Evaluation of different extractants to estimate bioavailable arsenic in soil Article Swipe
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· 2022
· Open Access
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· DOI: https://doi.org/10.21203/rs.3.rs-2046165/v1
· OA: W4297890193
Owing to the similar chemistry of phosphorus (P) and arsenic (As), sodium bicarbonate (0.5 N NaHCO 3 ) is commonly used to extract plant accessible As in soil. However, 0.5 N NaHCO 3 is not compatible with the ICP-MS measurement due to the large amount of dissolved solids. This investigation set out to devise a suitable extractant for determining extractable As in soil and measured by the ICP-MS. Paired soil and plant samples were collected from paddy fields in West Bengal, India. Soil was extracted with 0.5 M NaHCO 3 , 0.03 M (0.1 N) and 0.17 M (0.5 N) phosphoric acid (H 3 PO 4 ), 0.05 M (0.1 N) and 0.25 M (0.5 N) sulfuric acid (H 2 SO 4 ), and 0.01 M calcium chloride (CaCl 2 ). This made it possible to measure As by hydride generation-atomic absorption spectrophotometer (HG-AAS), while ICP-MS was used for the determination of As extracted from soil with different concentrations (0.1-1.5 M ) of HNO 3 . The NaHCO 3 extractable As was 1.45 and 1.23 mg kg − 1 for soil to extractant ratio of 1:20 and 1:5, respectively. Of these extractants, 1.5 N HNO 3 extractable As had the best correlation with As content in rice grain (r = 0.45**) and straw (r = 0.71**), comparable with standard extractant i.e. 0.5 N NaHCO 3 (r = 0.47** and r = 0.64** in case of grain and straw, respectively). A significant positive relationship of 1.5 N HNO 3 was obtained with 0.5 N NaHCO 3 . Thus, 1.5 N HNO 3 may serve as an extractant for soil As, which is compatible with ICP-MS analysis.
