UPSC CSE Prelims 2008
Which of the above are sources of methane, a major greenhouse gas?
Option (d):
All four listed items-rice fields, coal mining, domestic animals, and wetlands-are significant sources of methane (CH₄), a potent greenhouse gas.
Rice fields: Anaerobic conditions in waterlogged paddy fields promote the activity of methanogenic bacteria, which produce methane during the decomposition of organic matter.
Coal mining: Methane, often referred to as firedamp, is trapped within coal seams and is released into the atmosphere during the extraction process.
Domestic animals: Ruminant livestock, such as cattle and sheep, emit methane as a byproduct of enteric fermentation, a natural part of their digestive process.
Wetlands: Natural wetlands are a major natural source of methane, resulting from the anaerobic decomposition of organic matter by microbes in saturated soils.
Option (a) is incorrect because it excludes coal mining and domestic animals, both of which are significant anthropogenic sources of methane.
Option (b) is incorrect as it omits rice fields and wetlands, which are substantial sources of methane, both anthropogenic and natural, respectively.
Option (c) is incorrect because wetlands are a crucial natural source of methane and must be included when considering major methane sources.