长江三角洲地区大气二噁英类污染物输送-沉降模拟研究

Simulation of Transport-Deposition of Dibenzo-p-Dioxins and Dibenzo Furans in the Atmosphere in the Yangtze River Delta Region

大气中的二噁英类物质(PCDD/Fs)是一类难降解的有毒污染物,可对人类和其他哺乳动物的健康构成危害.二噁英类物质主要是由废物焚烧、金属冶炼和造纸化工等行业所产生.二噁英类物质为半挥发性物质,可以在气态和气溶胶之间相互转移,从而影响其大气物理和化学过程.利用耦合有机物吸收和黑碳吸附的二噁英类污染物颗粒态、气态相间分配模块和化学转化的区域大气化学、输送模式(CMAQ)模拟了2006年1月,4月,7月和10月长三角(长江三角洲)地区PCDD/Fs在大气中的输送、转化和沉降等演变过程,探讨了大气中二噁英类污染物的季节变化规律和沉降特征.模拟结果表明,长三角地区的二噁英类污染物排放存在着明显的长距离输送特征和区域影响;冬季大气二噁英类污染物浓度明显高于夏季,湿沉降是其主要的沉降途径.

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo-furans（PCDD/Fs） are toxic persistent organic pollutants（POPs）,which harm the health of humans and other mammals.Dioxins occur as by-products in the manufacturing of organochlorides,in the incineration of chlorine-containing substances,metal smelting,in the bleaching of paper and from other industries.Most PCDD/Fs are semi-volatile organic compounds that partition between gases and aerosols in the atmosphere,thus influencing atmospheric physical and chemical processes.In this work,we used the Community Multiscale Air Quality（CMAQ） regional air quality modeling system,which was modified for PCDD/Fs including the addition of the dual organic matter（OM） absorption and black carbon（BC） adsorption gas/particle partitioning model,as well as chemical transformations to simulate transfer,transformation and deposition of the PCDD/Fs in the atmosphere of the Yangtze River Delta region in January,April,July and October of 2006.The seasonal variation rules and deposition characteristics of PCDD/Fs in the atmosphere were discussed.The modeling results showed that emissions of PCDD/Fs in the Yangtze River Delta region had significant characteristics of long-range transport and regional influences.The results indicate that the concentration of PCDD/Fs in the atmosphere in winter was significantly higher than that in summer.Wet deposition was the primary deposition pathway of PCDD/Fs.Preliminary comparison of simulation results with observation data was also conducted.