selection of remedial

approaches for contaminated sites.

Figure 1: Schematic diagram of the GREENLAND decision support framework.

Each phase of the tool terminates in a decision point (Yes = proceed to next phase; No = return to options

appraisal), and the tool increases in complexity and time investment from phases 1 to 3. The tool can be

integrated into existing, well-established and utilised (national) DSTs / decision-frameworks, to ensure ease

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of operation and wide usage, and can be used to inform and support remediation option selection by a

range of wider stakeholders (consultants, planners etc).

This simple tiered framework has been provided in an MS Excel format. The tool is designed to interface with

existing national guidance at the options appraisal stage, although we recognise that the DST has equal

applicability at earlier (site planning) stages.

Step by step guide through the DST

In phase 1 of the model (initial concepts / feasibility), the user is referred to a series of worksheets outlining:

Definitions of GRO;

GRO scope and risk management capability (or High Level Operating Windows), and a quick reference on

GRO applicability (”Are GRO applicable at your site?”);

Examples of cases where application of phytomanagement strategies have led to demonstrable source

removal, pathway management or receptor protection (”success stories”);

An outline contaminant matrix to assess the applicability of various GRO options to different metal(loid)

contaminants (or combinations of these).

The user can navigate between these pages, and on to phase 2 or back to the overview page, by selecting

the hyperlinks given in the lower part of each worksheet.

In phase 2 of the model (exploratory stages / confirmation), the user is referred to a series of worksheets

outlining:

Stakeholder engagement guidelines, including general principles of stakeholder engagement when applying

GRO, criteria for the identification of different stakeholders profiles/categories, and example lists of

stakeholders;

A wider sustainability benefits identification and assessment module. While economic, social and

environmental benefits will clearly be site and project specific, a number of more generic qualitative, semi-

quantitative and fully quantitative tools and systems are available to enable identification and quantification

of wider benefits arising from application of GRO. Within this tool, we provide links to three

matrices/modules: The European Union FP7 HOMBRE project (grant 265097, www.zerobrownfields.eu)

Brownfield Opportunity Matrix (BOM) – an Excel-based qualitative screening tool to help decision makers

identify which services they can obtain from “soft reuse” interventions (including GRO) at a site, and how

these services interact; The SURF indicator sets on sustainability (with further links to external analysis

software resources), which provide a semi-quantitative ranking system based on key economic,

environmental and social indicators; and an outline cost calculator, developed within the GREENLAND

project, which incorporates user-entered cost data to estimate the economic value proposition of GRO at a

particular site. The cost calculator was based on a literature review and further detailed and extended by

testing the model on the different GREENLAND sites. The model was elaborated so that it is an easy to

understand and use tool for practitioners, with no additional data gathering required. Also, the model does

not elaborate on who performs the work (eg harvest by hand by scientists or by professional agency).

Therefore, the model should be used more as a guidance rather than for decision making.

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The cost calculator consists of two parts: data provision (two tabs) and a discounted cost calculation (1 tab).

In the first tab the user provides general information regarding the site (eg use, soil density, distances to

suppliers and buyers), the contamination (eg depth, element, concentration, goal ie extraction or

stabilisation) and the plant (eg rotation, density, biomass per part). In the second tab the user provides cost

data as well as a timing regarding the preparation (eg. license, leveling), start-up (eg purchase of plants and

seeds), maintenance (eg replacement of crops), harvest (eg type of machine, transport) and monitoring

(during and after the project) of the remediation or containment project. There is also an opportunity to

indicate potential revenues from the biomass. In the third tab the duration of the project is calculated as

well as detailed yearly costs throughout the project, the contribution of each cost type and a disounted total

project cost.

The user can navigate between these pages, and on to phase 3 or back to the overview page, by selecting

the hyperlinks given in the lower part of each worksheet.

