scholarly journals Methane distribution and oxidation around the Lena Delta in summer 2013

2017 ◽  
Author(s):  
Ingeborg Bussmann ◽  
Steffen Hackbusch ◽  
Patrick Schaal ◽  
Antje Wichels
Keyword(s):  
Methane Oxidation ◽  
Methane Flux ◽  
Methanotrophic Bacteria ◽  
Riverine Water ◽  
Lena River ◽  
Methane Distribution ◽  
Methane Oxidation Rate ◽  
Mixed Water ◽  
Polar Water ◽  
Lena Delta

Abstract. The Lena River is one of the biggest Russian rivers draining into the Laptev Sea. Due to predicted increasing temperatures, the permafrost areas surrounding the Lena Delta will melt at increasing rates. With this melting, high amounts of methane will reach the waters of the Lena and the adjacent Laptev Sea. Methane oxidation by methanotrophic bacteria is the only biological way to reduce methane concentrations within the system. However, the polar estuary of the Lena River is a challenging environment for bacteria, with strong fluctuations in salinity and temperature. We determined the activity (tracer method) and the abundance (qPCR) of aerobic methanotrophic bacteria. We described the methanotrophic population with MISA; as well as the methane distribution (head space) and other abiotic parameters in the Lena Delta in September 2013. In riverine water (S < 5) we found a median methane concentration of 22 nM, in mixed water (5 < S < 20) the median methane concentration was 19 nM and in polar water (S > 20) a median 28 nM was observed. The Lena River was not the methane source for surface water, and bottom water methane concentrations were mainly influenced by the concentration in surface sediments. However, the methane oxidation rate in riverine and polar water was very similar (0.419 and 0.400 nM/d), but with a higher relative abundance of methanotrophs and a higher estimated diversity with respect to MISA OTUs in the rivine water as compared to polar water. The turnover times of methane ranged from 167 d in mixed water, 91 d in riverine water and only 36 d in polarwater. Also the environmental parameters influencing the methane oxidation rate and the methanotrophic population differed between the water masses. Thus we postulate a riverine methanotrophic population limited by sub-optimal temperatures and substrate concentrations and a polar methanotrophic population being well adapted to the cold and methane poor environment, but limited by the nitrogen content. The diffusive methane flux into the atmosphere ranged from 4–163 µmol m2 d−1 (median 24). For the total methane inventory of the investigated area, the diffusive methane flux was responsible for 8 % loss, compared to only 1 % of the methane consumed by the methanotrophic bacteria within the system.

scholarly journals Methane distribution and oxidation around the Lena Delta in summer 2013

2017 ◽  
Vol 14 (21) ◽  
pp. 4985-5002 ◽  
Author(s):  
Ingeborg Bussmann ◽  
Steffen Hackbusch ◽  
Patrick Schaal ◽  
Antje Wichels
Keyword(s):  
Methane Oxidation ◽  
Methane Flux ◽  
Methanotrophic Bacteria ◽  
Riverine Water ◽  
Lena River ◽  
Methane Distribution ◽  
Mixed Water ◽  
Methane Concentrations ◽  
Polar Water ◽  
Lena Delta

Abstract. The Lena River is one of the largest Russian rivers draining into the Laptev Sea. The predicted increases in global temperatures are expected to cause the permafrost areas surrounding the Lena Delta to melt at increasing rates. This melting will result in high amounts of methane reaching the waters of the Lena and the adjacent Laptev Sea. The only biological sink that can lower methane concentrations within this system is methane oxidation by methanotrophic bacteria. However, the polar estuary of the Lena River, due to its strong fluctuations in salinity and temperature, is a challenging environment for bacteria. We determined the activity and abundance of aerobic methanotrophic bacteria by a tracer method and by the quantitative polymerase chain reaction. We described the methanotrophic population with a molecular fingerprinting method (monooxygenase intergenic spacer analysis), as well as the methane distribution (via a headspace method) and other abiotic parameters, in the Lena Delta in September 2013. The median methane concentrations were 22 nmol L−1 for riverine water (salinity (S)  < 5), 19 nmol L−1 for mixed water (5 < S < 20) and 28 nmol L−1 for polar water (S > 20). The Lena River was not the source of methane in surface water, and the methane concentrations of the bottom water were mainly influenced by the methane concentration in surface sediments. However, the bacterial populations of the riverine and polar waters showed similar methane oxidation rates (0.419 and 0.400 nmol L−1 d−1), despite a higher relative abundance of methanotrophs and a higher estimated diversity in the riverine water than in the polar water. The methane turnover times ranged from 167 days in mixed water and 91 days in riverine water to only 36 days in polar water. The environmental parameters influencing the methane oxidation rate and the methanotrophic population also differed between the water masses. We postulate the presence of a riverine methanotrophic population that is limited by sub-optimal temperatures and substrate concentrations and a polar methanotrophic population that is well adapted to the cold and methane-poor polar environment but limited by a lack of nitrogen. The diffusive methane flux into the atmosphere ranged from 4 to 163 µmol m2 d−1 (median 24). The diffusive methane flux accounted for a loss of 8 % of the total methane inventory of the investigated area, whereas the methanotrophic bacteria consumed only 1 % of this methane inventory. Our results underscore the importance of measuring the methane oxidation activities in polar estuaries, and they indicate a population-level differentiation between riverine and polar water methanotrophs.

