Methane and Dissolved Organic Matter in the Ground Ice Samples from Central Yamal: Implications to Biogeochemical Cycling and Greenhouse Gas Emission

• Main Authors: Petr B. Semenov, Anfisa A. Pismeniuk, Sergei A. Malyshev, Marina O. Leibman, Irina D. Streletskaya, Elizaveta V. Shatrova, Alexander I. Kizyakov, Boris G. Vanshtein
• Format: Article
• Language: English
• Published: MDPI AG 2020-11-01
• Series: Geosciences
• Subjects: permafrost; biogeochemical cycling; climate change; greenhouse gas emission; dissolved organic matter; ground ice
• Online Access: https://www.mdpi.com/2076-3263/10/11/450

Permafrost thawing leads to mobilization of the vast carbon pool into modern biogeochemical cycling through the enhanced release of dissolved organic matter (DOM) and production of greenhouse gases (CO₂ and CH₄). In this work, we focus on the study of methane and DOM distribution and genesis in the ground ice samples of thermodenudational exposure in the Central Yamal (Russian Arctic). We propose that the liberation of the ice-trapped CH₄ and generation of CO₂ by DOM mineralization are the earliest factors of atmospheric greenhouse gases emission as a result of permafrost thawing. The observed enormously “light ” isotope signatures of methane (δ¹³C < −80‰, δD < −390‰) found in the tabular ground ice units significantly divergent in morphology and localization within the exposuremay be related to subzero (cryogenic) carbonate reduction a as significant factor of the local methane enrichment. DOM is mainly formed (>88%) by biochemically refractory humic acids. Distribution of the labile protein-like DOM reflects the specific features of carbon and nitrogen cycles in the tabular ground ice and ice wedge samples. Tabular ground ice units are shown to be a significant source of methane and high quality organic matter as well as dissolved inorganic nitrogen (DIN). Ice wedges express a high variation in DOM composition and lability.