Carbonate system across the Antarctic Polar Front in the Drake Passage

Abstract

CO2 measurements were made across the Antarctic Polar Front in the Drake Passage during the 1998-1999 austral summer. These measurements include the partial pressure of CO2 (pCO2), pH (-log [H+]), total carbonate (TCO2), and total alkalinity (TA). Surface salinity, temperature, and pCO2 were automatically measured every two-minutes. Surface pH, TA, and TCO2 were determined every hour. Surface temperature, salinity, and nutrients showed strong variation across the polar front. SiO2 (70 mM), NO3 (15 mM), and PO4 (2 mM), for example, increased significantly going south traversing the front. The higher values of pCO2 were observed most of the cruise survey lines. Lower values of pCO2 were, however, found at the frontal zone only in early December 1998, while atmospheric pCO2 showed relatively constant values (ca 360 ppmv). The lower values of pCO2 at the frontal zone and positive correlation between pCO2 and nutrients south of the front suggest that the Antarctic Polar Front may be sink for CO2 during the cruise periods.