Currently a widespread occurrence of low oxygen concentrations in reservoirs and lakes worldwide has been generating methane that is worsening global warming. Yet while reservoirs and lakes from around the world have been facing a decrease in oxygen concentration in their lowermost layers due to land use, such occurrences are also due to climate change.
Low oxygen concentrations are known for their harmful effects on the quality of fish and water, however the effect on the concentration of methane and carbon dioxide is lesser known. Both gases as found in the planet’s atmosphere are well-known to be caused by greenhouse gasses, which increases the Earth’s warming temperature.
That is why the Virginia Tech researchers observed two reservoirs near Roanoke, namely Beaverdam and Falling Creek Reservoirs, as part of a study carried out in partnership with the Western Virginia Water Authority.
Researchers from Virginia Tech Published their Findings About the Correlation Between Oxygen and Methane Concentration
This study was one of the first to experiment at a whole-ecosystem scale as it is very difficult to manipulate a whole ecosystem.
Alexandria Hounshell, a postdoctoral researcher in the College of Science said they found in their study that low oxygen levels caused methane concentrations to be multiplied by 15 to 800 times at the scale of the whole ecosystem. Their study proved that the global warming will potentially increase in conjunction with the occurrence of low oxygen levels in reservoirs and lakes.
The team utilized an oxygenation system to fill oxygen in the Falling Creek Reservoir’s bottom waters, allowing the researchers to observe oxygen concentrations in a whole-ecosystem scale. On the other hand, the system was not installed in the Beaverdam Reservoir. The experiment was active and under observation for about three years in both reservoirs.
According to Cayelan Carey, a faculty member of the Global Chang Center, the reservoir with no oxygen in the lowermost layer had higher methane levels. The findings also showed that there is no correlation between oxygen levels and carbon dioxide levels in the reservoir as the carbon dioxide levels remained the same.
According to Carey, due to the two reservoirs being available for them to be experimented on, the researchers were able to manipulate the reservoirs to see what the future holds. Furthermore, they can say that there is a high chance that the reservoirs will become one of the high sources of methane as oxygen drops.
Ms. Hounshell added that the strength of their findings stretches for many years as the study confirmed the annual increases in methane concentrations in low oxygen environments, regardless of the related air temperature.