中国南部四背景地区春季大气碳质气溶胶特征与来源

春季分别同时在中国南方4个背景地区(海南尖峰岭、香港鹤嘴、浙江临安和云南腾冲)进行大气加密观测实验,并分析其大气中PM2.5质量浓度及其碳质颗粒组分(有机碳(OC)、元素碳(EC)和左旋葡聚糖).结果表明,各区域背景站点由于受不同污染源及传输过程影响而呈现出不同的特征:西南部腾冲站点与东部临安站点由于分别受到生物质燃烧和化石燃料燃烧等一次污染源的主导影响,而形成高OC、EC水平特征,且经受体示踪物方法估算腾冲站点受生物质燃烧对其OC的贡献均值可达到73%;尖峰岭站点由于二次污染及活跃的生物活动的共同作用,表现了高OC/EC比值及低碳质颗粒物浓度的特征,而鹤嘴站点则主要受海洋气团影响呈现出低碳质颗粒浓度与两两呈高度相关的特点,反映了其所在区域春季的背景特征.

Characteristics and sources of carbonaceous aerosols in spring at four background sites in South China

Intensive atmospheric measurements were conducted in spring simultaneously at four background sites in South China: Jianfengling (JFL) on Hainan Island, Hok Tsui (HT) in Hong Kong, Lin’an (LA) in Zhejiang province and Tengchong (TC) in Yunnan Province. PM2.5 mass concentrations and carbonaceous species, including organic carbon (OC), elemental carbon (EC) and levoglucosan (LG), were determined. These species exhibited distinct characteristics at each site due to different pollution sources and transport processes affecting the various sites. Higher OC and EC levels were found at TC and LA, indicating that these sites were under significant regional-scale influence by primary emissions, such as biomass burning and fossil fuel combustion, associated with long-range transport. The contribution of biomass burning to OC was estimated to be as high as 73% at TC, using a simplified receptor based model. High OC/EC ratios and low carbonaceous species levels at JFL may have resulted from secondary processes and primary biogenic emissions, while low carbonaceous aerosol loadings and good correlations between different species at HT reflected the background pollution level on the regional scale.