安阳北部郊区PM_(2.5)中水溶性无机离子季节变化、来源特征及其消光贡献

SEASONAL VARIATION, SOURCE AND LIGHT EXTINCTION CONTRIBUTION OF WATER-SOLUBLE INORGANIC IONS OF PM_(2.5) IN THE NORTHERN SUBURB OF ANYANG, CHINA

为探究安阳市北部郊区PM_(2.5)中水溶性无机离子(WSIIs)的季节变化、来源特征及其消光贡献,于2018年3月—2019年2月对PM_(2.5)中化学组分及气态污染物进行在线观测。结果表明:PM_(2.5)及WSIIs年均浓度分别为(76.68±73.00),(45.60±34.17)μg/m^(3),且二者均呈冬季浓度最高,夏季最低的趋势。不同季节铵盐的存在形式主要为(NH_(4))_(2)SO_(4)、NH_(4)NO_(3)和NH_(4)Cl。PMF源解析结果表明,二次硝酸盐、二次硫酸盐、扬尘源及燃烧源是WSIIs的主要来源。同时,基于改进的IMPROVE经验公式计算各组分的消光贡献,其结果显示二次离子组分(SNA)对大气消光的贡献超过67%。不利的气象条件下污染物的排放和积累是造成本地区冬季PM_(2.5)重污染的重要原因,同时,SNA尤其是SO_(4)_(2)-的迅速增加也会导致较高的PM_(2.5)浓度。因此,控制SNA浓度有利于降低大气PM_(2.5)浓度,同时也助于大气能见度的提升。

Seasonal variation,source characteristics as well as light extinction contribution of water-soluble inorganic ions(WSIIs)in PM_(2.5) were explored in the northern suburb of Anyang.Gaseous pollutants,PM_(2.5) samples,and their chemical components were online monitored from March 2018 to February 2019.The results showed that the annual average concentrations of PM_(2.5) and WSIIs were(76.68±73.00)μg/m^(3) and(45.60±34.17)μg/m^(3),respectively,which showed obvious seasonal variation with the maximum values in winter,and the minimum values in summer.NH_(4)^(+) most likely existed in the form of(NH_(4))_(2)SO_(4),NH_(4)NO_(3),and NH_(4)Cl in four seasons at the observation sites.The main sources of WSIIs were secondary nitrate,secondary sulfate,dust,and combustion source by using positive matrix factorization(PMF).Furthermore,the revised IMPROVE algorithm was used to estimate the extinction coefficient(best).The results illustrated that the extinction contribution of SNA could reach 67%.Finally,typical pollution episodes were explored in winter in this study.Continuous emission and accumulation of pollutants under unfavorable metrological conditions was the major cause of the PM_(2.5) pollution events at this site.Meanwhile,a rapid increase of SNA,especially SO_(2)-4,can lead to higher PM_(2.5) concentrations.Hence,the control of SNA is not only conducive to the reduction of regional PM_(2.5) concentration,but also to improving atmospheric visibility.