Characteristics of heavy metals and persistent organic pollutants in PM_2.5in two typical industrial cities, North China

We collected PM(2.5)samples in the cities of Jinan and Baotou, North China. Concentrations of 9 heavy metals (HMs) (Cr, As, Cd, Sb, Pb, Ni, Cu, Zn, Mn) and 2 persistent organic pollutants [polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls, (DL-PCBs)] (POPs), were determined. The concentrations of PM2.5-bound HMs exhibited apparent seasonal characteristics in both cities. In Jinan, the highest levels of As, Cd, Sb, Pb, Cu, Zn occurred in the heating season, while, the levels of Cr, Ni, Mn peaked in the windy season. In Baotou, The order of concentrations of HMs in PM(2.5)was as follows: heating season > non-heating season > windy season. In both cities, the heating season had the highest concentrations of 17 PCDD/Fs and 12 DL-PCBs. Only a small amount of them occurred in the windy season. In Baotou, sigma PCDD/Fs and sigma DL-PCBs levels were much higher than in Jinan, except in the non-heating season. The health risk of carcinogenic metal concentrations for adults was approximately twice than that for children. Notably, the Cr risk for adults slightly exceeded the critical value in Baotou.