Inhibitory effect of light on methane oxidation in the pelagic water column of a mesotrophic lake (Lake Biwa, Japan)

Murase, Jun; Sugimoto, Akihiro

doi:10.4319/lo.2005.50.4.1339

Cited by 81 publications

(80 citation statements)

References 11 publications

(17 reference statements)

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“…The opposite diel patterns has been observed in a deeper wind-sheltered tropical lake which became stratified and accumulated CH4 in anoxic bottom water during daytime, while nighttime convection transported the accumulated CH4 to the surface waters resulting in elevated night-time emissions (Crill et al 1988). It has been suggested that methanotrophs could be inhibited by light (Dumestre et al 1999;Murase and Sugimoto 2005) but presumably this would have a limited effect on methane oxidation in surface sediments. The results from this study and the literature show that diel patterns in CH4 concentrations and diffusive fluxes cannot be ignored.…”

Section: Discussionmentioning

confidence: 98%

Influence of weather variables on methane and carbon dioxide flux from a shallow pond

2014

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Freshwaters are important sources of the greenhouse gases methane (CH4) and carbon dioxide (CO2) to the atmosphere. Knowledge about temporal variability in these fluxes is very limited, yet critical for proper study design and evaluating flux data. Further, to understand the reasons for the variability and allow predictive modeling, the temporal variability has to be related to relevant environmental variables. Here we analyzed the effect of weather variables on CH4 and CO2 flux from a small shallow pond during a period of 4 months. Mean CH4 flux and surface water CH4 concentration were 8.0 [3.3-15.1] +/- A 3.1 mmol m(-2) day(-1) (mean [range] +/- A 1 SD) and 1.3 [0.3-3.5] +/- A 0.9 A mu M respectively. Mean CO2 flux was 1.1 [-9.8 to 16.0] +/- A 6.9 mmol m(-2) day(-1). Substantial diel changes in CO2 flux and surface water CH4 concentration were observed during detailed measurements over a 24 h cycle. Thus diel patterns need to be accounted for in future measurements. Significant positive correlations of CH4 emissions with temperature were found and could include both direct temperature effects as well as indirect effects (e.g. related to the growth season and macrophyte primary productivity providing organic substrates). CO2 flux on the other hand was negatively correlated to temperature and solar radiation, presumably because CO2 consumption by plants was higher relative to CO2 production by respiration during warm sunny days. Interestingly, CH4 fluxes were comparable to ponds with similar morphometry and macrophyte abundance in the tropics. We therefore hypothesize that CH4 and CO2 summer emissions from ponds could be more related to the morphometry and dominating primary producers rather than latitude per se. Data indicate that CH4 emissions, given the system characteristic frameworks, is positively affected by increased temperatures or prolonged growth seasons

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Section: Discussionmentioning

confidence: 98%

Influence of weather variables on methane and carbon dioxide flux from a shallow pond

2014

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“…Therefore, global estimates of CH 4 emissions from hydroelectric reservoirs that include downstream emissions (Lima et al, 2008;) calculated on the basis of the results from Amazonian reservoirs (Abril et al, 2005;Guérin et al, 2006;Kemenes et al, 2007) must be considered with caution as also pointed out by Narvenkar et al (2013).…”

Section: Contribution Of Downstream Emissions To Ch 4 Gross Emissionsmentioning

confidence: 99%

“…Each vial contained 60 mL of water and 100 mL of air. Vials were covered with aluminium foil to avoid the effect of light on any bacterial activity and incubated in the dark (Dumestre et al, 1999;Murase and Sugimoto, 2005) at 20 to 30 • C, depending on in situ temperatures. According to in situ concentration of CH 4 in the water, different amounts of CH 4 were added by syringe while withdrawing an equal volume of air from the headspace with a second syringe in order to obtain concentrations of dissolved CH 4 in the incubated water ranging from in situ to 4 times in situ.…”

Section: Aerobic Methane Oxidationmentioning

confidence: 99%

Low methane (CH<sub>4</sub>) emissions downstream of a monomictic subtropical hydroelectric reservoir (Nam Theun 2, Lao PDR)

