scholarly journals Microbial Organic Matter Degradation Potential in Baltic Sea Sediments Is Influenced by Depositional Conditions andIn SituGeochemistry

2018 ◽  
Vol 85 (4) ◽  
Author(s):  
Laura A. Zinke ◽  
Clemens Glombitza ◽  
Jordan T. Bird ◽  
Hans Røy ◽  
Bo Barker Jørgensen ◽  
...  
Keyword(s):  
Organic Matter ◽  
Baltic Sea ◽  
Microbial Communities ◽  
Carbon Cycling ◽  
Marine Sediments ◽  
Abiotic Factors ◽  
Organic Matter Degradation ◽  
Sediment Types ◽  
Polymer Hydrolysis ◽  
Sediment Carbon

ABSTRACTGlobally, marine sediments are a vast repository of organic matter, which is degraded through various microbial pathways, including polymer hydrolysis and monomer fermentation. The sources, abundances, and quality (i.e., labile or recalcitrant) of the organic matter and the composition of the microbial assemblages vary between sediments. Here, we examine new and previously published sediment metagenomes from the Baltic Sea and the nearby Kattegat region to determine connections between geochemistry and the community potential to degrade organic carbon. Diverse organic matter hydrolysis encoding genes were present in sediments between 0.25 and 67 meters below seafloor and were in higher relative abundances in those sediments that contained more organic matter. New analysis of previously published metatranscriptomes demonstrated that many of these genes were transcribed in two organic-rich Holocene sediments. Some of the variation in deduced pathways in the metagenomes correlated with carbon content and depositional conditions. Fermentation-related genes were found in all samples and encoded multiple fermentation pathways. Notably, genes involved in alcohol metabolism were amongst the most abundant of these genes, indicating that this is an important but underappreciated aspect of sediment carbon cycling. This study is a step towards a more complete understanding of microbial food webs and the impacts of depositional facies on present sedimentary microbial communities.IMPORTANCESediments sequester organic matter over geologic time scales and impact global climate regulation. Microbial communities in marine sediments drive organic matter degradation, but the factors controlling their assemblages and activities, which in turn impact their role in organic matter degradation, are not well understood. Hence, determining the role of microbial communities in carbon cycling in various sediment types is necessary for predicting future sediment carbon cycling. We examined microbial communities in Baltic Sea sediments, which were deposited across various climatic and geographical regimes to determine the relationship between microbial potential for breakdown of organic matter and abiotic factors, including geochemistry and sediment lithology. The findings from this study will contribute to our understanding of carbon cycling in the deep biosphere and how microbial communities live in deeply buried environments.

Invasive plant-derived dissolved organic matter alters microbial communities and carbon cycling in soils

2021 ◽  
pp. 108191
Author(s):  
Morgan Luce McLeod ◽  
Lorinda Bullington ◽  
Cory C. Cleveland ◽  
Johannes Rousk ◽  
Ylva Lekberg
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Microbial Communities ◽  
Carbon Cycling ◽  
Invasive Plant

scholarly journals Timescales for the development of methanogenesis and free gas layers in recently-deposited sediments of Arkona Basin (Baltic Sea)

2012 ◽  
Vol 9 (5) ◽  
pp. 1915-1933 ◽  
Author(s):  
J. M. Mogollón ◽  
A. W. Dale ◽  
H. Fossing ◽  
P. Regnier
Keyword(s):  
Organic Matter ◽  
Baltic Sea ◽  
Reactive Transport ◽  
Reaction Pathway ◽  
Organic Matter Degradation ◽  
Muddy Sediment ◽  
Transport Models ◽  
Methane Gas ◽  
Geochemical Profiles ◽  
Arkona Basin

Abstract. Arkona Basin (southwestern Baltic Sea) is a seasonally-hypoxic basin characterized by the presence of free methane gas in its youngest organic-rich muddy stratum. Through the use of reactive transport models, this study tracks the development of the methane geochemistry in Arkona Basin as this muddy sediment became deposited during the last 8 kyr. Four cores are modeled each pertaining to a unique geochemical scenario according to their respective contemporary geochemical profiles. Ultimately the thickness of the muddy sediment and the flux of particulate organic carbon are crucial in determining the advent of both methanogenesis and free methane gas, the timescales over which methanogenesis takes over as a dominant reaction pathway for organic matter degradation, and the timescales required for free methane gas to form.

