Research On The Health Assessment For Hainan Dongzhai Port Mangrove Wetland Aquatic Ecosystem

This paper studies on the aquatic ecosystem of Dongzhai Port Mangrove Wetland. Based on the methodologies of field investigation and comprehensive evaluation, this paper collects samples of water qualities, sediments, aquatic plants and aquatic animals from the aquatic ecosystem to make experimental analysis, then explores the pollution levels of each impact factor, potential danger from human, and effect on present health conditions of the whole water ecosystem, finally builds the comprehensive evaluation method of genetic algorithm fuzzy coupling to make an extensive assessment on the water ecosystem of Hainan Dongzhai Port Mangrove Wetland. It is of great value to establish research foundation for further protection of Dongzhai Port Mangrove Wetland.The research conclusions are as follows:(1) From an overall perspective, marine water quality of Dongzhai Port Mangrove Wetland has been quite seriously polluted. Therein, the organic pollution is rated degree 6, within the range of severe pollution. General eutrophication reaches degree 4, attached to a high level. Heavy metal pollution in seawater comes to a slight level, whose average content order is Zn>Cr>Pb>As>Cu>Cd>Hg.(2)In Dongzhai Mangrove Wetland sediments, AVS and SEM contents range widely in spatial variation, from 0.001 to 9.300μmol/g and from 0.053 to 1.363μmol/g respectively. The horizontal distribution shows decrease trend from inner harbor to the open area. Based on SEM-AVS and(SEM-AVS)/foc models, the evaluation indicates that most sediments are free of potential ecological risk.(3)Among all the heavy metals in Dongzhai Mangrove Wetland sediments, Cu, Zn, Cr and Ni are seriously polluted. In terms of SQGs ecological assessment evaluation principles and Toxic Unit principles, those heavy metals except Ni are unable to cause adverse bio-toxicity effects. Principal component analysis turns out that main pollution sources in Dongzhai Port are sanitary sewage and swine wastewater. The enrichment coefficient order of heavy metals in mangrove plants is: Cd > Cu > As > Ni> Zn> Hg> Cr> Pb.(4)In Dongzhai Port Mangrove Wetland, heavy metal content in three kinds of benthonic animals are more or less overproof. MPI model shows that compared with other two benthonic animals, turritella is more capable of accumulating heavy metals. THQ health assessment analysis declares normal ingestion of these three animals cannot bring healthy risk for human beings while the safe maximum is 292.9g wet weight per day. Mn and V standard concentration in aquatic products are 12.371 mg/kg and 0.526 mg/kg, respectively.(5)In Dongzhai Port Mangrove Wetland aquatic ecosystem, water quality is in inferior condition, sediments in moderate level, animals and plants in favorable situation. As the whole, the water ecosystem stays in a medium healthy state.According to detailed discussions on four parts of aquatic ecosystems of mangrove wetland and comprehensive assessments on the final model, water pollution was diagnosed as being relatively serious, and sediment quality was damaged, which are two health problems of aquatic ecosystems of mangrove wetland. In response to these problems, protection and management countermeasures were proposed, aiming to restore healthy aquatic ecosystems of mangrove wetland.