Distribution and partition of polycyclic aromatic hydrocarbon in surface water of the Pearl River Estuary, South China

Water samples were collected in the Pearl River Estuary in July 2002 and April 2003. The particulate and dissolved phase polycyclic aromatic hydrocarbons (PAHs) were determined. Total PAH concentrations in water samples were higher in April of 2003 (Cp: 4.0–39.1 ng/L or 445.1–1,089.9 ng/g; Cw: 15.9–184.2 ng/L) than in July of 2002 (Cp: 2.6–26.6 ng/L or 297.7–1,336.6 ng/g; Cw: 12.9–28.3 ng/L). It was found that 5, 6-ring PAHs enrich in the inner estuary samples and so did 3-ring PAHs in the July samples. Compositional differences in the suspended particulate matter (SPM) might be responsible for this observation. The partition coefficient (Kp) increased with the increasing of the particular organic carbon content of suspended particles as well as the salinity of water, decreased with the increase of the total suspended particles content of samples. A linear correlation between logKOC and logKOW was found in two sampling periods. The observed values of logKOC exceed their predicted values derived form linear free energy relationship between logKoc and logKow, which could be attributed to the nonlinear sorption of soot-like carbons in suspended particles.