Recent Sedimentary Records Of Primary Production And Nutrients In The Typical Areas Of The East China Sea And The Yellow Sea

Based on the observation in the typical areas of the East China Sea and the Yellow Sea BSi ,TOC, nitrogen forms and phosphorus forms data were used as the productivity and nutrient proxies.Three major aspects are addressed: distribution of BSi ,TOC, nitrogen forms and phosphorus forms in sediment, the correlations between BSi(TOC) and phytoplankton standing stock, the correlations between phosphorus(nitrogen) forms and BSi(TOC). The major results can be summarized as following:(1) Distribution of BSi and TOCThe BSi and TOC concents in sediments were high in the west investigated region.. In sediments of Yangtzi River estuary ,the TOC concents fluctuated with the depth and without the variation regularity. BSi contents, except for an maximum at the depth of 10 cm, the contents of BSi had no significant chages.In sediments of the central part of the south yellow sea. the TOC concents decreased and the BSi concents without significant chages with the increasing depth.(2)Distribution of phosphorus and nitrogen forms in sedimentIn sediments of the Yangtzi River estuary, IMOF-N is the main forms of transferable nitrogen. In the influence of changjiang diluted water,TN and nitrogen forms was higher in Northeast. In the influence of oxidation and reduction, IEF-N ,.IMOF-N and CF-N contents decreased with the depth. TN and OSF-N contents increased at first and then decreased with the depth.De-P is the main forms of TP and Or-P, Fe-P contents is comparative lower than other forms in the Yangtzi River estuary. TP, phosphorus and nitrogen forms concents is high in the nearshore of the Yangtzi River estuary because of continental input effect。De-P is the main forms of TP, accounts for 56.45% of TP and complexity in horizontal distribution. Au-P concents were high in 123E region and coincided with primary productivity. Vertical distribution of De-P, Au-Pand TP increase significantly with depth. Or-P concents showed a tendency to increase and vertical distribution of Ex-P and Fe-P has opposite to action. Phosphorus bioavailability is only little, accounts for 10.08%-11.02% of TP.Nitrogen forms contents was high in the northwest of the south yellow sea and is similar to distribution of fine-grained components. OSF-N were the predominant forms in the research area , accounted for 85% of TP and vertical distribution decreased in the surface sediment, IEF-N,OSF-N concents showed Similar distributing characteristics. Because of continental input and sediment environmenta effect vertical distribution of CF-N showed complex. IMOF-N in sediment cores increases at first and decreases later downwards Transferable nitrogen accounts for 20% of TOC and was rela tively smaller than others.Because of the influence of depositional center phosphorus forms contents is high in the 10694,12494 sediment cores especially Ex-P contents which is closely related to mineralization of Or-P. Decomposable Fe-P contents in sediment cores are small and vary greatly with the depth which suggested terrigenous sediment had notable influence on the central part of the south yellow sea. Au-P and De-P were the main forms of TP, accounts for 50% of TP and gradually increased with the depth.(3) The correlations between phosphorus (nitrogen) forms and BSi(TOC).In sedimengt of the Yangtzi River estuary, Au-P and De-P contents correlate negatively to the BSi contents. The Ex-P and Fe-P contents in sediments had close relation with TOC. OSF-N and IEF-N contents are correlated with BSi contents positively. There was positive correlation between IMOF-N and TOC.In the central part of the south yellow sea, there was positive correlation between Or-P, Fe-P, Ex-P and BSi, as to Au-P, De-P and TOC, CF-N and BSi.The rest of nitrogen forms had no correlation with TOC and BSi in the 10694 station.(4) Recent sedimentary records of primary production and the correlations between BSi (TOC)and phytoplankton standing stockIn sediments of the Yangtzi River estuary, the vertical distribution of TOC and BSi in different in long-term changes of phytoplankton quantity, which maybe relate to hydrodynamic factors and the redox conditions. Maximum value in vertical distribution of TOC,BSi in the yellow sea were in accordance with maximum valueof phytoplankton quantity in 1960s in sediment of 10694,10294 station.In the central part of the south yellow sea and the Yangtzi River estuary sea area, the TOC and BSi contents have no correlations with the phytoplankton standing stock. But there were linear relationship between BSi and the phytoplankton standing stock in sediment of H1-18 station which remained to be studied further considering lack of dating data.