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Knowledge Gaps: AbioticKnowledge Gaps: AbioticFactors and Ecosystem-Wide
Effects Prof. Richard Handy
School of Biomedical & Biology Sciences, University of Plymouth UKUniversity of Plymouth, UK.
NNI USA workshop: 6-7th October 2009, Arlington, Virginia
ContentsContents
T l i h ff il / di• Translating the effects on soils/sediments, primary producers, herbivores, carnivores, into
l i l l ffa population or ecosystem level effect.• Terrestrial and aquatic ecosystems.• Physico-chemistry and ecosystems.• Experimental ApproachesExperimental Approaches
Soils and Sediments
• At the base of the ecosystemL k ft th di t / il• Look after the sediments/soils.
AntibacterialAntibacterial Activity is I lInversely Related to
Particle Size
Neal, Ecotoxicology (2008) 17:362–371
Silver NPs:Silver NPs: Behaviour in
N t lNatural Estuarine Sediments
Bradford et al. (2009) ES&T
Silver NPs: No Effect on
NaturalNatural Microbes in
E iEstuarine Sediments
Muhling et al. (2009) Marine Environmental Research
Algae, Fungi, Terrestrial Plantsg , g ,Navarro et al. (2008) Ecotoxicology, 17:372–386
Unknown Effects on Nutrient Cycling, Water Depuration & Biomass ProductionWater Depuration & Biomass Production
Navarro et al. (2008) Ecotoxicology, 17:372–386
Dietary Exposurey p• Dietary bioavailability and uptake measurements are
needed.• Gut chemistry and NP adsorption onto epithelia.• Relate by feeding habit and gut anatomy, not by particle
h i t lchemistry alone.• Herbivores, carnivores, tropical, temperate.• Food webs: species sensitivity with/without• Food webs: species sensitivity with/without
biomagnification.• Gut function is about energy acquisition by animals.• Use bioenergetics to link individual with population level
effects.• Trade offs animals preserve growth at the expense of• Trade offs-animals preserve growth at the expense of
locomotion/behaviour and reproduction.
Uptake of NPs Across
EpitheliaBloodEpitheliaMucusUnstirred waterBulk water
Unstirred layer
p t e aNa+
N +
Na+Cl-Cl-
Cl-
Na+
Na+
Cl-
Cl-Na+
Cl-
ATP
HCO3-
3Na+
2K+Cl-
Cl-HCO3-
Tight junction
Ca2+
Ca2+ Me+Me+
Me+Me+
Me+
Me+
Handy et al., 2008.
Na+
Na+
Na+
Na+ Cl
Cl-
Cl-
Na+
Na+H+
CO2 CO2CA
ATPH+
ClHCO3
CO2CO2
CACa2+ Me+Me+
Me+
CH3-XCH3-XCH3-X
CH3-XCH3-X
Diffusion
Ecotoxicology, 17, 396–409
Na+
Na+Na+
Cl-
Ca2+
Ca2+
HS HS
HS
HS
Cl-HS
HSER/Golgi
vesicularTransport of NPs
Cl-
6 -18 mV
Na+ Ca2+ Mg2+
Mucous layer Donnan potential
1-3 mVTransepithelial potential
Dietary TiO :Dietary TiO2: Growth & Food
I k bIntake by Rainbow Trout
Ramsden et al (2009) Ecotoxicology 18:939-951Ecotoxicology, 18:939 951
No statistical differences between treatments (ANOVA, P > 0.05)
Dietary TiO2: Titanium Increases in Some Internal Organs But DynamicInternal Organs-But Dynamic.
Effect of Dietary Copper on Metabolic Rate of TroutC b ll t l (2002) CJFASCampbell et al. (2002) CJFAS
20
25
ol g
-1 h
-1)
15
umpt
ion
(um
o
5
10
Controlf oxy
gen
cons
u
0 200 400 600 800 1000 1200 1400 16000
ControlCopper
Rat
e of
Swimming Activity (bodylengths h-1)
Relationship Between Activity Level and Potential Mortalityand Potential Mortality
(after Priede 1977)
5
6
me
1.0
lity
%
S
3
4
age
tim 0.1
0.01 mor
talS
M
1
2
Perc
ent
0.001
oten
tial
0
0.02
0.08
0.14 0.
2
0.26
0.32
0.38
0.44 0.
5
0.56
0.62
0.68
0.74 0.
8
0.86
0.92
0.98
P
0.0001 Po
0 0 0 0 0 0 0 0 0 0 0 0 0 0
Metabolic rate relative to scope
Space and Time Effects in Ecosystems: Loss of p yBiological Clock in Trout After Dietary Copper.
