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

Polycyclic aromatic hydrocarbons (PAHs) in surface sediments taken from int ertidal flats in the Yangtze estuary and adjacent coastal areas were determ ined by GC-MS. The results have shown that total PAH concentration ranged f rom 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/Py r and two and three-ringed and four-ringed congeners in surface sediments. A pyrolytic origin was responsible for higher PAH concentration levels at t hree sampling sites. The degree of sediment contamination by PAHs in the st udy area is low to moderate in comparison with other estuarine and tidal fl at 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.