paudyn et al cold regions 53(1) 102-114

8/10/2019 Paudyn Et Al Cold Regions 53(1) 102-114

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Remediation of hydrocarbon contaminated soils in the

Canadian Arctic by landfarming

Krysta Paudyn a, Allison Rutterb ,, R. Kerry Rowe a, John S. Poland b

aGeoEngineering Centre at Queen's-RMC, Department of Civil Engineering, Queen's University, Kingston, Ontario, Canada K7L 3N6

b School of Environmental Studies, Queen's University, Kingston, Ontario, Canada K7L 3N6

Received 8 December 2006; accepted 24 July 2007

Abstract

One of the preferred methods for the remediation of fuel contaminated soil today is landfarming. This is particularly true for

remote sites because the method requires minimal equipment and is therefore by far the lowest cost option. The term landfarming

generally refers to the process whereby hydrocarbon contaminated soils are spread out in a layer about half a meter thick, nutrients

are added, and periodically the soils may be mixed. During landfarming, hydrocarbons can be lost through volatilization or

bioremediation and thus landfarming refers to the combination of the two processes.

In the challenging Arctic climate, the performance of landfarming studies has been variable and the relative contribution of the

two processes has not been studied. This paper describes the successful remediation of diesel-contaminated soils at the former

military base at Resolution Island, Nunavut. The site is 130 km from the nearest community and this isolation together with very

inclement weather and average summer temperatures of 3 C presents significant challenges for remediation. Trial landfarm plotswere established in 2003 to compare four sets of conditions; daily aeration, aeration every 4 days, addition of fertilizer with aeration

every 4 days and a control plot. The field trial has clearly demonstrated enhanced bioremediation when fertilizer was added and

also significant hydrocarbon losses due to aeration by rototilling. The rate of bioremediation was similar to the rate of volatilization

in the field trial. In addition to the landfarms established on site, extensive complementary laboratory experiments have been

carried out. Bioremediation was demonstrated at 5 C in the laboratory reactors and isoprenoid markers indicated increased

bioremediation with increased temperatures. In the reactor experiments, rate constants for volatilization and bioremediation

increased with temperature.

2007 Elsevier B.V. All rights reserved.

Keywords:Landfarming; Hydrocarbon; Remediation; Arctic; Bioremediation; Volatilization

1. Introduction

The term landfarming refers to the process where

hydrocarbon contaminated soils are spread out in a layer

of 0.31.0 m thick, nutrients are added and the soils are

mixed periodically. During the process of landfarming,

the total petroleum hydrocarbons, (TPH), may be lost

through volatilization or biodegradation. Landfarming

refers to the combination of the two processes. Treatment

regimes for landfarms vary with climate, location, tem-

perature and soil type. Enhanced bioremediation of con-

taminated soil typically involves the addition of nutrients

and water, and periodic tilling to mix and aerate the soil

(McCarthy et al., 2004). Additional amendments (e.g.,

Available online at www.sciencedirect.com

Cold Regions Science and Technology 53 (2008) 102 114www.elsevier.com/locate/coldregions

Corresponding author. Tel.: +1 613 533 2642; fax: +1 613 533

2897.

E-mail address:[email protected](A. Rutter).

0165-232X/$ - see front matter 2007 Elsevier B.V. All rights reserved.doi:10.1016/j.coldregions.2007.07.006
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bulking agents to increase aeration (Straube et al., 2003),

co-substrates to stimulate microbial metabolism

(Mphekgo and Cloete, 2004) or bacterial inoculations

(Straube et al., 2003) are sometimes added to speed the

remediation process. Landfarming has proven consis-

tently successful in warmer southern climates, (Mc-Carthy et al., 2004). For instance, in the 12-month

operational period of an Australian landfarm TPH levels

were remediated from 4644 ppm to less than 100 ppm

(Line et al., 1996).

In colder Antarctic and Arctic climates, trials involv-

ing landfarming or bioremediation have been conducted

with mixed results (Delille, 2000; Seklemova et al.,

2001; Aisablie et al., 2004; McCarthy et al., 2004).

