Eidt, Renata T.1, Kerr, Rodrigo1, Orselli, Iole B. M.1
1Laboratório de Estudos dos Oceanos e Clima, Instituto de Oceanografia, Universidade Federal do Rio Grande (FURG), Av. Itália km 8, Rio Grande, 96203-
900, RS, Brazil.
Understanding the processes of exchanges between ocean and atmosphere are extremely important when studying the global climate. The Southern Ocean presents an important role in the CO2 fluxes comprehension, due to its large oceanic area, low temperature and considerable seasonality.
Measurements of total alkalinity (AT) and total dissolved inorganic carbon (CT) from the Gerlache Strait were made for water samples collected in February 2015 (austral summer). Partial CO2 pressure in seawater (pCO2sw) was determined from AT, CT, temperature and salinity data using CO2calc; atmospheric pCO2 (pCO2atm) was obtained from Palmer Station. From ΔpCO2 and wind speed data (ECMWF-NOAA), CO2 flux was calculated using Wanninkhof (1992) exchange coefficient.
The fluxes along the Gerlache Strait showed different patterns responding to the influence of waters with distinct origins (i.e. warm waters from the Bellingshausen Sea and salty and cold waters from the Bransfield Strait). pCO2sw data ranged between 310 and 560 µatm, with the lowest values on the southwest region, a sheltered area influenced by ice melting and continental input. In general, the Gerlache Strait region acted as a weak source of CO2, with a mean flux of 1.2 ± 4.9 mmol m-2 d-1. However, the southwest area showed an average uptake of CO2 (-1.2
± 3.3 mmol m-2 d-1), whereas the northeast area acted mainly as a source of CO2 to the atmosphere (3.6 ± 5.2 mmol m-2 d-1).
As a coastal area with high biological production and strong seasonality, the Gerlache Strait represents an important spot for studies involving CO2 fluxes and its temporal and spatial variations.