有机酸无机离子对土壤镉铅解吸特性的影响

Effect of organic acid and inorganic ion on desorption character of cadmium and lead

为深入了解草甸棕壤中镉、铅的解吸行为,采用一次平衡法探讨有机酸、无机离子对镉、铅解吸特性的影响。结果表明,柠檬酸、草酸、组氨酸摩尔浓度较低时,有机配位体抑制镉的释放,而有机酸摩尔浓度较高时(>2 mmol·L-1)将明显促进镉的释放。柠檬酸、草酸、组氨酸对Pb的解吸率随有机酸摩尔浓度提高(0-20 mmol·L-1)而增大,对Cd、Pb浸提能力的大小关系为:柠檬酸﹥草酸﹥组氨酸。随解吸液中无机离子(C1-、SO42-、F-)摩尔浓度的增大,镉、铅的解吸率亦随之提高。无机离子对解吸土壤中Cd的影响力顺序是:C1->SO42->F-;对解吸土壤中Pb的影响力顺序是:SO42->C1->F-。

In order to understand the desorption behavior of Cd and Pb in meadow brown soil,a batch experiment was conducted to investigate the effect of organic acid and inorganic ion on the desorption characteristics of Cd and Pb.Results showed that when the concentration of organic acids（citric acid,oxalic acid and histidine） in desorption solution was relatively low,the presence of organic ligands inhibited Cd desorption.When organic acids’ concentration was higher（greater than 2 mmol/L）,the presence of organic acids obviously accelerated Cd desorption.Pb desorption rate in three organic acids solutions（citric acid,oxalic acid and histidine） increased with the concentration increase of organic acids（0-20 mmol.L-1）.The desorption capacities for Cd and Pb were ranked as follows： citric acid oxalic acid histidine.With the concentration increase of inorganic ions（C1-、SO42-、F-）,the desorption rate of Cd and Pb also increased.The influences of inorganic ions on Cd were ranked as follows： C1- SO42- F-.The influences of inorganic ions on Pb were ranked as follows： SO42- C1- F-.