Concentrations, Sources, and Health Risks of PM2.5 Carrier Metals in the Beijing Urban Area and Suburbs

Abstract

To explore the differences in pollution characteristics, sources, and health risks of PM2.5 carrier metals in urban and suburban areas in Beijing, daily PM2.5 samples were collected from Haidian and Daxing from June to November 2017 and the concentration of PM2.5 and 13 constituent metals were analyzed. The sources of these 13 metal elements were analyzed by positive matrix factorization (PMF), and the health hazards of a subset of 9 metals were evaluated using health risk assessment. The results showed that the concentrations of PM2.5 and 10 metal concentrations in the urban area including Cr, Co, Mn, and Ni were significantly different from those in suburban areas (P<0.05). The source analysis results show four key sources, although their relative contributions vary slightly between urban and rural areas. In urban areas, the main sources are motor vehicles (51.2%), coal burning (19.1%), dust (19.3%), and fuel oil (10.4%); in the suburbs, sources are motor vehicles (47.9%), coal burning (22.6%), dust (20.2%), and electroplating (9.3%). The results of the health risk assessment showed that all metal HQ values in the suburbs were less than 1, and there was no non-carcinogenic risk. Ni and Pb in urban areas, and Cd, Co, Ni, and Pb in suburban areas, do not present a cancer risk, while the R values of As (2.77×10-5), Cd (2×10-6), Co (1.76×10-6), and Cr(Ⅵ) (7.88×10-6) in urban areas and As (8.34×10-6) and Cr(Ⅵ) (4.94×10-6) in suburban areas present some risk of cancer.