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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 lipid content-normalizedtissueresidues of DDXs (log Cb, μg/kg-lipid)in N. arenaceodentata and the organic carbon-normalizedaccessible HOC concentrations (log Ce,μg/kg-OC) in both the PV8C (solid circle) and PV6C sediments(open circle).
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fig3: Linear correlation between the lipid content-normalizedtissueresidues of DDXs (log Cb, μg/kg-lipid)in N. arenaceodentata and the organic carbon-normalizedaccessible HOC concentrations (log Ce,μg/kg-OC) in both the PV8C (solid circle) and PV6C sediments(open circle).

Mentions: The performance of IDM was furtherevaluated by comparing the measured Ce of HOCs with 4 d accumulation of HOCs intothe marine polychaete N. arenaceodentata. A previousstudy showed that the uptake of HOCs by the polychaete reached a steadystate after 4 d of exposure.42 After 4d of exposure, tissue residue (Cb) ofHOCs was analyzed and expressed on both dry weight (dw) and lipidweight (lw) bases. Owing to the relatively low levels of PCBs in thesediment, only DDEs and DDDs were reliably detected in the tissuesamples. For example, Cb of DDEs was 1595.0± 326.8 μg/kg (dw) for the PV6C sediment exposure and 3282.0± 192.9 μg/kg (dw) for the PV8C sediment. The values forDDDs were 42.1 ± 11.7 and 161.2 ± 20.6 μg/kg (dw),respectively. Strong linear relationships were found between Ce (μg/kg) normalized by OC content and Cb (μg/kg) normalized by lipid contentfor DDEs and DDDs in the PV8C (R2 = 0.84) and PV6C (R2 = 0.94) sediments (Figure 3). The slopes for the linear relationships were 1.88 ±0.57 and 1.20 ± 0.22 for PV8C and PV6C sediments, respectively.Although more studies may be required to test other HOCs or organisms,the accessible concentration Ce derivedby IDM was clearly predictive of the bioaccessibility of DDT derivativesin the historically contaminated marine sediments to the benthic polychaete N. arenaceodentata.


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 lipid content-normalizedtissueresidues of DDXs (log Cb, μg/kg-lipid)in N. arenaceodentata and the organic carbon-normalizedaccessible HOC concentrations (log Ce,μg/kg-OC) in both the PV8C (solid circle) and PV6C sediments(open circle).
© Copyright Policy
Related In: Results  -  Collection

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

fig3: Linear correlation between the lipid content-normalizedtissueresidues of DDXs (log Cb, μg/kg-lipid)in N. arenaceodentata and the organic carbon-normalizedaccessible HOC concentrations (log Ce,μg/kg-OC) in both the PV8C (solid circle) and PV6C sediments(open circle).
Mentions: The performance of IDM was furtherevaluated by comparing the measured Ce of HOCs with 4 d accumulation of HOCs intothe marine polychaete N. arenaceodentata. A previousstudy showed that the uptake of HOCs by the polychaete reached a steadystate after 4 d of exposure.42 After 4d of exposure, tissue residue (Cb) ofHOCs was analyzed and expressed on both dry weight (dw) and lipidweight (lw) bases. Owing to the relatively low levels of PCBs in thesediment, only DDEs and DDDs were reliably detected in the tissuesamples. For example, Cb of DDEs was 1595.0± 326.8 μg/kg (dw) for the PV6C sediment exposure and 3282.0± 192.9 μg/kg (dw) for the PV8C sediment. The values forDDDs were 42.1 ± 11.7 and 161.2 ± 20.6 μg/kg (dw),respectively. Strong linear relationships were found between Ce (μg/kg) normalized by OC content and Cb (μg/kg) normalized by lipid contentfor DDEs and DDDs in the PV8C (R2 = 0.84) and PV6C (R2 = 0.94) sediments (Figure 3). The slopes for the linear relationships were 1.88 ±0.57 and 1.20 ± 0.22 for PV8C and PV6C sediments, respectively.Although more studies may be required to test other HOCs or organisms,the accessible concentration Ce derivedby IDM was clearly predictive of the bioaccessibility of DDT derivativesin the historically contaminated marine sediments to the benthic polychaete N. arenaceodentata.

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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