There are very few isotopic measurements of N₂O in the Atlantic Ocean, with only a handful of studies published that have collected such data. While concentration measurements are important for characterizing the distribution of N₂O and are somewhat standard on long-term research cruises, measurement of the isotopic composition of N₂O offers much more information about its formation pathways. A suite of around 450 extracted gas samples taken in the 1980s [Transient Tracers in the Ocean (TTO) and South Atlantic Ventilation Experiment (SAVE) cruises] are being measured for the isotopic composition of N₂O and its site preference. In addition to ‘bulk’ δ¹⁵N and δ¹⁸O measurements on N₂O, measurements of the intramolecular site preference (SP) are being made (referring to the difference in δ¹⁵N between the central alpha and beta N atoms), and offer novel process-level insights into N₂O production pathways. Making these measurements across large spatial and depth scales will help characterize the ways that N₂O is produced and consumed in the Atlantic Ocean, which will help improve global models of marine N₂O emissions. Pilot measurements of N₂O using TTO tanks from a North Atlantic site showed a characteristic profile with depth, with interesting decoupling between isotopic measurements that may reflect active N₂O cycling in a region where this has been suggested to occur. Measuring the isotopic composition of N₂O in North Atlantic samples could help characterize the sources of N₂O, with possible comparisons between these samples collected in the 1980s and current measurements in areas of deep water formation.

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