| Summary: | Seawater samples were collected in the US Beaufort Sea aboard the R/V Ukpik from 30 August to 5 September, 2015. These measurements were used to help constrain the source of methane to these waters, and by extension, the atmosphere. These seawater samples were prepared and analyzed for the dissolved concentration of methane [CH4], the stable carbon isotopes of methane (δ13C-CH4), and the natural radiocarbon content of methane (14C-CH4). New techniques were used to prepare the samples for the stable and radiocarbon isotopes of methane (Sparrow and Kessler, Limnology & Oceanography: Methods, 2017) and previously published techniques were used to determine dissolved methane concentration (Weinstein et al., Geochem. Geophys. Geosyst., 2016). The 14C-CH4 content and conventional 14C age uncertainty incorporates the collection, preparation, and measurement uncertainties. The δ13C-CH4 uncertainty is the measurement uncertainty associated with isotope ratio mass spectrometer or the cavity-ringdown spectrometer. The [CH4] uncertainty is 5.2% of the measurement.
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