An update on dissolved methane distribution in the subtropical North Atlantic Ocean

Abstract. Methane (CH4) is a potent greenhouse gas and plays significant role in recent increasing global temperatures. The oceans are natural source of methane contributing to atmospheric concentrations, yet our understanding the oceanic cycle poorly constrained. Accumulating evidence indicates that part CH4 produced oxygenated surface waters as by-product phytoplanktonic activity. This study focused on subtropical North Atlantic Ocean (26? N, 80? W 26? 18? W) where distribution dissolved concentrations associated air–sea fluxes during winter 2020 were investigated. Water samples from 64 stations collected upper water column up depths 400 m. oxic mixed layer was oversaturated with ranging 3–7 nmol L?1, highest 7–10 L?1 found east transect, consistent other regions world's oceans. high anomalies be phosphate-depleted abundance ubiquitous picocyanobacteria Synechococcus Prochlorococcus elevated. Although phyla cannot excluded, this suggests cyanobacteria contribute release region. calculation further confirmed CH4. provides corroborate key play helping explain oversaturation open ocean, otherwise known “ocean paradox”.