Open AccessVertical stratification and air‐sea CO 2 fluxes in the Patagonian shelf
Author(s) -
Bianchi Alejandro A.,
Bianucci Laura,
Piola Alberto R.,
Pino Diana Ruiz,
Schloss Irene,
Poisson Alain,
Balestrini Carlos F.
Publication year - 2005
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2004jc002488
Subject(s) - oceanography , stratification (seeds) , water column , hydrography , sink (geography) , continental shelf , transect , geology , water mass , front (military) , environmental science , pycnocline , atmospheric sciences , seed dormancy , botany , germination , cartography , dormancy , geography , biology
The thermohaline structure across the tidal fronts of the continental shelf off Patagonia is analyzed using historical and recent summer hydrographic sections. The near‐summer tidal front location is determined on the basis of the magnitude of vertical stratification of the water column as measured by the Simpson parameter. Sea surface and air CO 2 partial pressures based on data from eleven transects collected in summer and fall from 2000 to 2004 are used to estimate CO 2 fluxes over the shelf. The near‐shore waters are a source of CO 2 to the atmosphere while the midshelf region is a CO 2 sink. The transition between source and sink regions closely follows the location of tidal fronts, suggesting a link between vertical stratification of the water column and the regional CO 2 balance. The highest surface values of Chl a are associated with the strongest CO 2 sinks. The colocation of lowest CO 2 partial pressure ( p CO 2 ) and highest Chl a suggests that phytoplankton blooms on the stratified side of the fronts draw the ocean's CO 2 to very low levels. The mean shelf sea‐air difference in p CO 2 (Δ p CO 2 ) is −24 μatm and rises to −29 μatm if the shelf break front is included. Peaks in Δ p CO 2 of −110 μatm, among the highest observed in the global ocean, are observed. The estimated summer mean CO 2 flux over the shelf is −4.4 mmol m −2 d −1 and rises to −5.7 mmol m −2 d −1 when the shelf break area is taken into account. Thus, during the warm season the shelf off Patagonia is a significant atmospheric CO 2 sink.