scholarly journals Microbial activity, methane production, and carbon storage in Early Holocene North Sea peats

2021 ◽  
Vol 18 (19) ◽  
pp. 5491-5511
Author(s):  
Tanya J. R. Lippmann ◽  
Michiel H. in 't Zandt ◽  
Nathalie N. L. Van der Putten ◽  
Freek S. Busschers ◽  
Marc P. Hijma ◽  
...  
Keyword(s):  
North Sea ◽  
Carbon Sources ◽  
Methanogenic Archaea ◽  
Molecular Signatures ◽  
Pore Waters ◽  
Bacterial Populations ◽  
The North ◽  
Ch4 Production ◽  
Carbon Stores

Abstract. Northern latitude peatlands act as important carbon sources and sinks, but little is known about the greenhouse gas (GHG) budgets of peatlands that were submerged beneath the North Sea during the last glacial–interglacial transition. We found that whilst peat formation was diachronous, commencing between 13 680 and 8360 calibrated years before the present, stratigraphic layering and local vegetation succession were consistent across a large study area. Large carbon stores were measured. In situ methane (CH4) concentrations of sediment pore waters were widespread but low at most sites, with the exception of two locations. Incubation experiments in the laboratory revealed molecular signatures of methanogenic archaea, with strong increases in rates of activity upon methylated substrate amendment. Remarkably, methanotrophic activity and the respective diagnostic molecular signatures could not be detected. Heterotrophic Bathyarchaeota dominated the archaeal communities, and bacterial populations were dominated by candidate phylum JS1 bacteria. In the absence of active methanogenic microorganisms, we conclude that these sediment harbour low concentrations of widespread millennia-old CH4. The presence of large widespread stores of carbon and in situ methanogenic microorganisms, in the absence of methanotrophic microorganisms, holds the potential for microbial CH4 production if catalysed by a change in environmental conditions.

scholarly journals Microbial activity, methane production, and carbon storage in Early Holocene North Sea peats

2020 ◽  
Author(s):  
Tanya J. R. Lippmann ◽  
Michiel H. in 't Zandt ◽  
Nathalie N. L. Van der Putten ◽  
Freek S. Busschers ◽  
Marc P. Hijma ◽  
...  
Keyword(s):  
North Sea ◽  
Carbon Sources ◽  
Methanogenic Archaea ◽  
Molecular Signatures ◽  
Pore Waters ◽  
Bacterial Populations ◽  
The North ◽  
Peat Deposits ◽  
Micro Organisms

Abstract. Northern latitude peatlands act as important carbon sources and sinks but little is known about the greenhouse gas (GHG) budget of peatlands submerged beneath the North Sea during the last glacial-interglacial transition. We found that whilst peat formation was diachronous, commencing between 13,680 and 8,360 calibrated years before the present, stratigraphic layering and local vegetation succession were consistent across a large study area. The CH4 concentrations of the sediment pore waters were low at most sites, with the exception of two locations, and the stored carbon was large. Incubation experiments in the laboratory revealed molecular signatures of methanogenic archaea, with strong increases in rates of activity upon methylated substrate amendment. Remarkably, methanotrophic activity and the respective diagnostic molecular signatures could be not be detected. Heterotrophic Bathyarchaeia dominated the archaeal communities and bacterial populations were dominated by candidate phylum JS1 bacteria. Although CH4 accumulation is low at most sites, the presence of in situ methanogenic micro-organisms, the absence of methanotrophy, and large widespread stores of carbon hold the potential for GHG production if catalysed by a change in environmental conditions. Despite being earmarked as a critical source of CH4 seepage, seepage from these basal-peat deposits is restricted, as evidenced by low in situ CH4 concentrations.

scholarly journals Effect of Temperature on Stiffness of Sandstones from the Deep North Sea Basin

2020 ◽  
Author(s):  
Tobias Orlander ◽  
Katrine Alling Andreassen ◽  
Ida Lykke Fabricius
Keyword(s):  
North Sea ◽  
Temperature Effects ◽  
Mass Density ◽  
Thermal Strain ◽  
High Stress ◽  
Testing Temperature ◽  
Effect Of Temperature ◽  
Stress Regime ◽  
The North

Abstract Development of high-pressure, high-temperature (HPHT) petroleum reservoirs situated at depths exceeding 5 km and in situ temperature of 170 °C increases the demand for theories and supporting experimental data capable of describing temperature effects on rock stiffness. With the intention of experimentally investigating temperature effects on stiffness properties, we investigated three sandstones from the deep North Sea Basin. As the North Sea Basin is presently undergoing substantial subsidence, we assumed that studied reservoir sandstones have never experienced higher temperature than in situ. We measured ultrasonic velocities in a low- and high-stress regime, and used mass density and stress–strain curves to derive, respectively, dynamic and static elastic moduli. We found that in both regimes, the dry sandstones stiffens with increasing testing temperature and assign expansion of minerals as a controlling mechanism. In the low-stress regime with only partial microcrack closure, we propose closure of microcracks as the stiffening mechanism. In the high-stress regime, we propose that thermal expansion of constituting minerals increases stress in grain contacts when the applied stress is high enough for conversion of thermal strain to thermal stress, thus leading to higher stiffness at in situ temperature. We then applied an extension of Biot’s effective stress equation including a non-isothermal term from thermoelastic theory and explain test results by adding boundary conditions to the equations.

