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Comparative effectiveness of five solutions for extracting arsenic from soils irrigated with arsenic contaminated ground water

Islam, A.; Miah, M.A.M.; Riffat Shaheen; Mahmud, R.; Inoue, N.

International Journal of Sustainable Agricultural Technology 2(1): 61-66

2006


Accession: 015316668

A laboratory study with eight soil samples differing in soil type, physical and chemical properties, collected from Narayanganj and Satkhira district of Bangladesh was conducted to: (a) compare the effectiveness of five extracting solutions in relation to extract arsenic (As) from those soils; (b) compare the amounts of As liberated by the five extractants with that released by a hot HNO3+HClO4+H2SO4 digestion method to determine "total" As; and (c) observe the impact of As contaminated irrigation water on the soils of paddy field. Arsenic was determined by a Perkin-Elmer Aanalyst100 atomic absorption spectrometer equipped with a FIAS-100 flow injection hydride generation system. Irrigation with high-As contaminated groundwater resulted in significantly elevated total As content in soils (14.1-48.76 mg As/kg soil). Deionized distilled water and 0.01M CaCl2 solution generally extracted very negligible portion of As from the soils and did not exceed 0.2 ppm for any soils. The percentage of total As extracted by these two extractants was less than 0.4. The acidified oxalate extractant found most effective in extracting As from soils and extracted 81% of the total soil As. This result revealed that most of the soil As was Fe-associated. Arsenic extracted by this extractant in Satkhira soils was 20% higher than those extracted from Narayanganj soils. Except 0.5M NaHCO3, As extracted by all other extractants was strongly correlated with total soil As. Total soil As was strongly correlated with irrigation water As (r=0.811). The relative effectiveness of the extractants in removing As from soils was in the order of acidified oxalate>0.1M NaH2PO4>0.5M NaHCO3>0.01M CaCl2~deionized distilled water.

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