Showing papers on "Atmospheric methane published in 1981"
TL;DR: In this paper, the authors show that the principal means of methane escape is through the plants themselves as opposed to transport across the water-air interface via bubbles or molecular diffusion, and that existing data and flux-measurement methods are insufficient for reliable global extrapolations.
Abstract: Field measurements of methane fluxes from rice paddies, fresh water lakes, and saltwater marshes have been made to infer estimates of the size of these sources of atmospheric methane. The rice-paddy measurements, the first of their kind, show that the principal means of methane escape is through the plants themselves as opposed to transport across the water-air interface via bubbles or molecular diffusion. Nitrogen-fertilized plants release much more methane than unfertilized plants but even these measured rates are only one fourth as large as those inferred earlier by Koyama (1963, 1964) and on which all global extrapolations have been based to date. Measured methane fluxes from lakes and marshes are also compared to similar earlier data and it is found that extant data and flux-measurement methods are insufficient for reliable global extrapolations.
448 citations
TL;DR: Based on more than 16,000 measurements spanning nearly two years, the authors showed that the atmospheric concentration of CH4 is rising at a substantial rate of 1.9%±0.5% per year.
66 citations
TL;DR: Results indicate that cattle and sheep, on a global basis, release methane with an average delta(13C/12C) value of -60 and -63 per mil, respectively, which is similar to published values for marsh gas and cannot explain the 20 per mil higher values for atmospheric methane.
Abstract: The delta(13C/12C)--values of methane produced by fistulated steers, dairy cattle, and wethers, and dairy and beef cattle herds show a bimodal distribution that appears to be correlated with the plant type (C3 or C4, that is, producing either a three- or a four-carbon acid in the first step of photosynthesis) consumed by the animals. These results indicate that cattle and sheep, on a global basis, release methane with an average delta(13C/12C) value of -60 and -63 per mil, respectively. Together they are a source of atmospheric methane whose delta(13C/12C) is similar to published values for marsh gas and cannot explain the 20 per mil higher values for atmospheric methane.
60 citations
TL;DR: In this article, atmospheric observations spanning the past three years show that methane increased at 1.2 (plus or minus 0.3)% per year at Cape Grim in Tasmania (41 deg S).
Abstract: Atmospheric observations spanning the past three years show that methane increased at 1.2 (plus or minus 0.3)% per year at Cape Grim in Tasmania (41 deg S). This rate of increase can be compared to the 1.9 (plus or minus 0.4)% per year observed at Cape Meares in Oregon (45 deg N) over the past two years. Over the corresponding period the concentration at Cape Grim increased by 1.4 (plus or minus 0.4)% per year. The Southern Hemisphere data also suggest seasonal variations with minimum concentrations in March and maximum in September. These results are based on 26 large-volume stable air samples collected cryogenically in stainless steel flasks and 75 smaller-volume air samples collected in glass flasks, all analyzed by a gas chromatograph using a flame ionization detector.
58 citations
TL;DR: In this article, an automated methane/total hydrocarbon analyzer is presented, which can produce alternate methane and total hydrocarbons measurements every 7 seconds to provide the spatial resolution required for regional hydrocarbon measurements at aircraft speeds.
Abstract: An automated methane/total hydrocarbon analyzer is presented, which can produce alternate methane/total hydrocarbon measurements every 7 seconds to provide the spatial resolution required for regional hydrocarbon measurements at aircraft speeds. The construction and sampling techniques developed for the aircraft mounted system are discussed. A technique to periodically measure atmosphere oxygen is incorporated into the analyzer to ensure accurate hydrocarbon measurements, and a data collection methodology is developed to minimize errors resulting from changes in flame ionization detector sensitivity at different altitudes. Aircraft data acquired at the 1979 Southeastern Virginia Urban Plume Study are also presented, which illustrate the application of the instrument to a troposphere pollution plume.
6 citations
06 Mar 1981
TL;DR: This paper showed that cows and sheep, on a global basis, release methane with an average delta(/sup 13/C/sup 12/C) value of -60 and -63 per mil, respectively.
Abstract: The delta(/sup 13/C//sup 12/C) - values of methane produced by fistulated steers, dairy cattle, and wethers, and dairy and beef cattle herds show a bimodal distribution that appears to be correlated with the plant type (C/sub 3/ or C/sub 4/, that is, producing either a three- or a four-carbon acid in the first step of photosynthesis) consumed by the animals. These results indicate that cattle and sheep, on a global basis, release methane with an average delta(/sup 13/C//sup 12/C) value of -60 and -63 per mil, respectively. Together they are a source of atmospheric methane whose delta(/sup 13/C//sup 12/C) is similar to published values for marsh gas and cannot explain the 20 per mil higher values for atmospheric methane.
1 citations