Research has shown the presence of organisms adapted

to cold conditions at sites where hydrocarbon contam-

ination is present in these cold climate soils (Mohn andStewart, 2000). Hydrocarbon degrading extremophiles

are thus ideal candidates for the biological treatment of

polluted extreme habitats such as the Canadian Arctic,

(Rike et al., 2003; Mohn and Stewart, 2000). A wide

variety of microorganisms have been detected in the

active layer in Arctic soils in northern Canada and

Alaska (Deming, 2002). These cold habitats possess

sufficient indigenous microorganisms forin situ biore-

mediation, (Whyte et al., 1999; Ferguson et al., 2003).

They adapt rapidly to hydrocarbon contamination in the

soil, as demonstrated by significantly increased numbers

of oil degraders shortly after a pollution event (Atlas,1995). An increased number of the hydrocarbon degrad-

ing bacteria in response to oil spills has been reported by

bothWhyte et al. (1999) and Rike et al. (2001)illustrat-

ing that growth and proliferation of hydrocarbon

degrading bacteria have taken place under site-specific

conditions. Over the past several years, a number of

studies in both Arctic and Antarctic regions have shown

that microorganisms naturally occurring in harsh envi-

ronments are capable of degrading petroleum hydro-

carbons (McCarthy et al., 2004; Mphekgo and Cloete,

2004; Ferguson et al., 2003; Kerry, 1993).Landfarming has been used in cooler locations such

as alpine environments (Margesin and Schinner, 2001)

and Alaska (Reynolds et al., 1998) where summer tem-

peratures are much higher than those of the central and

eastern Canadian Arctic. Rates of biodegradation and

volatilization have been shown to be slower at low

temperatures (Snape et al., 2005), however the relative

rates and therefore their contributions to landfarming in

Arctic climates are still relatively unknown. The per-

centage of remediation attributable to aeration in various

field studies varies (Reimer et al., 2003; Chatham, 2003;

Ausma et al., 2002). In order to study the bioremediation

of hydrocarbons ratios of n-alkanes to pristine and

phytane can be used for good effect (Atlas, 1995;

Ferguson et al., 2003). There are many landfarms estab-

lished in cold climates, however, there is a paucity of

well documented field trials. This work describes a field

study specifically designed to assess the relative con-tributions of bioremediation and volatilization using

aerated and fertilized regimes. The trial landfarm ex-

periment was established at Resolution Island in the

summer of 2003 in order to determine the viability of the

landfarming technology for remediation of TPH con-

taminated soils at the site. Resolution Island is located at

the southeastern tip of Baffin Island approximately

310 km southeast of Iqaluit, Nunavut. The site is

accessible for fieldwork for approximately 3 months a

year and during that time often suffers from inclement

weather; including heavy fog and rainstorms. The aver-age temperature during the summer months is 3 C.

Resolution Island was the site of one of the military

bases that formed the Polevault Line. The site has been

the site of a major cleanup operation as it was highly

contaminated with polychlorinated biphenyls, (PCBs),

metals and petroleum hydrocarbons (Poland et al.,

2001).

Ex situstudies of landfarming have focused on nut-

rients (Ferguson et al., 2003; Braddock et al., 1997),

bioaugmentation (Mohn and Stewart, 2000; Van Veen

et al., 1997), cold adapted organisms (Kunihiro et al.,

2005; Mikan et al., 2002), oxygen depletion (Zytneret al., 2001) and water content (Ferguson et al., 2003).

Many studies attempt to assess the viability of biore-

mediation using radiolabelled linear hydrocarbons

(Mohn and Stewart, 2000; Braddock et al., 1997) but

the extrapolation to field studies is often difficult

(Zytner et al., 2001). In this study, laboratory reactors

were designed to model the trial landfarm established at

Resolution Island and to investigate the effect of

temperature on volatilization and bioremediation.

There are many hydrocarbon contaminated sites which

require remediation in the Arctic and there is currentlyno criterion available to determine if landfarming will be

viable at a given site. This study outlines the

experimental design and initial laboratory experiments

that are intended to establish these criteria and field

protocols.

