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Use of isotope dilution method to predict bioavailability of organic pollutants in historically contaminated sediments.

Jia F, Bao LJ, Crago J, Schlenk D, Gan J - Environ. Sci. Technol. (2014)

Bottom Line: At the steady state, the accessible fraction (E) derived by the isotope dilution method (IDM) ranged from 0.28 to 0.89 and was substantially smaller than 1 for most compounds, indicating reduced availability of the extensively aged residues.A strong linear relationship (R2=0.86) was found between E and the sum of rapid (Fr) and slow (Fs) desorption fractions determined by sequential Tenax desorption.This novel method is expected to be especially useful for historically contaminated sediments or soils, for which contaminant bioavailability may have changed significantly due to aging and other sequestration processes.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Sciences, University of California , Riverside, California 92521, United States.

ABSTRACT
Many cases of severe environmental contamination arise from historical episodes, where recalcitrant contaminants have resided in the environment for a prolonged time, leading to potentially decreased bioavailability. Use of bioavailable concentrations over bulk chemical levels improves risk assessment and may play a critical role in determining the need for remediation or assessing the effectiveness of risk mitigation operations. In this study, we applied the principle of isotope dilution to quantify bioaccessibility of legacy contaminants DDT and PCBs in marine sediments from a Superfund site. After addition of 13C or deuterated analogues to a sediment sample, the isotope dilution reached a steady state within 24 h of mixing. At the steady state, the accessible fraction (E) derived by the isotope dilution method (IDM) ranged from 0.28 to 0.89 and was substantially smaller than 1 for most compounds, indicating reduced availability of the extensively aged residues. A strong linear relationship (R2=0.86) was found between E and the sum of rapid (Fr) and slow (Fs) desorption fractions determined by sequential Tenax desorption. The IDM-derived accessible concentration (Ce) was further shown to correlate closely with tissue residue in the marine benthic polychaete Neanthes arenaceodentata exposed in the same sediments. As shown in this study, the IDM approach involves only a few simple steps and may be readily adopted in laboratories equipped with mass spectrometers. This novel method is expected to be especially useful for historically contaminated sediments or soils, for which contaminant bioavailability may have changed significantly due to aging and other sequestration processes.

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Linear correlation between the accessibility(E) given by the isotope dilution method and thesum of rapid and slowdesorption fractions (Fr + Fs) derived by Tenax desorption (slope =1.12 ± 0.13, R2 = 0.86, p < 0.0001).
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fig2: Linear correlation between the accessibility(E) given by the isotope dilution method and thesum of rapid and slowdesorption fractions (Fr + Fs) derived by Tenax desorption (slope =1.12 ± 0.13, R2 = 0.86, p < 0.0001).

Mentions: A goodlinear relationship (R2 = 0.86, p < 0.01) was observed between the E values and the sum of Fr and Fs (Figure 2). The linearslope (1.12 ± 0.13) was close to 1, implying that the accessibilitypredicted by IDM was close to the sum of Fr and Fs estimated from desorption kineticsand likely a better indicator for bioavailability than Fr. The concentrations of PCB 153 in the PV8C and PV6Csediments were relatively low (26.3 and 11.4 μg/kg), resultingin a large variance in the estimated Fr, Fs, and Fvs values for this PCB congener. For example, Fr, Fs and Fvs of PCB 153 in the PV6C sediment were 0.10 ± 0.33, 0.38± 3.42, and 0.52 ± 3.74, respectively. If the data pointsfor PCB 153 were excluded from the correlation, the linear relationshipfurther improved substantially (R2 = 0.93, p < 0.01).


Use of isotope dilution method to predict bioavailability of organic pollutants in historically contaminated sediments.

Jia F, Bao LJ, Crago J, Schlenk D, Gan J - Environ. Sci. Technol. (2014)

Linear correlation between the accessibility(E) given by the isotope dilution method and thesum of rapid and slowdesorption fractions (Fr + Fs) derived by Tenax desorption (slope =1.12 ± 0.13, R2 = 0.86, p < 0.0001).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4215882&req=5

fig2: Linear correlation between the accessibility(E) given by the isotope dilution method and thesum of rapid and slowdesorption fractions (Fr + Fs) derived by Tenax desorption (slope =1.12 ± 0.13, R2 = 0.86, p < 0.0001).
Mentions: A goodlinear relationship (R2 = 0.86, p < 0.01) was observed between the E values and the sum of Fr and Fs (Figure 2). The linearslope (1.12 ± 0.13) was close to 1, implying that the accessibilitypredicted by IDM was close to the sum of Fr and Fs estimated from desorption kineticsand likely a better indicator for bioavailability than Fr. The concentrations of PCB 153 in the PV8C and PV6Csediments were relatively low (26.3 and 11.4 μg/kg), resultingin a large variance in the estimated Fr, Fs, and Fvs values for this PCB congener. For example, Fr, Fs and Fvs of PCB 153 in the PV6C sediment were 0.10 ± 0.33, 0.38± 3.42, and 0.52 ± 3.74, respectively. If the data pointsfor PCB 153 were excluded from the correlation, the linear relationshipfurther improved substantially (R2 = 0.93, p < 0.01).

Bottom Line: At the steady state, the accessible fraction (E) derived by the isotope dilution method (IDM) ranged from 0.28 to 0.89 and was substantially smaller than 1 for most compounds, indicating reduced availability of the extensively aged residues.A strong linear relationship (R2=0.86) was found between E and the sum of rapid (Fr) and slow (Fs) desorption fractions determined by sequential Tenax desorption.This novel method is expected to be especially useful for historically contaminated sediments or soils, for which contaminant bioavailability may have changed significantly due to aging and other sequestration processes.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Sciences, University of California , Riverside, California 92521, United States.

ABSTRACT
Many cases of severe environmental contamination arise from historical episodes, where recalcitrant contaminants have resided in the environment for a prolonged time, leading to potentially decreased bioavailability. Use of bioavailable concentrations over bulk chemical levels improves risk assessment and may play a critical role in determining the need for remediation or assessing the effectiveness of risk mitigation operations. In this study, we applied the principle of isotope dilution to quantify bioaccessibility of legacy contaminants DDT and PCBs in marine sediments from a Superfund site. After addition of 13C or deuterated analogues to a sediment sample, the isotope dilution reached a steady state within 24 h of mixing. At the steady state, the accessible fraction (E) derived by the isotope dilution method (IDM) ranged from 0.28 to 0.89 and was substantially smaller than 1 for most compounds, indicating reduced availability of the extensively aged residues. A strong linear relationship (R2=0.86) was found between E and the sum of rapid (Fr) and slow (Fs) desorption fractions determined by sequential Tenax desorption. The IDM-derived accessible concentration (Ce) was further shown to correlate closely with tissue residue in the marine benthic polychaete Neanthes arenaceodentata exposed in the same sediments. As shown in this study, the IDM approach involves only a few simple steps and may be readily adopted in laboratories equipped with mass spectrometers. This novel method is expected to be especially useful for historically contaminated sediments or soils, for which contaminant bioavailability may have changed significantly due to aging and other sequestration processes.

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