Distribution and ecological risk assessment of polycyclic aromatic hydrocarbons in surface sediments and soils from Dishui Lake and its water exchange areas

Twenty-three surface sediment samples were collected from Dishui Lake and its surroundings, and 16 polycyclic aromatic hydrocarbons (PAHs) were analyzed using GC-MS. The distribution characteristics, possible sources and ecological risk were investigated. The results show that the concentrations of total PAHs range between 11.49 ng·g^-1 and 157.09 ng·g^-1 with a mean value of 66.60 ng·g^-1 in sediments from Dishui Lake, which is lower than the mean value in the catchment area but higher than that in the drainage area. Median and high molecular weight PAHs (4 rings, 5-6 rings) are the dominant compounds compared to the low molecular weight PAHs (2-3 rings) in surface sediments and soils from the lake's surroundings, while in Dishui Lake low and high molecular weight PAHs are the dominator. Based on the PAHs molecule ratios, using principal component analysis and multiple line regression, a combustion source is diagnosed in the lake's surroundings, while the mix sources of leakage of petroleum and combustion are found in Dishui Lake. Ecological risk assessment result indicates that PAHs in the sediments and soils in Dishui Lake and its water exchange areas pose little biological adverse impact.