2. Methodology

2.1. Trial landfarm

Three truckloads (30 m3) of TPH contaminated soil

were excavated from two diesel-contaminated areas on

103K. Paudyn et al. / Cold Regions Science and Technology 53 (2008) 102114


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site. The soil was displaced to an area that had been

previously leveled to a slope less than 5%. Heavy

equipment was used to homogenize the soil cache and

evenly distribute the material to each of the four plots.

Each plot measured 5 m by 5 m with a depth of

0.3 m. Maintenance and operation of the triallandfarm included subjecting each plot to a different

regime (Fig. 1). One plot was established as the

control plot and had no action other than sampling.

Aeration was achieved by rototilling. Two plots were

rototilled only; one every day and the other every

fourth day. The final plot was rototilled every 4 days

and, in addition, fertilizer was added to this plot. Thus

the four plots were maintained as follows: control

plot; daily aeration; aeration every 4 days; fertilizer

added with aeration every 4 days. As a result of

operational experiences during the first season, in thesecond season, the regime of aeration frequency

considered only fair days; fair days were defined as

days when it was not raining, snowing or excessively

foggy.

The fertilizer was added on day 16. Nitrogen and

phosphorus were added to the landfarm plots in the form

of granular agricultural fertilizers. Urea, containing 46%

nitrogen was the primary source for nitrogen while phos-

phorus was added as diammonium phosphate, (DAP),

which contained 20.1% phosphorus and 18.0% nitrogen

by weight. Nutrient additions were based on applying a

C:N:P ratio of 100:7.5:0.5. No additional fertilizer wasadded to any of the trial landfarm plots after the initial

application on day 16.

The soil at Resolution Island can be characterized as

follows. It is largely composed of sand and gravel par-

ticles with only 10% of particles finer than 75 M. Thesoil has no plasticity, the soil pH is 5.8 and the organic

content is 1.1%.

2.2. Laboratory reactor design

The reactor design is presented inFig. 2. The body ofthe individual reactors was constructed with polyvinyl

chloride (PVC) sewer pipe cut into 0.36 m lengths. The

length of the tube was chosen to accommodate approxi-

mately 1.2 kg of soil such that the soil level was below

the mid-point air inlet of the reactor. The landfarm

aeration process was simulated by inverting the reactor

Fig. 1. The trial landfarm at Resolution Island Nunavut. Maintenance regime as indicated in photograph.

104 K. Paudyn et al. / Cold Regions Science and Technology 53 (2008) 102114


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tube. At the reactor base a cap was glued in place while

at the top of the reactor tube a removable cap was press

fitted and sealed with electrical tape. Air was passed

through the reactors at mid-height through a 0.016-m

brass fitting which was screwed into the tapped sewer

pipe and sealed with Teflon tape. For the air outtake, a0.016-m brass fitting, was 0.08 m higher than the inlet

and at an angle of 120 to it. A ball valve was glued into

position beside the outtake tube of each reactor to allow

water to be added to the system. This arrangement

allowed the inversion of the tube without soil entering

the air passages. A 2.5-m long, 0.102-m diameter high

density polyethylene (HDPE) tube was used as an air

pressure containment vessel between the air source and

the individual reactors. This tube was affixed to the

laboratory compressed air line. Holes were drilled and

tapped into the tubing to support 24 pressure regulatorvalves that were then each attached to a reactor allowing

regulation of air flow through each reactor. The air

entering the manifold from the line was controlled to the

temperature of the room by passing source air through

10 m of coiled copper pressure tubing. In addition,

source air was passed through a 0.15-m long charcoal

filter (0.03 m diameter), which ensured that hydrocar-

bon contamination from the source line was eliminated.

Volatilized hydrocarbon was captured at the air outlet of

each reactor with a granulated activated coconut char-

coal (GAC) trap. Each trap was 0.20 m long with an

internal diameter of 0.015 m and filled with approxi-

mately 20 g of 1240 mesh granulated activated coco-

nut charcoal.

2.3. Reactor system

The individual reactors were designed to reflect thephysical conditions that contaminated soil was subject

to in a field landfarm. Depth, tillage (inversion of the

individual reactors), temperature, windspeed, moisture

content were each considered in the reactor design and

protocol. By monitoring both volatilized and residual

hydrocarbon, it was possible to attribute loss of TPH to

either bioremediation or aeration using a mass balance

approach.

