Distribution and Controlling Factors of Surface Seawater Partial Pressure of CO2 in the Northern Yellow Sea during Autumn
|School||Ocean University of China|
|Keywords||northern Yellow Sea pCO2 controlling fact|
Because of the unique geographical structure of the 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 autumn based on the data obtained using continuous underway measurements of pCO2 and related parameters in hydrology, chemistry and biology during October 2007.The results show that in autumn the pCO2 ranged from 354μatm to 435μatm, with an average of 395μatm. The Liaonan coastal area acted as a source of atmospheric CO2. But in the coastal area north of Shandong Peninsula, both sources and sinks of the atmospheric CO2 exist: the pCO2 was oversaturated in the area strongly influenced by the input of Bohai Sea coastal water and terrestrial materials, whereas it was undersaturated in the area with strong biological activity. Because of the strong biological activity, the central region occupied with the Yellow Sea Mixing Water acted as a large sink of atmospheric CO2 during autumn. On the whole, the northern Yellow Sea acted as a weak source of atmospheric CO2 during autumn.During autumn the pCO2 was mainly controlled by the biological activity. Higher temperature and higher DIC concentration in response to higher pCO2, respectively higher Chl a level associated with lower pCO2. Especially, in the central region 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 controlled 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 about 2.27×103tC in autumn. The area influenced by Bohai Sea coastal water account for 10% of the source although its area reach 0.4×104km2. Because of biological activity the area influenced by the Yellow Sea Mixing Water acted as a sink of atmospheric CO2 and it accounted for 99%.