In phase 3 of the model (design stages), the user is referred to a series of worksheets outlining:

Detailed operating windows for GRO. Here, we provide three MS Excel-based operating window matrices

which allow the user to check the outline applicability of GRO (grouped as phytoextraction,

phytostabilisation, and immobilisation/phytoexclusion) to a specific site, in terms of local soil pH, site plant

toxicity, climate, soil type, and depth of contamination. N.B. The purpose of these matrices is to highlight the

potential applicability of GRO at a site, NOT to confirm that GRO will be a successful risk management tool at

the site. Further technical and design input and expertise will be required to effectively design and implement

a GRO strategy that effectively manages contaminant risk, and delivers wider benefit.

Technical reference sheets, on: Design and Implementation; Selection of Plant Species, Cultivars and Soil

Amendments; Safe Biomass Usage; Indicators of Success and Methods; and Stakeholder Engagement.

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Appendix 6: Stakeholder engagement guidelines for application of “gentle”

remediation approaches (GROs).

Andy Cundy, Paul Bardos

Introduction

Definitions and key concepts

Stakeholder engagement is a broad inclusive and continuous process between a project and those

potentially affected by it. The World Bank (2012) describes the aims of stakeholder engagement as building

up and maintaining an open and constructive relationship with stakeholders and thereby facilitating a

project’s management of its operations, including its environmental and social effects and risks. Effective

stakeholder engagement is also seen as reducing key remediation project risks, for example failure to gain

acceptance and delays due to antagonistic relationships; and also as means of reducing project management

costs and timescale (RESCUE 2005; REVIT 2007).

Need for stakeholder engagement when applying GRO.

Stakeholder involvement has been identified as a key requirement for the optimal application of sustainable

remediation strategies (CL:AIRE, 2011), and in site regeneration more widely (REVIT, 2007; RESCUE, 2005).

Effective and sustained stakeholder engagement is critical to the acceptance of GROs, particularly for larger

projects, because (a) GROs are most likely to be used for sites where a soft end use is envisaged, and the

biological component of the remediation (e.g. plant cover) is likely to be an enduring part of the overall

regeneration of the land, and (b) to ensure that wider economic, environmental and social benefits from

GRO application are effectively delivered.

Current stakeholder engagement and guidance for land redevelopment and remediation

There are a range of definitions for what a stakeholder is (e.g. REVIT, 2007; World Bank, 2012), but common

features are that a stakeholder is an organisation, group or person who potentially could be affected,

directly or indirectly, by a project, its management decisions, or its outputs. Some definitions have a wider

scope to include any organisation, group or person who takes an interest in a project, or those who have the

ability to influence its outcomes (Reed et al., 2009). Hence the scope of who could be a stakeholder could be

very wide indeed, and some process of stakeholder identification is necessary to identify the most important

ones to engage with. The most efficient way to get a clear picture of who are the relevant stakeholders is to

carry out a stakeholder analysis, i.e. to identify all relevant stakeholders, to differentiate between different

categories of stakeholders and to investigate the relationships between the project and stakeholders and

among stakeholders themselves. A stakeholder analysis enables the prioritisation of stakeholders regarding

their interests and potential influence (adapted from Marega and Uratarič, 2011).

The engagement process will most likely encompass various levels of involvement for different categories of

stakeholders. The “rainbow diagram” (figure 1) classifies stakeholders according to the degree to which they

can affect or be affected by a problem or a management action (Chevalier and Buckles, 2008).

41

Figure 1: Rainbow diagram for classifying stakeholders according to the degree they can affect or be

affected by a problem or action (after Chevalier and Buckles, 2008).

