Pathways of methane in seawater: Plume spreading in an Arctic shelf environment (SW-Spitsbergen)

After discharge into the water column, local water currents fed by Atlantic water, coastal water, and freshwater outflows from the fjords further determine pathways and fate of the methane. We used δ18Owater and 222Rn data to trace origin and advection of the local water masses and water mixing processes. Methane spreads predominantly along pycnoclines and by vertical mixing. During transport methane is influenced simultaneously by oxidation and dilution, as well as loss into the atmosphere. Together these processes cause the spatial variability of the anomaly and heterogeneity in δ13CCH4 in this polar shelf environment.