Friday, September 27, 2013

Acid Rain Research

The researchers discovered that acid rain inhibits a swampland bacteria from producing methane, a greenhouse gas. Methane, a gas that contributes to warming our planet, is produced by natural processes and human activities. Increased amounts of methane and other greenhouse gases in our atmosphere are warming the Earth beyond its average temperature.

Carbon, heat and moisture are known to influence methane production by members of the Archaea, single-celled creatures. Under normal conditions, these microbes consume organic carbon in the soil for energy and release methane as a byproduct. Wetlands provide an ideal environment for these microbes. When acid rain drops sulfate onto wetlands, another type of bacteria, ones that reduce sulfate are able to out compete the Archea, limiting the total production of methane.

Wetlands may produce as much as 320 million tons of methane annually but only about half of that, or 160 million tons, is ultimately released to the atmosphere. The other 160 million tons never makes it to the atmosphere because it is destroyed via oxidation as it moves from wet soils below the water table through dry soil to the surface. Despite substantial oxidation, natural wetlands remain the single largest source of methane emission accounting for about one third of the global annual total methane.

"It's a complicated process because multiple factors at microscopic to global scales interact in these processes," said Elaine Matthews, a scientist at NASA's Goddard Institute for Space Studies (GISS), New York. Matthews is co-author of the study on acid rain and methane in wetlands. "The maximum emission of methane from wetlands occurs when conditions are warm and wet, while the biggest reduction in methane emissions is achieved when the location of wetlands, sulfates contained in acid rain, high temperatures and substantial precipitation all come together, to reduce optimal methane emissions from wetlands." These factors vary over time and space.

No comments:

Post a Comment