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Ground water, the main source of drinking and irrigation water, is contaminated by naturally occurring arsenic (As) in 61 out of 64 districts of Bangladesh. A study was conducted to assess the quality and impact of As contaminated irrigation water on agricultural soils and crops uptake and to know the spatial variability of As in soil, water and rice. More than hundred shallow tube wells (STW) were selected in Tala thana of Satkhira district in southwestern Bangladesh during boro (winter rice) season, 2002. As content in water, soil and plant parts were determined by hydride generation-atomic absorption spectrophotometer (HG-AAS). The mean value of As in the irrigation water samples was 150 µg/l. Water As content was moderately correlated with electrical conductivity (EC), P, K, Mg, Na and Mn content in water. The mean soil As content was 19.3 mg/kg. The As build up in the soils was influenced by water-As, P, Na, Ca, Mg and Fe and soil organic carbon, clay, exchangeable K, Ca and Mg contents. The mean As concentration in rice grain was 0.328 mg/kg, which was much below the maximum permissible limit (1 mg/kg). The contents of As in straw were several folds higher than in grain and increased with increasing As contents in water and soil. Contents of organic carbon, exchangeable Mg and silt in soil and Fe in water significantly influenced the uptake of As by rice. A well-developed pattern of spatial variability in As content in irrigation water, soil and rice grain was observed in the studied area resulting from differences in soil and land type.

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0503|AL-Wheat Program