杭州市多环芳烃的干、湿沉降

The dry,wet deposition of polycyclic aromatic hydrocarbons in Hangzhou city

多环芳烃(PAHs)是一类典型的持久性有机物,在各种环境介质广泛存在。为了研究干湿沉降对空气中PAHs的去除,采集了杭州市6个干沉降尘土样品、9个湿沉降雨水样品、5个湿沉降雪样品和6个地表径流样品,用高效液相色谱法(HPLC)测定了其中15种多环芳烃的浓度水平,比较了这些介质中PAHs的分布特点。结果表明,降尘中15种PAHs的总平均质量分数为4323ng·g-1;雨水、雪水和地表径流样品中15种PAHs的总平均质量浓度分别为558.4ng·L-1、765.1ng·L-1和576.3ng·L-1。地表径流、雨水、雪水和干沉降尘土4种样品中,都以4环PAHs为主,其次为3环PAHs。降雪比降雨对PAHs的去除效果更好,地表径流中PAHs主要来自雨水。根据杭州市大气降尘通量和降雨量,估算了PAHs的干湿沉降通量。杭州市辖区大气中每年PAHs的干湿沉降通量分别为1419.1kg和2689.8kg,湿沉降是PAHs去除的主要方式,约为干沉降去除总量的2倍。

Polycyclic aromatic hydrocarbons（PAHs）are one of the typical persistent organic compounds featured in regional and global cycling.In order to study the removal of PAHs by dry and wet deposition,twenty-six samples including six dust,nine rain,five snow and six surface runoff in Hangzhou city were collected.The concentrations of 15 PAHs in these media were determined by High Performance Liquid Chromatography.The mean values of total concentration of 15 PAHs were 4323 ng·g^-1,558.4 ng·L^-1,765.1 ng·L^-1 and 576.3 ng·L^-1,respectively,in dust,rain,snow and surface runoff samples,which were all predominated by 4-ring PAHs.The removal efficiency of PAHs by snow was higher than that by rain.The PAHs in surface runoff was mainly from rain.The PAHs fluxes of dry,wet deposition in Hangzhou city were estimated to be 1419.1 kg·a-1 and 2689.8 kg·a-1.