洞庭湖平原土壤铅活动性影响因素研究

为了系统地探讨洞庭湖平原土壤铅(Pb)活动性特征及其影响因素,本次研究在常德市、益阳市、株洲市共采集了110件水稻根系土样品,讨论了土壤Pb活动态含量和活动系数与有机质、pH值、阳离子交换量(CEC)等土壤理化性质的相关性,并据此建立了Pb活动态含量和活动系数的预测模型。研究结果表明:土壤Pb含量、pH值、有机质含量、CEC和风化程度都是影响Pb活动态含量及活动系数的主要因素。pH值、CEC和有机质含量都会影响土壤缓冲能力,进而影响Pb的活动性。土壤Cd含量和Zn/Pb值也与Pb活动态含量有显著相关性;在不同的浓度梯度内,Cd与Pb的交互作用不同;土壤具有较高的Zn/Pb 值时,Pb活动态含量较低。采用逐步回归法建立了土壤Pb活动态含量以及活动系数的预测模型,土壤Pb活动态含量用土壤pH、Pb含量、CEC和Na₂O/K₂O值进行预测,活动态系数用pH、CEC、SiO₂/Al₂O₃值进行预测,预测效果均较好。

Factors Affecting Mobility of Lead in the Soils of the Dongting Lake Plain,China

In order to systematically explore the mobility characteristics of Pb in the soils of the Dongting lake plain and its influence factors, 110 soil samples had been collected in Changde, Yiyang and Zhuzhou city. This study discussed the relationships between mobility of Pb and organic matter, pH, cation exchange capacity (CEC) and other parameters in soils. Based on their correlations, we established prediction models for the mobility of Pb. The results showed that Pb content, pH, organic matter content, CEC and weathering degree were the main factors affecting the mobile fraction and coefficient of Pb. They affected the mobility of Pb by changing the buffer capacity of the soil. Soil Cd content and Zn/Pb ratio were also significantly correlated with the mobile fraction of Pb. The interactions between Cd and Pb were different in different concentration gradients. The mobile fraction of Pb was lower when the soil had a higher Zn/Pb ratio. The multivariate stepwise regression analysis was adopted to establish prediction models for mobile fraction and mobility coefficient of Pb. The presented models had achieved good predicting effectiveness,when mobile fraction of Pb in soils was predicted by soil pH, Pb content, CEC and Na₂O/K₂O ratio and mobility coefficient of Pb was predicted by pH, CEC, SiO₂/Al₂O₃ ratio.