Comparison of Various Single Chemical Extraction Methods for Predicting the Bioavailability of Arsenic in Paddy Soils

The Codex Committee of Contaminants in Food (CCCF) has been discussing a new standard for arsenic (As)in rice since 2010 and a code of practice for the prevention and reduction of As contamination in rice since2013. Therefore, our current studies focus on setting a maximum level of As in rice and paddy soil byconsidering bioavailability in the remediation of As contaminated soils. This study aimed to select anappropriate single chemical extractant for evaluating the mobility of As in paddy soil and the bioavailability ofAs to rice. Nine different extractants, such as deionized water, 0.01 M Ca(NO3)2, 0.1 M HCl, 0.2 M C6H8O7,0.43 M HNO3, 0.43 M CH3COOH, 0.5 M KH2PO4, 1 M HCl, and 1 M NH4NO3 were used in this study. TotalAs content in soil was also determined after aqua regia digestion. The As extractability of the was in the orderof: Aqua regia > 1 M HCl > 0.5 M KH2PO4 > 0.43 M HNO3 > 0.2 M C6H8O7 > 0.1 M HCl > 0.43 M CH3COOH> deionized water > 1 M NH4NO3 > 0.01 M Ca(NO3)2. Correlation between soil extractants and As content inrice was in the order of : deionized water > 0.01 M Ca(NO3)2 > 0.43 M CH3COOH > 0.1 M HCl > 0.5 MKH2PO4 > 1 M NH4NO3 > 0.2 M C6H8O7 > 0.43 M HNO3 > 1M HCl > Aqua regia. BCF (bioconcentrationfactor) according to extractants was in the order of : 0.01M Ca(NO3)2 > 1 M NH4NO3 > deionized water > 0.43M CH3COOH > 0.1 M HCl > 0.43 M HNO3 > 0.2 M C6H8O7 > 0.5 M KH2PO4 > 1 M HCl > Aqua regia. Therefore, 0.01 M Ca(NO3)2 (r=0.78**) was proven to have the greatest potential for predicting Asbioavailability in soil with higher correlation between As in rice and the extractant. KCI Citation Count: 0