Characteristics of the Aquatic Environment and Causative Analysis of Eutrophication in Yueqing Bay

The distribution and variational characteristics of aquatic chemical parameters in the Yueqing Bay were discussed and the effect of waste water of continental source and aquaculture pollution itself on eutrophication was analyzed based on the data obtained in August and November, 2002 and February and May, 2003. The results showed that the average concentrations of DIN and DIP in four seasons were 0.630 and 0.039 mg/dm3 respectively. The water quality of 100% investigated stations in autumn and winter were the inferior Grade Ⅳ of sea water quality standard and 90 % stations in spring and summer were poorer than Grade Ⅳ of sea water quality standard. The average nutritive indexes in each season were 4 ～9, presenting a heavy level of eutrophication. Our investigation also indicated that the discharge of industrial and agricultural waste water and the drainage of domestic sewage along the bay as well as the unorderly and excessive development of mariculture were the three main factors resulting in eutrophication in the Yueqing Bay.