中国海峡西岸城市群冬季PM2.5和PM10中水溶性离子的污染特征

为了研究中国海峡西岸城市群冬季大气颗粒物水溶性离子的污染特征,采集该区域8个城市共14个采样点位(包含1个背景点)的PM2.5和PM2.5~10样品,采用离子色谱分析F-、Cl-、NO3-、SO42-、Na+、K+、NH4+、Ca2+和Mg2+ 9种水溶性离子的质量浓度.结果表明,海峡西岸城市群冬季大气颗粒物污染严重,PM2.5和PM10的日均值分别为89.65,135.65μg/m3,PM2.5占PM10的66.1%.城区水溶性无机离子主要集中在PM2.5上,其浓度分布存在空间差异,温州地区水溶性无机离子浓度处于较高水平;SO42-、NO3-和NH4+是水溶性无机离子的主要贡献者,其占PM2.5 中水溶性离子总量的79.6%~89.0%,占PM10的74.2%~83.4%.由于受冬季季风的影响,该区域非海盐离子对水溶性无机离子的贡献较大.NO3-/SO42-的质量浓度比显示,冬季海峡西岸城市群已处于机动车污染与燃煤污染并存的复合型污染状态.

Pollution characteristics of water-soluble ions in PM2.5 and PM10 in Haixi Urban Agglomeration in wintertime

The PM2.5and PM2.5-10samples were collected from 14sample sites in 8cities in Haixi Urban Agglomeration.The 9water-soluble ions(F-、Cl-、NO3-、SO42-、Na+、K+、NH4+、Ca2+、Mg2+) were determined.The concentrations of PM2.5and PM10were high,and the mean value of PM2.5and PM10were 89.65and 135.65μg/m3,respectively.The PM2.5was the main composition of the PM10and the proportion of PM2.5to PM10was 66.1%.Most of the water-soluble ions in cities were associated with the PM2.5.The concentrations of water-soluble ions in Wenzhou were higher than those in other cities.The dominatant water-soluble ions were SO42-,NO3-and NH4+,which accounted for 79.6%~89.0% of total ions in PM2.5and 74.2%~83.4% in PM10.Because of the monsoon in winter,the major ions in atmospheric particles were non-sea-salt ions.The higher mass ratio of NO3-/SO42-demonstrated that the Haixi Urban Agglomeration was under combined contamination in winter.