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Seasonal variations of carbon isotopic composition of methane from Indian paddy fields
Author(s) -
Rao D. K.,
Bhattacharya S. K.,
Jani R. A.
Publication year - 2008
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 - 10.1029/2006gb002917
Subject(s) - methane , paddy field , flux (metallurgy) , environmental science , seasonality , δ13c , fractionation , atmospheric sciences , atmospheric methane , carbon fibers , methane emissions , growing season , carbon dioxide , carbon cycle , environmental chemistry , chemistry , agronomy , stable isotope ratio , geology , ecology , materials science , physics , ecosystem , biology , organic chemistry , quantum mechanics , composite number , composite material
Systematic measurements of methane (CH 4 ) flux and δ 13 C of methane from two paddy fields, one each from southern and western India, were carried out. There is a significant variation in δ 13 C values of methane emitted during the entire season. The estimated annual emission rates of methane for the above two paddy fields are 16 and 9 g m −2 , respectively, which are in good agreement with methane flux values reported for paddy fields in the neighboring regions within India. Methane emitted in the beginning of the growing season is relatively enriched in 13 C, then depleted before harvesting, and finally enriched again at the end of season. Seasonal changes in δ 13 C of methane are probably due to changes in methane production, oxidation, and fractionation associated with transport. The flux‐weighted annual average values of δ 13 C are calculated to be −54.3‰ and −57.2‰ for the two investigated paddy fields, which are more enriched compared to that for paddy fields in Japan, China, and Italy.