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Atmospheric dry and wet depositional fluxes of polychorinated biphenyls over the Yangtze River Estuary

李敏桥
1. 中国科学院地球化学研究所, 环境地球化学国家重点实验室, 贵阳 550081;
2. 中国科学院大学, 北京 100049;
3. 复旦大学, 环境科学与工程系, 上海 200433

林田
1. 中国科学院地球化学研究所, 环境地球化学国家重点实验室, 贵阳 550081;
2. 中国科学院大学, 北京 100049;
3. 复旦大学, 环境科学与工程系, 上海 200433

郭天锋
1. 中国科学院地球化学研究所, 环境地球化学国家重点实验室, 贵阳 550081;
2. 中国科学院大学, 北京 100049;
3. 复旦大学, 环境科学与工程系, 上海 200433

郭志刚
1. 中国科学院地球化学研究所, 环境地球化学国家重点实验室, 贵阳 550081;
2. 中国科学院大学, 北京 100049;
3. 复旦大学, 环境科学与工程系, 上海 200433

摘要：大气干、湿沉降是水体持久性有机污染物的主要来源.长江口是我国陆海相互作用研究的关键区域，是大气污染物监测的重点区域.为了解长江口大气中多氯联苯（Polychlorinated Biphenyls，PCBs）的污染特征，本研究共采集了自2013年10月—2014年8月4个季度93对大气样品（气态和颗粒态）和13个雨水样品，分析了样品中7种典型PCBs浓度并估算了PCBs的干、湿沉降通量.结果表明：①长江口大气中PCBs （气态和颗粒态）浓度范围是2.37~207 pg·m^-3，平均浓度为44.9 pg·m^-3；与以海洋为背景的国内外大气中PCBs相比，浓度处于中度水平；大气中PCBs主要存在于气态中，占77%；夏季气态PCBs浓度明显高于其他3个季度；颗粒态PCBs浓度呈冬、春季高，夏、秋季低的特点.②PCBs的干沉降通量为681~2330 pg·m^-2·d^-1，年均值为1880 pg·m^-2·d^-1，冬、春季干沉降通量明显高于夏、秋季；湿沉降通量为184~1210 pg·m^-2·d^-1，年均值为863 pg·m^-2·d^-1，夏季湿沉降通量明显低于其他3个季节.总体上，PCBs干、湿沉降通量年均变化为865~3300 pg·m^-2·d^-1，年均值为2250 pg·m^-2·d^-1，干沉降占总沉降通量的69%.

Abstract：Atmospheric dry and wet depositions are important sources of persistent organic pollutants (POPs) to water. The Yangtze River Estuary is an important area for researches of air pollution and land-sea interactions. Ninety three air samples (gaseous and particle phases) and thirteen precipitation samples were collected from October 2013 to August 2014 over the Yangtze River Estuary to analyze seven PCBs. The results showed that:①The total concentrations of PCBs ranged from 2.37 to 207 pg·m^-3, with average value of 44.9 pg·m^-3. Compared with other domestic and oversea areas, the total concentrations of PCBs over the Yangtze River Estuary were at the middle levels. PCBs mainly distributed in the gaseous phase accounting for 77% of total concentrations. The concentrations of PCBs showed seasonal variations. Higher concentrations were found in summer than other seasons in gaseous phase, while, in particle phase, higher concentrations were found in winter. ②The dry deposition fluxes of PCBs ranged from 681 to 2330 pg·m^-2·d^-1 with the average value of 1880 pg·m^-2·d^-1. The wet deposition fluxes of PCBs ranged from 184 to 1210 pg·m^-2·d^-1 and the annual average was 863 pg·m^-2·d^-1. The total deposition fluxes of PCBs ranged from 865~3300 pg·m^-2·d^-1, and the average annual value was 2250 pg·m^-2·d^-1. The dry deposition fluxes accounted for 69% of total deposition fluxes.