For example, in relation to contaminated land management CLARINET (2002) suggests that some

stakeholders are at the “core” of the project decision making, and their views have a controlling influence on

project decisions. These may include, for example: the developer, site owner, regulator, planner and service

provider, and potentially those suffering loss as a result of a contamination problem (“Most affecting” or

“Most affected” classification in figure 2). Other stakeholders are not in this core group but their views may

affect, or should guide, project management decisions. These might include community groups, neighbours,

investors, insurers, campaigning groups, future site users, the press and governmental bodies such as

conservation bodies. In practice virtually all large-scale projects involving GROs will be influenced by the

views of the core group of stakeholders. Hence stakeholder engagement will be the extension of a more

active process of discussion with those outside of this core. Reed et al. (2009) uses a wider range of

categories, which may also be a useful means of categorising stakeholders:

Key players − stakeholders with high interest and influence.

Context setters – highly influential stakeholders, but having little interest.

Subjects − stakeholders having high interest but low influence.

Crowd – stakeholders who have little interest or influence over desired outcomes.

A generally accepted principle for consultation over land redevelopment or a remediation initiative is that it

needs to be organised so that views are identified and assessed early on, or up-stream, in the development

process (SU:BRIM Project, 2008). The REVIT Project (2007) identifies a spectrum of involvement measures

that can be applied to public participation, which are broadly similar to stakeholder engagement in general

as set out by IFC (2007) and repeated by the World Bank. This spectrum involves:

Inform - To provide the public with balanced and objective information to assist them in understanding

the problem, alternatives, opportunities and/or solutions.

Consult - To obtain public feedback for decision-makers on analysis, alternatives and/or decisions.

Involve - To work directly with the public throughout the process to ensure that public concerns and

aspirations are consistently understood and considered in decision making processes.

42

Collaborate - To partner with the public in each aspect of the decision including the development of

alternatives and the identification of the preferred solution.

Empower - To place final decision-making in the hands of the public.

The degree of engagement will depend on the type of project and the type of stakeholders involved. A

stakeholder engagement plan is seen as a prerequisite before engagement begins that sets out who will be

engaged with and how (World Bank, 2012; Revit, 2007). For GRO projects taking place over large scale sites

with substantial landscape impacts, it is perhaps safe to assume that restricting dialogue to core

stakeholders, with other stakeholders simply being informed, is likely to lead to major project risks. In some

cases soft end uses may be explicitly based on public empowerment, for example community based

regeneration projects to create amenity areas (e.g. National Urban Forestry Unit, 2001). However, for other

projects (e.g. where remediation takes place on land owned by a single private site owner (large farm, the

military etc.) a lesser level of public engagement may be needed depending on the remediation approach.

The engagement plan may well be iterative in nature (figure 2), with some initial scoping work required to

provide realistic project plans for discussion, for example:

1) Initial design work by a developer and consultant

2) Engagement processes with “core interests” to set out an initial range of viable options

3) Modified design scenarios

4) Wider engagement process with some feedback process to revise design scenarios.

This is not a definitive example, as for some projects community engagement may begin at a much earlier

stage.

Figure 2: Example of iterative stakeholder engagement approach.

There is a broad range of different stakeholder engagement techniques that start at early stages of planning

and redevelopment, which have been extensively reviewed (e.g. Reed et al., 2009; REVIT, 2007; World Bank,

2012). The Charrette process has been widely used for regeneration project master planning. The Charrette

process (www.charretteinstitute.org/charrette.html) is an interactive design workshop, in which the

stakeholders work directly with the design team to generate a project plan in a series of open format but

guided workshops. One of the principal benefits of the Charrette approach is its ability to synthesise the

contributions of all those involved into a meaningful and recognisable form - plans, visualisations and

sketches that are easily understood and form a consistent vision. Furthermore, it aims to involve a range of

43

stakeholders early on in the regeneration planning process so that they influence plans from the start of the

process and are not simply asked to approve expert produced plans. Examples of community based master

planning are described in SSCI (no date). Logic models can also be a useful means of identifying the benefits

and beneficiaries (or conceivably impacts and those affected) of a project, and are described in Doick (2010).

