%0 Journal article
%A Seltzer, Alan M.
%A Nicholson, David P.
%A Smethie, William M.
%A Tyne, Rebecca L.
%A Le Roy, Emilie
%A Stanley, Rachel H. R.
%A Stute, Martin
%A Barry, Peter H.
%A McPaul, Katelyn
%A Davidson, Perrin W.
%A Chang, Bonnie X.
%A Rafter, Patrick A.
%A Lethaby, Paul
%A Johnson, Rod J.
%A Khatiwala, Samar
%A Jenkins, William J.
%T Dissolved gases in the deep North Atlantic track ocean ventilation processes
%R 10.1073/pnas.2217946120
%J Proceedings of the National Academy of Sciences
%V 120
%N 11

%X 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.
%U http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/10525
%~  FID GEO-LEO e-docs