Campbell et al. (2002) CJFAS
2500
Control
15
20
25
30
m s
tatis
tic (S
)
m (%
incr
ease
)
1500
2000
0
5
10
15
6 9 12 15 18 21 24 27 30 33 36 39
Period (hours)
Perio
dogr
am
Dis
tanc
e sw
am
0
500
1000
Copper
68
101214
m s
tatis
tic (S
)Time (hours)
0 6 12 18 24 30 36 42 480246
6 9 12 15 18 21 24 27 30 33 36 39
Period (hours)
Perio
dgra
m
Fate, Behaviour and Biological Effect At Ecosystem Level
• No where near enough data to make accurate models!
• Field & mesocosmexperiments (top down).M d l f• Model from component parts/organismsparts/organisms (bottom up).
http://www.hgtech.com/images/MISC/CYCLEHG.GIF
Gold NPs in E iEstuarine
MesocosmsMesocosmsFerry et al., 2009. Nature
Nanotechnology.
Abiotic Factors• Abiotic factors relating to particle behaviour.
H ff t i t f h ( ti )– pH effects on point of zero charge (aggregation)– Ionic strength and divalent ions (“water hardness”)– Dissolved organic matter ligand chemistry– Dissolved organic matter, ligand chemistry.
• Broader hydrological and climate issues– Flow dynamics of rivers, micro-environments with y ,
different chemistry that may “concentrate” NPs.– Topography of sea bed, river bed etc.– Micro-climates; tree canopy, high altitude sites vulnerable
to precipitation; extreme temperatures.– Relationships with particle energy and temporal changes inRelationships with particle energy and temporal changes in
particle chemistry, or size (dissolution/weathering).
TiO2 NP Aggregation in SalinesVevers & Jha (2008) Ecotoxicology (2008) 17:410–420
Cell in Mitosis
Cytoplasmic processes, filopodia
Particulate and organic matter from coastal runoffs
Formation of aerosol, i k t bi d d l
Atmospheric inputs
Concentration of NPs in the surface microlayer
Dilution and transport t Changes in temperature
risk to seabirds and mammals
Toxicity to embryos and plankton
to open ocean
AggregationCoastal
Changes in temperature, ionic strength and natural organic matter with depthToxicity to pelagic species
gg gsediments
Accumulation of NPs
Precipitation to ocean floor
Accumulation of NPsor aggregates at interfaces?
Toxicity to benthos
Mobilisation of NPs by microbes
Ocean floor
Conclusions on Knowledge GapsConclusions on Knowledge Gaps
• Need to employ all our experimental tools– Study real ecosystems, and mesocosm approaches– Data on the individual physical and biological components of
ecosystems are also needed (reductionist approach).– Real wild-type organisms of ecological importance from different
phyla- not just standard OECD/ISO method organisms.• Our knowledge of the effects of NPs on plants is particularly
weak compared to animal biology.• More work on terrestrial systems.• Dietary exposure and food chain studies are neededDietary exposure and food chain studies are needed.• Bioenergetics to link individuals with populations• Abiotic factors relating to particle aggregation chemistry are
h l idnot the only ones to consider.• Micro-climate, micro-environments, hydrology etc.
Environmental Monitoring: What Compartments and Receptors (Organisms) to Prioritise?and Receptors (Organisms) to Prioritise?
• Uncertainty because of the knowledge gaps.• Sediments/soil and sediment dwelling organisms a prioritySediments/soil and sediment dwelling organisms a priority.• Key stone species in food webs.• Standard ecotoxicity test organisms
– The consensus view is that we should continue to use these in Europe (e.g. Crane et al., 2008, Ecotoxicology, 17, 421-437)
• Whole effluent testing/Direct toxicity assessment approaches?• Rapid Screening tools
– Microtox, MARA, etc. Need comparing against higher tier organisms in the laboratory to validate their use with NPs.
– Chemical methods need developing e.g., particle reactivity assays etc.• The usual combination of chemical and biological monitoring
in a tiered approachin a tiered approach• Review and re-visit more frequently as data on novel effects
emerge.
Research Priorities• The knowledge gaps! But which one is the most important?• Soil and sediments.• Food chains; sediments through to man• Food chains; sediments through to man.• Measurement techniques for NPs in complex matrices such as
soil, natural water, tissues.• “Plan B” on measurement; antibody/bioassay approaches
(endocrine disrupters & VTG assay analogy). • Plants and terrestrial ecosystems as one of the big knowledge y g g
gaps; tree canopy effects (air) and soil contamination (root functions of plants).
• More fundamental research rather than applied science so we• More fundamental research rather than applied science, so we don’t make “wrong assumptions” in our thinking.– Toxic mechanisms on key biochemical pathways; photosynthesis,
respiration geochemical cycles (nitrogen water)respiration, geochemical cycles (nitrogen, water).– Control systems in organisms; endocrine, immune, nervous systems.
• NPs as “delivery vehicles” for other contaminants.
Any Questions?Any Questions?