National Institute for Agro-Environmental Sciences, Kannondai 3-1-3, Tsukuba, Ibaraki, 305-8604, Japan.
Environ Sci Technol. 2009 Dec 15;43(24):9361-7. doi: 10.1021/es9022738.
Rice consumption is a major source of cadmium and arsenic for the population of Asia. We investigated the effects of water management in rice paddy on levels of cadmium and arsenic in Japanese rice grains. Flooding increased arsenic concentrations in rice grains, whereas aerobic treatment increased the concentration of cadmium. Flooding for 3 weeks before and after heading was most effective in reducing grain cadmium concentrations, but this treatment increased the arsenic concentration considerably, whereas aerobic treatment during the same period was effective in reducing arsenic concentrations but increased the cadmium concentration markedly. Flooding treatment after heading was found to be more effective than flooding treatment before heading in reducing rice grain cadmium without a concomitant increase in total arsenic levels, although it increased inorganic arsenic levels. Concentrations of dimethylarsinic acid (DMA) in grain were very low under aerobic conditions but increased under flooded conditions. DMA accounted for 3-52% of the total arsenic concentration in grain grown in soil with a lower arsenic concentration and 10-80% in soil with a higher arsenic concentration. A possible explanation for the accumulation of DMA in rice grains is that DMA translocates from shoots/roots to the grains more readily than does inorganic arsenic.
稻米是亚洲人群摄入镉和砷的主要来源。我们研究了稻田水分管理对日本稻米中镉和砷含量的影响。淹水会增加稻米中砷的浓度，而有氧处理则会增加镉的浓度。在抽穗前后 3 周进行淹水处理，可最有效地降低稻谷中镉的浓度，但这种处理会大大增加砷的浓度，而同期的有氧处理则能有效降低砷的浓度，但会显著增加镉的浓度。结果发现，抽穗后进行淹水处理比抽穗前进行淹水处理更能有效降低稻米中镉的含量，而不会导致总砷含量的增加，尽管它会增加无机砷的含量。在有氧条件下，二甲基砷酸（DMA）在谷物中的浓度非常低，但在淹水条件下会增加。在砷浓度较低的土壤中，DMA 占谷物中总砷浓度的 3-52%，在砷浓度较高的土壤中，DMA 占 10-80%。DMA 在稻米中的积累可能是因为 DMA 比无机砷更容易从茎叶/根系转运到谷物中。
