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 Lake mixing regime selects methane-oxidation kinetics of the methanotroph assemblage

2020 ◽  
Author(s):  
Magdalena J. Mayr ◽  
Matthias Zimmermann ◽  
Jason Dey ◽  
Bernhard Wehrli ◽  
Helmut Bürgmann
Keyword(s):  
Methane Oxidation ◽  
Oxidation Kinetics ◽  
Methane Monooxygenase ◽  
Stable Stratification ◽  
Stratified Lakes ◽  
Methane Oxidizing Bacteria ◽  
Half Saturation Constant ◽  
Genes Encoding ◽  
Natural Microbial Community ◽  
Methane Concentrations

Abstract. In freshwater lakes, large amounts of methane are produced in anoxic sediments. Methane-oxidizing bacteria effectively convert this potent greenhouse gas into biomass and carbon dioxide. These bacteria are present throughout the water column where methane concentrations can range from nanomolar to millimolar concentrations. In this study, we tested the hypothesis that methanotroph assemblages in seasonally stratified lakes are adapted to the contrasting methane concentrations in the epi- and hypolimnion. We further hypothesized that lake overturn would change the methane oxidation kinetics as more methane becomes available in the epilimnion. Together with the change of methane oxidation kinetics, we investigated changes in the transcription of genes encoding methane monooxygenase, the enzyme responsible for the first step of methane oxidation, with metatranscriptomics. We show that the half-saturation constant (Km) for methane, obtained from laboratory experiments with the natural microbial community, differed by two orders of magnitude between epi- and hypolimnion during stable stratification. During lake overturn, however, the kinetic constants in the epi- and hypolimnion converged along with a change of the transcriptionally active methanotroph assemblage. Conventional particulate methane monooxygenase appeared to be responsible for methane oxidation under different methane concentrations. Our results suggest that methane availability is important for creating niches for methanotroph assemblages with well-adapted methane-oxidation kinetics. This rapid selection and succession of adapted lacustrine methanotroph assemblages allows high methane removal efficiency of more than 90 % to be maintained even under rapidly changing conditions during lake overturn. Consequently, only a small fraction of methane stored in the anoxic hypolimnion is emitted to the atmosphere.

scholarly journals A statistical study of gravity waves from radiosonde observations at Wuhan (30° N, 114° E) China

2005 ◽  
Vol 23 (3) ◽  
pp. 665-673 ◽  
Author(s):  
S. D. Zhang ◽  
F. Yi
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
Extreme Values ◽  
Dynamical Instability ◽  
Strong Wind ◽  
Data Set ◽  
Height Range ◽  
Wave Parameters ◽  
Thermal Structures ◽  
Radiosonde Observation

Abstract. Several works concerning the dynamical and thermal structures and inertial gravity wave activities in the troposphere and lower stratosphere (TLS) from the radiosonde observation have been reported before, but these works were concentrated on either equatorial or polar regions. In this paper, background atmosphere and gravity wave activities in the TLS over Wuhan (30° N, 114° E) (a medium latitudinal region) were statistically studied by using the data from radiosonde observations on a twice daily basis at 08:00 and 20:00 LT in the period between 2000 and 2002. The monthly-averaged temperature and horizontal winds exhibit the essential dynamic and thermal structures of the background atmosphere. For avoiding the extreme values of background winds and temperature in the height range of 11-18km, we studied gravity waves, respectively, in two separate height regions, one is from ground surface to 10km (lower part), and the other is within 18-25km (upper part). In total, 791 and 1165 quasi-monochromatic inertial gravity waves were extracted from our data set for the lower and upper parts, respectively. The gravity wave parameters (intrinsic frequencies, amplitudes, wavelengths, intrinsic phase velocities and wave energies) are calculated and statistically studied. The statistical results revealed that in the lower part, there were 49.4% of gravity waves propagating upward, and the percentage was 76.4% in the upper part. Moreover, the average wave amplitudes and energies are less than those at the lower latitudinal regions, which indicates that the gravity wave parameters have a latitudinal dependence. The correlated temporal evolution of the monthly-averaged wave energies in the lower and upper parts and a subsequent quantitative analysis strongly suggested that at the observation site, dynamical instability (strong wind shear) induced by the tropospheric jet is the main excitation source of inertial gravity waves in the TLS.

scholarly journals Landfill GHG Reduction through Different Microbial Methane Oxidation Biocovers

