新疆石河子城区道路尘土的铅污染和铅同位素示踪研究

城市道路尘土中重金属污染已成为当前重大的环境问题之一.本文对我国西部石河子市城区道路尘土的重金属污染进行评价,利用电感耦合等离子体质谱法测定铅的含量及铅同位素组成,采用地积累指数法评价铅的污染程度.结果显示,石河子市城区道路尘土中重金属铅的含量范围为19.36 ～ 84.63 mg/kg,平均含量为37.85 mg/kg,高于当地土壤背景值,但明显低于我国其他大中型城市,表明当前石河子市的环境质量已经受到人为活动的干扰；尘土中铅的地积累指数在-0.59～1.54之间,平均值为0.30,属于轻度污染水平.利用铅同位素示踪法识别铅污染的来源,206pb/207Pb比值的范围是1.159 ～ 1.182,208 pb/207 Pb比值的范围是2.391 ～2.457,均接近于煤炭和建筑材料的铅同位素比值,初步判断石河子道路尘土的铅污染主要受到煤炭燃烧和城市建设的影响.

Lead Pollution and Isotopic Signature of the Dusts around Urban Roads in Shihezi City, Xinjiang Province

Heavy metal pollution on urban roads is an important problem for the city environment. Lead pollution characteristics in the dusts around urban roads has been studied and assessed in Shihezi, west China. Pb concentrations and Pb isotopic compositions in dusts were measured using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The Geoaccumulation Index was applied to the assessment of the degree of Pb pollution. The results show that the range of lead concentrations in the dusts is 19.36-84.63 mg/kg (mean concentration: 37.85 mg/kg), which is higher than the local soil background value and lower than values in other big cities in China. The results indicate that a considerable Pb contamination in the Shihezi city environment was significantly affected by anthropogenic activities. The range of the Geoaccumulation Index is-0.59-1.54 (average value is 0.30), indicating that Pb is at the lightly to moderately polluted' level. The Pb isotope ratios in dusts (²⁰⁶Pb/²⁰⁷Pb: 1.159-1.182 and ²⁰⁸Pb/²⁰⁷Pb: 2.391-2.457) were similar to those in coal combustion and building materials.