| 成都市冬季3次灰霾污染过程特征及成因分析 |
| 摘要点击 2177 全文点击 859 投稿时间：2020-02-19 修订日期：2020-04-16 |
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| 中文关键词 细颗粒物 组分特征 源解析 成都市 污染成因 |
| 英文关键词 fine particulate matter component characteristics source apportionment Chengdu pollution causes |
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| 中文摘要 |
| 基于成都市大气环境超级观测站气态污染物和PM2.5中组分在线监测数据，对2019~2020年成都市3次灰霾污染过程气象要素和组分特征进行分析，采用CMB模型模拟获得研究期间PM2.5污染来源及变化趋势，剖析各污染过程成因.结果表明：① 3次污染过程均发生在相对湿度和温度持续上升，风速和边界层高度持续降低的不利气象条件下，日均相对湿度均大于70%，日均温度均大于8℃，日均风速均低于0.8 m ·s-1，日均边界层高度均低于650 m；② 3次污染过程中主要组分均为NO3-、OC、NH4+和SO42-，其中NO3-质量浓度和占比污染时段较清洁时段增长倍数均高于其他组分，分别增加了1.47~2.09倍和0.22~0.35倍，NO3-是成都市冬季PM2.5污染的关键组分；③ 3次污染过程SOR均值为0.40，NOR均值为0.27，SO2和NOx的二次转化程度较高，SO2向SO42-转化以夜间非均相氧化反应为主，NOx向NO3-转化以非均相水解反应为主；④ 3次过程变化特征略有不同，过程Ⅰ呈现出明显的二次硝酸盐主导的特征，过程Ⅱ PM2.5浓度上升过程中主要受燃煤排放影响，PM2.5浓度高值时段主要受NO3-影响，过程Ⅲ总体仍为二次硝酸盐主导的特征，但部分污染时段化石燃料燃烧源排放有所增加；⑤二次硝酸盐、二次硫酸盐、机动车和燃煤源为研究期间主要污染来源，PM2.5浓度与二次硝酸盐贡献率正相关，与扬尘源贡献率负相关. |
| 英文摘要 |
| Based on the online monitoring data of gaseous pollutants and components in PM2.5 from Chengdu super observatory of atmospheric environment, the meteorological factors and component characteristics of three haze pollution process in Chengdu from 2019 to 2020 were analyzed. The CMB model was adopted to simulate the sources and variation trends of PM2.5 pollution during the study period, and the causes of each pollution process were analyzed. The results showed that all the three pollution processes occurred under adverse meteorological conditions, where the relative humidity and temperature continued to rise and the wind speed and boundary layer height continued to decrease. The average daily relative humidity was greater than 70%, average daily temperature was greater than 8℃, average daily wind speed was less than 0.8 m ·s-1, and average daily boundary layer height was less than 650 m. During the three events of pollution, the main components were NO3-, OC, NH4+, and SO42-. Among them, the mass concentration and proportion of NO3- increased by 1.47-2.09 and 0.22-0.35 times, respectively, during the pollution period as compared to those during the clean period. NO3- was a key component of PM2.5 pollution during winter in Chengdu. During the three pollution processes, the mean values of SOR and NOR were 0.40 and 0.27, respectively, and the secondary transformation degree of SO2 and NOx was high. The conversion of SO2 to SO42- was mainly dominated by heterogeneous oxidation at night, and the conversion of NOx to NO3- was dominated by heterogeneous hydrolysis. The characteristics of the three processes were slightly different. Process Ⅰ showed evident secondary nitrate-dominated characteristics. During the period of rising PM2.5 concentration in process Ⅱ, it was mainly affected by coal emissions, but during the periods of high PM2.5 concentration, it was mainly affected by NO3-. Process Ⅲ was also a nitrate-dominated process, but emissions of fossil fuel combustion had increased during certain polluted periods. Secondary nitrate, secondary sulfate, motor vehicles, and coal combustion were the main pollution sources during the study period. The PM2.5 concentration was positively correlated with the contribution of secondary nitrate and negatively correlated with the contribution of dust source. |
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