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Isotopic composition of methane released from wetlands: Implications for the increase in atmospheric methane
Author(s) -
Quay Paul D.,
King Stagg L.,
Lansdown John M.,
Wilbur David O.
Publication year - 1988
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/gb002i004p00385
Subject(s) - methane , atmospheric methane , wetland , environmental science , tundra , flux (metallurgy) , bog , methanogenesis , temperate climate , atmospheric sciences , greenhouse gas , peat , hydrology (agriculture) , environmental chemistry , chemistry , arctic , ecology , geology , oceanography , geotechnical engineering , organic chemistry , biology
Measurements of the δ 13 C of methane released from tropical, temperate, and arctic wetland sites are reported. The mean δ 13 C values (relative to PDB) for methane emitted from the Amazon floodplain, Minnesota peat bogs and Alaskan tundra are −53 ± 8, −66 ± 5 and −64 ± 5‰, respectively. These measurements combined with methane flux estimates yield a flux‐weighted global average δ 13 C value of −59 ± 6‰ for methane released from wetlands, a major natural methane source. The agreement between the measured δ 13 C for methane emitted from wetlands and the calculated steady state value of approximately −60‰ for the δ 13 C of preindustrial methane sources suggests that methane was predominantly produced biogenically in the preindustrial era. The industrial era time rate of change of the δ 13 C of the global methane flux is calculated from estimates of the growth rate of the major anthropogenically derived methane sources and the 13 C composition of these sources, and compared to the measured change in the δ 13 C of methane during the last 300 years. Based on these results, we estimate that 13 ± 8% of the current global methane flux is derived abiogenically from natural gas and biomass burning, whereas the remainder is derived biogenically primarily from wetlands, rice paddies, and livestock.