Distribution And Controlling Factors Of Surface Seawater Partial Pressure Of CO₂ In The Northern Yellow Sea During Winter

Because of the unique geographical structure of Shelf sea and the adjacent land, subject to the impact of human activities, the source / sink mechanism of CO2 is more complex. But for the Chinese area the carbon cycle and its mechanism are still relatively weak.Distribution and controlling factors of surface seawater partial pressure of CO2 (pCO2) were determined in the northern Yellow Sea during winter based on the data obtained using continuous underway measurements of pCO2 and related parameters in hydrology, chemistry and biology during January 2007.The results show that in winter the pCO2 ranged from 203μatm to 683μatm, with an average value of 408μatm. The region that is influenced by the Liaonan coastal current acted as a sink of atmospheric CO2, while the coastal region located in the north of Shandong Peninsula(west of 122oE ),characterized by high turbidity due to high suspended solids transported by Bohai circulation,acted as a strong source and the maximum of pCO2 reached 683μatm. But on the whole the northern Yellow Sea acted as a weak source of atmospheric CO2 during winter mainly because the most part of the northern Yellow Sea was full of Yellow Sea Mixing Water that was oversaturated in pCO2.In a word, during winter the pCO2 was mainly controlled by the seawater temperature, carbonate system balance and biological activity i.e. higher temperature and higher DIC concentration in response to higher pCO2, respectively, and higher Chl-a level associated with lower pCO2. Especially, in the Liaonan coast the pCO2 was significantly affected by the intense biological activity, and the pCO2 of the coastal region located in the north of Shandong Peninsula which hosted high turbidity was mainly controled by higher DIC level and terrestrial influence.the northern Yellow Sea is a source of the atmospheric CO2, and the carbon flux at the sea-atmosphere interface is about4.11×104tC in winter. The area influenced by Yellow Sea Mixing Water account for 50.1% of the sounce althoung its area reach 82% .Becauce of biological activity the area influenced by the Liaonan coastal current acted as a sink of atmospheric CO2 and it accounted for 97.3%.