• 关键词：青藏高原  道路交通活动  重金属  指数模型  CHAID决策树

• 基金项目：中国科学院“百人计划”项目；中组部青年千人计划（No.T12FR00010）

• 王冠星
• 北京交通大学城市交通复杂理论与技术教育部重点实验室, 北京 100044

• 闫学东
• 北京交通大学城市交通复杂理论与技术教育部重点实验室, 北京 100044

• 张凡
• 中国科学院青藏高原研究所, 北京 100101

• 曾辰
• 中国科学院青藏高原研究所, 北京 100101

• 高丹
• 北京交通大学城市交通复杂理论与技术教育部重点实验室, 北京 100044

• 摘要：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.

• Abstract：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.

• Key words：Qinghai-Tibet Plateau  traffic activities  heavy metal  exponential model  CHAID decidion tree

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