The dynamics of arsenic in four paddy fields in the Bengal delta

• Published in: Environmental pollution (1987) 2011-04, Vol.159 (4), p.947-953
• Main Authors: Stroud, Jacqueline L., Norton, Gareth J., Islam, M. Rafiqul, Dasgupta, Tapash, White, Rodger P., Price, Adam H., Meharg, Andrew A., McGrath, Steve P., Zhao, Fang-Jie
• Format: Article
• Language: English
• Subjects: Agricultural Irrigation; Applied sciences; Arsenic; Arsenic - analysis; Arsenic - chemistry; Arsenic - metabolism; Arsenic speciation; Bangladesh; Concentration gradient; Exact sciences and technology; Fresh Water - analysis; Fresh Water - chemistry; Grains; Groundwater; India; Irrigation; Oryza - metabolism; Oryza sativa; Pollution; Rice; Soil (material); Soil Pollutants - analysis; Soil Pollutants - chemistry; Soil Pollutants - metabolism; Soil pore water; Speciation; Water Pollutants, Chemical - analysis; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - metabolism
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2010.12.016

Irrigation with arsenic contaminated groundwater in the Bengal Delta may lead to As accumulation in the soil and rice grain. The dynamics of As concentration and speciation in paddy fields during dry season (boro) rice cultivation were investigated at 4 sites in Bangladesh and West Bengal, India. Three sites which were irrigated with high As groundwater had elevated As concentrations in the soils, showing a significant gradient from the irrigation inlet across the field. Arsenic concentration and speciation in soil pore water varied temporally and spatially; higher As concentrations were associated with an increasing percentage of arsenite, indicating a reductive mobilization. Concentrations of As in rice grain varied by 2–7 fold within individual fields and were poorly related with the soil As concentration. A field site employing alternating flooded-dry irrigation produced the lowest range of grain As concentration, suggesting a lower soil As availability caused by periodic aerobic conditions. ► Irrigation with As-contaminated groundwater resulted in a gradient of As concentration in the soil. ► Arsenic concentration in paddy standing water decreased as arsenite was oxidised to arsenate. ► Soil pore water As increased with the %arsenite, suggesting reductive mobilisation. ► Alternative flooded-dry conditions led to lowest range of As concentration in rice grain. Spatial variations of arsenic concentrations in paddy soil and waters do not correlate to within-field variations of arsenic concentrations in rice grain.