GRO - Current practice and recommendations

There is currently no detailed GRO-specific guidance for stakeholder engagement within Europe. Indeed,

such guidance may be deemed unnecessary given the existence of national government generic guidelines

for stakeholder engagement in planning and land redevelopment that can often be adopted for GRO

projects. Many GRO applications within Europe are essentially small-scale, involving pilot or trial projects on

land with an individual owner (e.g. Vangronsveld et al., 1995 and 2009; Friesl-Hanl et al., 2009). Here,

stakeholder engagement largely involves liaison with the site owner and the relevant regulatory authority,

and educational and research / proof-of-concept activities. At these sites, stakeholder activities are

dominated by communication and agreement rather than collaboration and empowerment, and are

focussed on a limited number of core stakeholders. Larger more complex sites will require more complex

stakeholder engagement, particularly in urban and sub-urban areas with large local populations and where

GRO-based remediation may be tied in with (and form a component of) longer-term site regeneration

aspects.

Given that drivers for dialogue often relate to the project context, locality and stakeholders rather than the

technical means of achieving remediation, there seems little justification for developing detailed GRO

technology-specific guidelines. Here, instead we define general principles of good practice for stakeholder

engagement for the benefit of those offering or thinking of utilising GROs and signpost to more detailed

sources and examples/case studies via the references listed on page 5. These principles can be summarised

as:

Identify and engage core and noncore stakeholders early in the process

Adopt a proactive not reactive approach to engagement

Engage stakeholders at all stages of the GRO process

Plan for long-term stakeholder engagement

Develop effective communication structures that allow a reciprocal, two-way dialogue

Ensure engagement is transparent and recorded

Recognise that criteria for assessing GRO may need to be subjective and objective

Set out all assumptions and procedures for implementing and monitoring GRO at the start of a project

Follow a logical, stepwise approach to engagement to avoid circular arguments and clearly address

subjective issues

These suggestions are consistent with the “Bellagio Principles” which set out a widely accepted view on how

to assess progress toward sustainable development, and which can be applied to brownfield regeneration

processes (Hardi and Zdan, 1997; Pediaditi et al., 2010).

The application of GRO may raise significant long-term site stewardship issues beyond those of more

conventional remediation methods, and so effective longer-term engagement strategies will be required to

ensure that site risk is effectively managed over the longer-term, and that full potential benefits of GRO (e.g.

CO2 sequestration, economic returns from biomass generation and “leverage” of marginal land, amenity and

educational value, ecosystem services etc.) are realised and communicated to stakeholders.

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Key references, cases and further reading

Chevalier, J.M., Buckles, D.J., 2008. SAS2: a Guide to Collaborative Inquiry and Social Engagement. Sage Publications. www.idrc.ca/EN/Resources/Publications/Pages/IDRCBookDetails.aspx?PublicationID=108

CL:AIRE, 2011. The SuRF-UK Indicator Set for Sustainable Remediation Assessment London, UK. ISBN 978-1-905046-1292-5 www.claire.co.uk/surfuk

CLARINET, 2002. Review of Decision Support tools for contaminated land management, and their use in Europe. SFT, Umweltbundesamt, Federal Environment Agency, Wien, Austria, 180 pp.

Doick, K.J., 2010. Learning lessons in monitoring brownfield land regeneration to greenspace through logic modelling, in: Fox H., Moore, H. (Eds.), Proceedings of ‘British Land Reclamation Society: Promoting sustainable land use’, Restoration and Recovery Conference 2010. (Glamorgan, Wales. 7

th-9

th September). ISBN: 978-184995-012-1

Friesl-Hanl, W., Platzer, K., Horak, O., Gerzabek, M.H., 2009. Immobilising of Cd, Pb, and Zn contaminated arable soils close to a former Pb/Zn smelter: a field study in Austria over 5 years. Environ. Geochem. and Health; 31, 581-594.

