Abstract
Abstract. Exchangeable organic carbon (OC) dynamics and CO2 fluxes in the Antarctic Peninsula during austral summer were highly variable, but the region appeared to be a net sink for OC and nearly in balance for CO2. Surface exchangeable dissolved organic carbon (EDOC) measurements had a 43 ± 3 (standard error, hereafter SE) μmol C L−1 overall mean and represented around 66% of surface non-purgeable dissolved organic carbon (DOC) in Antarctic waters, while the mean concentration of the gaseous fraction of organic carbon (GOC H–1) was 46 ± 3 SE μmol C L−1. There was a tendency towards low fugacity of dissolved CO2 (fCO2-w) in waters with high chlorophyll a (Chl a) content and high fCO2-w in areas with high krill densities. However, such relationships were not found for EDOC. The depth profiles of EDOC were also quite variable and occasionally followed Chl a profiles. The diel cycles of EDOC showed two distinct peaks, in the middle of the day and the middle of the short austral dark period, concurrent with solar radiation maxima and krill night migration patterns. However, no evident diel pattern for GOC H–1 or CO2 was observed. The pool of exchangeable OC is an important and active compartment of the carbon budget surrounding the Antarctic Peninsula and adds to previous studies highlighting its importance in the redistribution of carbon in marine environments.
Highlights
The ocean and the atmosphere exchange momentum, heat, gas and materials across an area of 361 × 106 km2
The salinity pattern was less variable; the higher values were located to the north of the Antarctic Peninsula, between 60 and 50◦W, whereas the lower values were found in the western sector of the Antarctic Peninsula and eastern limb of the domain (Fig. 2c)
The most saline sea-surface water was found during the ESASSI cruise, in the Weddell–Scotia confluence (34.2), whereas the less saline was observed in the western sector of the Antarctic Peninsula (33.4)
Summary
The ocean and the atmosphere exchange momentum, heat, gas and materials across an area of 361 × 106 km. The ocean and the atmosphere exchange momentum, heat, gas and materials across an area of 361 × 106 km2 These interactions play a major role in the dynamics of the Earth’s system (Siedler et al, 2001). Gas exchange plays a key role in climate regulation, as oceans have already absorbed a large fraction of anthropogenically produced CO2 (Sabine et al, 2004), the major greenhouse gas (GHG) contributing to global warming. Vast heterotrophic areas are found in the open ocean (which release CO2), fueled by allochthonous DOC inputs (Del Giorgio and Duarte, 2002), and the metabolic status of the ocean still remains under debate (Ducklow and Doney, 2013, and references therein). S. Ruiz-Halpern et al.: Ocean–atmosphere exchange of OC and CO2
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