Atmospheric aerosol samples collected in Beijing during 17-21 September 2004 were analyzed using the proton-induced X-ray emissions (PIXE) method,yielding concentrations of 20 elements.Analyzing the aerosol element size-spectrum distribution,enrichment factor (EF) and source over Beijing showed that under strong wind weather conditions,there were double peak distributions in the element size-spectra of Cu,S,K,Mn,As,Br,and Pb:one in fine mode and another in coarse mode.The peak in fine mode resulted from local emissions related to human activities,while the peak in coarse mode was caused by long range transport.The EF values of elements Ni,Cu,Zn,As,Se,Br,and Pb were relatively high,suggesting an evident characteristic polluted by regional aerosol.Results from factor analysis indicated that soil dust,coal-burning,industry and vehicle emissions contributed considerably to the autumn aerosol pollution in Beijing.
Urban aerosols have a large effect on the deterioration of air quality and the degradation of atmospheric visibility.Characterization of the chemical composition of PM 2.5 and in situ measurements of the optical properties of aerosols were conducted in July 2008 at an urban site in Guangzhou,Southern China.The mean PM 2.5 concentration for the entire period was 53.7±23.2 μg m 3.The mean PM 2.5 concentration (82.7±25.4 μg m 3) on hazy days was roughly two times higher than that on clear days (38.8±8.7 μg m 3).The total water-soluble ion species and the total average carbon accounted for 47.9%±4.3% and 35.2%±4.5%,respectively,of the major components of PM 2.5.The increase of secondary and carbonaceous aerosols,in particular ammonium sulfate,played an important role in the formation of haze pollution.The mean absorption and scattering coefficients and the single scattering albedo over the whole period were 53±20 M m 1,226±111 M m 1,and 0.80±0.04,respectively.PM 2.5 had a high linear correlation with the aerosol extinction coefficient,elemental carbon (EC) was correlated with aerosol absorption,and organic carbon (OC) and SO 4 2 were tightly linked to aerosol scattering.
应用WRF—Chem（Weather Research and Forecasting Model with Chemistry）模式模拟研究了2007年8月京津冀地区近地面O3、NO2、PM2.5浓度的时空变化特征，将模拟结果与观测数据进行详细对比，结果表明，模式可以较好地模拟O3、PM2.5，浓度的空间分布和时间变化特征，成功再现了8月33和PM2.5的几次积累增加过程，其中O，的模拟值与观测值的相关系数为0．69～0．86，PM2.5的相关系数为0．44～0．49，但模式对NO2的模拟相对较差，相关系数为0．27～0．43。北京、天津地区为O3月均低值区，月均体积浓度约30×10^-9，渤海及京津冀以西地区O3月平均体积浓度可达60×10^-9；PM2，呈现南高北低的分布特征，变化范围为120～240μg／m3。14时月平均03体积浓度在北京、天津地区低于周边地区，约为60×10^-9；而PM2.5质量浓度在环渤海地区和河北南部较高，为100～120μg/m^3。8月17日北京出现一次典型的高浓度O，污染事件，14时北京地区温度达到33℃，O3体积浓度为80×10^-9～110×10^-9。在局地排放、化学反应和外来输送的共同作用下，渤海西岸和北岸PM2.5的质量浓度超过120μg／m3，其中二次气溶胶质量浓度为50～100μg／m3，一次排放人为气溶胶质量浓度为10～20μg／m3，海盐质量浓度为1～7μg／m3，二次气溶胶是该地区PM2.5的主要贡献者。
The semi-diurnal mean aerosol mass concentration, chemical composition, and optical properties of PM2.5were investigated in Shanghai during the spring of 2012. Slight pollution was observed during the study period. The average PM2.5 concentration was 64.11 土 22.83(xg/m3. The mean coefficients of extinction,scattering, and absorption at 532 nm were 125.9 士 78.5,91.1 士 56.3,and 34.9 士 23.6 Mm-1, respectively. A relatively low mean single scattering albedo at 532 nm(0.73 士 0.04) and low level of elemental carbon(EC,2.67 士 1.96 |xg/m3) suggested that the light absorption was enhanced due to the internal mixing of the EC.Sulfate contributed the most to aerosol light scattering in Shanghai. The chemical composition of PM2.5was dominated by particulate organic matter, sulfate, nitrate, ammonium, and EC. Anthropogenic sources made a significant contribution to the emission and loading of the particulate pollutants. A relatively good correlation between the aerosol chemical composition and the cloud condensation nuclei(CCN) activation indicated that aerosol chemistry is an important factor that influences the saturated hygroscopicity and growth of the aerosol.
用中尺度数值天气模式Weather Research and Forecasting Model(WRF v3.2)对2006年中国地区1、4、7、10月4个月(分别对应冬、春、夏、秋)近地层气象要素进行模拟。并利用通榆、榆中和上海站的观测资料对模拟结果进行对比分析。结果表明:WRF模式能较好的模拟出各气象要素的变化特征。但是,各个季节的模拟效果并不相同。在半干旱的通榆和榆中两站,有关要素秋季的模拟最好,夏季较差。在上海站,夏秋两季比较差,冬春两季较好。对温度的模拟,上海站4个季节都偏低,通榆站夏季偏低,冬季偏高。对风速的模拟,通榆和榆中两站(通榆秋季除外)都偏低,上海站(夏季除外)都偏高。对感热通量和潜热通量的模拟,通榆站夏季感热通量偏大,潜热通量偏小,榆中站夏季感热通量和潜热通量的模拟值都偏大。
PM2.5 aerosols were sampled in urban Chengdu from April 2009 to January 2010, and their chemical compositions were characterized in detail for elements, water soluble inorganic ions, and carbonaceous matter. The annual average of PM2.5 was 165 μg m-3 , which is generally higher than measurements in other Chinese cities, suggesting serious particulate pollution issues in the city. Water soluble ions contributed 43.5% to the annual total PM2.5 mass, carbonaceous aerosols including elemental carbon and organic carbon contributed 32.0%, and trace elements contributed 13.8%. Distinct daily and seasonal variations were observed in the mass concentrations of PM2.5 and its components, reflecting the seasonal variations of different anthropogenic and natural sources. Weakly acidic to neutral particles were found for PM2.5 . Major sources of PM2.5 identified from source apportionment analysis included coal combustion, traffic exhaust, biomass burning, soil dust, and construction dust emissions. The low nitrate: sulfate ratio suggested that stationary emissions were more important than vehicle emissions. The reconstructed masses of ammonium sulfate, ammonium nitrate, particulate carbonaceous matter, and fine soil accounted for 79% of the total measured PM2.5 mass; they also accounted for 92% of the total measured particle scattering.
