长株潭地区土壤Cd和Pb固液分配特征与环境风险

区域尺度上土壤重金属下渗迁移的环境风险存在较大空间变异性.以长株潭城市及其周边土壤为对象，研究了不同土地利用类型，土壤Cd和Pb有效态含量和固液分配系数(K_d)的分布特征及其影响因素，并基于CaCl₂(固液比为1∶0.5)测定的K_d揭示了研究区土壤重金属下渗迁移的环境风险.结果表明，研究区土壤Cd和Pb有效态含量大小呈现出：自然林地>郊区农田>城市绿地>工业区绿地.土壤Cd的K_d均值为449.79 L·kg^-1,Pb的K_d均值为27 604.07 L·kg^-1,说明土壤Cd迁移性显著高于Pb.林地土壤重金属的K_d显著低于其它3种土地利用类型土壤.土壤Cd和Pb的K_d主要受土壤pH和重金属总量的影响.在此基础上，引入CaCl₂(固液比为1∶10)测定的重金属有效态含量作为因变量，构建的多元回归模型可以较好地预测土壤Cd和Pb的K_d,...

Solid-solution Partitioning Coefficients and Environmental Risk of Cd and Pb in Soil in Chang-Zhu-Tan Area

The leaching risk of heavy metals in soil has a large spatial variability on a regional scale. Taking the Chang-Zhu-Tan area as the research object, this work studied the distribution and influencing factors of available contents and solid-solution partition coefficient (K_d) of Cd and Pb in soil with land uses and clarified the environmental risk of heavy metals in soil based on K_d values measured by CaCl₂ (soil-to-water ratio, 1:0.5). The results showed that the contents of available Cd and Pb in soil followed the order of forest land>suburban farmland>urban green space>industrial green space. The average K_d of Cd in soil was 449.79 L·kg^-1, and that of Pb was 27604.07 L·kg^-1, indicating that the mobility of Cd in the soil was significantly higher than that of Pb. The K_d values of forest soil were significantly lower than that in the other land uses. The K_d values were mainly affected by soil pH and the total content of heavy metals in soil. Adopting the available content of heavy metals measured by CaCl₂ (soil-to-water ratio, 1:10) as a dependent variable, the multiple regressions effectively predicted the K_d values of Cd and Pb in soil, with R² values of 84.2% and 67.6%, respectively. The environmental risk assessment indicated that the leaching risk in 93.8%-96.1% of the sampling sites could be ignored, whereas a few sampling sites near factories with low pH may pose a risk to the groundwater environment. The mobility of heavy metals in soil and the distribution of pollution sources determined the leaching risk of heavy metals. The results provide a method and theoretical support for preventing the environmental risk of heavy metals in soil on a regional scale.