| With the reconstruction of paleoproductivity were finished in many sea areaaround the world, the study of reconstruction were began in shelf sea area recently.Based on the enhance of human activity during the last200years, Biogenic silica(BSi) and Total Organic Carbon (TOC) in this paper had been disscused. The EastChina Sea and the Yellow Sea was influenced by air-sea interaction, and highsedimentation rates offer high resolution records to register both marine and humanactivities changes.We investigated the horizontal and vertical distribution ofpaleoproductivity by sediments along two transects of this shelf sea area, located at35°N and the Yellow Sea warm current, they had been named transect A (includingA01，A02，A03，A04，A05) and transect B (including B01，B02，B03，B04，B05，B06，B07). According to the study, the conclusions are as follows:One: The Deposit velocities of stations showed the minishing tendency fromcoast to distant sea which is as same as the result of research before.Two:By the analysis of the linear fit analysis, correlation analysis and stabilityanalysis, we can learn that the content of BSi could be used as a index to reconstructthe paleoproductivity in the Yellow Sea and the East China Sea during the last200years. According to the equation of linear regression of the diatom and BSi contents,the paleoproductivity in each core could be calculated. It is clear that thepaleoproductivity was relatively low and stable in staion A03, which may beinfluenced by the Yellow sea warm current in the long-tern. However, thepaleoproductivity in station A01，A02, A04，A05of section A, showed morevariable.Compared with A04and A05,the content of paleoproductivity of station A01and A02was higher, as well as, the mirror images were showed in both side of stationA03, which may be influenced by the sway of the Yellow sea warm current: duringthe influence of the Yellow sea warm current, the content of paleoproductivity waslower, on the other hand, the content of it was higher. In section B the content ofpaleoproductivity was relatively stable, which may be caused by the same factor of heYellow sea warm current and so on. Cluster analysis was used to divided the area into two water masses：Group oneincluding A01，A02，B01，B02,which were influenced by the anthropogenic dischargemainly; Group two including A03，A04，A05，B03，B04，B05，B06，B07, whichwere influenced by the ocean itself change.In station A02and A04the content of BSi could be used as a index to reconstructthe paleoproductivity during long-term and the results were good to reaction thechange of the environment in the same time.Three: In this paper the marine-derived organic carbon (Ca) was used toreconstruct the paleoproductivity for the first time. Based on the analysis of the linearfit analysis, correlation analysis and stability analysis, we can learn that themarine-derived organic carbon (Ca) was better than the Total Organic Carbon (TOC)in the aspect of reconstructing of paleoproductivity.Surface and core sediment samples were collected to study the spatialdistributions of Total Organic Carbon (TOC) in sediments and to evaluate its potentialfor paleoproductivity reconstructions. The results showed that the TOC resource frommixed-source of organics and the importation of terrestrial organic carbon willseriously interfere with the biogeochemical process. In this paper, we calculated themarine-derived organic carbon (Ca) by the ratio of TOC/TN, and compared with thephytoplankton population.It is shows that TOC content is higher than Cacontent instations and the content of TOC increased generally in cores, in contrast, Cacontentwas relatively stable. As well as, Cahad a more positive relationship with the livingphytoplankton biomass than TOC. To further confirm the applicability and credibilityof the reconstruction potential of Cawe used the method of Tunnicliffe et al. to studythe stability of Cain sediments. The survey indicated that there was almost nodegradation of Cain sediments over the past200years Therefore, it is concluded thatCain sediments may be used as an index to reconstruct paleoproductivity fluctuations.According to the equation of linear regression of the standing crop and Cacontents,the paleoproductivity in each core could be calculated. It was showed that thepaleoproductivity was relatively high and unstable in station A02, which may beinfluenced by the terrestrial input. However, the paleoproductivity in stations far awayfrom the mainland of section A, showed relatively stable, In section B the trend ofpaleoproductivity was relatively identical, which were increased during the last200years. The stability of Cain core A02and A04were used to study the stability of Cainlong-term. It was showed in core A04that, there was a inflection turn up in about850years before present. It was no good to the reconstruction, the reason need to bestudied further.Four:Based on the calculation,we found that the marine-derived organiccarbon(Ca) burial flux was different in the area of the Yellow Sea, the station A02inthe coast had the highest content of85.91μmol/a·cm2,as well as, the station A05inthe distant sea had the lowest content of12.04μmol/a·cm2.With the comparation between the paleoproduction which had rebuilt beforeand the organic carbonin burial flux of sediment from the different area in the anoxicsediments of the East China Sea and the Yellow Sea, we found that the paleoproduct-ivity which were reconstructed before and the marine-derived organic carbon(Ca)burial flux were more related than total organic carbon(TOC). It was showed that, inmost stations in the southern Yellow Sea, the paleoproductivity and the Caburial fluxhas a close relation to each other, which means the the marine-derived organic carbon(Ca) burial flux can reflect the paleoproductivity well. On the other hand, in a fewstations, the paleoproductivity and the Caburial flux has not a close relation to eachother, which may be caused by the lowness of preservation efficiency of the paleopr-oductivity... |
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