| 省会城市不同功能区大气PM2.5化学组分季节变化及来源分析 |
| 摘要点击 2017 全文点击 698 投稿时间：2021-08-07 修订日期：2021-09-29 |
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| 中文关键词 细颗粒物 功能区 化学组分 化学质量平衡 来源解析 |
| 英文关键词 fine particulate matter functional area chemical composition chemical mass balance model source apportionment |
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| 中文摘要 |
| 为探究城市不同功能区大气PM2.5污染水平、成分季节差异特征以及来源，采集了省会城市济南市2019年不同季节（春、秋、冬）3类典型功能区（城市市区、工业区、城乡结合区）和环境背景点植物园区的PM2.5样品，对其浓度[ρ（PM2.5）]、化学组分（水溶性离子、碳质组分、元素）和来源进行分析.结果表明采样期间3类功能区ρ（PM2.5）在空间上呈现：工业区[（89.88±49.25）μg ·m-3]>城乡结合区[（86.73±57.24）μg ·m-3]>城市市区[（70.70±44.89）μg ·m-3]，远大于植物园区[（44.36±21.54）μg ·m-3].各功能区ρ（PM2.5）秋冬季明显高于春季，冬季最高值出现在城乡结合区，春季和秋季均为工业区最高.工业区各季PM2.5中的水溶性离子浓度较高，主要的水溶性离子NO3-、SO42-和NH4+的占比之和在城市市区秋季较大（52.30%），占比之和在城乡结合区与城市市区季节相差不大.春季各功能区SO42-浓度占比最大；秋季和冬季NO3-浓度占比最大，NO3-浓度占比最高出现在秋季的城市市区（29.98%）.工业区各元素浓度明显大于其他功能区，尤其是秋季Fe元素和冬季Pb元素浓度最高，城乡结合区冬季的Si元素浓度最高，K元素在工业区和城乡结合区秋冬季浓度较高.城乡结合区和工业区PM2.5中OC和EC浓度水平相近，高于城市市区，城市市区冬季OC/EC比值大于5，说明该区域采样时段燃煤的排放占主要来源.应用受体模型化学质量平衡来源解析结果表明，二次源（硫酸盐+硝酸盐+二次有机碳）的贡献率几乎占到PM2.5源类的一半，其中二次硝酸盐是3类功能区秋冬季PM2.5首要贡献源（31.90%~39.45%），秋季贡献率高低顺序为城市市区、城乡结合区和工业区，冬季贡献率高低顺序为城乡结合区、城市市区和工业区.机动车贡献率为9.81%~26.75%，在工业区和城乡结合区贡献率较大，其中工业区的春季贡献率最大.植物园区扬尘源的贡献突出，春季最大（25.75%），秋冬季是二次硝酸盐为PM2.5首要贡献源.二次源的分配贡献结果可知，各源贡献率有明显的季节和区域变化，季节上春季各区扬尘源贡献率最大，冬季燃煤源的贡献率比春、秋季高，工业源贡献率在工业区最大，城市市区和城乡结合区移动源的贡献率最大.因此，不同功能区PM2.5组分和来源有明显的区域特征性，城乡结合区移动源和民用燃煤源对PM2.5污染应引起重视. |
| 英文摘要 |
| To explore seasonal characteristics and source apportionment in the atmosphere of different functional areas of a provincial capital city, PM2.5 samples were collected from three typical functional areas (an urban area, industrial area, and urban-rural transition area) and a botanical garden area, which served as the ambient atmospheric background site, during three seasons (spring, autumn, and winter) in 2019 in Ji'nan. The mass concentration, chemical components (water-soluble ions, chemical elements, and carbon components), and sources of PM2.5 were analyzed in all PM2.5 samples. The results showed that during the observation period, the ρ(PM2.5) spatially followed a descending sequence of industrial area[(89.88±49.25) μg·m-3]>urban-rural transition area[(86.73±57.24) μg·m-3]>urban area[(70.70±44.89) μg·m-3] and was much higher than that in the botanical garden area[(44.36±21.54) μg·m-3]. ρ(PM2.5) in each functional area in autumn and winter was significantly higher than that in spring. The highest value of ρ(PM2.5) in spring and autumn was observed in the industrial area, whereas in winter, the highest value of ρ(PM2.5) was observed in the urban-rural transition area. The mass concentration of water-soluble ions in PM2.5 was relatively high in each season in the industrial area, and the sum of the proportions of NO3-, SO42-, and NH4+ in PM2.5 was the highest in the urban area in autumn (52.30%). The sum of the proportions of NO3-, SO42-, and NH4+ in PM2.5 was similar in the urban-rural transition area and urban area. The proportion of SO42- in PM2.5 in each functional area was the largest in spring. The proportion of NO3- in PM2.5was the largest in autumn and winter, and the highest value (29.98%) occurred in the urban area in autumn. The concentration of each element in the industrial area was significantly higher than those in other functional areas. The concentration of Fe in autumn and Pb in winter in the industrial area were the highest. The concentration of Si in winter was the highest in the urban-rural transition area, and the content of K in autumn and winter was much higher in the industrial area and urban-rural transition area. The mass concentrations of OC and EC in PM2.5 in the industrial area and urban-rural transition area were similar and were higher than those in the urban area. The OC/EC ratio in winter in the urban area was greater than 5, indicating that coal-burning emissions were the main pollution source during the sampling period in this region. The results of source analysis using the chemical mass balance model showed that secondary sources (sulfate+nitrate+secondary organic carbon) accounted for almost half of the PM2.5 source apportionment. Secondary nitrate was the main contributor to PM2.5 in autumn and winter in the three functional areas (31.90%-39.45%). The contribution rate of secondary nitrate followed the descending sequence of urban area, urban-rural transition area, and industrial area in autumn and urban-rural transition area, urban area, and industrial area in winter. The contribution rate of motor vehicles was 9.81%-26.75%, which was relatively high in the industrial area and urban-rural transition area, and the highest contribution rate of motor vehicles appeared in the industrial area in spring, whereas the contribution of the dust source in the botanical garden area was the largest, especially in spring (25.75%). In the botanical garden area, secondary sources were the main contributors to PM2.5 in autumn and winter. There were marked seasonal and area-related changes in the distribution of the contribution rate of each source. Seasonally, the dust sources of the three typical functional areas were large, and the contribution of coal-burning sources in winter was higher than that in spring and autumn. The highest number of industrial sources was found in the industrial area. The largest contribution of mobile sources occurred in the urban area and urban-rural transition area. In summary, the contributions of PM2.5 and its components and source apportionment in each typical functional area exhibited notable regional characteristics. Our results suggest that mobile sources and civil coal-fired sources should be particularly scrutinized as sources of pollution in the urban-rural transition area. |
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