Distribution and sources of polycyclic aromatic hydrocarbons in intertidal flat surface sediments from the Yangtze estuary, China

Polycyclic aromatic hydrocarbons (PAHs) in surface sediments taken from intertidal flats in the Yangtze estuary and adjacent coastal areas were determined by GC-MS. The results have shown that total PAH concentration ranged from 0.263-6.372 mg/kg in tidal flat surface sediments from the study area. Mean concentration level is 1.662 mg/kg. The concentration levels of total PAHs varied dramatically with in the region. They are characteristically at maximum near sewage discharge points. Petroleum-derived contamination may be a dominant source in the study area based on the distributions of Flu/Pyr and two and three-ringed and four-ringed congeners in surface sediments. A pyrolytic origin was responsible for higher PAH concentration levels at three sampling sites. The degree of sediment contamination by PAHs in the study area is low to moderate in comparison with other estuarine and tidal flat surface sediments elsewhere. However, anthracene and fluorene exceed the effects of low range (ER-L) values, showing a primary potential impact for the Yangtze estuarine tidal flat ecosystem.