Research On The Eco-environmental Quality And Ecological Risk Evaluation Of Estuaries In Jiangsu Coast

The coastal areas of Jiangsu province lies in the middle part of the coastal economic belt of China and its economical development lags behind relatively other areas of this province, but shows a broad prospects. With the acceleration of economical development and industrialization in recent years, the eco-environment of estuaries meets the severe challenge. Closely related with social-economic development, the estuary areas have become the most dynamic areas to develop and utilize water resource, so affected most directly and sensitively by the human activities. Therefore, the ecological environment is fairly fragile and the potential ecological risk is relatively high, which make the eco-environmental protection of estuaries necessary. There are still some serious problems about the eco-environment including heavy metal pollution and eutrophication in estuaries of Jiangsu province.In the dissertation, we have observed the present environmental situation of the coastal areas of Jiangsu province about heavy metals, nutrient elements. We have studied the contribution, characteristics and contents of pollutants in the surface water and surface sediment from estuaries. The coastal environmental quality was quantitatively and qualitatively described and discussed in two main aspects, one is heavy metals and the other is nitrogen and phosphorus for both surface water and surface sediment. Then the eco-environmental effects have been considered comprehensively.After having studied the spatial distribution and correlation of heavy metals and nutrient elements in estuaries of Jiangsu province, we have found that Cd, Cu, Cr showed obviously pollution, but Pb and Zn basically not. The total phosphorus (TP) exceeds the standard levels of aquatic system several times and is higher that those of total nitrogen (TN) for nutrient elements, but the proportion of the available P is lower than that of the available nitrogen. The relationships between heavy metals, nutrientelements and organisms, grain size, major elements are complex. In general, the characteristics are that N-P and organisms have a good correlation, the same to heavy metals and constant metals, but the contrary to grain size and heavy metals, nutrient elements.We have also discussed the main factors influencing the distribution of sediments and the pollution characteristics and effects on regions (the north, the middle and the south of coast). The characteristics of pollutants are affected by properties (including organic matter and sizes), environmental conditions, human activities and creature disturbance. By analyzing the principle component, we have discussed the main factors of influencing the pollution distribution and pollution characteristics in different regions (the north, the middle and the south).The analyses of the polluted sources and the origin of contaminants are made, which result from the industrial structure and the geological structure in different districts respectively. Seen from the regions, the estuaries in south have higher nutrient elements than those in north. The contents of pollutants don't depend on the scales of estuaries, but the impact of human activities. The highest contents of heavy metals mainly present in the estuaries of Guanhe, Sheyang, which are effected obviously by industries.As the ecology of estuaries in Jiangsu province is week, the ecological risk assessment is important. The dissertation have assessed the eco-environmental effect of heavy metals and nutrient elements by using the Classical Ecological risk index of Hakanson and Geoaccumulation index (Igeo) of Miiller. Among all the estuaries in Jiangsu province, Guannan and Sheyan have the highest ecological risk of heavy metals, Liangyuguan, Dafeng and Qidong middle and Dongtai least. Nutrient elements were assessed by using the equivalent pollution index method, quoting with the sediment quality assessment standard enacted by Canadian Environmental and Energy Department. It is found that the eco-environmental risk in south estuaries is higher than those in north and contributes greatly to the eutrophication of those estuaries, while the estuaries in middle areas have relatively low ecological risk and a poor contribution to estuarine eutrophication.Based on the above facts and conclusions, the techniques and managementtreasures fit to the present conditions of the estuaries in coast of Jiangsu province are provided, which mainly include monitoring regularly, controlling source, segregation of clean water and polluted water, establishing reasonable industrial distribution and so on.