杭州市PM10水溶性离子特征及源解析

Characteristics and source analysis of water-soluble ions in PM10 in Hangzhou

可吸入颗粒物(PM 10)是大气的主要污染物之一,对其进行控制有助于改善空气质量。2018年12月至2019年11月在杭州市采集PM10样品,分析样品中水溶性无机离子的组成特征及其季节变化规律,并通过潜在源贡献因子法(PSCF)、浓度权重轨迹分析法(CWT)、相关性分析和PMF模型等方法探讨PM 10中水溶性无机离子的来源。结果表明:PM10年均质量浓度为(105.97±50.01)μg/m 3,低于国家二级标准;受季风气候影响,PM 10季平均质量浓度在冬季最高,夏季最低;PM 10中各离子质量浓度由大到小排列为NO-3>SO 2-4>NH+4>Ca 2+>Na+>Cl->K+>Mg2+;NO-3,SO2-4,NH+43种离子,约占总水溶性无机离子质量浓度的85.0%,可见杭州市大气中二次气溶胶污染程度高,主要以(NH 4)2SO4和NH4NO3的形式存在;大气中PM10的水溶性离子主要来源有机动车排放源相关性二次气溶胶、生物质燃烧源、煤燃烧源相关性二次气溶胶、海洋源以及土壤和建筑扬尘源等5类。

PM10 is one of the main pollutants in the atmosphere and the control of PM 10 is in favor of improving the air quality of Hangzhou.PM10 samples were collected from Dec.2018 to Nov.2019 in Hangzhou to analyze the composition and seasonal variation of water-soluble inorganic ions in the samples.Based applying the potential source contribution method(PSCF),the concentration-weighted trajectory(CWT)analysis,correlation analysis and PMF model,the sources of water-soluble inorganic ions in PM 10 were explored.The results showed that the average annual mass concentration of PM 10(105.97±50.01)μg/m 3 was lower than the secondary national standards in GB 3095-2012.Influenced by the monsoon climate,PM 10 had the highest and lowest seasonal average concentration in winter and summer,respectively.The concentrations of water-soluble inorganic ions in PM 10 showed a sequence as follows:NO-3>SO 2-4>NH+4>Ca 2+>Na+>Cl->K+>Mg 2+.The NO-3,SO 2-4 and NH+4 ions accounted for about 85%of the total concentration of the water-soluble inorganic ions,indicating that the secondary aerosol pollution in Hangzhou,which was mainly in the form of(NH 4)2SO 4 and NH 4NO 3,was serious.The main sources of the water-soluble inorganic ions in PM 10 in Hangzhou included 5 kinds,i.e.,secondary aerosol related to vehicle emission,biomass combustion,secondary aerosol related to coal combustion,marine sources and soil and dust from buildings.