Pollution Characteristics of Polycyclic Aromatic Hydrocarbons in Unsaturated Zone of the Different Workshops at a Large Iron and Steel Industrial Site of Beijing, China

摘要

The distribution, compositions, sources and ecological risk for polycyclic aromatic hydrocarbons (PAHs) in industrial fields at a large iron and steel enterprise are discussed. Maximum Sigma PAHs concentrations in soils of different workshops ranged from 17.50 to 11266.80 mg.kg(-1). The Sigma PAHs concentrations of the field could classify three categories due to different discharge ways and combustion condition: 1000 mg.kg(-1), 10-1000 mg.kg(-1), 10 mg.kg(-1). The spatial distribution of BaP concentration in the coking topsoil was affected by fugitive emissions significantly. Peak values of PAHs occurred in silt lens in 20-30 m depth indicated that pore size radius and conductivity of unsaturated zone played a critical role in the vertical distribution. The strong linear correlation between the multiple organic contaminants indicated that benzene series worked as co-solvents and competitors in unsaturated zone to promote PAHs migration. Nap and Phe were the most abundant compounds in the coking and coal stockyard sites, while Fla, BbF, Pyr, Phe and Chry predominated in other workshops affected by different sources in which coal combustion was the primary source of PAHs. The calculated TEQ of the coking site was found highest and BaP was the most concerning pollutant of the field since the values accounted for 57.8-64.4% of total PAHs in the different workshops.