Air–Water Greenhouse Gases Exchange in Surface Waters of Deception Island (South Shetland Archipelago, Antarctica): Assessment of Drivers of Spatial Variability

Abstract

Greenhouse gases (GHGs) such as Carbon Dioxide (CO2), Methane (CH4), and Nitrous Oxide (N2O) play critical roles in global climate change. CO2 dominates due to its high concentration and long atmospheric lifetime, while CH4 and N2O also exert strong heat‐trapping effects despite shorter residence times. Deception Island, in the Southern Ocean, combines active volcanism with extensive penguin colonies, offering a unique setting to quantify natural GHG sources. This study provides concentrations and fluxes of GHGs in an inner bay, coastal and external ocean fringes and freshwater systems to assess the role of volcanic and biological activity on the emissions. Sampling included measurements of partial pressure of CO2 (pCO2), CH4, N2O and biogeochemical variables, such as Dissolved Oxygen, pH, Total Alkalinity (AT), Dissolved Organic Carbon, Temperature (T) and Salinity (S). Results revealed high spatial variability in GHG concentrations in marine systems, where pCO2 ranged from 181 to 25,000 μatm, CH4 exceeded 400 nM and N2O varied from negligible levels to 50 nM. Overall, most areas acted as net GHG sources to the atmosphere, with maximum fluxes of CO2 and CH4 in volcanic sites reaching 1,300 and 0.5 mmol m−2 d−1, respectively. Elevated CH4 (>50 mmol m−2 d−1) and N2O (>2 mmol m−2 d−1) effluxes were also found in endorheic ponds located inside penguin colonies, thereby indicating that these birds play a significant role in natural GHG emissions. These findings highlight that complex geological and biological processes drive significant GHG emission variability in the region and underscore the need to refine global estimates from remote environments.