scholarly journals Observing and modelling phytoplankton community structure in the North Sea

2017 ◽  
Vol 14 (6) ◽  
pp. 1419-1444 ◽  
Author(s):  
David A. Ford ◽  
Johan van der Molen ◽  
Kieran Hyder ◽  
John Bacon ◽  
Rosa Barciela ◽  
...  
Keyword(s):  
Community Structure ◽  
North Sea ◽  
Phytoplankton Community ◽  
Marine Biodiversity ◽  
Phytoplankton Community Structure ◽  
Pigment Analysis ◽  
The North ◽  
The North Sea ◽  
In Situ Observations

Abstract. Phytoplankton form the base of the marine food chain, and knowledge of phytoplankton community structure is fundamental when assessing marine biodiversity. Policy makers and other users require information on marine biodiversity and other aspects of the marine environment for the North Sea, a highly productive European shelf sea. This information must come from a combination of observations and models, but currently the coastal ocean is greatly under-sampled for phytoplankton data, and outputs of phytoplankton community structure from models are therefore not yet frequently validated. This study presents a novel set of in situ observations of phytoplankton community structure for the North Sea using accessory pigment analysis. The observations allow a good understanding of the patterns of surface phytoplankton biomass and community structure in the North Sea for the observed months of August 2010 and 2011. Two physical–biogeochemical ocean models, the biogeochemical components of which are different variants of the widely used European Regional Seas Ecosystem Model (ERSEM), were then validated against these and other observations. Both models were a good match for sea surface temperature observations, and a reasonable match for remotely sensed ocean colour observations. However, the two models displayed very different phytoplankton community structures, with one better matching the in situ observations than the other. Nonetheless, both models shared some similarities with the observations in terms of spatial features and inter-annual variability. An initial comparison of the formulations and parameterizations of the two models suggests that diversity between the parameter settings of model phytoplankton functional types, along with formulations which promote a greater sensitivity to changes in light and nutrients, is key to capturing the observed phytoplankton community structure. These findings will help inform future model development, which should be coupled with detailed validation studies, in order to help facilitate the wider application of marine biogeochemical modelling to user and policy needs.

scholarly journals Cryptic roles of tetrathionate in the sulfur cycle of marine sediments: microbial drivers and indicators

2020 ◽  
Vol 17 (18) ◽  
pp. 4611-4631 ◽  
Author(s):  
Subhrangshu Mandal ◽  
Sabyasachi Bhattacharya ◽  
Chayan Roy ◽  
Moidu Jameela Rameez ◽  
Jagannath Sarkar ◽  
...  
Keyword(s):  
Sediment Cores ◽  
Sulfur Cycle ◽  
Growth Media ◽  
Pore Waters ◽  
Bacterial Populations ◽  
Metagenome Analysis ◽  
Minimum Zone ◽  
Chemolithotrophic Bacteria

Abstract. To explore the potential role of tetrathionate in the sedimentary sulfur cycle, population ecology of microorganisms capable of metabolizing this polythionate was revealed at 15–30 cm resolution along two, ∼3 m long, cores collected from 530 and 580 m below the sea level, off India's west coast, within the oxygen minimum zone (OMZ) of the Arabian Sea. Metagenome analysis along the cores revealed widespread occurrence of genes involved in the formation, oxidation, and reduction of tetrathionate; high diversity and relative abundance were also detected for bacteria that are known to render these metabolisms in vitro. Results of slurry culture of the sediment samples in thiosulfate- or tetrathionate-containing microbial growth media, data obtained via pure-culture isolation, and finally metatranscriptome analyses corroborated the in situ functionality of the tetrathionate-forming, tetrathionate-oxidizing, and tetrathionate-reducing microorganisms. Ion chromatography of pore waters revealed the presence of up to 11.1 µM thiosulfate in the two cores, whereas tetrathionate remained undetected in spectroscopic assay based on its reaction with cyanide. While thiosulfate oxidation by chemolithotrophic bacteria prevalent in situ is the apparent source of tetrathionate in this ecosystem, high biochemical and geochemical reactivity of this polythionate could be instrumental in its cryptic status in the sulfur cycle. Potential abiotic origin of tetrathionate in the sediment horizon explored could neither be ruled out nor confirmed from the geochemical information available. On the other hand, tetrathionate potentially present in the system can be either oxidized to sulfate or reduced back to thiosulfate/sulfide via chemolithotrophic oxidation and respiration by native bacterial populations, respectively. Up to 2.01 mM sulfide present in the sediment cores may also reduce tetrathionate abiotically to thiosulfate and elemental sulfur. However, in the absence of measured data for O2 or other oxyanions having possibilities of serving as electron acceptors, the biogeochemical modalities of the oxidative half of the tetrathionate cycle remained unresolved.