Processes ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 591 ◽  
Author(s):  
Isabella Pecorini ◽  
Renato Iannelli
Keyword(s):  
Methane Oxidation ◽  
Treatment Plant ◽  
Field Trials ◽  
Pilot Scale ◽  
Msw Compost ◽  
Ghg Reduction ◽  
Global Impacts ◽  
Final Covers ◽  
Oxidation Efficiency ◽  
Specific Oxidation

Emissions from daily and final covers of municipal solid waste (MSW) landfills can produce significant impacts on local and global environments. Simplifying, landfills can cause local impacts with odor emissions and global impacts with GHGs. This work focuses on hydrogen sulfide (H2S) and methane (CH4) emissions, with the aim of studying how it is possible to reduce their impacts by means of biofiltration systems. Both field and laboratory investigations have been carried out in Casa Rota Landfill (Tuscany, Italy). In the field trials, four pilot-scale biocovers made of compost from a source-selected organic fraction (SS compost), compost from a mechanical biological treatment plant—the residual fractions of the MSW, a mixed compost (SS-MSW compost) and sand were monitored in the daily cover area of the landfill, where high emissions were detected. Results showed that high CH4 and H2S emissions reductions occurred in the mixed SS-MSW compost plot, given a maximum methane oxidation efficiency of greater than 98% and an average oxidation efficiency of about 75%. To assess the specific oxidation rate, laboratory tests using SS-MSW compost sampled from the biocovers were done.

Modelling microbial growth and biomass accumulation during methane oxidation in unsaturated soil

2020 ◽  
Vol 57 (2) ◽  
pp. 189-204
Author(s):  
Song Feng ◽  
Anthony Kwan Leung ◽  
Hong Wei Liu ◽  
Charles Wang Wai Ng ◽  
Wan Peng Tan
Keyword(s):  
Methane Oxidation ◽  
Unsaturated Soil ◽  
Reactive Transport ◽  
Microbial Growth ◽  
Gas Permeability ◽  
Biomass Accumulation ◽  
Gas Diffusion ◽  
Class B ◽  
Water Gas ◽  
Soil Pores

Microbial aerobic methane oxidation (MAMO) affects methane emissions through landfill covers by not only consuming methane, but also causing biomass accumulation associated with bacterial growth. Although the reduction of soil porosity by biomass accumulation has been well recognized, most existing models ignore this effect when estimating MAMO efficiency. The present study proposes a newly improved theoretical model that could consider the effects of both microbial growth and biomass accumulation on MAMO during coupled water–gas–heat reactive transport in unsaturated soil. Comprehensive batch incubation tests were performed to determine the input parameters required. Part of a set of published experimental data was used to validate the new model, while the remainder of the dataset was used to evaluate the model predictability of soil–microbe interaction (i.e., class B prediction). When ambient temperature is relatively high (30 °C), ignoring biomass accumulation would lead to an overestimation of MAMO efficiency by more than three times. As the biomass accumulated in soil pores, the water permeability, gas permeability, and gas diffusion in the unsaturated soil reduced, consequently limiting the supply of oxygen to the bacteria for MAMO to take place.

scholarly journals Light-Dependent Aerobic Methane Oxidation Reduces Methane Emissions from Seasonally Stratified Lakes

PLoS ONE ◽  
2015 ◽  
Vol 10 (7) ◽  
pp. e0132574 ◽  
Author(s):  
Kirsten Oswald ◽  
Jana Milucka ◽  
Andreas Brand ◽  
Sten Littmann ◽  
Bernhard Wehrli ◽  
...  
Keyword(s):  
Methane Oxidation ◽  
Methane Emissions ◽  
Stratified Lakes

scholarly journals Abundance and Activity of Methanotrophic Bacteria in Littoral and Profundal Sediments of Lake Constance (Germany)

2008 ◽  
Vol 75 (1) ◽  
pp. 119-126 ◽  
Author(s):  
M. Rahalkar ◽  
J. Deutzmann ◽  
B. Schink ◽  
I. Bussmann
Keyword(s):  
Methane Oxidation ◽  
Lake Constance ◽  
Type I ◽  
Sediment Depth ◽  
Oxidation Activity ◽  
Oxidation Rates ◽  
Methane Oxidizing Bacteria ◽  
Littoral Sediment ◽  
Sediment Layers

