十堰市城区冬季PM_(2.5)污染特征与来源解析

Pollution Characteristics and Source Apportionment of PM_(2.5) in Winter in Shiyan City

为探讨内陆山区城市湖北省十堰市冬季PM_(2.5)污染特征及来源构成,于2016年1月12日—2月4日在4个采样点位同步采集PM_(2.5)样品,分析了无机元素、水溶性离子、有机碳和元素碳的质量浓度.并采集了十堰市主城区城市扬尘、裸露山体尘、建筑水泥尘、燃煤源、机动车尾气、工业源及餐饮油烟源等7类污染源,初步建立十堰市本地的污染源成分谱库,利用统计学方法研究冬季PM_(2.5)的污染特征,并采用CMB受体模型及"二重源解析技术"分析其来源构成.结果表明:冬季采样期间,十堰市ρ(PM_(2.5))平均值达到110.65μg/m3,超过GB 3095—2012《环境空气质量标准》二级标准24 h浓度限值,并且随空气RH(相对湿度)增加污染加重.城区3个采样点PM_(2.5)化学组成及特征的空间差异不明显.PM_(2.5)中ρ(TC)最高,其次是ρ(NO_3^-)和ρ(SO_4^(2-)),与二次反应、机动车尾气、煤燃烧等密切相关.ρ(NO_3^-)/ρ(SO_4^(2-))为1.22,说明机动车尾气的影响较大.二次粒子、燃煤源和机动车尾气是十堰市城区冬季大气PM_(2.5)的主要来源,贡献率分别为51.2%、10.9%和10.1%.研究显示,十堰市城区冬季ρ(PM_(2.5))超过GB 3095—2012二级标准,PM_(2.5)的污染控制应以二次粒子、燃煤和机动车为主,采取多源控制原则.

To investigate the pollution characteristics and source apportionment of PM2.5 in Shiyan City（an inland mountainous city）,ambient PM2.5 samples were collected simultaneously at four environmental monitoring sites from January 12 thto February 4 th,2016.Chemical analysis was also conducted for elements,water-soluble inorganic ions,organic carbon（OC） and elemental carbon（EC）.Seven kinds of pollution sources,including resuspended dust,bare mountain dust,construction dust,coal combustion source,mobile vehicle exhaust,industry exhaust and residential meat cooking were studied,and the local chemical profiles of the pollution sources in Shiyan City were preliminary established. Statistical methods were used to study the PM2.5 pollution characteristics in winter in Shiyan City.Source apportionment of PM2.5 was carried out by using the chemical mass balance（CMB） receptor model and the‘dual source analytical technique＇. The average mass concentration of PM2.5 was around 110. 65 μg/m3,which exceeded the level II 24-hour limit values of the Ambient Air Quality Standard（NAAQS,GB 3095-2012）. The concentration of PM2.5 increased with the relative humidity. There is no obvious spatial difference of the PM2.5 mass concentrations and their components among the three urban monitoring sites. The most important components in PM2.5 were TC,NO3^-and SO42-,which were closely related to the secondary reactions,mobile vehicle exhausts and coal combustions. The average ρ（NO3-） /ρ（SO42-） value was 1. 22,indicating that the contribution of mobile sources was moreimportant. The secondary transformation,coal combustion and mobile vehicle emissions were identified as the most important sources for PM2.5,with 51. 2%,10. 9% and 10. 1% respectively. The results showed that the PM2.5 mass concentrations in winter in Shiyan City exceeded the level II 24-hour limit values of NAAQS and the pollution control of PM2.5 should be focused on multiple sources,such as secondary transformation,coal combustion and mobile vehicle emissions.