Source-specific health risks of PM2.5-associated trace metals: A comparative study of the Yangtze River Delta and Pearl River Delta regions in China

J. Xie1, L. Jin1, X. Luo2, J. Li3 and Xiangdong Li*,1

1 Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong

2 International Center for Ecology, Meteorology, and Environment, School of Applied Meteorology, Nanjing University of Information Science and Technology, China

3 State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, China

cexdli@polyu.edu.hk

PM2.5 pollution has become one of the most severe environmental problems in China in recent decades, and caused a wide range of health issues. For health-oriented air pollution control, it is vital to rank the contribution of different emission sources according to the health risks posed by hazardous components in PM2.5, such as trace metals. In this study, we investigated the variations of PM2.5-associated metals from March 2016 to February 2017 in two densely populated regions of China - the Yangtze River Delta (YRD) and the Pearl River Delta (PRD) across urban-suburban-rural gradients. The major emission sources of metals were evaluated by the Positive Matrix Factorization (PMF) model, and quantitatively apportioned to the health risks on the basis of the concentrations of bioaccessible metals extracted by simulated lung fluids. The results showed that the particulate trace metal profiles reflected the land-use gradient within each region, with the highest concentrations of anthropogenically enriched metal (e.g., Cu, Pb, As, Cd, and Zn) at the suburban-industrial site of the YRD and at the semirural-industrial site of the PRD due to the urban and industrial activities. The estimated pulmonary bioavailability of trace elements was generally high for As, Mn and V (>60%), moderate for Co, Ni, Cu and Cd (20%-60%), and low for Fe, Zn, and Pb (<20%). The resulting carcinogenic and non-carcinogenic health risks posed by these elements were around 1.4 times higher in the YRD than in the PRD region. Arsenic was the dominant contributor to the total excessive cancer risks of these elements in both regions. Non-traffic combustion (coal/biomass/waste) was the dominant contributing source of metal-posed cancer and non-cancer risks in both regions, except for traffic emission as the largest contributor in the suburban-industrial site in the YRD. Our comprehensive analysis of two key regions in China provided region-specific insights into the health risks of PM2.5-associated trace metals in linkage to their major emission sources.

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