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由于含甲基砷的农药残留或土壤中微生物的砷甲基化作用,除了无机砷,水稻籽粒中也可以检测到相当含量的不同形态的甲基砷.通过水培试验研究了不同形态砷在水稻幼苗中的吸收、转运、转化和外排.结果表明,水稻中各形态砷的含量排序为:亚砷酸盐(As(Ⅲ))>单甲基砷盐(MMA(Ⅴ))>砷酸盐(As(Ⅴ))>二甲基砷盐(DMA(Ⅴ)),但从地下部向地上部的转运系数排序为:DMA(Ⅴ)>As(Ⅲ)>As(Ⅴ)>MMA(Ⅴ).实验中未发现水稻体内无机砷向甲基砷的转化,甲基砷向无机砷的转化比例也较低,但观察到MMA(Ⅴ)部分被还原为MMA(Ⅲ).相比其地上部和地下部的吸收量,DMA(Ⅴ)在水稻中通过木质部(向上)和韧皮部(向下)的转运比例在4种形态砷中最高.甲基砷(MMA(Ⅴ)和DMA(Ⅴ))通过根系外排的速率和比例明显的高于无机砷(As(Ⅲ)和As(Ⅴ)).实验结果表明,不同形态砷的累积与其在水稻体内的吸收、运移及砷的根系外排密切相关.
Due to the arsenic methylation of pesticides containing methyl arsenic or microorganisms in soils, in addition to inorganic arsenic, a considerable amount of different forms of methyl arsenic can also be detected in rice grains. The results showed that the contents of arsenic in rice were as follows: arsenite (As (Ⅲ))> monomethyl arsenate (MMA (Ⅴ))> arsenic (Ⅴ)> As (Ⅴ)> As (Ⅴ)> As (Ⅴ)> As (Ⅴ)> As (Ⅴ)> As (Ⅴ)> As (Ⅴ) No conversion of inorganic arsenic to methyl arsenic in rice was found in the experiment, and the ratio of conversion of methyl arsenic to inorganic arsenic was also lower, but MMA (V) was observed to be reduced to MMA (Ⅲ) The uptake rates of above and below ground, DMA (Ⅴ) were the highest in four kinds of arsenic in rice through the xylem (upward) and phloem (downward) Ⅴ)) was significantly higher than that of inorganic arsenic (As (Ⅲ) and As (Ⅴ)). The results showed that the accumulation of different forms of arsenic and its absorption, transport and arsenic root Closely related efflux.