Deshmukh

Guerin²,

Labat

et al. 2016

Biogeosciences

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Abstract. Methane (CH 4 ) emissions from hydroelectric reservoirs could represent a significant fraction of global CH 4 emissions from inland waters and wetlands. Although CH 4 emissions downstream of hydroelectric reservoirs are known to be potentially significant, these emissions are poorly documented in recent studies. We report the first quantification of emissions downstream of a subtropical monomictic reservoir. The Nam Theun 2 Reservoir (NT2R), located in the Lao People's Democratic Republic, was flooded in 2008 and commissioned in April 2010. This reservoir is a trans-basin diversion reservoir which releases water into two downstream streams: the Nam Theun River below the dam and an artificial channel downstream of the powerhouse and a regulating pond that diverts the water from the Nam Theun watershed to the Xe Bangfai watershed. We quantified downstream emissions during the first 4 years after impoundment (2009)(2010)(2011)(2012) on the basis of a high temporal (weekly to fortnightly) and spatial (23 stations) resolution of the monitoring of CH 4 concentration.Before the commissioning of NT2R, downstream emissions were dominated by a very significant degassing at the dam site resulting from the occasional spillway discharge for controlling the water level in the reservoir. After the commissioning, downstream emissions were dominated by degassing which occurred mostly below the powerhouse. Overall, downstream emissions decreased from 10 GgCH 4 yr −1 after the commissioning to 2 GgCH 4 yr −1 4 years after impoundment. The downstream emissions contributed only 10 to 30 % of total CH 4 emissions from the reservoir during the study.Most of the downstream emissions (80 %) occurred within 2-4 months during the transition between the warm dry season (WD) and the warm wet season (WW) when the CH 4 concentration in hypolimnic water is maximum (up to 1000 µmol L −1 ) and downstream emissions are negligible for Published by Copernicus Publications on behalf of the European Geosciences Union. C. Deshmukh et al.: Low methane (CH 4 ) emissions downstreamthe rest of the year. Emissions downstream of NT2R are also lower than expected because of the design of the water intake. A significant fraction of the CH 4 that should have been transferred and emitted downstream of the powerhouse is emitted at the reservoir surface because of the artificial turbulence generated around the water intake. The positive counterpart of this artificial mixing is that it allows O 2 diffusion down to the bottom of the water column, enhancing aerobic methane oxidation, and it subsequently lowered downstream emissions by at least 40 %.

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“…For methane to accumulate in the mid-water, it requires that methane oxidation is less than production. It has been proposed that methane oxidation is decreased by light in the photic zone (Murase and Sugimoto 2005); we therefore tested for this effect in Lake Stechlin.…”

mentioning

confidence: 99%

Paradox reconsidered: Methane oversaturation in well‐oxygenated lake waters

Tang

Mcginnis

Frindte

et al. 2014

Limnology & Oceanography

121

144

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The widely reported paradox of methane oversaturation in oxygenated water challenges the prevailing paradigm that microbial methanogenesis only occurs under anoxic conditions. Using a combination of field sampling, incubation experiments, and modeling, we show that the recurring mid-water methane peak in Lake Stechlin, northeast Germany, was not dependent on methane input from the littoral zone or bottom sediment or on the presence of known micro-anoxic zones. The methane peak repeatedly overlapped with oxygen oversaturation in the seasonal thermocline. Incubation experiments and isotope analysis indicated active methane production, which was likely linked to photosynthesis and/or nitrogen fixation within the oxygenated water, whereas lessening of methane oxidation by light allowed accumulation of methane in the oxygen-rich upper layer. Estimated methane efflux from the surface water was up to 5 mmol m 22 d 21 . Mid-water methane oversaturation was also observed in nine other lakes that collectively showed a strongly negative gradient of methane concentration within 0-20% dissolved oxygen (DO) in the bottom water, and a positive gradient within $ 20% DO in the upper water column. Further investigation into the responsible organisms and biochemical pathways will help improve our understanding of the global methane cycle.

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Inhibitory effect of light on methane oxidation in the pelagic water column of a mesotrophic lake (Lake Biwa, Japan)

Cited by 81 publications

References 11 publications

Influence of weather variables on methane and carbon dioxide flux from a shallow pond

Influence of weather variables on methane and carbon dioxide flux from a shallow pond

Low methane (CH<sub>4</sub>) emissions downstream of a monomictic subtropical hydroelectric reservoir (Nam Theun 2, Lao PDR)

Paradox reconsidered: Methane oversaturation in well‐oxygenated lake waters

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Inhibitory effect of light on methane oxidation in the pelagic water column of a mesotrophic lake (Lake Biwa, Japan)

Cited by 81 publications

References 11 publications

Influence of weather variables on methane and carbon dioxide flux from a shallow pond

Influence of weather variables on methane and carbon dioxide flux from a shallow pond

Low methane (CH&lt;sub&gt;4&lt;/sub&gt;) emissions downstream of a monomictic subtropical hydroelectric reservoir (Nam Theun 2, Lao PDR)

Paradox reconsidered: Methane oversaturation in well‐oxygenated lake waters

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Low methane (CH<sub>4</sub>) emissions downstream of a monomictic subtropical hydroelectric reservoir (Nam Theun 2, Lao PDR)