珠江三角洲秋季生物质燃烧对有机气溶胶的贡献

Contribution of autumn biomass burning to organic aerosol in the Pearl River Delta region

本研究基于2018年和2019年秋季在珠江三角洲地区的两次外场观测,应用热脱附-化学电离飞行时间质谱(FIGAERO-ToF-CIMS)获取了高时间分辨率(每小时)的生物质燃烧示踪物左旋葡聚糖的浓度数据,并估算出生物质燃烧对有机气溶胶(OA)的贡献值.结果表明,秋季珠江三角洲地区城市站点和区域站点的左旋葡聚糖平均浓度分别为(0.07±0.08)和(0.14±0.12)μg/m^(3),呈现区域站点高于城市站点的空间分布特征以及早晨和夜间出现峰值的日变化特征.观察到两个站点的左旋葡聚糖与CO和乙腈之间相关性较低,但与OA之间呈现显著正相关关系.进一步基于受体示踪物法估算出生物质燃烧对OA的平均贡献分别为7.4%(城市站点)和11.4%(区域站点),且两个站点均显示出生物质燃烧对OA的贡献在夜间明显高于白天.

In this study,we applied thermal desorption chemical ionization Time-of-Flight mass spectrometer(FIGAERO-ToF-CIMS)to obtain high temporal resolution(i.e.,hourly)measurements of levoglucosan,which is a widely-used tracer for biomass burning emissions.Using the dataset,we estimate the contributions of biomass burning to organic aerosol(OA)at an urban and a regional site in the autumn of Pearl River Delta(PRD)region.The results demonstrated that the average concentrations of levoglucosan at the urban and regional sites in the autumn PRD region were(0.07±0.08)and(0.14±0.12)μg/m^(3),respectively.We show that concentrations observed at the regional site were higher than the urban site.The diurnal variation of levoglucosan peaked in the morning and at night at both sites.It was observed that levoglucosan was poorly correlated with CO and acetonitrile at both sites,whereas significantly positive correlation was obtained with OA.The average contributions of biomass burning to OA were further estimated based on the tracer method to be 7.4%(urban site)and 11.4%(regional site),respectively,with significantly higher contributions at night than during the day.