Each reactor was filled with 1.2 kg of diesel-con-

taminated soil from Resolution Island. Air was passed

through each of the closed vessels and volatilized TPHfrom the soil was collected on charcoal tubes at the

reactor air outlet. The charcoal filters were replaced and

analyzed for TPH periodically and the soil in each

reactor was also analyzed periodically. Moisture content

was carefully monitored and maintained in the range

of 1015% by the periodic addition of water. Flow

rate through each reactor was monitored daily and kept at

1 L/min. Reactor systems, each comprising 24 reactors,

were set up in three temperature controlled rooms

maintained at 5 C, 8 C and 18 C.

Two sets of reactor experiments are reported on here.

In the first experimental set, at each temperature, reactors

Fig. 2. Design of the laboratory reactors used for the ex situwork.



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significance difference between plots on day one of the

trial but all other samplings showed a significant differ-

ence between the plots (pb0.05 on day 16,pb0.005 all

other sampling days). At the end of the first season (day

31) all three treatment plots were significantly different

(t-test, p b0.05) than the control plot and the TPH con-

centration in the fertilizer added, aerated every 4 days

treatment plot was significantly lower than the other two

treatment plots (t-test,pb0.05). At the end of the second

season the same trend continued and it was clear that the

rate of remediation was as follows: control plotbaeratedevery 4 daysbaerated dailyb fertilized and aerated every

4 days (t-test, pb0.05). By the end of the third season

there were no significant differences between the three

treatment plots but all three treatment plots were still

significantly different than the control plot (t-test, pb

0.05). Initial TPH levels for all plots were 2800 ppm and

final concentration in the fertilizer added plot was below

200 ppm. Significant variations were noted for TPH

concentrations in each plot for a given season and the

average relative standard deviations for the data points in

Fig. 3 was 28%. Weathered TPH contaminated soil is

difficult to homogenize which contributes to the problem

of obtaining consistent data under both field and labo-

ratory conditions. Lower results were obtained when

sampling occurred on wet days where the landfarm was

Fig. 4. C17/Pr Ratios for the trial landfarm over the three seasons.

Fertilizer was added on day 16. Five samples were taken from eachplot and averaged. Error bars are one standard deviation.

Fig. 3. Concentrations of TPH in soil for the trial landfarm over the three seasons. Five samples were taken from each plot and averaged. Error bars are

one standard deviation.



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waterlogged and the sample water content was 15%

or greater. This is consistent with reports by Fine et al.

(1997)that sorption of hydrocarbons to soils is reduced

as water content increases. Despite large variations

the results show a clear trend. The fertilized plot shows

a striking decrease in TPH levels by over 90%. Thedaily aerated plot and the aerated every 4 days shows

losses in excess of 80%. These data are consistent

with successful landfarm results reported byChatham

(2003) and Reynolds et al. (1998). The control plot

TPH levels were reduced (t-test,pb0.05) but remained

above 1000 ppm after 3 seasons. Rate constants for the

loss of TPH based on first order reactions are discussed

below.

Pristane (Pr), (C19H40) and phytane (Ph), (C20H42)

are two isoprenoid alkanes present in diesel fuel. Also

present in diesel fuel are straight chain isomers C17H36(C17) and C18H38 (C18) of similar boiling points to

pristane and phytane respectively. The branched nature

of the pristine and phytane compounds makes them

relatively resistant to biodegradation when compared to

the linear counterparts (Atlas, 1995). The nature of the

compounds yields similar rates of volatilization, and

therefore major volatilization will result in no net change

in the isomeric ratios. A measurable change in the iso-

meric ratios is an indication that bioremediation is oc-

curring in the affected soil (Snape et al., 2005; Kerry,

1993).

The C17/Pr ratios were calculated using the chroma-

tograms of extracted soil samples from the plots to

determine if significant bioremediation was occurring.

