基于多参数指标的长江口滨岸多环芳烃来源辨析

Polycyclic Aromatic Hydrocarbons Sources Identification Based on Multiple Indices from the Yangtze Estuarine and Nearby Coastal Areas

在长江口滨岸及临近排污口、滨岸河流、城市中心城区采集悬浮颗粒物、表层沉积物、街道灰尘等样品,分别利用GC-MS和GC-C-IRMS定量分析了不同环境介质中的多环芳烃(PAHs)与有机单体化合物稳定碳同位素(!13C),开展了基于PAH环数、分子量特征比值和有机单体化合物稳定碳同位素组成等参数指标的长江口滨岸悬浮颗粒物与表层沉积物中PAHs源解析研究。研究结果显示,长江口滨岸悬浮颗粒物与表层沉积物中的PAH化合物主要以3￣4环为主,与吴淞排污口、石洞口污水处理厂、黄浦江、滨岸小河流以及上海中心城区等潜在来源区域不同环境介质中的PAHs组成特征相似,主要来源于汽油、柴油、煤炭和木材的不完全燃烧以及石油残余物的混合。其中,木材和煤炭不完全燃烧形成的PAHs以及石油残余物,枯季经过滨岸河流及排污口直接输入,洪季则为城市街道灰尘被暴雨冲刷,随地表径流最终汇入河口;汽车排放(汽油、柴油不完全燃烧)产生的PAHs主要富集在城市交通区和商业区的街道灰尘中,枯季借助区域盛行风迁移至河口区,洪季则主要通过暴雨径流冲刷进入河口。

Samples of suspended particulate matters （SPMs）, surface sediment and road dusts were collected in the Yangtze estuarine and nearby coastal areas, coastal rivers, and Shanghai metropolitan area, respectively. Sixteen polycyclic aromatic hydrocarbons （PAHs） in the USEPA priority-controlled list were determined by GC-MS and compound-specific stable carbon isotopes of individual PAHs were analyzed by GC-C-IRMS. PAHs sources of SPMs and surface sediments in the Yangtze estuarine and nearby coastal areas were examined using multiple source identification techniques which integrated molecular mass indices with organic compound-specific stable isotopes. The results showed that the third and fourth rings PAH compounds were dominant in SPMs and surface sediments, similar to those in Wusong sewage discharge outlet, Shidongkou sewage disposal plant, Huangpu River, coastal rivers and Shanghai metropolitan area. Principal component analysis （PCA） integrated with molecular mass indices indicated that gasoline, diesel oil, coal and wood combustion and petroleum were the main sources for PAHs in the Yangtze Estuary. Use of PAH compound-specific stable isotopes tracked PAHs input pathways. PAHs derived from wood and coal combustion and petroleum were input into the Yangtze estuarine and nearby coastal areas by coastal rivers, sewage discharge outlets in dry season and urban storm water runoff in flood season. PAHs derived from vehicle emissions were mainly accumulated in road dusts from urban traffic lines and commercial district, which entered the coastal area by the northwest prevailing wind in dry season and storm water runoff in flood season.