【摘要】 采用平衡批处理法,研究了3种有机酸及其两两混合液在序列pH值梯度下(pH3.0~7.0)对华南山地红壤Cd解吸行为的影响.结果表明,草酸与苹果酸不利于Cd的解吸,反而促进了吸附,其中草酸只是在较高浓度(20mmol.L-1)且土壤溶液pH>5.0时促进解吸.随着pH值升高,草酸、苹果酸以及不含有机酸的对照溶液对红壤中Cd的解吸率都快速下降.柠檬酸在pH<5.0时不利于Cd解吸;在pH>5.0时显著促进Cd解吸,但两种浓度柠檬酸解吸特征有所不同,在低浓度(2mmol.L-1)下对镉的解吸率呈降低-升高-降低变化,在高浓度(20mmol.L-1)下呈降低-升高变化.在低pH条件下(pH3.0、4.0),苹果酸最有利于Cd的解吸,但3种酸对Cd解吸率差别不大,在较高pH条件下(pH5.0~7.0),柠檬酸最有利于解吸,且解吸率大大高于草酸与苹果酸.有机酸混合没有明显的交互作用,对Cd的解吸率介于相应单独有机酸之间.更多还原

【Abstract】 Cadmium (Cd) pollution greatly threatens the environment of South China,where t he economy developed very fast during last 20 years. In this paper,batch experi ments were conducted to study the effects of three organic acids and their mixed solutions on the Cd desorption of red soil in this region. The results showed that oxalic acid and malic acid retarded the Cd desorption,but oxalic acid promoted it when the concentration was 20 mmol·L -1 and soil pH value was higher than 5.0. With the increase of soil pH,Cd desorption decreased rapidly in the presence of oxalic acid and malic acid. Citric acid retarded Cd desorption at pH<5.0,but promoted it at pH>5.0. When the concentration of citric acid was 2 mmol·L -1 and pH value changed from 3.0 to 7.0,Cd desorption declined first,increased then,and declined again. But,at the citric acid concentration of 20 mmol·L -1 ,Cd desorption declined first till pH 4.0,and increased then till pH 7.0. At low pH (3.0 and 4.0),malic acid desorbed most Cd; whi le at high pH (5.0～7.0),citric acid desorbed most Cd. The Cd desorption rate was much higher in the presence of citric acid than oxalic acid and malic acid. Organic acids did not interactive effect on Cd desorption. The Cd desorption rate by mixed acids was within the range of that by single acid alone.更多还原