‘In‐situ’ internal pipeline cleaning, heating and coating services in the North Sea

1987 ◽  
Vol 34 (2) ◽  
pp. 6-8
Author(s):  
P.J. Bryant ◽  
B.C. Goff ◽  
I.S. Lancaster
Keyword(s):  
North Sea ◽  
The North ◽  
The North Sea

scholarly journals High-resolution analysis of a North Sea phytoplankton community structure based on in situ flow cytometry observations and potential implication for remote sensing

2015 ◽  
Vol 12 (13) ◽  
pp. 4051-4066 ◽  
Author(s):  
M. Thyssen ◽  
S. Alvain ◽  
A. Lefèbvre ◽  
D. Dessailly ◽  
M. Rijkeboer ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Community Structure ◽  
North Sea ◽  
High Frequency ◽  
Phytoplankton Community ◽  
Phytoplankton Community Structure ◽  
The North ◽  
The North Sea ◽  
Daily Scale

Abstract. Phytoplankton observation in the ocean can be a challenge in oceanography. Accurate estimations of its biomass and dynamics will help to understand ocean ecosystems and refine global climate models. Relevant data sets of phytoplankton defined at a functional level and on a sub-meso- and daily scale are thus required. In order to achieve this, an automated, high-frequency, dedicated scanning flow cytometer (SFC, Cytobuoy b.v., the Netherlands) has been developed to cover the entire size range of phytoplankton cells whilst simultaneously taking pictures of the largest of them. This cytometer was directly connected to the water inlet of a PocketFerryBox during a cruise in the North Sea, 08–12 May 2011 (DYMAPHY project, INTERREG IV A "2 Seas"), in order to identify the phytoplankton community structure of near surface waters (6 m) with a high spatial resolution basis (2.2 ± 1.8 km). Ten groups of cells, distinguished on the basis of their optical pulse shapes, were described (abundance, size estimate, red fluorescence per unit volume). Abundances varied depending on the hydrological status of the traversed waters, reflecting different stages of the North Sea blooming period. Comparisons between several techniques analysing chlorophyll a and the scanning flow cytometer, using the integrated red fluorescence emitted by each counted cell, showed significant correlations. For the first time, the community structure observed from the automated flow cytometry data set was compared with PHYSAT reflectance anomalies over a daily scale. The number of matchups observed between the SFC automated high-frequency in situ sampling and remote sensing was found to be more than 2 times better than when using traditional water sampling strategies. Significant differences in the phytoplankton community structure within the 2 days for which matchups were available suggest that it is possible to label PHYSAT anomalies using automated flow cytometry to resolve not only dominant groups but also community structure.

scholarly journals Straw application in paddy soil enhances methane production also from other carbon sources

2013 ◽  
Vol 10 (8) ◽  
pp. 14169-14193 ◽  
Author(s):  
Q. Yuan ◽  
J. Pump ◽  
R. Conrad
Keyword(s):  
Priming Effect ◽  
Carbon Sources ◽  
Methanogenic Archaea ◽  
Rice Fields ◽  
Soil Environment ◽  
Traditional Management ◽  
Positive Priming ◽  
Hydrogenotrophic Methanogenesis ◽  
Ch4 Production ◽  
Straw Application

Abstract. Flooded rice fields are an important source of the greenhouse gas methane. Methane is produced from rice straw (RS), soil organic matter (SOM), and rice root organic carbon (ROC). Addition of RS is widely used for ameliorating soil fertility. However, this practice provides additional substrate for CH4 production and results in increased CH4 emission. Here, we found that decomposing RS is not only a substrate of CH4 production, but in addition stimulates CH4 production from SOM and ROC. Apart from accelerating the creation of reduced conditions in the soil environment, RS decomposition exerted a positive priming effect on SOM-derived CH4 production. In particular, hydrogenotrophic methanogenesis from SOM-derived CO2 was stimulated, presumably by H2 released from RS decomposition. On the other hand, the positive priming effect of RS on ROC-derived CH4 production was probably caused by the significant increase of the abundance of methanogenic archaea in the RS treatment compared with the untreated control. Our results show that traditional management of rice residues exerts a positive feedback on CH4 production from rice fields, thus exacerbating its effect on the global CH4 budget.

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