Features of the Lena River runoff influence on the adjacent Laptev Sea shelf

2021 ◽  
Author(s):  
Vladimir Rogozhin ◽  
Alexander Polukhin ◽  
Evgeniy Yakushev ◽  
Igor Semiletov
Keyword(s):  
Fresh Water ◽  
River Runoff ◽  
Total Alkalinity ◽  
Shelf Zone ◽  
Laptev Sea ◽  
Shirshov Institute ◽  
Riverine Water ◽  
Lena River ◽  
The Laptev Sea ◽  
Lena Delta

&lt;p&gt;The annual runoff of river water into the Laptev Sea is 745 km&lt;sup&gt;3&lt;/sup&gt;, most of the runoff belongs to the Lena River - 525 km&lt;sup&gt;3&lt;/sup&gt;. &amp;#160;Long-term variability in the volume of the Lena River runoff play a significant role in the variability of the scale of distribution of freshwater lenses in the Laptev Sea. The processes that take place in the area of &amp;#8203;&amp;#8203;intense river runoff have an impact both in the shelf zone and in the open part of the sea due to the transfer of large-area lenses of freshened water. The influence of river runoff is considered from the Lena Delta to the continental slope of the Laptev Sea.&lt;/p&gt;&lt;p&gt;The data on physical and chemical properties of the Laptev Sea shelf used in this investigation was obtained during the expeditions of the Shirshov Institute of Oceanology in 2015 and 2017 and the Pacific Oceanological Institute in 2018-2020.&lt;/p&gt;&lt;p&gt;The distribution of hydrochemical parameters in the Lena Delta area in 2019 was typical for the river-sea mixing zone. The distribution of silicate was mixed, i.e. horizontal stratification prevailed in the near-surface layers, and vertical stratification in the bottom layers. The maximum values &amp;#8203;&amp;#8203;were observed in the near-mouth area, reaching indicators over 30 &amp;#181;M / L, which generally coincides with the values &amp;#8203;&amp;#8203;of this indicator in 2015 and more than in 2017.&lt;/p&gt;&lt;p&gt;When considering the distribution of specific alkalinity (total alkalinity-salinity ratio), which serves as a proxie of riverine water, it is worth noting the deepening of the boundary by 0.07 units. In 2019, this border was at depths of 20 to 40 meters, which is an atypical indicator for this water area. Apparently, this has happened owing to an increase in the supply of carbonate ions, which is noticeable from an increase in the values &amp;#8203;&amp;#8203;of carbonate alkalinity in the Lena River waters (Arctic Great Rivers Observatory data).&lt;/p&gt;&lt;p&gt;The calculation of the parts of fresh water, based on salinity data in 2019, showed that the maximum values &amp;#8203;&amp;#8203;were observed near the Lena River delta and amounted to 30-35%. Northward, the part of riverine water was up to 10% only in the surface layer. Comparing with similar calculations performed for the 2015 and 2017 sections, it should be noted that the part of fresh water has decreased. Perhaps this is due to the inflow of continental runoff in 2019 was the lowest over the considered period.&lt;/p&gt;&lt;p&gt;Funding: The work was carried out within the framework of the Shirshov Institute of Oceanology state assignment (theme No. 0149-2019-0008), with funding of the Russian Scientific Foundation (project No. 19-17-00196) and the grant of the President of the Russian Federation MK-860.2020.5.&lt;/p&gt;

scholarly journals Distribution of methane in the Lena Delta and Buor-Khaya Bay, Russia

2013 ◽  
Vol 10 (7) ◽  
pp. 4641-4652 ◽  
Author(s):  
I. Bussmann
Keyword(s):  
River System ◽  
Methane Flux ◽  
Main Process ◽  
Laptev Sea ◽  
Terrestrial Environment ◽  
Lena River ◽  
Permafrost Soils ◽  
Methane Concentrations ◽  
Lena Delta ◽  
Isotopic Signal

