长江三角洲河网地区典型城镇街尘中多环芳烃的污染特征

街尘是一种重要的环境介质,其携带的污染物在城镇化过程中对河网地区的水环境构成了一定的威胁.为初步探讨长江三角洲河网地区典型街尘中多环芳烃(PAHs)的污染特征,以杭嘉湖平原河网地区饮用水水源河流上游典型小城镇的街尘为研究对象,对工业区、交通干道、旧居区、新居区和商业区5种土地利用类型的15个采样点进行街尘样品采集和粒径分级,测试街尘的密度、有机质含量以及16种U.S.EPA优控PAHs含量等指标.结果表明,粒径为<63、63～125、125～250和250～900μm街尘中总多环芳烃(∑PAHs)的平均含量分别为7261、5835、4660和2909μg·kg-1,粒径越小,PAHs含量越高,其生态风险越大.不同土地利用类型的街尘中PAHs的含量顺序依次为:工业区>交通干道>旧居区>新居区>商业区.街尘中PAHs和有机质含量存在显著正相关关系,且街尘粒径越小,有机质和PAHs的相关性越强.源解析结果表明,街尘中的PAHs多为燃烧源.

The Pollution Characteristics of Polycyclic Aromatic Hydrocarbons in Street Dust from a Typical Town in the Yangtze River Delta

Street dusts are an important environmental medium,and pollutants associated in street dusts have an environmental risk to the aquatic environment in stream network.To evaluate the contamination with polycyclic aromatic hydrocarbons(PAHs)of typical street dust particles in the Yangtze River Delta,street dust particles were collected by a vacuum cleaner from 15 different town streets of five different land uses:industrial zones,trunk roads,business districts,old residential areas,and new residential areas in a typical town,which located at the upstream reach of a drinking water source river in Hang-Jia-Hu plain region.The density,organic matter contents and the contents of 16 PAHs from the U.S.EPA priority pollutant list in street dust particles with different particle sizes were measured.Results showed that the total contents of 16 PAHs(∑PAHs)in <63,63~125,125~250 and 250~900μm fractions were 7261,5835,4660 and 2909μg·kg-1,respectively.The smaller street dust particles had higher contents of total PAHs and had higher ecological risk.The order of PAH contents was:industrial zones >trunk roads >old residential areas >new residential areas >business districts.There were significantly positive correlation between organic matter contents and PAH contents in street dust particles,and the smaller street dust particles had stronger correlations.The source apportionment indicated that the combustion process was the dominant source of PAHs in street dust particles.