Multi-phase distribution of organic micropollutants in Xiamen Harbour, China

Xiamen Harbour, in the Xiamen Special Economic Zone of the People's Republic of China, was studied for its water and sediment quality, by determining the levels of 16 polycyclic aromatic hydrocarbons (PAHs), 12 polychlorinated biphenyls (PCBs) and 18 organochlorine insecticides in water, suspended particulate matter (SPM), pore water and sediment samples from nine stations in the Harbour. Total PAH concentrations varied from 106 to 945 ng/l in water, <1 to 3548 ng/l in pore water, and 247 to 480 ng/g dry weight in surficial sediments. Total PCB levels varied from 0.1 to 1.7 ng/l in water, 2.7 to 34.8 ng/l in pore water, and <0.01 to 0.32 ng/g dry weight in sediments. The levels of all insecticides were in the range of 6.6-19.6 ng/l (water), 11.8-78.5 ng/l (pore water), and <0.01-0.58 ng/g dry weight (sediment). The levels of total hexachlorocyclohexane (HCHs) in sediments varied from <0.01 to 0.14 ng/g dry weight, and those of total DDTs were in the range of <0.01-0.06 ng/g dry weight. The micropollutants were present in higher levels in pore water than in surface water, due possibly to higher concentrations of dissolved organic carbon or colloids with which the hydrophobic pollutants are strongly associated. Such a concentration gradient implies a potential flux of pollutants from sediment pore water to overlying water. The levels of pollutants in sediments are one to several orders of magnitude lower than those found in 1993, suggesting their decreased inputs in recent years in the form of fresh and less contaminated material and possible degradation over a period of time. Further work is needed to quantify the levels of these contaminants in suspended particulate matter, which are currently below the limits of detection. (C) 2000 Elsevier Science Ltd.