Abstract. The Lena River is one of the largest Russian rivers draining into the Laptev Sea. The permafrost areas surrounding the Lena are predicted to thaw at increasing rates due to global temperature increases. With this thawing, large amounts of carbon – either organic or in the gaseous forms carbon dioxide and methane – will reach the waters of the Lena and the adjacent Buor-Khaya Bay (Laptev Sea). Methane concentrations and the isotopic signal of methane in the waters of the Lena Delta and estuary were monitored from 2008 to 2010. Creeks draining from permafrost soils produced hotspots for methane input into the river system (median concentration 1500 nM) compared with concentrations of 30–85 nM observed in the main channels of the Lena. No microbial methane oxidation could be detected; thus diffusion is the main process of methane removal. We estimated that the riverine diffusive methane flux is 3–10 times higher than the flux from surrounding terrestrial environment. To maintain the observed methane concentrations in the river, additional methane sources are necessary. The methane-rich creeks could be responsible for this input. In the estuary of Buor-Khaya Bay, methane concentrations decreased to 26–33 nM. However, within the bay no consistent temporal and spatial pattern could be observed. The methane-rich waters of the river were not diluted with marine water because of a strong stratification of the water column. Thus, methane is released from the estuary and from the river mainly by diffusion into the atmosphere.

scholarly journals Methylocella Species Are Facultatively Methanotrophic

2005 ◽  
Vol 187 (13) ◽  
pp. 4665-4670 ◽  
Author(s):  
Svetlana N. Dedysh ◽  
Claudia Knief ◽  
Peter F. Dunfield
Keyword(s):  
Methane Oxidation ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Methanotrophic Bacteria ◽  
Soluble Methane Monooxygenase ◽  
Cell Counts ◽  
Carbon Compounds ◽  
Methane Fluxes ◽  
The One ◽  
Pcr Targeting

ABSTRACT All aerobic methanotrophic bacteria described to date are unable to grow on substrates containing carbon-carbon bonds. Here we demonstrate that members of the recently discovered genus Methylocella are an exception to this. These bacteria are able to use as their sole energy source the one-carbon compounds methane and methanol, as well as the multicarbon compounds acetate, pyruvate, succinate, malate, and ethanol. To conclusively verify facultative growth, acetate and methane were used as model substrates in growth experiments with the type strain Methylocella silvestris BL2. Quantitative real-time PCR targeting the mmoX gene, which encodes a subunit of soluble methane monooxygenase, showed that copies of this gene increased in parallel with cell counts during growth on either acetate or methane as the sole substrate. This verified that cells possessing the genetic basis of methane oxidation grew on acetate as well as methane. Cloning of 16S rRNA genes and fluorescence in situ hybridization with strain-specific and genus-specific oligonucleotide probes detected no contaminants in cultures. The growth rate and carbon conversion efficiency were higher on acetate than on methane, and when both substrates were provided in excess, acetate was preferably used and methane oxidation was shut down. Our data demonstrate that not all methanotrophic bacteria are limited to growing on one-carbon compounds. This could have major implications for understanding the factors controlling methane fluxes in the environment.

The link between Soil Methane Oxidation Rate and Abundance of Methanotrophs Estimated by Quantitative PCR

Microbiology ◽  
2020 ◽  
Vol 89 (2) ◽  
pp. 182-191
Author(s):  
A. F. Sabrekov ◽  
M. V. Semenov ◽  
I. E. Terent’eva ◽  
Yu. V. Litti ◽  
D. V. Il’yasov ◽  
...  
Keyword(s):  
Methane Oxidation ◽  
Quantitative Pcr ◽  
Oxidation Rate ◽  
Methane Oxidation Rate ◽  
Soil Methane Oxidation

scholarly journals Lake overturn as a key driver for methane oxidation

2019 ◽  
Author(s):  
M. Zimmermann ◽  
M. J. Mayr ◽  
D. Bouffard ◽  
W. Eugster ◽  
T. Steinsberger ◽  
...  
Keyword(s):  
Methane Oxidation ◽  
Microbial Growth ◽  
Methane Flux ◽  
Strong Wind ◽  
Surface Cooling ◽  
Data Set ◽  
Stratified Lakes ◽  
Methane Oxidizing Bacteria ◽  
Key Driver ◽  
Oxidation Efficiency

