低分子有机酸对石灰性土壤中Pb、Cd的淋洗效应

摘要

采用振荡淋洗方法研究柠檬酸、苹果酸、酒石酸3种常见低分子有机酸对污染石灰土壤中Pb、Cd的淋洗净化效应.结果表明,与对照(CK)相比,随着3种有机酸添加浓度的增加,均可显著增加土壤中Cd的解吸量(P<0.05);而苹果酸、酒石酸在各添加浓度下均能不同程度抑制土壤中Pb的解吸,柠檬酸在较低添加浓度下抑制,而在较高浓度下(>10.0 mmol/L)又能促进Pb的解吸.Pb、Cd的解吸率曲线表明,同一有机酸对土壤中不同重金属(Cd、Pb)的解吸规律(促进解吸、抑制解吸)存在明显差异,不同有机酸对土壤中同一重金属(Cd或Pb)的解吸量也存在明显差异.Pb的解吸分配系数(Kd)呈钟形分布,而Cd的Kd则随有机酸浓度的增加呈减小趋势.%The effects of citric acid, malic acid and tartaric acid on leaching of Pb,Cd in contaminated soil were researched by oscillating methods. The results showed that compared with the control,desorption amount of Cd significantly increased with the addition of citric acid,malic acid and tartaric acid(P<0.05). Malic acid and tartaric acid inhibited the desorption of Pb in different degree. Citric acid in low concentration inhibited but promoted in high concentration(>10.0 mmol/L) the desorption of Pb. The desorption rate curve indicated that the effect of the same or different organic acid on different heavy metal or the same heavy metal(promotion and inhibition) varied obviously. The desorption distribution coefficient of Pb(Kd) presented bell-shaped distribution,but the Kdof Cd decreased with organic acid increasing.