Pollution Characteristics and Health Risk Assessment of Heavy Metals in PM2.5 of Different Air Masses During Heating Season in Tianjin

Abstract

In order to explore the pollution characteristics and health risks of heavy metals in PM2.5 in Tianjin, heavy metal samples (Pb, Cd, Cr, As, Zn, Mn, Co, Ni, Cu, and V) in PM2.5 were analyzed from November 2020 to March 2021 using the Xact-625 heavy metal online analyzer. The spatial and temporal distribution characteristics were analyzed using the HYSPLIT model, and the health risks of heavy metals were analyzed using the US EPA risk assessment model. The results indicated that the average total concentration of the 10 heavy metal elements was (261.56±241.74) ng·m-3, among which the concentrations of Cr ［converted Cr(Ⅵ)］ and As were higher than the annual average limit of the National Ambient Air Quality Standard (GB 3095-2012). According to the back trajectory results, the medium-distance transmissions from northwest areas (NO.1), the long-distance transmissions from northwest areas (NO.2), the transmissions from southwest areas (NO.3), and the transmissions from northeast areas (NO.4) were the major sources in Tianjin City. The heavy metals of different air masses presented different pollution characteristics and health risks; the concentration of PM2.5, the total concentration of the 10 heavy metal elements, and the total carcinogenic risk of the five heavy metal elements of the NO.3 air mass were the highest, whereas the total non-carcinogenic risk of the 10 heavy metal elements of the NO.2 air mass was higher than that of the other two air mass. The health risk assessment showed that Mn posed non-carcinogenic risks to children, and Cr and As presented carcinogenic risk. Meanwhile, Cd of the NO.3 air masses also presented carcinogenic risk.