PM2.5/PM10-bound PAHs in Hotan city: Concentrations, sources, and contribution to •OH

The air pollution in Hotan, Xinjiang is serious and the high concentration of polycyclic aromatic hydrocarbons (PAHs) cannot be ignored. Studies on the characteristics of PAHs in the region are still limited. In this paper, PM10 and PM2.5 samples were collected from the urban area of Hotan in summer and winter, and the concentrations, sources and contributions to hydroxyl radicals (& BULL;OH) of 12 PAHs were analyzed. The mean concentrations of PM2.5/PM10-bound PAHs were much higher in winter (150 & PLUSMN; 38.8 ng/m3 and 156 & PLUSMN; 38.1 ng/m3) than in summer (6.34 & PLUSMN; 6.28 ng/m3 and 7.64 & PLUSMN; 6.75 ng/m3), with greater contributions from medium and high molecular weight PAHs. PAHs are mainly derived from vehicle emissions, coal and biomass combustion, with coal combustion making the largest contribution to & BULL;OH concentrations. The combination of air mass trajectory clustering and potential source contribution factor analysis (PSCF) revealed that long-range transport contributed less to the PAHs content, and local domestic source emissions dominated. Studies have shown a significant positive correlation between PAHs and & BULL;OH concentrations, indicating that PAHs are oxidatively toxic to humans. Controlling PAHs emission in winter in Hotan and reducing the concentration of PAHs in respirable particulate matter will help to reduce the damage to human health.