On the distribution of dissolved methane in Davis Strait, North Atlantic Ocean

Abstract

Depth profiles of dissolved methane were measured along three transects of Davis Strait and the northern Labrador Sea in October 2011. Concentrations ranged from 0.2nmolL−1 (6% saturation) in the remarkably methane depleted Baffin Bay Deep Water to 38.8nmolL−1 (1057% saturation) in localised subsurface anomalies near the Baffin Island Shelf. These anomalies may be the result of natural gas seepage and this hypothesis is supported by the distribution of potential sea surface oil slicks detected by satellite radar backscatter. In contrast, methane concentrations within the Baffin Island Current 200km to the south of these anomalies were only slightly above atmospheric equilibrium. Methane was moderately supersaturated in West Greenland Shelf Water (<200%) with a distribution consistent with a sediment source. These measurements represent the first detailed baseline study of the vertical distribution of dissolved methane in an important Canadian Arctic Archipelago outflow region.