AbstractMany seasonally stratified lakes accumulate substantial amounts of the greenhouse gas methane in the anoxic zone. Methane oxidizing bacteria in the water column act as a converter, oxidizing methane into carbon dioxide and biomass before it reaches the atmosphere. Current observations and estimates of this methane oxidation efficiency are diverging, especially for the lake overturn period. Here we combine a model of turbulent mixing, gas exchange and microbial growth with a comprehensive data set for autumn mixing to quantify the relevant physical and microbial processes. We show that the microbial methane converter is effectively transforming the increased methane flux during the overturn period. Only rare events of pronounced surface cooling in combination with persistently strong wind can trigger substantial outgassing. In the context of climate change, these results suggest that changes in the frequency of storms may be even more important for methane emissions from temperate lakes than gradual warming.

scholarly journals Detailed Patterns of Methane Distribution in the German Bight

2021 ◽  
Vol 8 ◽  
Author(s):  
Ingeborg Bussmann ◽  
Holger Brix ◽  
Götz Flöser ◽  
Uta Ködel ◽  
Philipp Fischer
Keyword(s):  
Spatial Resolution ◽  
German Bight ◽  
Methane Concentration ◽  
Spatial Dynamics ◽  
Methane Flux ◽  
Accurate Estimation ◽  
Small Scale ◽  
Input Concentration ◽  
Temporal And Spatial ◽  
Methane Distribution

Although methane is a widely studied greenhouse gas, uncertainties remain with respect to the factors controlling its distribution and diffusive flux into the atmosphere, especially in highly dynamic coastal waters. In the southern North Sea, the Elbe and Weser rivers are two major tributaries contributing to the overall methane budget of the southern German Bight. In June 2019, we continuously measured methane and basic hydrographic parameters at a high temporal and spatial resolution (one measurement per minute every 200–300 m) on a transect between Cuxhaven and Helgoland. These measurements revealed that the overall driver of the coastal methane distribution is the dilution of riverine methane-rich water with methane-poor marine water. For both the Elbe and Weser, we determined an input concentration of 40–50 nmol/L compared to only 5 nmol/L in the marine area. Accordingly, we observed a comparatively steady dilution pattern of methane concentration toward the marine realm. Moreover, small-scale anomalous patterns with unexpectedly higher dissolved methane concentrations were discovered at certain sites and times. These patterns were associated with the highly significant correlations of methane with oxygen or turbidity. However, these local anomalies were not consistent over time (days, months). The calculated diffusive methane flux from the water into the atmosphere revealed local values approximately 3.5 times higher than background values (median of 36 and 128 μmol m–2 d–1). We evaluate that this occurred because of a combination of increasing wind speed and increasing methane concentration at those times and locations. Hence, our results demonstrate that improved temporal and spatial resolution of methane measurements can provide a more accurate estimation and, consequently, a more functional understanding of the temporal and spatial dynamics of the coastal methane flux.

scholarly journals Оптические свойства растворенного органического вещества поверхностного слоя воды моря Лаптевых

2019 ◽  
Vol 126 (3) ◽  
pp. 383
Author(s):  
А.Н. Дроздова
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Continental Slope ◽  
Riverine Water ◽  
Lena River ◽  
Humic Compounds ◽  
Fluorescence Maximum ◽  
Autochthonous Organic Matter ◽  
Main Component ◽  
Lena River Delta

AbstractFeatures of fluorescence of humic compounds transported by the Lena River runoff in September 2015 are considered. The change in optical properties of dissolved organic matter, namely, fluorescence spectra and absorption coefficients at a wavelength of 350 nm, on the transect from the Lena River delta to the continental slope is demonstrated. For humic compounds of terrigenous origin, the position of the fluorescence maximum has been determined at excitation wavelengths of 270, 310, and 355 nm. It has been shown that fresh riverine waters of Lena River propagate throughout the entire shelf and humic compounds are the main component of the colored fraction of dissolved organic matter. In samples collected near the continental slope, the presence of labile autochthonous organic matter has been revealed. The content of dissolved organic matter in riverine water in 2015 is comparable with results of previous investigations and amounts to 548 μM/L.

scholarly journals Modification of methane oxidation pathways during long-term incubations of methanic lake sediments

2021 ◽  
Author(s):  
Hanni Vigderovich ◽  
Werner Eckert ◽  
Michal Elul ◽  
Maxim Rubin-Blum ◽  
Marcus Elvert ◽  
...  
Keyword(s):  
Lake Sediments ◽  
Carbon Isotope ◽  
Iron Oxides ◽  
Methane Oxidation ◽  
Electron Acceptors ◽  
Anaerobic Oxidation Of Methane ◽  
Methanotrophic Bacteria ◽  
Oxidation Of Methane ◽  
Isotope Measurements

