Vertical distributions of nitrogen and phosphorus in sediment cores of Zhelin Bay

The main objects of this thesis are to describe the vertical distributions and historical developmental tendency of nitrogen and phosphorus forms in the sediments at nine key sampling stations of Zhelin Bay.The results showed that except for S2 and S6 where are located in Sanbaimen northwest of the bay and the center of a large-scale cage-fish culture,respectively,vertical profiles of TOM(total organic nitrogen),TKN(Kjeldhal nitrogen) and phosphorus forms in all other stations generally presented such a characteristic with three stages of deposition-decomposition-accumulation resulted from diagenesis.Some nitrogen and phosphorus forms in S2 and S6 did not decrease but increase in the cores below 10 cm,indicating the fast accumulation of pollutants resulted from high pollution and weak water exchanging in these waters.Vertical bio-disturbance from zoo-benthos might be one of the most important factors to cause fluctuant change of concentrations of nitrogen and phosphorus forms with depth in deposition and decomposition stages.However,vertical bio-disturbance affected NH+4 the most significantly.Au-P(authigenic phosphorus) and OP(organic phosphorus) mirrored with each other below the subsurface,suggesting that a transformation between them is not the only way of phosphorus redistribution,and other forms may be related with that.No mirror relationship between Au-P and OP found in the subsurface might be because of the decomposition of microbials.