Dissolved methane in the Beaufort Sea and the Arctic Ocean, 1992–2009; sources and atmospheric flux. (7th November 2016)

• Record Type: Journal Article
• Authors: Lorenson, Thomas D.; Grienert, Jens; Coffin, Richard B.
• Other Names: Wickland Kimberly guestEditor.; Hamdan Leila guestEditor.
• Is Part Of: Limnology and oceanography. Volume 61(2016)Supplement 1
• Page Start: S300
• Page End: S323
• Publication Date: 2016-11-07
• Subjects: Limnology -- Periodicals; Oceanography -- Periodicals; Océanographie; Limnologie; Limnology; Oceanography; Computer network resources; Périodique électronique (Descripteur de forme); Ressource Internet (Descripteur de forme); Periodicals; 551.4805
• DOI: 10.1002/lno.10457
• Languages: English
• ISSNs: 0024-3590

Abstract

Abstract: Methane concentration and isotopic composition was measured in ice‐covered and ice‐free waters of the Arctic Ocean during 11 surveys spanning the years of 1992–1995 and 2009. During ice‐free periods, methane flux from the Beaufort shelf varies from 0.14 mg CH4 m −2 d −1 to 0.43 mg CH4 m −2 d −1 . Maximum fluxes from localized areas of high methane concentration are up to 1.52 mg CH4 m −2 d −1 . Seasonal buildup of methane under ice can produce short‐term fluxes of methane from the Beaufort shelf that varies from 0.28 mg CH4 m −2 d −1 to 1.01 mg CH4 m −2 d −1 . Scaled‐up estimates of minimum methane flux from the Beaufort Sea and pan‐Arctic shelf for both ice‐free and ice‐covered periods range from 0.02 Tg CH4 yr −1 and 0.30 Tg CH4 yr −1, respectively to maximum fluxes of 0.18 Tg CH4 yr −1 and 2.2 Tg CH4 yr −1, respectively. A methane flux of 0.36 Tg CH4 yr −1 from the deep Arctic Ocean was estimated using data from 1993 to 1994. The flux can be as much as 2.35 Tg CH4 yr −1 estimated from maximum methane concentrations and wind speeds of 12 m/s, representing only 0.42% of the annual atmospheric methane budget of ∼ 560 Tg CH4 yr −1 . There were no significant changes in methane fluxes during the time period of this study. Microbial methane sources predominate with minor influxes from thermogenic methane offshore Prudhoe Bay and the Mackenzie River delta and may include methane from gas hydrate. Methane oxidation is locally important on the shelf and is a methane sink in the deep Arctic Ocean.