Reconstruction Of Paleoproductivity Of The Last 200 Years In The Typical Areas Of The East China Sea And The Yellow Sea And Its Influential Factors

Horizontal and vertical distribution of paleoproductivity index (BSi,TOC) in the typical areas of the East China Sea and the Yellow Sea is analyzed, and linear regression is done to get the correlations between the contents of BSi, TOC and the phytoplankton standing crop of surface sediments in all sampling sites and sediments of different age. BSi,TOC is used to rebuild paleo-productivity of the last 200 years. According to the study, the conclusions are as follows:One: Deposit velocities of 10594, 10694, 12694 were 0.350cm/a,0.143cm/a,0.153cm/a by 210Pb, deposit histories of three stations are about 150a, 200a, 230a. Deposit velocity of H1-18 was 0.225cm/a, and deposit history is about 130a.Two: From the hotizontal distributions, we get that the contents of BSi,TOC show the diminishing tendency from north to south and from coast to distant sea. The standing crop of phytoplankton shows the same tendency.From the vertical distribution, we get that the vertical contents of BSi was steady in the South Yellow sea. Except the biggest value in 1966, the vertical contents was steady in the Yangtzi River estuary. It is obvious in the South Yellow sea The percentage of TOC shows the diminishing tendency with the increase of age, this tendency was related to mineralization and degradation of organic matter. This investigation shows that TOC/TN was between 4.60 and 12.61 in the South Yellow sea, so organic matter of the sediments belonged to organic matter of mixed source, TOC/TN exceeded 20 in the Yangtzi River estuary, so organic matter of this sea is(was) from land source.Three: The correlations between BSi, TOC and diatom, Chla are all good in the surface sediments of the South Yellow sea, the correlation between BSi and diatom is best, BSi,TOC and the biomass of phytoplankton have bad correlations. The correlations between BSi and the standing crop of phytoplankton are all good, TOC is exactly on the contrary in the Yangtzi River estuary and the Coast of Fujian and Zhejiang.The correlations between BSi and the standing crop of phytoplankton were all good in the pillar samples of the South Yellow sea, TOC is exactly on the contrary. The peak value of BSi and the standing crop of phytoplankton was coherent in history, the high value of TOC was usually in the surface, the high value of the biomass of phytoplankton and diatom were usually in the 60era and the intermediate stage of 80 era of 20th century. The high value of Chla was about the intermediate stage of 80 era, so the correlations between TOC and the standing crop of phytoplankton are bad. Except that BSi and Chla has bad correlation, BSi,TOC and the standing crop of phytoplankton have good correlations in the Yangtzi River estuary.Four: The standing crop of phytoplankton is calculated by BSi in the typical areas of the East China Sea and the Yellow Sea. The conclution is that the high value of the standing crop of phytoplankton were usually in the 10-20era, 30era, about 60era, initial period of 80era and the intermediate stage of 80era of the 19th century in the South Yellow sea. The small value were usually in the 50 era and 70 era of the 20th century. The high value of the standing crop of phytoplankton are usually in the age of 60 and 80, the end of 40 and the end of 80 of the 19th century in the Yangtzi River estuary, the small value is in the 20th century, the contents in other years were steady. This conclusion matches with the conclusion of the standing crop of phytoplankton calculated by TOC. So BSi and TOC are all used as good indexes to rebuild the paleoproductivity of the Yangtzi River estuary.The standing crop of phytoplankton is calculated by BSi and TOC have evident differences. This may be related to the low stocking efficiency of TOC in the sediments. So BSi is a better index on rebuilding paleo-productivity than TOC.Five: The correlations of different phosphorus species and BSi, TOC are better than the correlations of different nitrogen species and BSi, TOC, So different phosphorus species influenced primary productivity more greatly. The correlations of TOC, BSi and different phosphorus and nitrogen species of the South Yellow sea are better than the Yangtzi River estuary, this may be related to the peaceful hydrodynamic conditions and small particle size of the South Yellow sea, and the complicated hydrodynamic conditions and big particle size of the Yangtzi River estuary.Temperature, source entry, anchovy scales deposition and indexes of paleo-productivity, the standing crop of phytoplankton had invariably correlations. source entry and anchovy scales deposition are evident. So source entry and anchovy scales deposition influence paleo-productivity greatly.