Small Ponds, Big Emissions, Big Dams, Small Steps
Finding solutions to the growing concern about methane emissions produced by human activities is important, but the natural sources of methane should not be ignored. According to whatsyourimpact.org and the EPA, between 36-40 percent of methane emissions come from natural sources such as wetlands, termites and bodies of water.
Early studies at Yale University on carbon (CO2) and methane (CH4) emissions of small ponds and lakes indicate that a higher proportion of emissions come from small ponds and estuaries compared to larger bodies of water. Citing Meredith Holgerson and Peter Raymond's study through the Yale School of Forestry and Environment Studies (2016), Jim Shelton with Yale News notes that ponds less than a quarter acre make up 8 percent of the total surface area of global lakes and ponds but account for 15 percent of carbon emissions as well as 40 percent of methane emissions. The shallower depths and higher perimeter-to-surface-area ratio lead to more carbon and methane reaching the surface from gas produced by sediment on the pond floor. Simply put, the decomposing leaf litter and trees that accumulate on pond floors produce methane and the small size of ponds means more of the methane is released into the atmosphere. Holgerson and Raymond are pioneers in this area but still recognize that further research is need given the difficulty of tracking these smaller bodies of water globally. Nonetheless, it presents an opportunities to explore strategies to reduce emissions in these smaller ponds as a part of the overall methane emissions reduction effort.
Recapturing some of the methane to be used as electricity is being explored as possible solution to the emissions problem from hydroelectric dams. When a dam is built this submerges a significant amount of leaf litter and vegetable matter that decomposes and produces methane similar to that in small ponds but on a larger scale. According to an article by John Platt on Mother Nature Network (2012) power plant engineers are working toward solutions to recapture the methane to be use as natural gas to produce electricity. The potential solutions from these findings are a small step in the right direction and are also promising for the reduction of emissions produced in small ponds as the technology could become more refined and scaled.
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