Correct option is C
Methane (CH₄) is a potent greenhouse gas produced primarily by anaerobic decomposition of organic matter in environments where oxygen is limited or absent. The major natural and anthropogenic sources of methane include landfills, wetlands, and paddy fields.
Landfills produce methane as organic waste decomposes anaerobically.
Wetlands are the largest natural source of methane due to waterlogged conditions that promote anaerobic decomposition.
Paddy fields emit methane due to flooded soil conditions that create anoxic environments favorable for methanogenic bacteria.
However, mountain rivers are generally well-oxygenated environments where aerobic decomposition dominates, so they are not significant sources of methane.
Hence, the correct combination is (A), (C), and (D).
Information Booster:
Methane is produced mainly by methanogenic archaea under anaerobic conditions.
Landfills contribute significantly to anthropogenic methane emissions.
Wetlands cover about 5% of Earth's surface but produce nearly 20-30% of natural methane emissions.
Paddy cultivation is a major anthropogenic source, especially in countries with large rice production.
Methane has a global warming potential approximately 25 times greater than CO₂ over 100 years.
Reducing methane emissions is crucial for climate change mitigation strategies.
Additional Information:
Landfills: Anaerobic breakdown of organic waste leads to methane production, captured in some places for energy use.
Mountain rivers: Typically have fast-flowing, oxygen-rich water; aerobic conditions limit methane production, making them minor or negligible sources.
Wetlands: Natural methane hotspots due to stagnant water and decaying vegetation under anaerobic conditions.
Paddy fields: Waterlogged fields promote anaerobic microbial activity, leading to methane release, especially in traditional flooded rice farming.
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