Small lakes, temporary ponds release CO2 even when dry
Staff Writer |
Temporary lakes and ponds emit CO2 all year even when they are dry and dry areas actually emit a larger amount of carbon into the atmosphere.
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This phenomenon could have an impact on the global carbon cycle that controls Earth’s climate, according to a study led by the lecturer Biel Obrador, form the Faculty of Biology of the University of Barcelona, and Núria Catalán, from the Catalan Institute for Water Research (ICRA).
The new article, published in the journal Scientific Reports, changes the classic paradigm on the role of temporary lakes and ponds as emitters of carbon to the atmosphere and their impact on the planet's greenhouse effect.
The role of continental waters in the global carbon cycle is still quite unknown - despite its importance - in particular in small or temporary aquatic systems (with dry periods).
This is one of the first published studies on carbon fluxes over the hydrological cycle of temporary water systems, with a special interest both in flooded areas and areas without water (even during dry phases in summer).
According to the lecturer Biel Obrador (UB), first author of the article, "up to a decade ago, it was thought that continental waters had an irrelevant role on global fluxes regarding the atmosphere, as a result of the tiny area they occupy compared to big carbon compartiments, like the oceans."
Moreover, the researcher adds that "even small ponds ─which are not usually larger than a basketball court─, are the most frequent lacustrine ecosystems in the planet, the amount of knowledge on carbon cycle in freshwater ponds comes from big permanent lakes (with water during all year)."
In the study, the experts analysed fluxes of COâ‚‚ and methane (CHâ‚„) -two gases with a powerful greenhouse effect- in small temporary ponds in Menorca - with a wide range of hydrological properties and hydroperiods (duration of wet phases) that oscillated between several months and some days or weeks.
The temporary ponds emit COâ‚‚ during the whole year, according to the study. Also, the amount of COâ‚‚ released into the atmosphere -around two kilograms of COâ‚‚ per square meter and year- is similar to the one emitted by turbulent fluxes waters (rivers, creeks, streams) and this value triples the fluxes of COâ‚‚ coming from permanent lakes, reservoirs and lagoons.
"Emissions of these gases result from the biogeochemical processes that occur in these ecosystems, in particular due the biological activity of microbial communities.
"According to the environmental conditions and composition of organic matter, these microorganisms produce gases such as COâ‚‚ and CHâ‚„ as a result of the respiration of organic matter in the sediment," says Biel Obrador, member of the Department of Evolutionary Biology, Ecology and Environmental Sciences of the UB. ■