Arsenic Accumulation in Rice Grains: Effects of Cultivars and Water Management Practices

Abstract

Arsenic (As) accumulation in rice grains is a threat to human health and marketability of rice products. In an effort to minimize As uptake by rice grains, field experiments were conducted to investigate As accumulation in rice grains of three cultivars in monosodium methanearsonate-treated soil under saturated and flooded water management practices. Results indicated that As concentrations in rice grains were cultivar-dependent and influenced by water management. Soil flooding would substantially enhance the As accumulation with a great variation among cultivars. Extractable As in the soil was positively correlated with sodium dithionite-sodium citrate-sodium bicarbonate solution-extractable Fe, suggesting a strong association of As with ferric (hydr)oxide. Additional laboratory studies showed a strong affinity of synthetic ferric (hydr)oxide with monosodium methanearsonate. This study demonstrated that selection of less As-responsive rice cultivars and use of saturated water management in paddy fields could be an effective means to minimize As accumulation in rice grains.