Title: The regional budget of atmospheric methane of a highly populated area
Abstract: A regional methane budget for the catchment area of Heidelberg has been established, using quasi-continuous measurements of the atmospheric methane concentration and its stable isotope ratios (13C12C, D/H). Methane in Heidelberg shows a mean concentration offset of 155 ppbv relative to background air. This concentration offset is due to a direct influence from - mainly anthropogenic - continental European methane sources. Using parallel atmospheric 222Radon observations, and the observed CH4 concentration offset, we estimated the mean CH4 flux density within the catchment area to be (12±6) gCH4 m−2 yr−1. This is three times the global average for continental surfaces. From the stable isotope observations we derived the isotopic composition of the mean methane source to be δ13Csource(PDB) = (−54.3±1.7)‰ and δDsource(SMOW) = (−270±41)‰. In an independent approach we evaluated the distribution of methane sources from source statistics within a catchment area of ca. 500 km radius around Heidelberg. With help of a simple dispersion model we then calculated their contributions to the concentration offset at the sampling site. Using the isotopic composition of the mean source as constraint to adjust the specific emissions of individual sources it turned out that the major contributions to the observed concentration offset in Heidelberg are from cattle (37%), landfills (27%), coal mining (12%), agricultural wastes (11%), burning of fuels (8%), and gas leakages (5%). This source mix is more or less the same as in the whole catchment area (e.g. Central Europe).
Publication Year: 1993
Publication Date: 1993-01-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 43
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