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

Geosciences ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 450
Author(s):  
Petr B. Semenov ◽  
Anfisa A. Pismeniuk ◽  
Sergei A. Malyshev ◽  
Marina O. Leibman ◽  
Irina D. Streletskaya ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Greenhouse Gases ◽  
Greenhouse Gas Emission ◽  
Inorganic Nitrogen ◽  
Biogeochemical Cycling ◽  
Ground Ice ◽  
Carbon And Nitrogen ◽  
Ice Wedge ◽  
Permafrost Thawing

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.

Effects of increased concentrations of inorganic nitrogen and dissolved organic matter on phytoplankton in boreal lakes with differing nutrient limitation patterns

2015 ◽  
Vol 77 (3) ◽  
pp. 511-521 ◽  
Author(s):  
Carmen T. Daggett ◽  
Jasmine E. Saros ◽  
Brenda Moraska Lafrancois ◽  
Kevin S. Simon ◽  
Aria Amirbahman
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Nutrient Limitation ◽  
Inorganic Nitrogen ◽  
Boreal Lakes

scholarly journals Chemical characterization of water extractable organic matter from plants: A better understanding of soil dissolved organic matter sources and path in permafrost thawing regions 

2021 ◽  
Author(s):  
Alienor Allain ◽  
Marie Anne Alexis ◽  
Yannick Agnan ◽  
Guillaume Humbert ◽  
Edith Parlanti ◽  
...  
Keyword(s):  
Organic Matter ◽  
Solid State ◽  
Dissolved Organic Matter ◽  
Vascular Plants ◽  
Inorganic Material ◽  
Bulk Sample ◽  
Permafrost Thawing ◽  
Extractable Organic Matter ◽  
Water Extractable

&lt;p&gt;In present permafrost thawing context, dissolved organic matter (DOM) is a key component that controls organic and inorganic material transfer from soil to hydrographic systems. In terrestrial environments, vegetation is the main source of DOM, before degradation by microorganisms. DOM stoichiometry, aromaticity, composition or quantity control its fate, and referential data characterizing the initial DOM originating from plant biomass leaching are scarce.&lt;/p&gt;&lt;p&gt;To better understand its dynamic, this study focuses on the characterization of water extractable organic matter (&amp;#8220;WEOM&amp;#8221;: a proxy of DOM) of main plant species belonging to different plant functional types typical of the subarctic region (lichen, willow, birch, and &lt;em&gt;Eriophorum&lt;/em&gt;).&lt;/p&gt;&lt;p&gt;Dissolved organic carbon (C) and dissolved nitrogen (N) contents of WEOM samples were measured, as well as organic C and total N contents of ground plant leaf samples (&amp;#8220;bulk&amp;#8221; samples). C/N ratio of bulk samples and WEOM fractions were compared to evaluate the potential extractability of C and N. The composition of both WEOM and bulk samples were characterized through solid state &lt;sup&gt;13&lt;/sup&gt;C Nuclear Magnetic Resonance (NMR) and compared. Absorbance and 3D fluorescence measurements were also performed on WEOM samples to characterize their optical properties.&lt;/p&gt;&lt;p&gt;WEOM is significantly more extractable in vascular plants compared to non-vascular ones. Moreover, N is more extractable than C in all lichen species and &lt;em&gt;Eriophorum&lt;/em&gt;, whereas C is as extractable as N in &lt;em&gt;Salix &lt;/em&gt;and &lt;em&gt;Betula pubescens&lt;/em&gt; samples.&lt;em&gt; Betula nana&lt;/em&gt; is the only species with C more extractable than N.&lt;/p&gt;&lt;p&gt;The solid state &lt;sup&gt;13&lt;/sup&gt;C NMR spectra of bulk sample are very similar to the spectra of corresponding WEOM, except for &lt;em&gt;Eriophorum&lt;/em&gt;. For this species, carbonyl C contributes to 5% of bulk sample spectrum, compared to 14% of the WEOM spectrum.&lt;/p&gt;&lt;p&gt;Based on absorbance measurements, optical index were calculated: E2/E3 is significantly higher for non-vascular plants, whereas E2/E4, E3/E4 and slope ratio (S&lt;sub&gt;R&lt;/sub&gt;) do not show significant difference between plant functional types. In 3D fluorescence spectra, the contribution of &amp;#8220;Protein-like&amp;#8221; peak is lower for vascular plants compared to lichens, and is maximum for &lt;em&gt;Eriophorum&lt;/em&gt;.&lt;/p&gt;&lt;p&gt;Our results highlighted the influence of plant species on the quantity and quality of produced DOM: WEOM production process is different between vegetation species due to the quality, especially hydrophobicity and extractability of bulk OM components. The high contribution of C-N bonds in WEOM of &lt;em&gt;Eriophorum &lt;/em&gt;might be especially important for potential complexation between DOM and trace elements like cadmium (Nigam et al., 2000). Likewise, aromatic C observed only in vascular plant WEOM samples are known to bond have a good affinity with many elements like iron, vanadium and chromium (Gangloff et al., 2014). Under climate change, vegetation cover of the Arctic region is evolving with the moving of the treeline northward and a local increase of the proportion of shrubs (Berner et al., 2013). Accordingly, significant change of DOM composition are expected with potential influence on organic and inorganic material dynamics.&lt;/p&gt;&lt;p&gt;Berner et al., (2013). Glob. Chang. Biol. 19:3449-3462&lt;/p&gt;&lt;p&gt;Gangloff et al., (2014). Geochim. Cosmochim. Ac. 130:21-41&amp;#160;&amp;#160;&lt;/p&gt;&lt;p&gt;Nigam et al., (2000). Chem. Speciation Bioavailability 12:125-132&lt;/p&gt;

