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| Last Updated:: 12/07/2024

Climate Change-Methane

Climate Change - Methane
Methane (CH4) is a colourless, odourless, non-toxic and flammable gas, and is the most simple of the hydrocarbons. Mixed with certain proportions of air, it can be dangerously explosive. Methane is a greenhouse gas that occurs naturally and its production has kept pace with the world's population growth.
Methane is produced by the breakdown of plant materials in landfills, swamps and marshes. Digestion, rotting and incomplete burning all produce methane. Methane is found in oil, gas and coal deposits. Methane gas is also produced by livestock, other animals and humans. Natural processes contribute about one-half of the methane in the atmosphere; the rest comes from agriculture and the production of fossil fuels.
Methane Emission
Rice paddy soil is among the most important anthropogenic sources of methane. Methane is produced anaerobically after the flooding of rice fields, either from acetate or hydrogen/carbon dioxide as substrate. In contrast, methanotrophic microorganisms oxidize methane to carbon dioxide in the presence of molecular oxygen in the root zone or at the air/water interface, thus reducing the overall methane emissions to the atmosphere.
Figure 1: Microbial turnover of methane and transport pathways of gases in wetlands.
CH4 production, transport and consumption
Figure 2: CH4 production, transport and consumption in the rice rhizosphere. Reactions within the shaded ellipse indicate the microbial transformations of root exudates into methane. The blue and red arrows show the diffusion of CH4 and O2 through the plant aerenchyma.
Methane impacts on Climate change
  • Soils can be a source or a sink for methane depending on their oxidative condition.
  • Significant methane production occurs at redox potentials more negative than -100 Mv (rates increase).
  • Dependence on redox potential means that properties controlling rates of oxygen diffution and consumption exert strong control.
  • Where methane production conditions are met a strong response to tempreture exists (Q10 = 4 with an optimum near 35°C).
Flood imigation
Drip/ Sprinkler imigation
Dry land