温州市 PM2．5中水溶性离子污染特征及来源分析

摘要

2015年1～12月在温州市区采集448个PM2．5样品，采用离子色谱法分析PM2．5中9种水溶性离子（SO2－4、NO3－、N H＋4、Cl－、Na＋、K＋、Ca2＋、M g2＋和F－）的浓度，研究其污染特征、化学组分和来源．采样期间9种水溶性离子总浓度为39．97μg · m －3，SO2－4、NO3－和NH＋4占所测水溶性离子总量的（40．19±10．04）％．离子总浓度的季节变化特征为冬季＞春季＞秋季＞夏季，从空间分布上看，多数季节市站采样点 PM2．5中离子总浓度低于南浦、龙湾和瓯海采样点．相关性分析结果显示，PM2．5值与 NH＋4、Ca2＋、Na＋、K＋、Cl－、NO3－、SO2－4浓度显著相关，PM2．5中SO2－4和NH＋4的主要结合方式为（NH4）2SO4．硫氧化速率（SOR）和氮氧化速率（NOR）的年均值分别为0．44±0．09和0．13±0．04，表明温州市PM2．5中SO2－4和NO3－主要由二次转化形成．主成分分析结果表明，温州市PM2．5中水溶性离子主要来源于燃煤（火力发电和工业燃煤）、生物质燃烧、机动车尾气以及道路和建筑扬尘．%We collected 448 samples of PM2 .5 at urban area of Wenzhou from January to December ,2015 .Water‐sol‐uble ionic constituents(SO2 -4 ,NO3- ,NH+4 ,Cl- ,Na+ ,K+ ,Ca2+ ,Mg2+ and F-)associated to PM2 .5 were detec‐ted by Ion Chromatogram (IC) ,chemical composition ,variation characteristics ,as well as the source apportionment were analyzed .The average mass concentration of the 9 ions was found to be 39 .97 μg · m -3 .Secondary inorganic species SO2 -4 、NO3- and NH+4 were the major components of water‐soluble ions in PM2 .5 ,with a contribution of (40 .19 ± 10 .04)% .The order of total ions concentration was winter > spring > autumn > summer ,showing obvious seasonal variations ,and from the space ,the concentrations of PM 2 .5‐bound water‐soluble ions were lower in Shizhan in most of the seasons .The results of correlation analysis showed that PM 2 .5 and NH+4 、Ca2+ 、Na+ 、K+ 、Cl- 、NO3- 、SO2 -4 had a significant negative correlation ,and most of SO2 -4 and NH+4 existed as (NH4 )2SO4 in Wenzhou city .In addition ,the sulfate oxidizing rate (SOR) and nitrate oxidizing rate (NOR) were (0 .44 ± 0 .09) and (0 .13 ± 0 .04) ,respectively .It indicated that SO2 -4 and NO3- in PM2 .5 were resulted by the secondary transfor‐mation .Principal component analysis (PCA) results suggested that water‐soluble inorganic ions in PM2.5 mainly came from coal combustion (thermal power generation and coal‐fired industry ) ,biomass combustion ,vehicle ex‐haust emission ,road and construction dust .