Towards a method for high vertical resolution measurements of the partial pressure of CO 2 within bulk sea ice

Abstract

Fluxes of atmospheric CO 2 have been reported over sea ice during winter and spring. These fluxes are partly driven by the gradient of the CO 2 concentration between sea ice and the atmosphere. We present a new non-destructive method to measure the pCO 2 of bulk sea ice at its in situ temperature. This method is based on an equilibration procedure between sea ice and a standard gas of known CO 2 concentration. The concentration is measured by gas chromatography with a precision of 5%. Tests were performed on artificial standard sea ice and confirmed the reproducibility of the technique in the range of precision of the gas chromatograph. To test the accuracy of this method, the first profiles of pCO 2 measured in bulk sea ice are reported and compared with direct in situ measurements of brine pCO 2 over depth-integrated intervals.