For the 3 plots with no fertilizer added, (Fig. 4)theC17/Prratios did not change significantly indicating that no

measurable bioremediation was occurring. Moreover,

for the plot that had fertilizer applied, the C17/Pr ratios

were dramatically reduced indicating significant biore-

mediation had occurred. Similar results were found for

the C18/Ph ratios although there were small but signi-

ficant decreases (t-test, pb0.05). for the non-fertilized

plots. Overall the data therefore demonstrates that biore-

mediation is viable at the site but shows that aeration can

also achieve very significant reductions in TPH. The

addition of fertilizer is low maintenance and economi-cally enticing when comparing this option to daily

tilling. The fertilized plot was rototilled every 4 days but

it is not clear how necessary this soil aeration step was in

assisting the bioremediation; oxygen is necessary for

bioremediation of TPH to occur. Zytner et al. (2001)

found evidence of oxygen depletion after 30 days.

Laboratory experiments described below were set up to

address this issue and facilitate the development of an

optimal landfarm operation protocol in cold climates.

Fig. 5. Concentrations of TPH in soil in the laboratory reactors at 5 and 18 for control, aerated daily, aerated every 4 days and aerated every 4 days andfertilized. Six reactors were used for each regime at each temperature.



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3.2. Laboratory reactors

The reactor sets indicated that by aerating every

4 days and fertilizing, the TPH contaminated soil could

be remediated at all 3 temperatures. The TPH levels

generally decreased with time, with the control samples,which were not rotated, showing the least decrease of

the four regimes. In the first set, after approximately

5 months, 78% of the TPH had been remediated from

the soil at 18 C in the fertilized reactors. The TPH in the

soil at 8 C and 5 C was remediated 36% and 51%

respectively. For both reactor sets, the decrease in TPH

was significantly better (pb0.05) at 18 C as compared

to 5 C, indicating, as would be expected, improved

remediation with increased temperature. The remedia-

tion at these lower temperatures is important because it

demonstrates that this regime is applicable to sites withcolder temperatures than Resolution Island. Cold tempe-

rature hydrocarbon degraders have been isolated (Rike

et al., 2001) and remediation at 2 and 5 C has been

demonstrated by Zytner et al. (2001). The fertilized

reactors exhibited the largest decrease in TPH con-

centration over the course of the experiment for all

temperatures.

Fig. 5illustrates the differences between the 5 C and

18 C reactor sets from the first set of reactors. The

fertilized aerated every 4 days reactor systems were

significantly different than the control reactor systems

(t-test, pb0.05) by day 42 at 5 C and by day 54 at18 C. The average relative standard deviation of the

data points in Fig. 5 is 19%. At 18 C, the results are

similar to the landfarm with the fertilized and rotated

every 4 days reactor systems being significantly dif-

ferent (t-test,pb0.05) than the non-fertilized and rotated

every 4 days reactor on sampling days 42, 52, 138 and

169. At 5 C the difference is less clear with aerationalone as effective as fertilizer added and aerated every

4 days for most of the trial; there is no significantly

difference (pb0.05) until days 127 and 169 at 5 C. The

C17/Pr ratios presented inFig. 6indicate that there was a

C17/Pr isoprenoid ratio decrease in only the reactors to

which nutrients were added. The decrease in the ratio

increases with temperature (Fig. 6). The C17/Pr ratios

indicate that bioremediation is delayed and slower at

5 C. Results of the second reactor set showed little

difference between the 4- and 12-day rotation schedule.

However in the field, daily aeration did result in an

increased rate of volatilization. For the fertilized set offour reactors that were not rotated but had fertilizer

added, bioremediation was evident. This result holds

promise for in situbioremediation.

Analysis of the charcoal tubes enabled the amount of

TPH lost through aeration alone to be quantified. Data

for the first set of experiments is presented inTables 1

and 2.Table 1indicates the total TPH volatilized from

the reactors while inTable 2the mass of TPH volatilized

as a function of time at 18 C is given. As one would

Table 1

Total mass of TPH collected on charcoal traps (mg) over duration of

the experiment (169 days)

Reactor type Code Total mass of TPH collected on

charcoal traps (mg)

18 C 8 C 5 CControl CP 1200 460 390

Everyday A-1D 2580 1420 1510

Every 4 days A-4D 2270 1180 1210

Fertilizer F-4D 1960 1100 1160

Experimental code: CP = control plot; A = aeration alone while F =

fertilizer added; -xD = rotation every x days.

