Topic
Atmospheric methane
About: Atmospheric methane is a research topic. Over the lifetime, 2034 publications have been published within this topic receiving 119616 citations.
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TL;DR: The operation of a remote, multi-path system using Chirped Laser Dispersion Spectroscopy for quantification of atmospheric methane concentrations over extended areas is demonstrated, a technology that shows potential for monitoring emissions from wetlands.
Abstract: Existing technologies for quantifying methane emissions are often limited to single point sensors, making large area environmental observations challenging. We demonstrate the operation of a remote, multi-path system using Chirped Laser Dispersion Spectroscopy (CLaDS) for quantification of atmospheric methane concentrations over extended areas, a technology that shows potential for monitoring emissions from wetlands.
26 citations
TL;DR: It was found that biofilters have great potential for reducing CH4 in diluted LFG and the retention time in the columns was not a factor limiting the oxidation process.
26 citations
TL;DR: Atmospheric methane concentration levels were detected using a custom built laser dispersion spectrometer in a long open-path beam configuration and the instrument's analytical model is validated and used for quantitative instrumental optimization.
Abstract: Atmospheric methane concentration levels were detected using a custom built laser dispersion spectrometer in a long open-path beam configuration. The instrument is driven by a chirped distributed feedback mid-infrared quantum cascade laser centered at ~1283.46 cm-1 and covers intense rotational-vibrational transitions from the fundamental ν4 band of methane. A full forward model simulating molecular absorption and dispersion profiles, as well as instrumental noise, is demonstrated. The instrument's analytical model is validated and used for quantitative instrumental optimization. The temporal evolution of atmospheric methane mixing ratios is retrieved using a fitting algorithm based on the model. Full error propagation analysis on precision gives a normalized sensitivity of ~3 ppm.m.Hz-0.5 for atmospheric methane.
26 citations
TL;DR: In this article, the authors considered the Black Sea as a "biogeochemical bucket" and the single station as a basin-wide integrator of processes affecting methane, and reported measurements of d 13 C-CH4 and d 2 H-CH 4 at a central station in the Black sea.
Abstract: We report measurements of d 13 C-CH4 and d 2 H-CH4 at a central station in the Black Sea. We considered the Black Sea as a ‘‘biogeochemical bucket’’ and the single station as a basin-wide integrator of processes affecting methane. Considering the rapid (3.6–18 yr) turnover of methane and the similarity of these stable isotope distributions to the methane concentration and oxidation rate profiles [Reeburgh, Ward, Whalen, Sandbeck, Kilpatrick, Kerkhof, 1991. Black Sea methane geochemistry. Deep-Sea Research 38, S1189–S1210], it appears that methane is being added approximately as fast as it is being oxidized. Methane can be thought of as ‘‘running in place’’ in the Black Sea water column. Recent reports of extensive vents on the northern side of the Black Sea suggest that they might be a methane source capable of effectively balancing the Black Sea methane budget. Unfortunately, we have limited information on basin-wide seep fluxes and cannot identify them with stable isotope measurements. Methane oxidation (and accompanying isotope fractionation) is so extensive that the water-column stable isotope measurements provide little information on methane sources. Future measurements of 14 C-CH4 should permit partitioning Black Sea methane sources into fossil and recent
25 citations
TL;DR: In this article, the first ever quantification of tree stem methane emissions from Melaleuca quinquenervia, a widespread iconic Australian lowland tree and globally invasive species, was presented.
Abstract: Tree stem mediated methane emissions represent a potentially important yet poorly constrained source of atmospheric methane. Here we present the first ever quantification of tree stem methane emissions from Melaleuca quinquenervia, a widespread iconic Australian lowland tree and globally invasive species. Under two distinct hydrological conditions (wet and dry) we captured 431 tree stem flux measurements encompassing six different vertical stem heights along a 50 m topo-gradient transect, separated into three distinct hydrological zones (upper, transitional and lower). The tree stem methane fluxes closely reflected local topography/hydrology and ranged from − 30.0 to 123,227 µmol m−2 day−1, with the maximum values amongst the highest values reported to date. The highest methane emissions were observed during wet conditions, within the inundated lower zone and from near the tree stem bases and water table. The average methane flux per tree (scaled to 1 m of stem) for the transitional and lower zones was 52-fold and 46-fold higher during wet conditions compared to dry, whereas the upper zone emissions changed little between seasons. Adjacent soil fluxes followed similar trends along the hydrology gradient with the upper zone tree stem emissions offsetting the adjacent soil methane sink capacity. A clear trend of sharply decreasing methane emissions with stem-height suggests a soil methane origin. A 45-h time-series of two trees within the lower zone revealed three to fourfold diel variability, with elevated morning-time fluxes. Overall, the study revealed that seasonal hydrological conditions and topo-gradient substantially regulated the methane emissions from M. quinquenervia and that this previously overlooked pathway should be accounted for within wetland methane budgets, especially during inundated conditions.
25 citations