资源环境科技发展态势分析平台

Although particulate matter (PM)-driven haze is a common phenomenon in many Chinese cities, studies on the sources of its key components, such as organic carbon (OC) and elemental carbon (EC), are poorly constrained. In this study, PM with aerodynamic diameters less than 10 (PM10), 2.5 (PM2.5), and 1m (PM1) were collected at an urban site in the core city of the Pearl River Delta region in summer 2013. The average PM10, PM2.5, and PM1 mass concentrations were 10928.4, 57.715.0, and 50.913.2g/m(3), respectively. A PM-driven haze bloom-decay process was observed from 9 to 14 July and studied based on radiocarbon (C-14) and stable nitrogen isotope (N-15). The C-14 results revealed that 87% of EC and 53% of OC in PM2.5 were derived from fossil sources on a typical summer day (9 July), while these values fell to 79% and 40% on 12 July and 76% and 29% on 13 July, respectively, due to the invasion of nonfossil-enriched air masses from rural/suburban areas. In addition, a N-15-derived model showed that nonfossil sources contributed 5% of NH3 on 9 July, which increased to about 80% on 12 and 13 July. However, the N-15-NO3- values were relatively stable, probably because of the large area of overlap in N-15-NOx from biomass burning and traffic exhaust. To our knowledge, this work is the first study to report both daily C-14 and N-15 signals in China and identify nonfossil sources from rural/suburban areas as triggers of summer haze.