Study On Environmental Quality Assessment Of Marine Sediment

Sediment is an important part of the integrated aqueous environment. The aqueous ecological system health will be damaged if the benthic ecological environment quality deteriorates. It was reported extensively that sediment had become the "cumulation" for pollutants in aqueous environment due to its concentrating heavy metals and POPs. Pollution in sediment has adverse effects not only to benthos, but also to the organisms at the upper food chain and human beings. In the meantime, sediment pollution is also the potential second pollution source to water environment. The assessment of marine sediment environmental quality is one of the hot spot of aqueous pollution study. The relative research is focused on the aspect of bioavailability and toxicity of pollutants in marine sediment, and the sediment quality criteria on the basis of dose-response relationship. This paper discussed the above 2 problems theoretically and practically.1. Develop the relationship between dose (bio-availability) of priority pollutants and biological response (toxicity) in marine sediment.A. Response relationship between chemical activity and toxicity of heavy metals in marine sediment.The toxicity of metals-contaminated sediment was assessed by equilibrium partitioning approach. The mechanism and process of reaction between AVS and toxic metals were studied intensively. The relationship among AVS, toxic metals contents in interstitial water and toxicity of metals were determined. It was shown that the metals contents in sediment normalized by AVS could be the practical tool for predicting and assessing chemical partitioning and bioavailability of toxic metals in sediment.B. Response relationship between PCBs contents in sediment and bio-effect of benthic fish. The test organisms (Paralichthysolicaceus) were exposed to PCBs with different spikedcontents. It was found that the EROD activities significantly mounted up with the increase of spiked quantity. Therefore, there exists a dose-response relationship between EROD activities and specific pollutant contents. The field survey proved that EROD activities in target organisms were positively correlated with PCBs contents in sediment. EROD induction infish liver by PCBs demonstrated the ability of this bio-effect index to be an available and effective indicator of exposure to PCBs in marine sediment. C.Pollutants transfer from sediment to water column and organism tissues.The eluviation of pollutants in sediment and concentration of pollutants from sediment to organism tissue were studied in order to quantitatively determined pollutants transfer. For seriously polluted sediment, it was proved that pollutants transfer across sediment-overlaying water interface and result in aqueous environmental quality decreasing. There existed apparent concentration and magnifying of benthic organisms to pollutants in sediment.2. Develop marine sediment quality criteria by integrated bio-effect database-based approach.A large number of data were obtained by laboratory tests and from literatures, including sediment chemical measurement data, benthos community data, sediment acute and chronic toxicity test data and tissue residual contents. Various identification methods were chosen to judge bio-effect of sediment. In this process, the results of laboratory tests and human health risk evaluation were combined. The integrated bio-effect database was developed on the basis of relationship between the dose of pollutants in marine sediment and biological response. The marine sediment quality criteria were calculated by a statistical method. Threshold effect level (TEL) and probable effect level (PEL) were calculated by the following equation.ine obtained marine sediment criteria satisfied the relative requirements tor environmental quality criteria. The criteria were quite different from the background criteria that were used before in China, and were comparable to the foreign sediment criteria data.The results obtained by this thesis are of great significance to marine sedi...