Field monitoring of toxic organic pollution in the sediments of Pearl River estuary and its tributaries

Field monitoring of the toxic organic compounds (PCBs, PAHs, organochlorine pesticides) in the top sediments of Pearl River Estuary and its up-streams were made. It was found that the highest concentrations of these toxic org anic compounds occurred in the sediment sampled at Macau inner harbor (ZB01 3),which is a sink of suspended fine particles transported from the upstrea m waterways. Because of the affinity of the hydrophobic organic compounds ( PAHs, PCBs) for the solid phase, these fine particle depositions led to acc umulation of these compounds in the sediment of Macau. The atmospheric dry deposition may be another source of the toxic organic pollution in the sedi ment.