Research On The Eco-environmental Quality And Ecological Risk Evaluation Of Jiaozhou Bay In Qingdao

Jiaozhou Bay is a famous estuary for large-scale mariculture in Qingdao. With constantly increasing in fishery culture and nutrient input to the estuaries within decades,The area received a lot of pollutants, the ecological environment has been significantly changed,resulting in harmful algal blooms hitting this area frequently damage to the ecosystem. The ecological environment is fairly fragile and the potential ecological risk is relatively high,which make the eco-environmental protection of Jiaozhou Bay necessary. There are still some serious problems about the eco-environment including heavy metal pollution and eutrophication in Jiaozhou Bay. In the dissertation,We have observed the present environmental situation of Jiaozhou Bay about heavy metals,nutrient elements. We have studied the contribution,characteristics and contents of pollutants in the bottom water,surface sediments and biology. The environmental quality was quantitatively and qualitatively described and discussed in two main aspects,one is heavy metals and the other is nutrient. Then the eco-environmental effects have been considered comprehensively.After having studied the spatial distribution and correlation of heavy metals and nutrient elements in Jiaozhou Bay,we have found that Cu,Hg showed obviously pollution in surface sediments,but other heavy metals basically not. The concentration of Hg,Pb in bottom water showed obviously pollution, exceed the standard levels. The pollution of heavy metals in biology is serious. Value of heavy metals exceeded biology quality criteria,expecially As,only one station did not exceed the criteria. the content of DIN in Jiaozhou Bay and adjacent waters is very rich, about 50% of the entire body of water is measured value to the third and fourth standard, compared with the nitrogen , phosphorus pollution lighter, most stations are in line with water second standard quality.From the relevance of heavy metals of surface sediments in Jiaozhou Bay and the TOC ,we can found that only Cr and TOC exists a certain relevance, other heavy metals and organic matter correlation is not very high, which may be related to the occurrence of these elements in the state. It may also be associated with human activities and the introduction of the importation. However, there exists good correlation between heavy metals, it reflects these elements have the co-existence geochemical characteristics, Migration laws is quite similar. From the correlation between nutrients, it can be seen the relevance between SiO3-Si, DIN and PO4-P are very high. This shows that the source of three nutrients are similar. As the ecology of Jiaozhou Bay is week,the ecological risk assessment is important. The dissertation have assessed the eco-environmental effect of heavy metals in surface sediments by using the Clssical Ecological risk index of Hakanson and Geoaccumulation index of Muller. The Licun estuary have the highest ecological risk of heavy metals,the northeast of Jiaozhou Bay second. In addition, this article evaluated the heavy metals in biology by using single factor method and made the following conclusions : the content of heavy metal in biology did not exceed the evaluation criteria; The concentration of Cd in calms exceeded the maximum permissible level according to the codes of Human consumption standards. This means pollution impact of heavy-metal in clams in Jiaozhou Bay is not obvious. Except essential elements for life such as Cu, Zn have high enrichment factor of clams, the concentration coefficient of the lives of non-essential elements such as Cd, As was higher than that of other heavy metals, in particular As, which may be related to the excessive use of the pesticides and chemical fertilizers,.We have also discussed the nutrient structural and limiting factor. DIN/PO4-P is highest in the northeast of the bay and lower to the mouth. SiO3-Si/DIN is higher in the northwest and northeast and lower in center of the bay. SiO3-Si/PO4-P become low from northeast to southwest and the mouth. Phosphorus is the main limiting factor of phytoplankton and silicon is the potential.The results of calculating the eutrophication index showed that there is serious eutrophication status in survey sea. The area in eutrophication status distribute in the northeast of Jiaozhou Bay and coastal area. The percentage of dissolved inorganic nitrogen contributing to eutrophication is about 44.2% in this sea area. The percentage of dissolved inorganic phosphate contributing to eutrophication is about 31.5%. Chemical oxygen demand contributes least to eutrophication ,the contribution rate is 24.3%. The distribution of organic pollution index is similar to the distribution of eutrophication index. This distribution pattern was mainly affected by the capacity of water exchange,sewage discharge from terrestrial,the distribution and species of mariculture.