Ponds Emit Greenhouse Gases

According to latest study small ponds play a disproportionately large role in global greenhouse gas emissions from inland waters.

Although ponds less than a quarter of an acre in size make up only 8.6 percent of the surface area of the world’s lakes and ponds, they account for 15.1 percent of carbon dioxide (CO2) emissions and 40.6 percent of diffusive methane (CH4) emissions.

This study is the first to include these small ponds in global estimates of CO2 and CH4 emissions, largely because they are difficult to map and were thought to play a small role in carbon cycling.

Ponds play an important role in the carbon cycle as gases produced at the bottom of small ponds are able to reach the top more often than what occurs in larger lakes, due to greater water mixing and shallower waters. As a result, CO2 and CH4 generated in the sediments affects the entire pond.

The researchers also found that CO2 and CH4 concentrations were greatest in smaller ponds and decreased as the ponds and lakes grew larger.

The reason being that small ponds have a high perimeter-to-surfacearea ratio, for example, and accumulate a higher load of terrestrial carbon – so-called “leaf litter”, sediment particles and other material, the study showed.