Publication: Assessment of lead availability in contaminated soil using isotope dilution techniques
Issued Date
2005-09-15
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ISSN
00489697
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2-s2.0-24644509350
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Mahidol University
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SCOPUS
Bibliographic Citation
Science of the Total Environment. Vol.348, No.1-3 (2005), 244-256
Suggested Citation
N. Tongtavee, J. Shiowatana, Ronald G. McLaren, Colin W. Gray Assessment of lead availability in contaminated soil using isotope dilution techniques. Science of the Total Environment. Vol.348, No.1-3 (2005), 244-256. doi:10.1016/j.scitotenv.2004.12.066 Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/16515
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Title
Assessment of lead availability in contaminated soil using isotope dilution techniques
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Abstract
Isotope dilution methods using a stable isotope tracer (207Pb) were developed for the determination of Pb availability in contaminated soils. The methods included determination of E values (isotopically exchangeable pool), L values (plant labile pool) and isotopic exchange kinetics (IEK). Isotopically exchangeable Pb was monitored at different exchange times based on measurement of the207Pb/208Pb ratio in soil solution following addition of the tracer. The rate of decrease in the207Pb/208Pb ratio in solution could be described by using the same IEK equation as used previously with radioisotope tracers. The amounts of isotopically exchangeable Pb in Pb-contaminated soils estimated from long-term IEK parameters were in good agreement with directly determined E values up to 15 days. However, values of some of the fitted IEK parameters cast doubts on the validity of using the IEK approach with207Pb, most probably as a result of irreversible fixation of some of the spike by reactive surfaces in the soils. Estimation of isotopically exchangeable Pb using short-term kinetics data was unsuccessful, substantially underestimating E values. Results for the control (uncontaminated) soil were highly variable, most probably as a result of fixation of tracer by the soil and poor analytical precision due to low solution Pb concentrations. A compartmental analysis of the variation in E values with time indicates a good potential for estimating bioavailable Pb in contaminated soils. The amounts of available Pb obtained from summation of the E1minand E1 min-24 hpools (E(available)), accounting for an average of 57.62% of total soil Pb, were significantly correlated with both the L values and with Pb extracted from soil with EDTA. © 2005 Elsevier B.V. All rights reserved.