Sea ice and the air-sea exchange of CO2

The objective of this thesis was to improve the state of knowledge concerning the inorganic carbon dynamics, including the precipitation of CaCO3 in sea ice and its significance for the polar carbon cycle as well as to obtain improved estimates of the diurnal and long-term CO2 flux on small scales during the winter-spring-summer transition. To study the exchange of CO2 between sea ice and the atmosphere as well as the biogeochemical parameters and the spatial and temporal distribution of ikaite in sea ice during different seasons, three field studies were conducted in the Arctic and Antarctic. High pCO2 values in sea ice of up to 3900 μatm were observed. The resulting fluxes ranged between -3.41 and 9.5 mmol m-2 d-1. Ikaite was found mostly in the uppermost layers of sea ice. Based on the observations the efflux from Arctic sea ice to the atmosphere can be expected to result in a flux of several Tg C a-1. The findings in this thesis support the concept of the sea ice driven carbon pump.