Abstract: By adopting GC/MS techniques, this paper analyzed the vertical distribution of 16 priority polycyclic aromatic hydrocarbons (PAHs) proposed by US EPA in a dated 0-20 cm sediment core from Qinghai Lake in Northwest China, and identified the possible sources of the PAHs. The total PAHs (sum of 16 the priority PAHs, TPAHs) concentration in the core ranged from 495.1 to 1172.5 ng·g^-1, and had an increasing trend from deeper layer to surface layer. The vertical profile of the sediment PAHs in Qinghai Lake was basically similar to that in the East China Sea and the Pearl River Estuary, but clearly different from that in developed countries. The sediment PAHs in Qinghai Lake were dominated by 2-3 rings PAHs (including naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, and anthracene), accounting for 72.4%±8.9% of TPAHs on an average. The sediment PAHs in Qinghai Lake were mainly originated from the long-distance atmospheric transport resulting from low temperature combustion of domestic coal and woods, but the PAHs from high temperature process (such as vehicle emission) had an obvious increasing trend in recent years.

Key words: Earthworm, Methamidophos, Acetochlor, Cu, Combined pollution, Ecological toxicity