昌吉市冬季碳质气溶胶浓度特征、影响因素及来源

Characteristics, influencing factors and sources of carbonaceous aerosol concentration in winter in Changji City

  • 摘要: 为探究昌吉市冬季碳质气溶胶浓度特征、影响因素、来源及潜在贡献源区,基于碳质气溶胶小时数据,结合随机森林模型、正定矩阵因子分解法(PMF)及潜在源贡献因子分析法(PSCF)进行分析。结果表明,污染日有机碳(OC)和元素碳(EC)浓度分别为清洁日的1.8倍和1.4倍,其浓度均为昼低夜高,OC、一次有机碳(POC)及二次有机碳(SOC)在污染日呈显著双峰型分布,污染日SOC在碳质气溶胶增量中占主导地位,且污染日SOC的生成受前体物及生成环境的影响增大。PMF源解析表明,昌吉市碳质气溶胶的主要来源为生物质/煤炭燃烧(42.6%)、汽油车排放(26.8%)、柴油车排放(18.4%)和道路扬尘(12.2%)。污染日生物质/煤炭燃烧和汽油车排放的贡献更为突出。PSCF结果显示,清洁日碳组分的潜在源区分布在本地西南方向,污染日OC浓度主要受到本地及西南方向的影响,EC和POC则受到远距离传输源的多重影响。

     

    Abstract: Based on the hourly data of carbonaceous aerosol, this study explored the characteristics, influencing factors, sources and potential contributing regions of carbonaceous aerosol concentration in Changji City in winter, using the random forest model, positive matrix factorization (PMF) and potential source contribution factor analysis (PSCF) methods. The results showed that the concentrations of organic carbon (OC) and elemental carbon (EC) on pollution days were 1.8 times and 1.4 times those on clean days, respectively, and their concentrations were lower in the day and higher at night. OC, primary organic carbon (POC) and secondary organic carbon (SOC) showed a significant bimodal distribution on pollution days, and SOC played a dominant role in the increment of carbonaceous aerosol on pollution days. The generation of SOC on pollution days was greatly influenced by the precursors and the environmental conditions. The PMF source analysis showed that the main sources of carbonaceous aerosols in Changji City were biomass/coal combustion (42.6%), gasoline vehicle emissions (26.8%), diesel vehicle emissions (18.4%) and road dust (12.2%). Biomass combustion and gasoline vehicle emissions contributed more prominently on pollution days. The PSCF results showed that the potential sources of carbon components on clean days were distributed in the local southwest direction, OC concentration on pollution days was mainly affected by the local and southwest direction, and EC and POC were affected by multiple long-distance transport sources.

     

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