Showing papers on "Atmospheric methane published in 1980"

On the possible increase of the atmospheric methane and carbon monoxide concentrations during the last decade

Abstract: Various published measurements of the background concentrations of ground level atmospheric methane suggest an increase from ∼1.6 ppm to ∼1.7 ppm over the past decade. To supplement these analyses, we have analyzed ten years of continuous data from three urban/suburban sites and find that the annual minima in the monthly midmeans of daily minima follow this suggested pattern in both direction and magnitude. A similar but less well-characterized result is obtained for carbon monoxide as well.

Methane addition to an arctic lake in winter

Abstract: The possible USC of buried pipelines to transport natural gas (-99% methane) through the Canadian arctic prompted us to study some of the dynamics of methane metabolism in an arctic lake at 63”38’N lat. The two basins of the lake were separated during winter 1977-1978 by a curtain and 300 kg of methane was dissolved into one side, to a maximum of 120 PM * liter-’ or 0.7 M * rnm2. Oxidation occurred throughout the water column but the highest rates were at or near the sediment surface. High phosphate and nitrate additions did not stimulate oxidation. The sediments generated methane naturally and winter concentrations in undisturbed lakes were 0.2-1-O PM *liter-‘. The added methane disappeared at a slow, steady rate of 1.89 mM. me2* d-l or 0.32 HIM * liter-‘. d-’ from February to June. The oxygen depletion rate of the entire experimental basin was 0.244 g* rn+.d-l, compared with 0.210 in the control basin, and was not measurably affected by artificially added methane; a winter pipeline rupture would therefore probably not result in sevcrc oxygen depletion in downstream lakes. These and other results were not expected based upon our knowledge of methane dynamics in temperate lakes.

The chemistry and transport of methane and carbon monoxide in the troposphere

Abstract: The present understanding of the physical and chemical behavior of methane, carbon monoxide and the chemical species involved in the conversion of CH4 to CO in the troposphere is reviewed. Following a brief summary of CO and CH4 emission and reactions in urban areas, attention is given to measurements of the spatial and temporal distributions of CO and CH4 in the rural atmosphere, the contribution of the oceans to atmospheric CO and CH4 concentrations, and interactions of CH4 and CO with soils and vegetation. Estimates of the transport of CH4 and CO from the troposphere to the stratosphere are discussed, and photochemical reactions of the constituents are examined. Two- and three-dimensional models for CH4 and CO transport are presented, and possible future variations in atmospheric abundances of the molecules are considered. Finally, present estimates of the global methane and carbon dioxide budgets are summarized, and it is pointed out that, despite the large contribution of anthropogenic sources, the budgets appear to be in balance.