| Popis: |
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 since 2013. Therefore, our current studies focus on setting a maximum level of As in rice and paddy soil by considering bioavailability in the remediation of As contaminated soils. This study aimed to select an appropriate single chemical extractant for evaluating the mobility of As in paddy soil and the bioavailability of As to rice. Nine different extractants, such as deionized water, 0.01 M Ca(NO₃)₂, 0.1 M HCl, 0.2 M C 6 H 8 O 7 , 0.43 M HNO₃, 0.43 M CH₃COOH, 0.5 M KH₂PO₄, 1 M HCl, and 1 M NH₄NO₃ were used in this study. Total As content in soil was also determined after aqua regia digestion. The As extractability of the was in the order of: Aqua regia > 1 M HCl > 0.5 M KH₂PO₄ > 0.43 M HNO₃ > 0.2 M C 6 H 8 O 7 > 0.1 M HCl > 0.43 M CH₃COOH> deionized water > 1 M NH₄ NO₃ > 0.01 M Ca(NO₃)₂. Correlation between soil extractants and As content in rice was in the order of : deionized water > 0.01 M Ca(NO₃)₂ > 0.43 M CH₃COOH > 0.1 M HCl > 0.5 M KH₂PO₄ > 1 M NH₄NO₃ > 0.2 M C 6 H 8 O 7 > 0.43 M HNO₃ > 1M HCl > Aqua regia. BCF (bioconcentration factor) according to extractants was in the order of : 0.01M Ca(NO₃)₂ > 1 M NH₄NO₃ > deionized water > 0.43 M CH₃COOH > 0.1 M HCl > 0.43 M HNO₃ > 0.2 M C 6 H 8 O 7 > 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 As bioavailability in soil with higher correlation between As in rice and the extractant. |
