[Sources and Health Risks of Heavy Metals in Atmospheric PM_2.5 Based on APCS-MLR and PMF Models]

Atmospheric PM_2.5 samples were collected from Nan Kang City, Jiangxi Province, in four seasons from October 2018 to July 2019 to explore the pollution characteristics, sources, and health risks of heavy metals. The contents of 11 heavy metals (Cu, Fe, Zn, Mn, Cd, Co, As, Ba, Pb, Cr, and Ti) were determined using inductively coupled plasma mass spectrometry (ICP-MS), and the pollution characteristics of Cu, Fe, Zn, Mn, Cd, Co, As, Ba, and Pb were analyzed. Combined with enrichment factor analysis, multivariate analysis (maximum variance rotation factor analysis), absolute principal component linear regression (APCS-MLR), and positive definite matrix factor (PMF) models, the sources of heavy metals in atmospheric PM_2.5 were quantitatively analyzed, and the human health risks of these elements were evaluated. The results showed that the average mass concentration of PM_2.5 in the study area during the sampling period was 46.98 μg·m^-3, which exceeded the national ambient air quality secondary standard, with the highest concentration observed in winter. The concentrations of the nine heavy metals were ranked as follows: Fe > Zn > Pb > As > Mn > Cu > Ba > Cd > Co. The results of enrichment factor analysis showed that the content of most metal elements in atmospheric PM_2.5 in the study area exceeded the environmental background value of soil in Layer A of Jiangxi Province. Except Fe and Ba, the other heavy metals were relatively enriched in the environment and were greatly affected by human activities. Factor analysis showed that the heavy metal pollution sources of atmospheric PM_2.5 in the study area mainly fell into four categories: motor vehicle sources, industrial sources, coal burning sources, and natural sources; Mn, Cu, and Zn were mainly from motor vehicle sources; Co was mainly from industrial sources represented by the furniture factory; As, Cd, and Pb were mainly from coal burning; and Fe and Ba were mainly from natural sources. APCS-MLR and PMF model analysis showed that the pollution sources caused by human activities (motor vehicle sources, industrial sources, and coal sources) had a higher contribution rate, and the contribution rate of coal sources in the two models ranged from 20-40%. Health risk assessment analysis showed that Cu, Pb, Zn, Mn, Cd, Co, and As did not have non-carcinogenic risks, and the non-carcinogenic risks were in the order of children > adult men > adult women. As and Mn had potential carcinogenic risks for all three groups, and the carcinogenic risk for adult men was the highest.