嘉兴市区加油站周边土壤中重金属铅的分布特征及影响评价

Distribution Characteristic and Impact Assessment of Pb in the Soil Around the Gas Stations in Jiaxing City

在嘉兴市区11个加油站周边采集了表层土壤样品(0～20 cm),以硝酸-盐酸-氢氟酸构成三元酸系统,采用微波消解法预处理土壤样品,火焰原子吸收分光光度计法测定土壤中的铅含量,运用单因子污染评价法对该区域土壤重金属污染水平进行了评价.监测数据显示,嘉兴市区加油站周边表层土壤中铅的含量为20.5～40.6 mg/kg,平均值为31.6 mg/kg.以国家土壤环境质量标准一级标准作为评价标准时,土壤中铅污染指数变化范围为0.59～1.16,表明各加油站周边土壤中,只有少数点位显示轻度铅污染状况.本实验又对加油站周边土壤中重金属铅含量和土壤pH值、土壤有机质、周边车流量和建站年限等因素进行了关联分析.结果表明,周边车流量与土壤中铅含量相关性较高,相关系数为0.88,建站年限其次,相关系数为0.22,而与土壤的pH值、土壤有机质相关关系不明显.

Eleven typical soil samples around gas stations in Jiaxing city were selected and microwave extraction method with nitric acid,hydrochloric and acid-hydrofluoric acid digestion system was used to digest the soil samples.Atomic absorption spectrometry method was applied to determine lead content in the soil samples.Then method of single-factor pollution was adopted to evaluate lead contamination in the soil samples.The results show that the concentration of lead in the soil around the gas station in Jiaxing city ranges from 20.5 mg/kg to 40.6 mg/kg,the average concentration is 31.6 mg/kg.Taking the first class standard of national soil environmental quality standard as evaluation criteria,pollution index of Pb ranges from 0.59 to 1.16.All the conclusions reveal that the soil around the gas station is polluted at certain degrees.Afterwards,relationship between the Pb content in the soil and parameters of soil pH,SOM,number of the vehicle and years of the gas stations were analyzed in detail.Significant correlation between the Pb contents and vehicle number is discovered and the relationship coefficient is 0.88.Posterior relationship consists in the Pb contents and founded years of the gas stations,and the coefficient is 0.22.Whereas there are not any distinctive correlation consisted in Pb content and the other two parameters.