基于场降雨的北京某高架桥雨水径流中多环芳烃污染特征

Pollution characteristics of polycyclic aromatic hydrocarbons in urban viaduct stormwater runoff based on event rainfall process

以北京市某高架桥的典型场次雨水径流作为研究对象,通过对多场雨水径流中多环芳烃(PAHs)的监测,研究了高架桥雨水径流中PAHs的污染特性以及冲刷规律.结果表明,随着降雨历时的增加,雨水径流中PAHs浓度呈现先增加后减小的变化趋势,实验均值中w(Flu)/w(Pyr)为0.94,因此,高架桥雨水径流中溶解态PAHs主要来源于石油燃料的不完全燃烧.雨水径流中溶解态PAHs以三环、四环组分为主,五和六环次之,二环组分最少.高架桥雨水径流中PAHs存在浓度和质量初期冲刷现象,∑16PAHs和四环组分在不同降雨事件中均存在浓度初期冲刷现象,∑16PAHs及各环组分在降雨强度大、降雨历时长的场降雨存在明显的质量初期冲刷现象,而降雨强度小的场降雨质量初期冲刷不明显.

Taking the typical stormwater runoff of a viaduct in Beijing as the research object, the PAHs pollution and flush characteristic on the viaduct were studied through the monitoring of PAHs in the stormwater runoff. The results showed that the concentration of PAHs increased firstly and then decreased during rainfall process. The average value of w(Flu)/w(Pyr) was 0.94, which means that dissolved PAHs in viaduct stormwater runoff mainly originated from incomplete combustion of petroleum fuel. Dissolved PAHs in the runoff were mainly composed of tricyclic and tetracyclic PAHs, followed by pentacyclic and hexacyclic PAHs, and bicyclic PAHs were the least. There were exit both of the concentration and quality first flush phenomenon of PAHs in the viaduct stormwater runoff, the ∑16PAHs and tetracyclic PAHs in the stormwater runoff have the obvious phenomenon of concentration first flush phenomenon. ∑16PAHs and its components were all existing obvious first flush phenomenon under high rainfall intensity and long duration of rainfall, while the first flush phenomenon was less obvious in lower rainfall intensity.