重庆主城区大气PM_(10)及PM_(2.5)来源解析

Source Apportionment of PM_(10) and PM_(2.5) in Urban Areas of Chongqing

为探讨重庆主城区4个季节大气PM10和PM2.5的主要来源,于2012年2—12月在重庆主城区的工业区、文教区和居住区5个环境监测点同步采集PM10及PM2.5样品,分析了无机元素、水溶性离子、有机碳和元素碳含量及其分布特征.采集了重庆主城区土壤尘、建筑水泥尘、扬尘、移动源(包括机动车、施工机械及船舶)、工业源(包括固定燃烧源及工业工艺过程源)、生物质燃烧源及餐饮源等7类污染源,建立了重庆市本地化的污染源成分谱库.利用CMB(化学质量平衡)受体模型及二重源解析技术分析了PM10及PM2.5的来源.结果表明:重庆主城区大气中ρ(PM10)及ρ(PM2.5)的年均值分别为153.2和113.1μg/m3,超过GB3095—2012《环境空气质量标准》二级标准限值2倍以上.大气PM10的主要来源为扬尘、二次粒子和移动源(贡献率分别为23.9%、23.5%和23.4%),大气PM2.5主要来源于二次粒子和移动源(贡献率分别为30.1%和27.9%).PM10和PM2.5的主要源类贡献率差别不大,表明研究区域内大气颗粒物污染控制应采取多源控制原则.大气PM10来源的季节性变化特征表现为春季和秋季主要以扬尘为主、夏季和冬季主要以二次粒子为主.

In order to identify and quantify sources of particulate matter, ambient samples of PM10 and PM2.5 were collected simultaneously from five environmental monitoring sites （ located in industrial, cultural and educational, and residential districts） from February to December 2012. The samples were analyzed for elemental components, water-soluble ions, organic carbon （OC） and elemental carbon （EC）. Chemical source profiles were reported for soil dust, construction dust, resuspended dust, mobile vehicle exhaust （including motor vehicles, construction machinery and ships）, biomass burning emissions and residential meat cooking. Chemical mass balance （CMB） receptor model was applied to analyze the source apportionment of PM10 and PM2.5. The results showed that the annual average concentrations of PM10 and PM2.5 were 153.2 and 113. 1 μg/m^3, respectively. The two parameters exceeded the limit values for Class 2 according to the National Ambient Air Quality Standard （GB 3095-2012）. The most important sources were identified as resuspended dust, secondary particles and mobile vehicle exhaust for PM10 （23.9% , 23.5% and 23.4% respectively） and as secondary particles and mobile sources for PM2.5（30. 1% and 27.9% respectively）. It is urgent to simultaneously control multiple sources to improve the air quality. The seasonal variation of PM10 indicated the dominance of resuspended dust in spring and autumn and that of secondary particles in summer and winter.