Characteristics and Sources of Metals in TSP and PM2.5 in an Urban Forest Park at Guangzhou

Urban forest parks play important roles in improving environments, protecting biodiversity and even public welfare. Aerosols, including total suspended particles (TSP) and particulate matter with aerodynamic diameter less than 2.5 mu m (PM2.5), were simultaneously collected in an urban forest park (Dafushan) at Guangzhou, southern China, from January 2012 to December 2013. The concentrations of 12 metals (Al, Cd, Co, Cr, Cu, Hg, Mn, Mo, Ni, Pb, Se, and Zn) in both TSP and PM2.5 were quantified using an inductively coupled plasma-mass spectrometer. The origins and possible sources of the studied metals in the PM2.5 and TSP were evaluated using the crustal enrichment factors and the principal component analysis, respectively. The results showed that Dafushan urban forest park was polluted by PM2.5 rather than by TSP. The PM2.5 and TSP in the forest park exhibited seasonal patterns with significantly higher contents in the dry season compared with the rainy season. The metals Al, Zn, Pb were the most abundant, while Hg was the lowest metals in the aerosols. The ratios of PM2.5/TSP ratio indicated that the metals were predominant in the finer particles (PM2.5). The crustal enrichment factors indicated that Cd, Cu, Mo, Pb, Se and Zn in the aerosols originated from anthropogenic sources, while Al and Mn were mainly of crustal origin. The principal component analysis implied that industrial activities, traffic-related emissions, and soil dust were the main possible sources of the metals in both PM2.5 and TSP in Dafushan forest park.