PAHs in the surface water and sediments of the middle and lower reaches of the Han River, China: Occurrence, source, and probabilistic risk assessment

Abstract

Polycyclic aromatic hydrocarbons (PAHs) pose versatile risks to the environment and human health. However, studies on their occurrences, spatial distributions, seasonal variations, possible sources and potential risks of the Han River are still not clear. In this study, 16 PAHs were investigated in the surface water and sediments from 15 sampling sites of the Middle and Lower Reaches of the Han River during the dry, normal, and flood seasons. It was found that the sum concentration of PAHs (ΣPAHs) determined by GC-MS ranged from 18.3 to 146.8 ng/L (mean 77.4 ng/L) in surface water, while it was 137.1–1478.4 ng/g (mean 679.6 ng/g) in sediments. The two to three rings PAHs in surfer water and four-five-ring in sediments PAHs comprised the majority of the detected compounds. The level of PAHs in dry season was higher than that in the flood and normal seasons, and the distributions of PAHs varied substantially along the river without clear trend in surface water and sediments. The sources of PAHs in surface water and sediments were mainly from biomass and coal combustion, followed by petroleum combustion. The human health risk of PAHs were evaluated using the risk entropy method of Kalf in surface water, and the mean effects range-median quotient method in sediments, respectively. Overall, the potential health risks caused by PAHs are still acceptable with special concerns about certain specific issues.