【摘要】 PM_2.5污染已成为目前我国空气污染领域关注的焦点问题。为研究厦门地区PM_2.5污染的不同类型,于2013年1月、4月、7月和10月选择厦门市五个代表性环境监测站进行了同步的PM_2.5离线滤膜和在线数据采集,并收集了同期的AQI、SO₂、NO₂、CO、O₃及气象数据。对滤膜中的水溶性无机离子、元素和碳组分进行了实验分析。基于实验分析数据,利用IMPROVE方程定量计算了厦门空气污染期间PM_2.5中不同组分的颗粒物消光系数。根据不同组分消光系数的大小,将厦门市的PM_2.5污染分为三种类型:硫酸盐主导污染类型、有机物主导污染类型以及各区域不同污染物主导污染类型。对不同污染类型的成因进行了深入分析,发现其主要与本地污染物排放、外来污染物输送以及气象要素有关。更多还原

【Abstract】 Background, aim, and scope Under the rapid economic expansion in China, air pollution has become a serious environmental problem. Indeed, the air in China now contains high concentrations of PM_2.5（fine particulate matter） whose equal aerodynamic diameters are <2.5 μm(PM_2.5). It is a mixture of inorganic components, organic matter, and water, it have been proven to affect human health, climate, ecosystems, and agriculture, and it also has adverse environmental effects, such as decreased visibility. Materials and methods the offline filters for collecting PM_2.5 were conducted at five environmental monitoring stations including Gulangyu（GLY）, Huli（HL）, Hongwen（HW）, Jimei（JM） and Xidong（XD） in January, April, July and October in 2013. Each sample was run for 24 h with quartz and teflon filters, respectively. All the filters were weighted before sampling, and quartz filter samples were pre-combusted at 800℃ for 3 h. Elements were analyzed by Energy Dispersive X-Ray Fluorescence（EDXRF） using teflon filters. For quartz filters, they all were cut into two pieces, one piece was selected for detecting water soluble ions by ion chromatograph while another part were used for obtaining OC/EC by DRI Model 2001 Thermal and Optical Carbon Analyzer following the IMPROVE-A thermal/optical reflectance protocol. Meanwhile, online data of PM_2.5 were also collected as well as the data of AQI, SO₂, NO₂, CO, O₃ and meteorological parameters in Xiamen. Results Using the IMPROVE equation, the extinction coefficient of different species were calculated for various air pollution types, and then according to the value of extinction coefficients, PM_2.5 pollution can be divided into three types at Xiamen including sulfate dominated type, OM（organic matter） dominated type and different pollutants dominated type. In 26 July, Sulfate dominated type is characterized by that（NH₄）₂SO₄ has the highest contribution for extinction coefficient at all five stations, and the values were 237.0 M ? m^-1, 371.5 M ? m^-1, 337.0 M ? m^-1, 277.6 M ? m^-1 and 399.1 M ? m^-1 for GLY, HW, HL, JM and XD, respectively. Similarly, in 12 October, OM has the highest contribution for extinction coefficient at all five stations with the value of 229.2 M ? m^-1, 128.4 M ? m^-1, 184.7 M ? m^-1, 122.3 M ? m^-1 and 183.1 M ? m^-1 for GLY, HW, HL, JM and XD, respectively. Differently, in 21 January, the components with highest contribution to extinction coefficient is different for each station, and the greatest contributor at GLY, HW, HL, JM and XD is NH4NO3(241.2 M ? m^-1), OM(120.2 M ? m^-1), NH₄NO₃(226.2 M ? m^-1),（NH₄）₂SO₄(201.2 M ? m^-1) and OM(212.6 M ? m^-1), respectively. Discussion Analyzing the variations of AQI, SO₂, NO₂, CO, O₃ and meteorological parameters, it was concluded that sulfate type was caused by the local emissions combined with pollutants transported form long distance, OM dominated type is related to the increase of wind speed, and different pollutants dominated type was mainly due to local emissions. Conclusions The results indicated that decreased visibility at Xiamen is caused by various factors, such as local emissions and long-range transport. According to the species that has the greatest extinction coefficient during pollution period, the pollution type can be divided into sulfate dominated type, OM dominated type and different pollutants dominated type. Recommendations and perspectives It should be considered the various pollution type when the government regulate the pollution emissions to deal with the air pollution.更多还原