研究报告

  • 王恬爽,牛笑应,文惠,陈杨,王鑫.兰州地区大气污染的化学组成及来源解析[J].环境科学学报,2022,42(11):351-360

  • 兰州地区大气污染的化学组成及来源解析
  • Chemical composition and source attribution of air pollutants in Lanzhou
  • 基金项目:国家自然科学基金(No.42025102)
  • 作者
  • 单位
  • 王恬爽
  • 兰州大学大气科学学院, 半干旱气候变化教育部重点实验室,兰州 730000
  • 牛笑应
  • 兰州大学大气科学学院, 半干旱气候变化教育部重点实验室,兰州 730000
  • 文惠
  • 兰州大学大气科学学院, 半干旱气候变化教育部重点实验室,兰州 730000
  • 陈杨
  • 兰州大学大气科学学院, 半干旱气候变化教育部重点实验室,兰州 730000
  • 王鑫
  • 兰州大学大气科学学院, 半干旱气候变化教育部重点实验室,兰州 730000;天津大学地球系统科学学院, 表层地球系统科学研究院,天津 300072
  • 摘要:为探究大气污染的特征,于2020年5月—2021年4月在中国西北部的兰州市区采集了总悬浮颗粒物样品227个,利用离子色谱仪、热/光碳分析仪对主要水溶性离子、元素碳(EC)和有机碳(OC)的质量浓度进行了测定.结果显示,兰州地区大气总悬浮颗粒物质量浓度均值为(376.7±974.8) μg·m-3,高于国家环境空气质量二级标准(NAAQS),呈昼低夜高的变化特征主要是由于兰州地区夜间大气多处于静稳状态导致的污染物累积效应.水溶性阴、阳离子按质量浓度排序为NO3->SO42->Cl-、Ca2+>NH4+>Na+>K+>Mg2+,其中二次离子(NO3-、SO42-、NH4+)占总水溶性离子的62.68%,不同季节的气象条件导致了水溶性离子不同的季节特征差异;NO3-/SO42-比值均大于1,说明兰州地区大气污染以移动源为主;另外OC/EC比值均大于2,说明整个采样期间均有SOC生成.最后利用正定矩阵因子分解模型(PMF)确定了兰州地区大气污染的6种主要来源:交通源、生物质燃烧源、道路扬尘源、土壤扬尘源、燃煤源和二次气溶胶源,其中,道路扬尘源及二次气溶胶源对兰州地区春季及冬季大气污染的贡献显著.
  • Abstract:To explore the characteristics of air pollutants, we collected 227 TSP samples in the center of Lanzhou in northwest China from May 2020 to April 2021. The major water-soluble ions and mass concentration of elemental carbon (EC) and organic carbon (OC) were measured by the ion chromatography and thermal-optical carbon analyzer. The results exhibited that the mean TSP concentration was (376.7±974.8) μg·m-3 in Lanzhou, which was higher than that of the 2th National Ambient Air Quality Standard (NAAQS). The air pollutants also exhibited higher values in the nighttime than that in the daytime, which may resulted in the accumulation processes due to the stable meteorological condition in the nighttime. The average concentrations of ionic abundances exhibited a trend of NO3->SO42->Cl- for anions, and Ca2+>NH4+>Na+>K+>Mg2+ for cations. The fractional secondary ions (NO3-, SO42- and NH4+) accounted for 62.68% of the total water-soluble ions, which were mainly dominated by the local meteorological conditions in different seasons. The ratio of NO3-/SO42- (> 1) indicated that the air pollutants in Lanzhou mainly originated from local traffic sources. In contrast, the OC/EC ratios (> 2) exhibited significant SOC formation processes during the entire sampling period. Finally, we used a positive matrix factorization (PMF) model to explore the potential sources of air pollutants in Lanzhou. The results indicated a six-factor/sources solution, which mainly included traffic source, biomass burning, road dust, soil dust, coal burning, and secondary aerosol formation processes. The road dust and secondary aerosol formation processes were significantly dominant in the spring and winter seasons.

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