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Fractionation of arsenic in soil by a continuous-flow sequential extraction method
J Shiowatana1, R G McLaren, N Chanmekha
1Dep. of Chemistry, Mahidol Univ., Bangkok, Thailand. scysw@mahidol.ac.th
Journal of Environmental Quality
|January 16, 2002
Summary
A new continuous-flow method simplifies soil arsenic (As) fractionation, offering faster, more reliable results than traditional batch techniques. This advancement aids in understanding arsenic
Area of Science:
- Environmental Chemistry
- Soil Science
- Analytical Chemistry
Background:
- Traditional batch sequential extraction methods for soil metals are time-consuming and prone to errors.
- Accurate fractionation of soil arsenic (As) is crucial for environmental risk assessment.
Purpose of the Study:
- To develop and validate a continuous-flow sequential extraction method for soil As.
- To compare the new method's efficiency and accuracy with conventional batch techniques.
- To assess the method's applicability in real-world contaminated soil samples.
Main Methods:
- Development of a continuous-flow system for sequential extraction using water, NaHCO3, NaOH, and HCl.
- Digestion of the residue with HNO3 and HF acids.
- Analysis of As using graphite furnace atomic absorption spectrometry (GFAAS).
Main Results:
- The continuous-flow method demonstrated simplicity, rapidity, and reduced risk of contamination.
- Good recoveries of total soil As (97-115%) were achieved.
- Fractionation data were comparable to conventional batch techniques, with useful extractograms generated for As, Al, Fe, and Ca.
Conclusions:
- The continuous-flow sequential extraction method is a viable, efficient alternative to traditional batch methods for soil As fractionation.
- The method provides detailed extractograms that support understanding of As associations in different soil fractions.
- Applicability was demonstrated using soils from mining and cattle dip sites in Thailand and Australia.