Abstract. Anaerobic oxidation of methane (AOM) is one of the major processes limiting the release of the greenhouse gas methane from natural environments. In Lake Kinneret sediments, iron-coupled AOM (Fe-AOM) was suggested to play a substantial role (10–15 % relative to methanogenesis) in the methanic zone (> 20 cm sediment depth), based on geochemical profiles and experiments on fresh sediments. Apparently, the oxidation of methane is mediated by a combination of mcr gene bearing archaea and aerobic bacterial methanotrophs. Here we aimed to investigate the survival of this complex microbial interplay under controlled conditions. We followed the AOM process during long-term (~18 months) anaerobic slurry experiments of these methanic sediments with two stages of incubations and additions of 13C-labeled methane, multiple electron acceptors and inhibitors. After these incubation stages carbon isotope measurements in the dissolved inorganic pool still showed considerable AOM (3–8 % relative to methanogenesis). Specific lipid carbon isotope measurements and metagenomic analyses indicate that after the prolonged incubation aerobic methanotrophic bacteria were no longer involved in the oxidation process, whereas mcr gene bearing archaea were most likely responsible for oxidizing the methane. Humic substances and iron oxides are likely electron acceptors to support this oxidation, whereas sulfate, manganese, nitrate, and nitrite did not support the AOM in these methanic sediments. Our results suggest in the natural lake sediments methanotrophic bacteria are responsible for part of the methane oxidation by the reduction of combined micro levels of oxygen and iron oxides in a cryptic cycle, while the rest of the methane is converted by reverse methanogenesis. After long-term incubation, the latter prevails without bacterial methanotropic activity and with a different iron reduction pathway.

scholarly journals Characterization of particulate organic matter in the Lena River delta and adjacent nearshore zone, NE Siberia – Part I: Radiocarbon inventories

2015 ◽  
Vol 12 (12) ◽  
pp. 3769-3788 ◽  
Author(s):  
M. Winterfeld ◽  
T. Laepple ◽  
G. Mollenhauer
Keyword(s):  
Organic Matter ◽  
Carbon Isotope ◽  
Particulate Organic Matter ◽  
Coastal Erosion ◽  
Stable Carbon Isotope ◽  
Mixing Model ◽  
Transport Pathways ◽  
Particulate Nitrogen ◽  
Lena River ◽  
Lena Delta

Abstract. Particulate organic matter (POM) derived from permafrost soils and transported by the Lena River represents a quantitatively important terrestrial carbon pool exported to Laptev Sea sediments (next to POM derived from coastal erosion). Its fate in a future warming Arctic, i.e., its remobilization and remineralization after permafrost thawing as well as its transport pathways to and sequestration in marine sediments, is currently under debate. We present one of the first radiocarbon (14C) data sets for surface water POM within the Lena Delta sampled in the summers of 2009–2010 and spring 2011 (n = 30 samples). The bulk Δ14C values varied from −55 to −391 ‰ translating into 14C ages of 395 to 3920 years BP. We further estimated the fraction of soil-derived POM to our samples based on (1) particulate organic carbon to particulate nitrogen ratios (POC : PN) and (2) on the stable carbon isotope (δ13C) composition of our samples. Assuming that this phytoplankton POM has a modern 14C concentration, we inferred the 14C concentrations of the soil-derived POM fractions. The results ranged from −322 to −884 ‰ (i.e., 3060 to 17 250 14C years BP) for the POC : PN-based scenario and from −261 to −944 ‰ (i.e., 2370 to 23 100 14C years BP) for the δ13C-based scenario. Despite the limitations of our approach, the estimated Δ14C values of the soil-derived POM fractions seem to reflect the heterogeneous 14C concentrations of the Lena River catchment soils covering a range from Holocene to Pleistocene ages better than the bulk POM Δ14C values. We further used a dual-carbon-isotope three-end-member mixing model to distinguish between POM contributions from Holocene soils and Pleistocene Ice Complex (IC) deposits to our soil-derived POM fraction. IC contributions are comparatively low (mean of 0.14) compared to Holocene soils (mean of 0.32) and riverine phytoplankton (mean of 0.55), which could be explained with the restricted spatial distribution of IC deposits within the Lena catchment. Based on our newly calculated soil-derived POM Δ14C values, we propose an isotopic range for the riverine soil-derived POM end member with Δ14C of −495 ± 153 ‰ deduced from our δ13C-based binary mixing model and δ13C of −26.6 ± 1 ‰ deduced from our data of Lena Delta soils and literature values. These estimates can help to improve the dual-carbon-isotope simulations used to quantify contributions from riverine soil POM, Pleistocene IC POM from coastal erosion, and marine POM in Siberian shelf sediments.

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