Hardi, P., Zdan , T.J., 1997. Assessing sustainable development, International Institute for Sustainable Development, 161 Portage Avenue East - 6th Floor, Winnipeg, Manitoba, R3B 0Y4, Canada, ISBN 1-895536-07-3, http://www.iisd.org/pdf/bellagio.pdf

IFC (International Finance Corporation), 2007. Stakeholder Engagement: A Good Practice Handbook for Companies Doing Business in Emerging Markets, Washington, DC: International Finance Corporation. http://www.ifc.org/ifcext/enviro.nsf/attachmentsbytitle/p_stakeholderengagement_full/$file/ifc_stakeholderengagement.pdf

Marega, M., Uratarič, N., 2011. Guidelines on stakeholder engagement in preparation of integrated management plans for protected areas. April 2011, NATREG project, South East Europe Transnational Cooperation Programme. www.southeast-europe.net; www.natreg.eu.

National Urban Forestry Unit, 2001. Urban Forestry in Practice, Community involvement in land reclamation Case Study 25, National Urban Forestry Unit, Wolverhampton WV10 9RT, UK. http://www.bbcwildlife.org.uk/sites/birmingham.live.wt.precedenthost.co.uk/files/CS%2025%20-%20Community%20Involve.pdf Accessed Jan 2013

Pediaditi, K., Doick, K., Moffat, A.J., 2010. Monitoring and evaluation practice for brownfield regeneration to greenspace initiatives: A meta-evaluation of assessment and monitoring tools. Landscape & Urban Planning, 97, 23-36

Reed, M.S., Graves, A., Dandy, N., Posthumus, H., Hubacek, K., Morris, J., Prell, C., Quinn, C.H., Stringer, L.C., 2009. Who’s in and why? A typology of stakeholder analysis methods for natural resource management. J. Environ. Manage. 90, 1933–1949

RESCUE Project, 2005. The RESCUE Manual: Best Practice Guidance for Sustainable Brownfield Regeneration. Land Quality Press, a Division of Land Quality Management Ltd. ISBN 0-9547474-0-2

REVIT Project, 2007. Working towards more effective and sustainable brownfield revitalisation policies, Stakeholder engagement a toolkit. Interreg IIIB project http://www.revit-nweurope.org/selfguidingtrail/27_Stakeholder_engagement_a_toolkit-2.pdf Accessed Jan 2013

SU:BRIM Project (2008) Community Engagement, Urban Regeneration, and Sustainability. SUBR:IM bulletin 8 (SUB 8) www.claire.co.uk.

The Scottish Sustainable Communities Initiative – SSCI (xxxx) Charrette Series Report http://www.scotland.gov.uk/Resource/Doc/260590/0105938.pdf , accessed Jan 2013.

Vangronsveld, J., Van Assche, F., Clijsters, H, 1995. Reclamation of a bare industrial area contaminated by non-ferrous metals: in situ metal immobilisation and revegetation. Environ. Pollut. 87; 51-59.

Vangronsveld, J., Herzig, R., Weyens, N. et al. 2009. Phytoremediation of contaminated soils and groundwater: lessons from the field. Env. Sci. Poll. Res, 16, 765-794.

World Bank, 2012. Getting to Green - A Sourcebook of Pollution Management Policy Tools for Growth and Competitiveness. Pollution Management Sourcebook The International Bank for Reconstruction and Development / THE WORLD BANK 1818 H Street, NW, Washington, DC 20433, USA. http://go.worldbank.org/QRULF0VED0

A full discussion of these arguments, and a wider remit and context for the application of Gentle Remediation Options (GRO) within sustainable remediation strategies, can be found in the published article: Cundy A.B., R.P.Bardos, A.Church, M.Puschenreiter, W.Friesl-Hanl, I.Mueller, S.Neu, M.Mench, N.Witters and J.Vangronsveld (2013) Developing principles of sustainability and stakeholder engagement for “gentle” remediation approaches: the European context. Journal of Environmental Management, 129, 283-291.

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Appendix 7: Further GRO examples from the GREENLAND site network

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