Chinaʹs Yangtze estuary: II. Phosphorus and polycyclic aromatic hydrocarbons in tidal flat sediments

Concentrations of phosphorus (P) and polycyclic aromatic hydrocarbons (PAHs) were determined in tidal flat sediments from the Yangtze estuary and Hangzhou Bay. The amount of total P in surface sediments ranges from 18.0 to 31.4 μmol g−1 along the southern coast. The spatial and temporal distribution of P in tidal flats is closely related to geomorphological location and contaminant input, especially in association with variations in hydrodynamic conditions. Speciation of P in sediments was extracted sequentially. Results show that calcium phases are dominant in the total P of tidal flat sediments, which is similar to marine sediments. The main diffusion of dissolved P is from overlying water to sediment in the coastal environment of the Yangtze estuary. diment cores from the Baoshan (BS) and Donghai (DH) sites were extracted for PAH analysis. The total concentration of PAHs ranges from 0.061 to 7.618 μg g−1 at the BS site, and from 0.005 to 2.370 μg g−1 at the DH site. The distribution of total and individual PAHs in the sediment shows a subsurface maximum, following by decreased levels to the surface and with depth. The pattern of PAH abundance suggests that there has been significant petroleum contamination in the Yangtze estuary. A few individual PAHs, such as acenaphthalene and anthracene in surface samples of the two cores, are in excess of current sediment quality criteria in the Yangtze estuary. The present study suggests that anthropogenic activities enhance contaminant inputs to the estuary.