Carbonate system properties in the Gerlache Strait, Northern Antarctic Peninsula (February 2015): I. Sea-Air CO2 fluxes

Hydrographic and carbonate system properties were determined in the Gerlache Strait-a coastal site in the Northern Antarctic Peninsula (NAP)-during early February 2015. It was part of an effort to monitor changes in marine inorganic carbon chemistry in Antarctic coastal zones. Here we describe surface observations performed during the NAUTILUS I cruise and compare results with earlier studies in the region. The focus of this first part of this study is to describe the spatial patterns of sea-air carbon dioxide (CO2) fluxes and relating the results with physical-chemical and biological parameters. In order to determine the CO2 fluxes, we use several available parameterizations for estimation of the gas transfer velocity coefficient, thus providing a range of the results' uncertainties. Contrasting with results found twenty years ago, the Gerlache Strait was estimated here to be a monthly net source for CO2 of 0.50±0.45 mol m−2 month−1 during February 2015, based on shipboard wind measurements and Wanninkhof's (2014) gas transfer velocity relationship. That was probably driven by to warm water intrusions in combination with a phytoplankton community mainly dominated by small flagellates (particularly cryptophytes). Yet, in order to determine whether the region acts as an annual sink or source of CO2, there is a need for additional studies focusing on short time-scales throughout a year.