Open AccessInvestigation of cattle methane production and emission over a 24‐hour period using measurements of δ 13 C and δ D of emitted CH 4 and rumen water
Author(s) -
Bilek R. S.,
Tyler S. C.,
Kurihara M.,
Yagi K.
Publication year - 2001
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2001jd900177
Subject(s) - rumen , fractionation , methane , zoology , methanogenesis , hydrogen , chemistry , analytical chemistry (journal) , environmental chemistry , biology , food science , organic chemistry , fermentation
We have conducted a series of experiments to determine the effects different diets, including the addition of unsaturated fatty acids, had on isotopic signatures of CH 4 emissions from dairy cattle. Measurements of emitted δ 13 CH 4 , δ 13 CO 2 , and δ D ‐CH 4 were made on gases collected over a 24‐hour period from animal chambers containing individual Holstein cows. Some measurements of δ D ‐H 2 O from samples collected directly from the rumen were also made. We observed variation in δ 13 CH 4 values with time after feeding and a correlation in δ 13 C between emitted gases and diet. The average δ 13 CH 4 value, which includes all samples of emitted gases, was −70.6±4.9‰ ( n = 57). Measurements of δ D ‐CH 4 over the 24‐hour sampling period had an average value of −357.8±15.0‰ ( n = 56). These δ D measurements are among the lightest reported for CH 4 produced by cattle. Our cattle data indicate that hydrogen incorporated into the CH 4 produced by CO 2 reduction in high H 2 concentration environments is fractionated to a greater degree than that incorporated in systems with relatively low H 2 conditions, such as wetlands. Our results support bacterial studies that have demonstrated large hydrogen fractionation in high H 2 concentration systems during methanogenesis.