广州市PM_(2.5)总碳稳定碳同位素特征及来源解析

Stable carbon isotope characterization and the source of total carbon in Guangzhou PM_(2.5)

含碳气溶胶对气候和环境具有重要影响,是大气PM_(2.5)中重要组成成分。本研究于2017—2018年秋季(9—10月)和冬季(12—1月)在广州市采集了123个PM_(2.5)样品,进行总碳浓度(TC)和稳定碳同位素(δ^(13)C)组成分析。结果表明,采样期间广州市秋、冬季TC浓度分别为2.2~14.9和2.4~23.4μg/m^(3),δ^(13)C分别为–27.68‰~–24.75‰和-26.96~-24.59‰,均呈现出秋低冬高的变化趋势。根据样品的δ^(13)C分析结果,结合贝叶斯模型以及后向轨迹聚类分析等方法对广州TC的源解析结果表明,采样期间广州市大气PM_(2.5)中TC秋、冬季主要来源为机动车尾气和生物质燃烧,其贡献秋季分别为52.40%和36.30%,冬季分别为62.30%和18.10%,秋季生物质燃烧贡献约是冬季2倍。

Carbonaceous aerosols have an important impact on climate and environment and are the major component of atmospheric PM_(2.5).In this study,a total of 123 PM_(2.5) samples were collected in Guangzhou in the fall(September-October)and winter(December-January)of 2017-2018,and the concentration of total carbon(TC)and the stable carbon isotopecomposition(δ^(13)C)of PM_(2.5) samples were measured.Based on that the δ^(13)C values of different carbon sources are different,the carbon source of aerosols in Guangzhou were identified using sample δ^(13)C results combined with Bayesian model,backward trajectory,clustering analysis and other methods.The results showed that both TC concentration and δ^(13)C value of aerosols in Guangzhou exhibited a trend of low in fall and high in winter.The calculation of the Bayesian model suggested that the main carbon sources of aerosols were motor vehicle exhaust and biomass,with contributions of 52.40% and 36.30% in fall and 62.30% and 18.10% in winter,respectively.That is,the contribution of biomass combustion was approximately one times higher in fall than in winter.