The Distribution Of Nitrogen，phosphorus Forms And The Relationship With The Total Phytoplankon In The Yellow Sea And The East China Sea Continental Shelf

Surface sediments of the Yellow Sea and the East China Sea continental shelf,columnar sediments of typical sea area were the main research object in this paper.There were four aspects: the plane, vertical distribution of different nitrogen,phosphorus forms and their characteristics; comparative analysis of distribution ofnitrogen and phosphorus forms in typical sea area sediments; the relationshipbetween different nitrogen, phosphorus forms and the total phytoplankton; thechanges of different nitrogen and phosphorus forms in about two hundred yearsdeposition time series in the Yellow Sea and the East China Sea continental shelf andtheir impact factors by the means of the210Pb dating method. The main results wereas follows:1. The distribution of different nitrogen, phosphorus forms and their characteristics inthe Yellow Sea and the East China Sea continental shelf(1) High content of transferable nitrogen (TF-N) appeared in the central of southYellow Sea and they accounted for16.81%of total nitrogen (TN). IMOF-N was theadvantage form of TF-N in surface area and its distribution presented a trend ofgradual increase from inshore to offshore. However, the distribution of IEF-Npresented an opposite tendency. CF-N distributed more evenly over the whole surveyarea. The content of OSF-N in the north was higher than that in the south and thehighest content appeared in the central of south Yellow Sea. For phosphorus forms:Fe-P presented a trend of gradual decrease from inshore to the open sea. De-Pdistributed uniformly in the whole survey area, except in the central of Yangtzeestuary waters. Au-P and Or-P decreased gradually from inshore to offshore. Thehighest contents of TP and Ex-P appeared near the Yangtze estuary waters.(2) The vertical distribution of different fractions of nitrogen and phosphorus intypical sea area varied. There was a wide variation in different nitrogen forms of theYangtze estuary, compared with that in the central South Yellow Sea; the averagecontents of Or-P and De-P in Yangtze estuary were significantly lower than that in the central of south Yellow sea. The vertical distribution of TP changed little in the SouthYellow Sea and the Yangtze estuary, the content of Au-P in H1-18was much lowerthan that in the central of south Yellow sea; In Sanggou Bay, the contents of TF-N, TNand biological available phosphorus in the upper core sediment were higher than thatin the bottom of the column.(3) Due to different environmental conditions and sediment sources, thedistribution of nitrogen and phosphorus forms in different sediment conditionspresented different characteristics. In this survey, the contents of Or-P, OSF-N andDe-P in surface sediments from Sanggou Bay Culture Zones were higher than that inthe South Yellow Sea and the Yangtze estuary, but the contents of Fe-P, IMOF-N weremuch lower than that in the South Yellow Sea and the Yangtze estuary. Sanggou Baywas engaged in farming activity for a long time, which may result in the formation ofanaerobic sediments, and anaerobic environment can contribute the iron phosphaterock to be reduced and dissolved.2. The decadal variability of nitrogen and phosphorus forms from the Yellow Sea andthe East China Sea continental shelf in about two hundred years(1) Since the1960s, the contents of TN, TF-N, IEF-N, OSF-N, TP, Ex-P and Or-Pincreased fluctuating in the central south Yellow sea, which showed that human lifesewage and the pollutants of industrial, agricultural production had a great influenceon the contents of nitrogen and phosphorus in sediments with the development ofcoastal economic in that period.(2) The contents of TF-N, IMOF-N, TN, TP and Ex-P in the Yangtze estuary had agood correspondence with river runoff and sediment discharge in recent years, whichindicated that the change of water and sediment further influenced the contents ofnitrogen and phosphorus forms in the sediments.(3) The contents of Ex-P and Fe-P in10694and12694stations decreased graduallysince the1850s, which may be associated with the traffic diversions of Yellow River in1855. In1855, the Yellow River swung back into the Bohai Sea, which reduced thesediment loading into the Yellow Sea.(4) Due to farming activities and industrial production, the contents of variousnitrogen and phosphorus forms in Sanggou Bay increased gradually since the1960s.Industrial production and human activities brought a lot of nutrients into Bay, whichincreased the contents of nitrogen and phosphorus forms significantly. 3.The relationship between different nitrogen, phosphorus forms and the totalphytoplankton in the Yellow Sea and the East China Sea continental shelf(1) IEF-N, IMOF-N and BSi in surface and columnar sediments in the centralSouth Yellow Sea were correlated significantly, while the relevance of BSi and variousforms of nitrogen were not obvious in Yangtze estuary and along the coast of Fujianand Zhejiang. IEF-N, IMOF-N and BSi were correlated significantly in Sanggou Bay,while the relevance of BSi and CF-N, OSF-N were not obvious. Thus IEF-N andIMOF-N had a greater contribution on the total phytoplankton.(2) The forms of phosphorus had a good correlation with BSi in the central SouthYellow Sea. TP, Or-P and BSi were correlated significantly along the coast of Fujianand Zhejiang. However, the relevance of BSi and various forms of nitrogen were notobvious in Yangtze estuary, except Au-P. Compared with other phosphorus forms, Ex-P,Fe-P and Or-P had a correlation with BSi. Fe-P, Ex-P, and Or-P were the advantageforms in sediments and they accounted for61.2%and71.0%of the total phosphorus inSanggou Bay, respectively. Potentially biological available phosphorus all had somerelevance with BSi. Fe-P, Ex-P, and Or-P had a greater contribution to the totalphytoplankton. Through the nutrient regeneration on sediment-water interface,potentially biological available phosphorus would promote the growth ofphytoplankton and affect the aquatic environment eutrophication and primaryproductivity.