From pre-freshet to pre-freeze: a field survey of the fate of organic matter remobilized from the thawing permafrost to the coastal waters of the Mackenzie Delta region

2020 ◽  
Author(s):  
Martine Lizotte ◽  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Coastal Waters ◽  
Drainage Basin ◽  
Numerical Models ◽  
Biogeochemical Cycling ◽  
The Arctic ◽  
Mackenzie Delta ◽  
Delta Region ◽  
Temporal Sampling

&lt;p&gt;Thawing of permafrost in the Mackenzie Delta region of northern Canada, coupled with an increase in river discharge, prompts the release of particulate and dissolved organic matter from the largest Arctic drainage basin in North America into the Arctic Ocean. While this ongoing process is well-recognized and its rate is accelerating, the fate of the newly-mobilized organic matter as it transits from the watershed through the delta and into the marine system remains poorly understood. In the framework of the H2020 Nunataryuk project, and in partnership with ArcticNet and Sentinel North, we conducted intensive field expeditions in the Mackenzie Delta from April to September 2019. The temporal sampling scheme of this project allowed the investigation of ambient conditions in the coastal waters under a full ice cover prior to the spring freshet, during the ice break-up, in summer, as well as in fall prior to the freeze-up period. In order to capture the fluvial-marine transition zone and with specific challenges related to shallow waters and changing seasons, the field sampling was conducted using several platforms: helicopters, snowmobiles and small boats. Water column profiles of physical and optical variables were measured on site, and water and sediment samples were collected and preserved for the determination of the composition and sources of particulate and dissolved organic matter, as well as its biogeochemical cycling in the coastal environment. Beyond improving our understanding of the origin and fate of this re-mobilized organic matter, the data gathered will serve as a new basis for the ground truthing of remotely sensed images in a changing arctic environment. Finally, the tuned satellite data will be incorporated into numerical models, providing better predictions of the impacts of permafrost thaw on local biogeochemical cycling and ultimately on sea-air fluxes of carbon dioxide and global climate.&lt;/p&gt;

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