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成都冬季PM2.5化学组分污染特征及来源解析
摘要点击 330  全文点击 115  投稿时间:2018-05-07  修订日期:2018-07-12
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中文关键词  成都  细颗粒物  水溶性离子  OC/EC  昼夜差异  源解析
英文关键词  Chengdu  PM2.5  water-soluble ion  OC/EC  day-night difference  source apportionment
作者单位E-mail
吴明 南京信息工程大学大气物理学院, 气象灾害教育部重点实验室, 气候与环境变化国际合作联合实验室, 气象灾害预报预警与评估协同创新中心, 中国气象局气溶胶与云降水重点开放实验室, 南京 210044 279462024@qq.com 
吴丹 南京信息工程大学环境科学与工程学院, 江苏省大气环境与装备技术协同创新中心, 江苏省大气环境监测与污染控制高技术研究重点实验室, 南京 210044  
夏俊荣 南京信息工程大学大气物理学院, 气象灾害教育部重点实验室, 气候与环境变化国际合作联合实验室, 气象灾害预报预警与评估协同创新中心, 中国气象局气溶胶与云降水重点开放实验室, 南京 210044  
赵天良 南京信息工程大学大气物理学院, 气象灾害教育部重点实验室, 气候与环境变化国际合作联合实验室, 气象灾害预报预警与评估协同创新中心, 中国气象局气溶胶与云降水重点开放实验室, 南京 210044 tlzhao@nuist.edu.cn 
杨清健 南京信息工程大学大气物理学院, 气象灾害教育部重点实验室, 气候与环境变化国际合作联合实验室, 气象灾害预报预警与评估协同创新中心, 中国气象局气溶胶与云降水重点开放实验室, 南京 210044  
中文摘要
      2017年1月1~20日在成都地区分昼夜对PM2.5进行连续膜样品采集,并在实验室测定了其主要化学组分(水溶性离子和碳质组分)的质量浓度.观测期间,PM2.5的平均质量浓度为(127.1±59.9)μg·m-3;总水溶性离子的质量浓度为(56.5±25.7)μg·m-3,其中SO42-、NO3-和NH4+是最主要的离子,质量浓度分别为(13.6±5.5)、(21.4±12.0)和(13.3±5.7)μg·m-3,一共占到了水溶性离子的85.6%;有机碳(OC)和元素碳(EC)的平均质量浓度分别为34.0 μg·m-3和6.1 μg·m-3,分别占PM2.5质量浓度的26.8%和4.8%.昼夜污染对比显示,PM2.5白天和夜晚质量浓度分别为(120.4±56.4)μg·m-3和(133.8±64.0)μg·m-3,夜间污染更为严重.SO42-、NO3-和NH4+白天浓度高于夜间,这与白天光照促进了二次离子的形成有关;而Cl-、K+、OC和EC浓度夜间明显升高,可能是受夜间煤和生物质燃烧排放增加的影响.通过对近年来成都冬季PM2.5化学组分的研究进行文献总结和比较后发现,SO42-浓度显著降低,从2010年的50.6 μg·m-3降低到2017年的13.6 μg·m-3;而NO3-浓度变化不大,维持在20 μg·m-3左右.PM2.5中离子酸碱平衡分析表明,成都冬季PM2.5由于NH4+的相对过剩而呈现出碱性,与以往呈偏酸性结果存在差异.对成都冬季NO3-/SO42-的比值进行计算,NO3-/SO42-平均值为1.57,表明移动源对PM2.5污染影响更大.OC与EC的相关性表明,白天和夜间OC与EC的相关系数分别为0.82和0.90(P<0.01),OC与EC来源具有一致性.SOC估算结果显示,白天和夜间SOC浓度分别为8.5 μg·m-3和11.9 μg·m-3,占到OC的28.1%和31.8%.K+/EC平均值为0.31,并且K+与OC之间相关系数为0.87(P<0.01),说明生物质燃烧对成都冬季碳质气溶胶有一定影响.主成分分析表明,成都冬季PM2.5主要来源于燃烧源(燃煤、生物质燃烧等)、二次机污染源以及土壤和扬尘源,其贡献率分别为32.8%、34.5%和21.5%.
英文摘要
      Day-night PM2.5 samples were continuously collected in Chengdu from January 1 to 20, 2017, and the concentrations of major chemical components (water-soluble ions and carbonaceous components) were measured in the laboratory. During the observation period, the average mass concentration of PM2.5 was (127.1±59.9) μg·m-3. The mass concentration of water-soluble ions was (56.5±25.7) μg·m-3 and SO42-, NO3-, and NH4+ were the most dominant ions with a concentration of (13.6±5.5), (21.4±12.0), and (13.3±5.7) μg·m-3, respectively, accounting for 85.6% of the water-soluble ions. The average mass concentrations of organic carbon (OC) and elemental carbon (EC) were 34.0 and 6.1 μg·m-3, respectively, accounting for 26.8% and 4.8% of the PM2.5 mass concentration, respectively. The comparison of the average day-night concentration shows that the daytime and nighttime mass concentrations of PM2.5 are (120.4±56.4) and (133.8±64.0) μg·m-3, respectively, and that the nighttime pollution is more serious. The SO42-, NO3-, and NH4+ concentrations are higher during the day than at night, which is related to daytime light, which promotes the formation of secondary ions. The Cl-, K+, OC, and EC concentrations increase significantly, which may be affected by increased emissions from coal and material combustion. Based on the literature review and comparison of the winter chemical composition of PM2.5 in Chengdu in recent years, the SO42- concentration significantly decreases from 50.6 μg·m-3 in 2010 to 13.6 μg·m-3 in 2017. The NO3- concentration changes little; it is maintained at~20 μg·m-3. The analysis of the acid-alkali ion balance shows that PM2.5 in Chengdu is alkaline due to the relative overgrowth of NH4+, which is different from previous partially acidic results. The average value of NO3-/SO42- is 1.57. Mobile sources have a greater impact on the PM2.5 pollution in Chengdu in winter. The correlation coefficients of OC and EC between daytime and nighttime are 0.82 and 0.90, respectively (P<0.01), which indicates that the OC and EC sources are consistent. The SOC estimation shows that the SOC concentrations during the day and night are 8.5 μg·m-3 and 11.9 μg·m-3, respectively, accounting for 28.1% and 30.8% of the OC, respectively. The K+/EC average value is 0.31 and the correlation coefficient between K+ and OC is 0.87 (P<0.01), indicating that biomass combustion has a certain influence on the carbonaceous aerosol in Chengdu in winter. The principal component analysis shows that the winter PM2.5 in Chengdu mainly originates from combustion sources (coal burning, biomass burning, etc.), secondary inorganic sources, and soil and dust sources. The contribution rates are 32.8%, 34.5%, and 21.5%, respectively.

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