Concentration characteristics and potential sources of polycyclic aromatic hydrocarbons in atmospheric deposition in Shanghai

To study the atmospheric deposition in Shanghai, we have collected deposition samples in August, September and October in 2014. The concentration, spatial distribution and composition of sixteen polycyclic aromatic hydrocarbons (PAHs) were analyzed. Atmospheric deposition fluxes of ∑15PAHs at eight sampling sites were also calculated. The potential sources of PAHs were apportioned by positive matrix factorization model (PMF), which could produce a quantitative interpretation. Our results indicated that the total concentrations of PAHs ranged from 0.458 μg/L to 21.013 μg/L in atmospheric deposition. Furthermore, the PAHs concentrations in dissolved phase varied from 0.174 μg/L to 0.625 μg/L, while in particulate phase from 0.275 μg/L to 20.455 μg/L. The atmospheric deposition flux of ∑15PAHs in sampling sites ranged from 0.24 μg/(m²·d)to 14.74 μg/(m²·d)and the mean deposition flux of ∑15PAHs was 2.77 μg/(m²·d). According to the apportionment results using PMF model, the first major sources of PAHs were categorized as mobile vehicle exhausts, such as gasoline car exhausts and diesel car exhausts, which constantly contribute 40.23% to the total PAHs pollution. Another four sources (residential cooking, coal combustion, oil spill and volatilization, coking and coal smelting) identified by PMF model, account for 23.73%, 14.75%, 14.35% and 6.92% respectively.