北方常见农作物根际土壤中铅、锌的形态转化及其植物有效性

采用盆栽试验结合形态分析技术研究了北方地区常见农作物对污染土壤中铅(Pb)、锌(Zn)的形态转化及其植物有效性的影响。土壤Pb、Zn形态分析结果显示,与非根际土壤相比,多数作物根际可交换态、碳酸盐结合态、有机质结合态Pb比例降低,而铁锰氧化物结合态、残渣态Pb则显著增加;Zn则表现为可交换态比例略呈降低趋势,碳酸盐结合态、铁锰氧化物结合态与有机质结合态升高,残渣态Zn则大幅下降。这提示,作物根际土壤Pb存在由松结合态向紧结合态转化的现象,从而植物有效性降低;而根际土壤Zn的形态变化则与Pb相反,即由紧结合态向松结合态转化,相应地提高了Zn的植物有效性。

Transformation and phytoavailability of lead and znic forms in rhizospheric soil of common crops in north of China

The fractionations of lead(Pb)and zinc(Zn)in the rhizospheric soil of common crops were studied by pot experiment and a sequential extraction.Comparing with control soil,exchangeable,bound to carbonate compounds and bound to organic matter Pb decreased slightly,but bound to Fe-Mn oxides and residual Pb increased significantly in rhizospheric soil.As for Zn,the exchange-able trended down,the residual strongly decreased,but bound to carbonate compounds,bound to organic matter and bound to Fe-Mn oxides all increased.These results revealed that the phenomena that Pb in rhizospheric soil of crops transform from loose-bound to tight-bound forms existed so that it reduced zinc phytoavailability.Contrary to Pb,the transformation from tight-bound to loose-bound forms accordingly increased the zinc phytoavailability.