Ponds Play a Complex Role in the Global Greenhouse Gas Cycle, Studies Show

Ponds are small, shallow water bodies that are often overlooked in the study of global carbon cycle and climate change. These can be natural or artificial, and can vary in size, shape, depth, and productivity.

Ponds can also play a dual role in the carbon cycle: they can sequester carbon from the atmosphere and store it in their sediments, or they can release carbon as greenhouse gases, such as carbon dioxide (CO2) and methane (CH4).

How do ponds sequester and release carbon?

(Photo : JEFF PACHOUD/AFP via Getty Images)

Ponds sequester carbon through two main processes: photosynthesis and sedimentation.

Photosynthesis is the process by which aquatic plants, algae, and cyanobacteria use light energy to convert CO2 and water into organic matter and oxygen.

Meanwhile, sedimentation is the process by which organic matter sinks to the bottom of the pond and accumulates over time.

The organic matter in the sediment can be preserved for long periods under anaerobic conditions, thus removing carbon from the atmosphere.

Ponds release carbon through two main processes: respiration and ebullition.

Respiration is the process by which aquatic organisms, including plants, animals, and microbes, use oxygen to break down organic matter and release CO2 and water, while ebullition is the process by which bubbles of gas escape from the sediment to the water surface and then to the atmosphere.

The gas can be either CO2 or CH4, depending on the availability of oxygen and the type of microbes involved.

CH4 is a more potent greenhouse gas than CO2, as it has a higher global warming potential.

Also Read: Pond Turtles Have Eyes Like Humans

How much greenhouse gas do ponds emit?

According to two related studies by Cornell researchers, ponds may emit more greenhouse gas than they store, making them net sources of emissions.

The studies used 22 Cornell Experimental Ponds, which are identical artificial ponds constructed in 1964, to measure the amount of carbon sequestered and released by ponds.

The researchers found that the ponds sequestered a significant amount of carbon in their sediments, comparable to wetlands and mangroves.

They estimated that natural and artificial ponds globally sequester 65% to 87% of the total amount estimated to be stored by all lakes.

However, they also found that the ponds emitted a large amount of CH4 to the atmosphere, especially during summer months. They calculated that the ponds emitted 5% of the global CH4 emissions from inland waters.

The researchers concluded that the net effect of ponds on the global greenhouse gas budget was negative, meaning that they emitted more than they stored.

They suggested that ponds could contribute to climate change by enhancing the greenhouse effect.

Ponds are important components of the global carbon cycle, but they may also be hidden sources of greenhouse gas emissions.

The balance between these processes determines whether ponds are net sinks or sources of emissions.

Recent research finds that ponds may emit more greenhouse gas than they store, making them net sources of emissions. Ponds could therefore have a negative impact on climate change by increasing the atmospheric concentration of greenhouse gases.

Related article: European, North American Ponds Reveal High Methane Emission, May Contribute to Climate Change More