Question

Reservoirs emit carbon dioxide and methane . what could be the source? lang Answer​

Answer 1

Answer:

The "fuel" for the methane, carbon dioxide and nitrous oxide emitted by dams is the rotting of the vegetation and soils flooded by reservoirs, and of the organic matter (plants, plankton, algae, etc.) that flows into, and is produced in, reservoirs over their lifespan.

Explanation:

Greenhouse gases, primarily methane (CH4) and carbon dioxide (CO2), are emitted from all of the dozens of reservoirs where measurements have been made. Gases are emitted from the surface of the reservoir, at turbines and spillways, and for tens of kilometers downstream (see schematic). Emissions are highest in hot climates. Hydro plants in the tropics with large reservoirs relative to their generating capacity can have a much greater impact on global warming than fossil fuel plants generating equivalent amounts of electricity (see graph below).The "fuel" for these emissions is the rotting of organic matter from the vegetation and soils flooded when the reservoir is first filled. The carbon in the plankton and plants that live and die in the reservoir, the detritus washed down from the watershed above, and the seasonal flooding of plants along the reservoir fringes, ensure that emissions continue for the lifetime of the reservoir. Emission levels vary widely between different reservoirs depending upon the area and type of ecosystems flooded, reservoir depth and shape, the local climate, and the way in which the dam is operated. For instance, China's reservoirs are often deep but sludge-filled, while Brazil's reservoirs are shallow and in a tropical zone. Both cases can lead to high emissions.