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Environmental controls over methyl halide emissions from rice paddies
Author(s) -
Redeker K. R.,
Cicerone R. J.
Publication year - 2004
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 - 10.1029/2003gb002092
Subject(s) - halide , methyl iodide , chloride , paddy field , bromide , greenhouse gas , saturation (graph theory) , environmental science , agronomy , soil water , environmental chemistry , chemistry , soil science , ecology , biology , inorganic chemistry , mathematics , organic chemistry , combinatorics , medicinal chemistry
This paper examines primary controlling factors that affect methyl halide emissions from rice paddy ecosystems. Observations of four cultivars under multiple growth conditions during studies in commercial fields and the University of California, Irvine, greenhouse lead to the conclusion that daily emissions of methyl halides are primarily determined by the growth stage of the rice plant, with the exception that methyl chloride emissions show no clear seasonal pattern. Methyl chloride emissions appear to be more from the paddy water and/or soil as opposed to the plants; however, in soils with high chloride content, these emissions appear to peak during the reproductive phase. Strong secondary influences include air temperature, soil halide concentration, and soil pore water saturation. The cultivars studied had statistically separate seasonally integrated emissions. Irradiant light and aboveground biomass appear to have little effect on emissions. Emissions of methyl chloride, methyl bromide, and methyl iodide are estimated to be 3.5, 2.3, and 48 mg/m 2 /yr, or 5.3, 3.5, and 72 Gg/yr, from rice paddies globally.