Ocean-Atmosphere CO₂ Fluxes in the North Atlantic Subtropical Gyre: Association with Biochemical and Physical Factors during Spring

摘要

Sea surface partial pressure of CO₂ (pCO₂) was measured continuously in a transect of the North Atlantic subtropical gyre between Santo Domingo, Dominican Republic (18.1° N, 68.5° W) and Vigo, Spain (41.9° N, 11.8° W) during spring 2011. Additional biogeochemical and physical variables measured to identify factors controlling the surface pCO₂ were analyzed in discrete samples collected at 16 sites along the transect at the surface and to a depth of 200 m. Sea surface pCO₂ varied between 309 and 662 μatm, and showed differences between the western and eastern subtropical gyre. The subtropical gyre acted as a net CO₂ sink, with a mean flux of −5.5 ± 2.2 mmol m−2 day−1. The eastern part of the transect, close to the North Atlantic Iberian upwelling off the Galician coast, was a CO₂ source with an average flux of 33.5 ± 9.0 mmol m−2 day−1. Our results highlight the importance of making more surface pCO₂ observations in the area located east of the Azores Islands since air-sea CO₂ fluxes there are poorly studied.