The Study Of Phytoplankton And Biosilicon In The Yellow Sea And The Bohai Sea

Phytoplankton are the main primary producers in the ocean.They can convert inorganic carbon into organic carbon through photosynthesis.They can pass up the food chain to higher levels of nutrition.They can sink to the bottom of the ocean and be preserved by means of phytoplankton deposition,pellet packing settlement of phytoplankton fecal pellets,and net settlement of transparent extracellular aggregates(TEP),and then the rapid increase of CO2 concentration in the atmosphere is slowed down.Diatoms as the main groups of phytoplankton and primary producers,account for about 20%of the world’s primary production and about 40%of marine primary production,the equivalent of all organic carbon content produced by rain on the earth.As a necessary nutrient for the growth and reproduction of diatoms,silicon is absorbed and utilized by diatoms to form the cell wall of diatoms,becoming the main source of marine biological silicon(BSi).The silicon imported from the land source is repeatedly absorbed and used by diatoms,which are eventually preserved in the sea floor with the cell wall of the dead diatoms and become a huge mineral of silicon.Diatoms accumulate carbon at the same time as they deposit silicon,forming major Marine sinks.Therefore,the biological carbon pump is also often called the "biological silicon pump" in the ocean.Therefore,the study of spatial and temporal distribution of BSi is of great significance to the carbon cycle and silicon cycle,and the research results can provide scientific basis for national CO2 emission reduction and marine fishery resources policy formulation.This paper takes the Yellow Sea and Bohai Sea as the research object.Phytoplankton samples and BSi samples from the Yellow Sea and Bohai Sea in the spring of 2014,the summer of 2015,the autumn of 2014 and the winter of 2016 are determined by microscopy and double leach method respectively.The spatial and temporal distribution characteristics of phytoplankton abundance,community structure and BSi content in the Yellow Sea and Bohai Sea are systematically analyzed(including the characteristics of plane distribution and vertical distribution and seasonal variation).Combining the yellow sea cold water mass flow,explore the main factors controlling the distribution of the BSi with the temperature,salinity,nutrient,chlorophyll,and the same voyage phytoplankton abundance and community structure of correlation analysis.The creative results are:(1)The Yellow Sea cold water mass made the water of 30m-50m presented high salinity and low temperature in the sea of 122°E-124°E,34°N-39°N in the summer.(2)The content of biosilicon was measured by the double leach method proposed by Ragueneau et al.,and the characteristics of the distribution of BSi in 2014-2016 were obtained:the average concentration of biosilicon in the Yellow Sea and the Bohai Sea was the highest in winter and the lowest in spring.In the vertical direction,it was the highest in winter and the lowest in spring.The horizontal distribution is highest in the Bohai sea,and the nearshore is higher than the outer sea.(3)The abundance of diatom cells was mainly related to hydrological features and current distribution in the Yellow Sea and the Bohai Sea,and the distribution of temperature and salinity had some influence on it.