Organic matter degradation characteristics of coastal marine sediments collected from the Seto Inland Sea, Japan

2020 ◽  
Vol 225 ◽  
pp. 103854 ◽  
Author(s):  
Satoshi Asaoka ◽  
Waqar Azeem Jadoon ◽  
Akira Umehara ◽  
Kazuhiko Takeda ◽  
Sosuke Otani ◽  
...  
Keyword(s):  
Organic Matter ◽  
Marine Sediments ◽  
Seto Inland Sea ◽  
Organic Matter Degradation ◽  
Coastal Marine Sediments ◽  
Coastal Marine ◽  
The Seto Inland Sea

scholarly journals Timescales for the development of methanogenesis and free gas layers in recently-deposited sediments of Arkona Basin (Baltic Sea)

2011 ◽  
Vol 8 (4) ◽  
pp. 7623-7669 ◽  
Author(s):  
J. M. Mogollón ◽  
A. W. Dale ◽  
H. Fossing ◽  
P. Regnier
Keyword(s):  
Organic Matter ◽  
Baltic Sea ◽  
Reactive Transport ◽  
Reaction Pathway ◽  
Organic Matter Degradation ◽  
Muddy Sediment ◽  
Transport Models ◽  
Methane Gas ◽  
Geochemical Profiles ◽  
Arkona Basin

Abstract. Arkona Basin (southwestern Baltic Sea) is a seasonally-hypoxic basin characterized by the presence of free methane gas in its youngest organic-rich muddy stratum. Through the use of reactive transport models, this study tracks the development of the methane geochemistry in Arkona Basin as this muddy sediment becomes deposited during the last 8 kyr. Four cores are modeled each pertaining to a unique geochemical scenario according to their respective contemporary geochemical profiles. Ultimately the thickness of the muddy sediment and the flux of particulate organic carbon are crucial in determining the advent of both methanogenesis and free methane gas, the timescales over which methanogenesis takes over as a dominant reaction pathway for organic matter degradation, and the timescales required for free methane gas to form.

scholarly journals An Areal Assessment of Subseafloor Carbon Cycling in Cold Seeps and Hydrate-Bearing Areas in the Northern South China Sea

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Yanping Zhang ◽  
Min Luo ◽  
Yu Hu ◽  
Hongbin Wang ◽  
Duofu Chen
Keyword(s):  
Organic Matter ◽  
South China Sea ◽  
Carbon Cycling ◽  
South China ◽  
Northern South China Sea ◽  
Continental Margins ◽  
Cold Seeps ◽  
Carbonate Precipitation ◽  
Organic Matter Degradation ◽  
China Sea

