青藏高原路侧土壤重金属含量分布规律及影响因素研究

以青藏高原G214、S308和G109国(省)道的部分路段为研究对象,采集了这3个路段不同位置处距路侧不同距离的100个表层土壤样品,利用电感耦合等离子体质谱仪(ICP-MS)测定了各样品中重金属元素Cu、Zn、Cd、Pb的含量.同时,用非线性回归法拟合了Cu、Zn、Cd、Pb元素含量随距路侧距离变化的曲线,并用CHAID决策树分析法分析了影响路侧土壤Cu、Zn、Cd、Pb元素含量的主导因素.结果表明:3个研究路段路侧土壤重金属平均含量均超过土壤背景值,已产生一定的富集;Cu、Zn、Cd、Pb 4种重金属元素含量随距路侧距离的增加均呈指数型下降趋势;影响研究路段重金属含量的主导因素因不同的元素各异,影响Cu、Zn、Pb、Cd含量的主导因素分别为海拔、土壤类型、车流量和路侧距离.

Influencing factors of heavy metal concentration in roadside-soil of Qinghai-Tibet Plateau

This study collected a total of 100 topsoil samples from different locations with different roadside distances in three highway sections G214, S308 and G109 in Qinghai-Tibet Plateau. The heavy metals including Cu, Zn, Cd, and Pb concentrations were measured by the Inductively Coupled Plasma Mass Spectrometry(ICP-MS). The relationship between heavy metal concentrations and roadside distance were fitted by using a nonlinear regression approach. The most important influencing factors on the heavy metal concentrations were examined using the CHAID decision tree analysis approach. The results showed that the mean concentrations of the four metals in the roadside soils exceed their corresponding background value, suggesting that there have been some accumulation of the for heavy metals in the roadside soil. The four metals concentrations exponentially decline with the increase of roadside distance, and the most important influencing factors on the concentrations vary with different metals. More specifically, Cu, Zn, Cd, and Pb are primarily influenced by the altitude, soil type, traffic volume and roadside distance, respectively.