Polycyclic aromatic hydrocarbons (PAHs) in riparian soils of the middle reach of Huaihe River: A typical coal mining area in China

Abstract

In the present research work, the concentration, distribution, composition, sources, potential toxicity, and ecological risk of PAHs in riparian soils of the middle reach of Huaihe River (along a 430-kilometer stream gradient) were studied. The total concentrations of PAHs varied from 210 to 39000 ng g−1, with a mean concentration of 3400 ± 8400 ng g−1 and a median value of 760 ng g−1. The middle section (Huainan-Bengbu section) with frequent coal mining and utilization activities was found to be the most contaminated region. High molecular weight (5- and 6- ring PAHs) and medium molecular weight (4- ring PAHs) PAHs were predominant. Based on the diagnostic ratios method and positive matrix factorization (PMF) model, PAHs in riparian soils were mainly originated from pyrogenic sources including vehicle emissions, and biomass and coal combustion. The calculation of total TEQBaP concentrations and risk quotient (RQ) indicated a low to moderate risk level of PAHs in most regions of the study area, but some specific sites showing high toxicity and ecological risk should be caused alarm and attention.