TY  - JOUR
A1  - Seltzer, Alan M.
A1  - Nicholson, David P.
A1  - Smethie, William M.
A1  - Tyne, Rebecca L.
A1  - Le Roy, Emilie
A1  - Stanley, Rachel H. R.
A1  - Stute, Martin
A1  - Barry, Peter H.
A1  - McPaul, Katelyn
A1  - Davidson, Perrin W.
A1  - Chang, Bonnie X.
A1  - Rafter, Patrick A.
A1  - Lethaby, Paul
A1  - Johnson, Rod J.
A1  - Khatiwala, Samar
A1  - Jenkins, William J.
T1  - Dissolved gases in the deep North Atlantic track ocean ventilation processes
Y1  - 2023
VL  - 120
IS  - 11
JF  - Proceedings of the National Academy of Sciences
DO  - 10.1073/pnas.2217946120
N2  - Gas exchange between the atmosphere and ocean interior profoundly impacts global climate and biogeochemistry. However, our understanding of the relevant physical processes remains limited by a scarcity of direct observations. Dissolved noble gases in the deep ocean are powerful tracers of physical air-sea interaction due to their chemical and biological inertness, yet their isotope ratios have remained underexplored. Here, we present high-precision noble gas isotope and elemental ratios from the deep North Atlantic (~32°N, 64°W) to evaluate gas exchange parameterizations using an ocean circulation model. The unprecedented precision of these data reveal deep-ocean undersaturation of heavy noble gases and isotopes resulting from cooling-driven air-to-sea gas transport associated with deep convection in the northern high lati-tudes. Our data also imply an underappreciated and large role for bubble-mediated gas exchange in the global air-sea transfer of sparingly soluble gases, including O2, N2, and SF6. Using noble gases to validate the physical representation of air-sea gas exchange in a model also provides a unique opportunity to distinguish physical from biogeochemical signals. As a case study, we compare dissolved N2/Ar measurements in the deep North Atlantic to physics-only model predictions, revealing excess N2 from benthic denitrification in older deep waters (below 2.9 km). These data indicate that the rate of fixed N removal in the deep Northeastern Atlantic is at least three times higher than the global deep-ocean mean, suggesting tight coupling with organic carbon export and raising potential future implications for the marine N cycle.
UR  - http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/10525
ER  -