Fig. 6. C17/Pr ratios in the laboratory reactors at three temperature from

the first reactor set. Six reactors were used for each regime at eachtemperature.

Table 2Mass of TPH collected during experiment per day (mg/day) at 18 C

Reactor code Mass of TPH collected during experiment per day

(mg/day)

Days from start of experiment

130

days

3151

days

5277

days

78126

days

127169

days

CP 9 6 4 10 5

A-1D 24 17 16 16 8

A-4D 22 11 11 14 9

F-4D 21 12 11 10 5

Experimental code: CP = control plot; A = aeration alone while F =fertilizer added; -xD = rotation every x days.



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expect, the amount of TPH volatilized increased with

temperature (Ausma et al., 2002). In addition, the mass

volatilized increased with the frequency of rotating the

reactors. Thus, for the six control samples averaged in

the first line ofTable 1, the amount of TPH aerated for

the three temperatures of 18 C, 8 C, and 5 C was

1200, 460 and 390 mg respectively. For the 18 C

reactor sets, the amount of TPH volatilized was 1200 mg

for the control samples, 2270 mg and 1960 mg for thetwo sets rotated every 4 days and 2580 mg for the set

rotated every day (Table 1). These results indicate that

volatilization of TPH increases with a regime that in-

cludes aeration. Similar trends are seen at all tempera-

tures in the second set of reactors. The mass of TPH

volatilized decreased with time (Table 2). This is to be

expected as the mass of TPH remaining in the soil

decreases with time as it is removed from the system.

The charcoal tubes enabled the calculation of a mass

balance for the reactor systems. In each experiment, no

net loss or gain of TPH should be evident unlessbioremediation is occurring.Fig. 7indicates the net loss

of TPH in the second set of reactors. Both sets show that

TPH was removed from the soil in the fertilized reactors

by both volatilization and bioremediation while all other

reactors only exhibit loss through volatilization. These

experiments indicate that both mechanisms were

occurring in the fertilized regimes even at temperatures

as low as 5 C. These laboratory results support the

results obtained in the field study at Resolution Island. It

should be pointed out that there is large imprecision for

TPH concentrations in soil analysis (approximately 30%

variation) due to the heterogeneity of the soil. This is

further extenuated when calculating for a mass balance

and is indicated in a large coefficient of variation for

each system (Fig. 7).

3.3. Rate constants

In previous studies, the TPH degradation has been

modeled using first order rate constants in both

unfertilized and fertilized soil systems (Demque et al.,1997; Zytner et al., 2001). For this system, the rate of

loss of TPH is proportional to its concentration.

d TPH

dt kTPH

where [TPH] is the concentration of TPH and t is the

time. Integration of above equation yields

ln TPH t kt ln TPH 0 and TPH t TPH 0ekt

where [TPH]t is the TPH concentration at time t and

[TPH]0is the initial concentration of TPH in the system.

The first order rate constant,k, is the slope of the line for

a plot of the natural log of [TPH] with respect to time.

The fit of the line to the average TPH data can be

described by ther2 value, where a value of 1.0 indicates

a perfect fit. The fit of the line gives an indication of the

fraction of the variance in the slope of the line. A

fraction of variance (r2) of less than 0.90 may be due to

the large error, associated with the average TPH in soil

values (20%) used to calculate the first order rate

constants. The nature of the Arctic climate, especially

Fig. 7. Net loss of TPH in the second reactor set, {TPH initial (soil)TPH final (soil)1169 TPH (charcoal)}mg=TPHnet. Error bars represent thecoefficient of variation for each regime.



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the extreme temperatures in the winter season, has led to

the assumption that biodegradation exhibits a hiatus

during the winter season when the soil is frozen (Rike

et al., 2001). However other models (Huesemann and

Truex, 1996) and some studies (Zimov et al., 1996;Oechel et al., 1997; Jones et al., 1999) have shown that

bioremediation sometimes occurs in the winter months

but with significantly reduced microbial activity and in

no lower than 5 C temperatures (Cline and Schimel,

1995).

