Emissions of Methyl Halides and Methane from Rice Paddies
K. R. Redeker,1
N.-Y. Wang,1
J. C. Low,2
A. McMillan,1
S. C. Tyler,1
R. J. Cicerone12*
Methyl halide gases are important sources of atmospheric inorganic
halogen compounds, which in turn are central reactants in many
stratospheric and tropospheric chemical processes. By observing
emissions of methyl chloride, methyl bromide, and methyl iodide from
flooded California rice fields, we estimate the impact of rice
agriculture on the atmospheric budgets of these gases. Factors
influencing methyl halide emissions are stage of rice growth, soil
organic content, halide concentrations, and field-water management.
Extrapolating our data implies that about 1 percent of atmospheric
methyl bromide and 5 percent of methyl iodide arise from rice fields
worldwide. Unplanted flooded fields emit as much methyl chloride as
planted, flooded rice fields.
1 Department of Earth System Science,
2 Department of Chemistry, University of California,
Irvine, CA 92697, USA.
*
To whom correspondence should be addressed. E-mail:
rjcicero{at}uci.edu
