Study of the sediment contamination levels in a mangrove swamp polluted by a marine oil spill

Oil residues tend to persist in mangrove sediments for a relatively longer period of time than other coastal habitats because of the anoxic and water logging natures of the sediments. One typical mangrove swamp in Hong Kong SAR was polluted by an oil spill accident taken place in November 2000 with oil washed onto the shore and coated onto the mangrove canopy. The degree of oil contamination in sediments was affected by sediment texture and topography of the mangrove swamp. The substratum at different locations within the mangroves had various degree of contamination by spilled crude oil. The degree of contamination depended on the topography of the mangrove swamp and the texture of the sediment. Potential persistence of oil residues was possible in spite of the warm weather of the Pearl River Estuary region and the fact that the mangrove substratum is washed by tidal water twice a day. This is an abstract of a paper presented at the 25th Arctic and Marine Oilspill Program Technical Seminar (Calgary, Alberta 6/11-13/2003).