Rate constants have been calculated for the experi-

mental landfarm and the laboratory reactors (Tables 3

and 4). For the landfarm, it was assumed that reme-

diation did not occur in the winter months (Table 3).

This is not unreasonable since soil temperatures as low

as 40 C can be expected from mid-September to late

June (Schimela et al., 2004). Therefore, the time scalewas adjusted to exclude the winter months, when the

landfarm was unmanaged, from the rate calculation. For

the summer field season, the average soil temperature

was 9.3 C. Rate constants from this experiment agree

with those from previous studies (Zytner et al., 2001).

Data for the second laboratory set are presented in

Table 4; similar results were obtained for reactor set 1.The rate constants have been calculated in two ways

from the rate of loss of hydrocarbon to the charcoal

traps, k(GAC) (volatilization only) or from the TPH

concentration data, k(TPH), (volatilization and biore-

mediation). Rate constants for bioremediation, k(BIO),

were obtained by subtraction of the TPH derived rate

constant aeration rate from the nutrient added equivalent

treatment.

An examination of the rate constants with respect to

the mechanism of aeration indicates that the data can

generally be described by first order kinetics. In thereactor experiments, rate constants increase with tempe-

rature and with the frequency of aeration. The k(GAC)

data yields a high fraction of variance with frequent

aeration (r2N0.94 in 90% of cases). Without rototilling

the rate of volatilization is likely dependent on rate of

diffusion of TPH in soil. The field control plot yields a

rate constant of 0.007 day1. This predominantly repre-

sents loss due to aeration and any losses due to erosion.

For the daily aeration field plot the calculated rate con-

stant is 0.017 day1 while the 4-day rototilling regime

yields a value of 0.015 day1. Thus, not unexpectedly,

the daily aeration regime resulted in a greater loss ofTPH due to volatilization. The C17/Pr ratios for both

Table 4

First order rate constants for TPH remediation for reactor set 2

Temperature Code Rotation frequency k(GAC) r2 k(TPH) r2 k(BIO)

C day day1 day1 day1

5 CP 0 0.001 0.89 0.002 0.58

5 F-0D 0 0.001 0.87 0.006 0.65 0.004

5 A-4D 4 0.002 0.98 0.002 0.95

5 F-4D 4 0.002 0.92 0.009 0.67 0.007

5 A-12D 12 0.001 0.94 0.003 0.50 5 F-12D 12 0.001 0.87 0.009 0.68 0.009

8 CP 0 0.001 0.90 0.002 0.40

8 F-0D 0 0.007 0.81 0.007 0.85 0.005

8 A-4D 4 0.002 0.97 0.005 0.95

8 F-4D 4 0.002 0.89 0.012 0.83 0.008

8 A-12D 12 0.001 0.81 0.005 0.78

8 F-12D 12 0.001 0.84 0.012 0.94 0.007

18 CP 0 0.002 0.98 0.003 0.83

18 F-0D 0 0.001 0.88 0.012 0.70 0.009

18 A-4D 4 0.003 0.97 0.006 0.92

18 F-4D 4 0.003 0.96 0.016 0.95 0.010

18 A-12D 12 0.003 0.94 0.005 0.79

18 F-12D 12 0.002 0.85 0.016 0.67 0.011

Experimental code: CP = control plot; A = aeration alone while F = fertilizer added; -xD = turning of laboratory reactors every x days.

Table 3

Rate constants calculated for the on site landfarm at Resolution Island

Temperature Code Rototilling frequency k(TPH) r2 k(BIO)

C day day1 day1

9 CP 0 0.007 0.58

9 A-1D 1 0.017 0.80

9 A-4D 4 0.015 0.94

9 F-4D 4 0.026 0.83 0.011

Experimental code: CP = control plot; A = aeration alone while F =

fertilizer added; -xD = rototilling every x days.



11/13


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in soil in cold climates by landfarming with various

summer soil temperature conditions as well as contain-

ment strategies.

Acknowledgements

Department of Indian Affairs and Northern De-

velopment (DIAND) and the Northern Scientific Train-

ing Program (NSTP), (Indian and Northern Affairs

Canada).

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