A recent study published in the journal Limnology and Oceanography Letters was the first to uncover that the size of lakes and the presence of nutrients directly influenced the levels of greenhouse gases that are emitted from the water body into the atmosphere. While it was previously understood that greenhouse gases were released through both natural and constructed eutrophic lakes, there was no knowledge regarding the differences in the emissions rates of these gases based on the sizing and productivity of the lake. The study concluded that shallow water bodies emit significantly higher amounts of greenhouse gases.
Through the use of satellite and sensor technology, detailed geographical data on lakes, global lake observations and statistical surveys, researchers discovered the effects of lake sizes and productivity on greenhouse gas emission. Data was correlated to global lake sizes and productivity distributions in order to get a more accurate assessment of annual greenhouse gas emissions. Using this information, researchers concluded that previous estimates were inaccurate and that effects of aquatic greenhouse gases emission is close to 20% of that of fossil fuel emissions and will continue to increase as lakes become more eutrophic. Ultimately, if the world’s lakes and other surface water continue to become more eutrophic, the level of greenhouse gas emissions from lakes could negate any reductions made by reducing fossil fuel emissions.
One of the key drivers of global climate change is the release of greenhouse gases into the atmosphere. The study revealed that lakes and other shallow water bodies are significant emitters of CO2, CH4, and N2O. According to lead author Tonya DelSontro, their work shows “conclusively that methane, which is emitted from lakes in bubbles, is the dominant greenhouse gas coming from lakes and surface waters globally. The greener or more eutrophic these water bodies become, the more methane is emitted, which exacerbates climate warming." Furthermore, methane and nitrous oxide, both of which are emitted from eutrophic lakes, seemingly have a much greater potential for causing global warming effects.
What Causes Eutrophic Lakes
Eutrophication is the leading global cause of impairment in freshwater ecosystems. In fact, according to a survey conducted by the States of the World’s Lakes, eutrophication affects 40% of all lakes in North America, 54% of Asian lakes, 53% of lakes in Europe, 41% of lakes in South American and 28% of African lakes. Often characterized by excessive plant and algae growth, eutrophic lakes have become an increasing problem as a result of human activities including both point-source discharges of wastewater and nonpoint loadings of fertilization nutrients, such as phosphorus and nitrogen. The excessive plant and algae growth limits oxygen levels, blocks sunlight, creates a foul smell, causes fish kill and overall deteriorates the water quality.
Our Unique and Effective Solution for Eutrophic Lakes
Our uniquely engineered process for water improvement, called Continuous Laminar Flow Inversion and Oxygenation, sets the stage for other functions to take place that lead to eutrophication reversal and water quality improvement. Unlike ordinary diffused air systems, surface aerators, hypolimnetic aerators, or propeller-aspirator aerators, our process oxygenates an entire lake or water body from top to bottom.
While most bottom diffusers create turbulence and re-suspend sediment, phosphorus, and nitrogen into the water column, the CLEAN-FLO Process was engineered to eliminate this problem. It functions in two primary ways. First, the Clean-Flo system relies on the surface tension between millions of tiny bubbles and the water column to move water from the bottom to the surface and increase the water column's interface with the atmosphere. Because of their design, Clean-Flow's diffusers operate on the principle of laminar flow and do not create turbulent currents of water. Second, the Clean-Flo system increases dissolved oxygen by the direct diffusion, or transfer, of oxygen between bubbles and water. This dual process results in rapid re-oxygenation and consistently high dissolved oxygen concentrations throughout the waterbody. This creates a myriad of benefits to the aquatic ecosystem.
Proven Results for Improving Eutrophic Lakes
An example of this process was demonstrated in a project for a water utility in Puerto Rico. Blue-green algae and weeds overtook the Toa Vaca Dam - a large drinking water reservoir - in Puerto Rico. The reservoir had become highly eutrophic with increased levels of fish kills. The treatment of raw water coming from a eutrophic reservoir was a real challenge because of the algae and organic matter entering the utility's treatment plants. These increased its costs and posed significant challenges to meeting its treatment objectives and budget.
Clean-Flo designed a laminar flow inversion-oxygenation system for the reservoir along with a treatment program for bioaugmentation. The system was installed in 2012, and the bioaugmentation products were added approximately four months later. The benefits of our restoring method for the Toa Vaca reservoir are several and verifiable:
- Reduction of overall treatment plant cost by 25-35%
- Reduction of sludge production by 35-40%
- Better taste and color of drinking water- elimination of yellow water
- Reduction of disinfection byproducts including TTHM
- Reduced impact of water scarcity
- Increased biodiversity
- Elimination of fish kills
- Improved water infrastructure for sustainable economic development