Question

Methane (CH4) is an important greenhouse gas that is produced and consumed by a variety of biotic and abiotic processes—some of which have been heavily altered by human activity.  For each of the following, explain whether you expect (or know) them to be large sources of methane to the atmosphere, and why (i.e., what conditions favor methanogenesis,and are they found in these ecosystems):

Livestock:

Rice Paddies:

Freshwater ecosystems:

The ocean:

Answer 1

Large sources methane contributors to atmosphere are oceans. The ocean bottoms with less or no oxygen supply emit high amounts of methane. Rice paddies and livestock are next large sources of methane production. Freshwater ecosystems contain considerable amounts of O₂ due to which methane is produced in less quantities.

The livestock, mainly the ruminants contain methanogenic bacteria which produce the huge amounts of methane. The livestock dung is rich source of methane and hence is used as source of biogas. The termites produce very high quantities of methane. These are mostly occur in waterlogged rice fields and even in digestive system of ruminants. The ocean floor contains wide variety of organisms that may produce huge amounts of methane by methanogenesis. The methanogenic bacteria are main source of methane production in ocean floors.

Less amounts of oxygen and availabiliy of huge amounts of CO₂ and hydrogen favor the methanogenesis or methane production.