Methane concentration and stable isotope ratios in seawater and sea ice, Utqiagvik shelf, Alaska

Arctic seawater was collected at two sites close to Utqiagvik, North Slope, Alaska on 7, 9, 11 and 15 April 2016 in the Beaufort Sea. Site "Elson Lagoon" (EL) was located North of Utqiagvik (7.4.2016, 71.334° N, -156.363° W), covered with 1.5 m thick sea ice and shallow with approximately 1.5 m depth. Water was collected from a depth of 1.5 m in a narrow layer of water between the sea ice and the sediment. Site "Ice Mass Balance Buoy" (IMB) was located 1 km offshore of Utqiagvik (7.4.2016, 71.373° N, -156.548° W, and 9.4.2016 - 15.4.2016, 71.372° N, -156.540° W). This site was characterized by 1 m thick fast ice cover and a water depth of approximately 7 m. Water was collected at five depths from 1 to 6.5 m.