水稻不同生育期土壤砷形态分布特征及其生物有效性研究

采用田间原位试验和Tessier连续提取方法,在水稻（Oryza sativa L.）不同生育期研究了重金属复合污染高、中、低3个水平下的土壤砷的形态分布特征及其生物有效性。结果表明：在水稻不同生育期中,土壤各种形态的砷质量分数均表现为高污染水平土壤〉中等污染水平土壤〉低污染水平土壤;土壤中砷在水稻整个生育期均以残留态为主,占90%以上,交换态砷所占比例最低,不到0.5%;不同形态砷之间大都显著正相关,但是两种有效性较高的砷形态（交换态和碳酸盐结合态）与有机态砷之间的相关性较差;土壤砷的生物有效性表现为高污染水平土壤〉中等污染水平土壤〉低污染水平土壤,且随着水稻生育期的延长,土壤砷的生物有效性逐渐升高。

Fractionation,distribution and bioavailability of arsenic in soils polluted by combined heavy metals at different growth stages of rice

Fractionation,distribution and bioavailability of arsenic（As） in soils polluted by the three levels（low,moderate and high） of combined heavy metals（As,Cd and Pb） were studied in situ through Tessier sequential extraction method at the different growth stages of rice（Oryza sativa L.）.The concentrations of all As fractions and the bioavailability of As in the soils followed the order：high moderate low level pollution at all growth stages of rice.The main fraction of As in different polluted soils was residual form,accounting for more than 90% of total As,and the exchangeable As accounted for less than 0.5% and was the least fraction.There were significantly positive correlations between the most of As fractions,but the exchangeable and carbonate-bound As were poorly correlated with organic As.The bioavailability of As increased with the elongation of rice growth periods.