ABSTRACT The abundances and activities of aerobic methane-oxidizing bacteria (MOB) were compared in depth profiles of littoral and profundal sediments of Lake Constance, Germany. Abundances were determined by quantitative PCR (qPCR) targeting the pmoA gene and by fluorescence in situ hybridization (FISH), and data were compared to methane oxidation rates calculated from high-resolution concentration profiles. qPCR using type I MOB-specific pmoA primers indicated that type I MOB represented a major proportion in both sediments at all depths. FISH indicated that in both sediments, type I MOB outnumbered type II MOB at least fourfold. Results obtained with both techniques indicated that in the littoral sediment, the highest numbers of methanotrophs were found at a depth of 2 to 3 cm, corresponding to the zone of highest methane oxidation activity, although no oxygen could be detected in this zone. In the profundal sediment, highest methane oxidation activities were found at a depth of 1 to 2 cm, while MOB abundance decreased gradually with sediment depth. In both sediments, MOB were also present at high numbers in deeper sediment layers where no methane oxidation activity could be observed.

scholarly journals Does vegetation affect the methane oxidation efficiency of passive biosystems?

2015 ◽  
Vol 38 ◽  
pp. 240-249 ◽  
Author(s):  
Éliane M. Ndanga ◽  
Robert L. Bradley ◽  
Alexandre R. Cabral
Keyword(s):  
Methane Oxidation ◽  
Oxidation Efficiency

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 The direct effect of aerosols on solar radiation based on satellite observations, reanalysis datasets, and spectral aerosol optical properties from Global Aerosol Data Set (GADS)

2007 ◽  
Vol 7 (1) ◽  
pp. 753-783 ◽  
Author(s):  
N. Hatzianastassiou ◽  
C. Matsoukas ◽  
E. Drakakis ◽  
P. W. Stackhouse ◽  
P. Koepke ◽  
...  
Keyword(s):  
Optical Properties ◽  
Solar Radiation ◽  
Hydrological Cycle ◽  
Regional Scale ◽  
Local Scale ◽  
Transfer Model ◽  
Surface Cooling ◽  
Anthropogenic Aerosols ◽  
Aerosol Optical Properties ◽  
Data Set

Abstract. A global estimate of the seasonal direct radiative effect (DRE) of natural plus anthropogenic aerosols on solar radiation under all-sky conditions is obtained by combining satellite measurements and reanalysis data with a spectral radiative transfer model. The estimates are obtained with detailed spectral model computations separating the ultraviolet (UV), visible and near-infrared wavelengths. The global distribution of spectral aerosol optical properties was taken from the Global Aerosol Data Set (GADS) whereas data for clouds, water vapour, ozone, carbon dioxide, methane and surface albedo were taken from various satellite and reanalysis datasets. Using these aerosol properties and other related variables, we generate climatological (for the 12-year period 1984–1995) monthly mean aerosol DREs. The global annual mean DRE on the outgoing SW radiation at the top of atmosphere (TOA, ΔFTOA) is 1.62 Wm−2 (with a range of –10 to 15 Wm−2, positive values corresponding to planetary cooling), the effect on the atmospheric absorption of SW radiation (ΔFatmab) is 1.6 Wm−2 (values up to 35 Wm−2, corresponding to atmospheric warming), and the effect on the surface downward and absorbed SW radiation (Δ Fsurf, and ΔFsurfnet, respectively) is –3.93 and –3.22 Wm−2 (values up to –45 and –35 Wm−2, respectively, corresponding to surface cooling.) According to our results, aerosols decrease/increase the planetary albedo by –3 to 13% at the local scale, whereas on planetary scale the result is an increase of 1.5%. Aerosols can warm locally the atmosphere by up to 0.98 K day−1, whereas they can cool the Earth's surface by up to –2.9 K day−1. Both these effects, which can significantly modify atmospheric dynamics and the hydrological cycle, can produce significant planetary cooling on a regional scale, although planetary warming can arise over highly reflecting surfaces. The aerosol DRE at the Earth's surface compared to TOA can be up to 15 times larger at the local scale. The largest aerosol DRE takes place in the northern hemisphere both at the surface and the atmosphere, arising mainly at ultraviolet and visible wavelengths.

scholarly journals Microbial methane oxidation efficiency and robustness during lake overturn

2021 ◽  
Author(s):  
M. Zimmermann ◽  
M. J. Mayr ◽  
H. Bürgmann ◽  
W. Eugster ◽  
T. Steinsberger ◽  
...  
Keyword(s):  
Methane Oxidation ◽  
Oxidation Efficiency
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