有机酸对Pb、Cd的土壤化学行为和植株效应的影响

有机酸对Pb、Cd的络合作用将其对土壤吸附Pb、Cd的影响和植株效应差异的研究表明,柠檬酸、草酸与Pb、Cd络合能力的大小与重金属本身的性质有关,络合作用影响土壤对Pb、Cd的吸附量,柠檬酸降低土壤对Pb、Cd的吸附,草酸则增加土壤对Pb、Cd的吸附.水培试验表明,柠檬酸可减轻Pb对小麦、水稻幼苗的毒害.柠檬酸对Cd的植株外观毒性效应影响不显著,但能促使植株茎叶、根中Cd含量下降.Pb和Cd复合处理条件下,Cd存在促使水稻植株对Pb吸收量增加,Pb存在抑制水稻植株对Cd的吸收.

Effect of organic acids on soil chemical behavior of lead and cadmium and their toxicity to plants

The interaction between organic acids(citric and oxalic acids)and heavy metals was examined in this paper.Equilibrium dialysis showed that the extent organic acids bound metals depended on the metal involved,and their binding pro- perties affected the adserption of Pb and Cd by soil,which was increased in the presence of oxalic acid,and decreased in the presence of citric acid.The effect of citric acid on the behavior and toxicity of Pb and Cd to plants was also studied.The presence of citric acid could reduce the toxicity of Pb,and inhibit the uptake of Cd in shoots and roots.However,there was no significant effect on the apparent toxicity of Cd.The interaction between Pb and Cd was found to be complicated.The Pb content in rice was higher in the presence of Cd,while the content of Cd is lower in the presence of Pb.