Spatial variation and sources of polycyclic aromatic hydrocarbons (PAHs) in surface sediments from the Yangtze Estuary, China.

The spatial distributions and sources of polycyclic aromatic hydrocarbons (PAHs) in surface sediments from the Yangtze Estuary were systematically analyzed. The results indicated significant spatial variations. The mean of ∑PAHs in different sampling times in a year varied from 128.5 ± 51.4 to 307.8 ± 108.9 ng g(-1). Samples collected during the flood season showed higher PAH concentrations and larger PAH fluctuations compared with those collected during the dry season. This variation was mainly ascribed to the change in the river flow rate. Higher values of ∑PAHs were observed in the inner estuary than the adjacent coastal area over a year because of diffusion and degradation effects. Analysis of PAH abundance revealed a predominant proportion of light PAHs with two to three rings, with phenanthrene being the most abundant. Based on principal component analysis, vehicular emissions, coal and biomass combustion were the main sources of PAHs.