Gas hydrates, acting as a dynamic methane reservoir, store methane in the form of a solid phase under high-pressure and low-temperature conditions and release methane through the sediment column into seawater when they are decomposed. The seepage of methane-rich fluid (i.e., cold hydrocarbon seeps) fuels the chemosynthetic biota-inhabited surface sediments and represents the major pathway to transfer carbon from sediments to the water column. Generally, the major biogeochemical reactions related to carbon cycling in the anoxic marine sediments include organic matter degradation via sulfate reduction (OSR), anaerobic oxidation of methane (AOM), methanogenesis (ME), and carbonate precipitation (CP). In order to better understand the carbon turnover in the cold seeps and gas hydrate-bearing areas of the northern South China Sea (SCS), we collected geochemical data of 358 cores from published literatures and retrieved 37 cores and corresponding pore water samples from three areas of interest (i.e., Xisha, Dongsha, and Shenhu areas). Reaction-transport simulations indicate that the rates of organic matter degradation and carbonate precipitation are comparable in the three areas, while the rates of AOM vary over several orders of magnitude (AOM: 8.3-37.5 mmol·m-2·yr-1 in Dongsha, AOM: 12.4-170.6 mmol·m-2·yr-1 in Xisha, and AOM: 9.4-30.5 mmol·m-2·yr-1 in Shenhu). Both the arithmetical mean and interpolation mean of the biogeochemical processes were calculated in each area. Averaging these two mean values suggested that the rates of organic matter degradation in Dongsha (25.7 mmol·m-2·yr-1) and Xisha (25.1 mmol·m-2·yr-1) are higher than that in Shenhu (12 mmol·m-2·yr-1) and the AOM rate in Xisha (135.2 mmol·m-2·yr-1) is greater than those in Dongsha (27.8 mmol·m-2·yr-1) and Shenhu (17.5 mmol·m-2·yr-1). In addition, the rate of carbonate precipitation (32.3 mmol·m-2·yr-1) in Xisha is far higher than those of the other two regions (5.3 mmol·m-2·yr-1 in Dongsha, 5.8 mmol·m-2·yr-1 in Shenhu) due to intense AOM sustained by gas dissolution. In comparison with other cold seeps around the world, the biogeochemical rates in the northern SCS are generally lower than those in active continental margins and special environments (e.g., the Black sea) but are comparable with those in passive continental margins. Collectively, ~2.8 Gmol organic matter was buried and at least ~0.82 Gmol dissolved organic and inorganic carbon was diffused out of sediments annually. This may, to some extent, have an impact on the long-term deep ocean carbon cycle in the northern SCS.

scholarly journals Resistance and Resilience of Soil Nitrogen Cycling to Drought and Heat Stress in Rehabilitated Urban Soils

2021 ◽  
Vol 12 ◽  
Author(s):  
Mehdi Fikri ◽  
Catherine Joulian ◽  
Mikael Motelica-Heino ◽  
Marie-Paule Norini ◽  
Jennifer Hellal
Keyword(s):  
Organic Matter ◽  
Drought Stress ◽  
Microbial Communities ◽  
Nitrogen Cycling ◽  
Carbon Cycling ◽  
Urban Soils ◽  
Terrestrial Ecosystems ◽  
Soil Functions ◽  
Microbial Activities ◽  
Stress Changes

In the context of climate change and biodiversity loss, rehabilitation of degraded urban soils is a means of limiting artificialization of terrestrial ecosystems and preventing further degradation of soils. Ecological rehabilitation approaches are available to reinitiate soil functions and enhance plant development. However, little is known about the long-term stability of rehabilitated soils in terms of soil functions when further natural or anthropogenic perturbations occur. Based on rehabilitated urban soils, the present study sought to evaluate the resistance and resilience of soil functions linked to carbon cycling and phosphate dynamics in addition to nitrogen cycling and related microbial communities after a heat and drought stress. A laboratory experiment was conducted in microcosms under controlled temperature conditions, with four contrasted soils collected from a rehabilitated urban brownfield; an initial, non-rehabilitated soil (IS), a technosol with a high organic matter level (HO), and two technosols with less organic matter (LO1 and LO2), together with their respective controls (no stress). Changes in potential denitrification (PDR), nitrification (PNR) rates, and their interactive relationships with soil microbial activities and soil physicochemical properties were determined following a combined heat (40°C) and drought stress period of 21 days. Measurements were carried out immediately after the stress (resistance), and then also 5, 30, and 92 days after soil rewetting at 60% water holding capacity (resilience). Microbial activities involved in soil functions such as carbon cycling and phosphate dynamics proved to be of low resistance in all soils except for IS; however, they were resilient and recovered rapidly after rewetting. On the other hand, the microbial activities and gene abundances that were measured in relation to nitrogen cycling processes showed that for denitrification, activities were more rapidly resilient than gene abundances whereas for nitrification the activities and gene abundances were resilient in the same way. Results suggest that, unless the soils contain high amounts of organic matter, microbial communities in imported soils can be more vulnerable to environmental pressures such as drought and heat than communities already present. This should be considered when rehabilitating degraded soils.

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