北方沿海城市大气PM_(2.5)组分特征及来源分析:以青岛市为例

Composition Characteristics and Source Apportionment of Atmospheric PM_(2.5) in Northern Coastal Cities:A Case Study of Qingdao City

为探究北方沿海城市大气PM_(2.5)的化学组分特征及其关键来源,本文选择典型代表城市青岛市作为研究对象,在2021年3月−2022年2月采集大气PM_(2.5)样品,测定水溶性无机离子、碳组分及化学元素等组分,深入分析大气PM_(2.5)化学组分特征,采用正定矩阵因子分解(PMF)和潜在源贡献函数(PSCF)对青岛市PM_(2.5)的主要贡献源类和潜在源区进行分析研究.结果表明:①采样期间青岛市PM_(2.5)浓度平均值为42.2μg/m^(3),NO_(3)^(−)、NH_(4)^(+)、SO_(4)^(2−)、OC是PM_(2.5)的主导成分,浓度分别为11.77、5.76、5.20和6.67μg/m^(3),占比分别为27.88%、13.65%、12.32%和15.80%.②各组分浓度季节性变化与PM_(2.5)浓度变化基本一致,呈现冬季最高、夏季最低,春季、秋季相差较小的变化特征.③PMF模型解析结果表明,二次无机源是青岛市PM_(2.5)的主要来源,贡献率达42.8%;其次为二次有机源以及燃煤和生物质燃烧源,贡献率分别为18.1%、15.7%;机动车源贡献率为8.8%,海盐和船舶源贡献率为6.0%;而扬尘源和工艺过程源贡献率相对较低,分别为5.3%和3.3%.冬季燃煤和生物质燃烧源贡献率(24.4%)明显高于其他季节;春季和秋季扬尘源贡献率较高,分别为6.5%和9.8%;夏季二次有机源、海盐和船舶源以及机动车源的贡献率高于其他季节,贡献率分别达23.1%、12.4%和16.3%.④江苏省北部以及山东省中东部是青岛市各类源的主要潜在源区,江苏省东北部、长三角地区以及黄海海域是海盐和船舶源的主要潜在源区.研究显示,二次源是青岛市大气污染物的主要来源,燃煤源和生物质燃烧源、机动车源、海盐和船舶源的影响也不容忽视.二次源、机动车源以及海盐和船舶源可能是北方沿海城市PM_(2.5)的重点关注源类,在大气污染防治措施制定时需要加强对其的精细化管理.

In order to systematically analyze the chemical component characteristics and main sources of PM_(2.5)in the atmosphere of northern coastal cities,this study selected Qingdao City as the research object and collected ambient PM_(2.5)samples in Laoshan District,Qingdao City from March 2021 to February 2022.Water-soluble inorganic ions,carbon components,and chemical elements were measured,and the chemical composition characteristics of atmospheric PM_(2.5)were analyzed.Positive matrix factorization(PMF)and potential source contribution function(PSCF)were used to analyze the main contributing sources and potential source areas of ambient PM_(2.5)in Qingdao City.The results show that:(1)The average concentration of PM_(2.5)during the sampling period was 42.2μg/m^(3).NO_(3)^(−),NH_(4)^(+),SO_(4)^(2−)and OC were the dominant components in PM_(2.5),with concentrations of 11.77,5.76,5.20 and 6.67μg/m^(3),accounting for 27.88%,13.65%,12.32%and 15.80%of mass concentrations of PM_(2.5),respectively.(2)The seasonal variations in the concentrations of each component were basically consistent with the changes in PM_(2.5)concentrations,showing the characteristics of highest in winter,lowest in summer,and little difference in spring and autumn.(3)PMF apportioned results showed that secondary inorganic sources were the primary source of ambient PM_(2.5)in Qingdao City,with a contribution rate of 42.8%.The contribution rates of secondary organic sources and coal and biomass combustion mixed sources to ambient PM_(2.5)were 18.1%and 15.7%,respectively.The contribution of motor vehicles was 8.8%,and that of sea salt and ships was 6.0%.The contributions from dust source and industrial process sources were relatively lower(5.3%and 3.3%,respectively).The contribution of the mixed sources of coal combustion and biomass burning in winter(24.4%)was substantially higher than in other seasons.The contributions of dust sources in spring and autumn were 6.5%and 9.8%,respectively.The contributions of secondary organic sources(23.1%),mixed sources of sea salt and ships(12.4%),and motor vehicles(16.3%)in summer were higher than those in other seasons.(4)Northern Jiangsu Province and central and eastern Shandong Province were the main potential source areas of various ambient PM_(2.5)in Qingdao City.Northeast of Jiangsu Province,the Yangtze River Delta and the Yellow Sea were the main potential source areas of mixed source of sea salt and ships of ambient PM_(2.5)in Qingdao City.The results showed that the secondary sources were the main sources of air pollutants in Qingdao City,among which the effects of coal and biomass combustion sources,motor vehicle sources,sea salt and ship sources could not be ignored.Secondary sources,motor vehicle sources,sea salt and ship sources may be key sources of PM_(2.5)in northern coastal cities,and refined management should be strengthened when formulating air pollution prevention and control measures.