Los freshwater ecosystems represent approximately the half the emissions global of methane. This powerful gas greenhouse effect It is the second component responsible for global warming, after carbon dioxide.
Los rivers and streams They emit substantial amounts. However, so far there has been little documentation on the rates of these emissions on a global scale, the mechanisms that control them, and the patterns that follow.
Hence the value of the contributions of the study Global methane emisiones from rivers and streamspublished this week in the magazine Nature.
The research team found that methane emissions in tropical areas are similar to those in much colder rivers.
An international team of researchers, with the participation of experts from the Center for Advanced Studies of Blanes (CEAB-CSIC), has compiled and analyzed all the published data on concentrations and emissions of methane in rivers and streams. Following the compilation of more than 20,000 methane concentration data, and coupled with high-resolution hydrological records that capture the movement and distribution of the water, models of machine learning for predict emissions of methane in all the rivers of the world.
Sampling procedure for boiling methane in a Wisconsin river. / Luke Loken
The scientists saw that the emissions of this gas in tropical zones son Similar to those of rivers much colder even from the arctic tundra. They concluded that, to unlike other aquatic systems (like lakes), the methane emissions in rivers depend less on internal factors such as water temperature. Instead, they are highly influenced by the landscape features that surrounds them, for land-water connections.
Las emissions are higher when rivers and streams drain land rich in organic matter and short of oxygen (a shortage that favors bacteria that produce methane, while decomposing organic matter). Zones of wetlandsas well as the heavily modified habitats by people often generate these conditions.
“Humans are actively modifying river networks around the world and, in general, these changes appear to favor methane emissions,” he explains. Gerard Rocher-Roslead author of the study, researcher at CEAB-CSIC and at the Swedish University of Agricultural Sciences.
Heavily modified environments such as streams closed than drain agricultural fieldsthe rivers under sewage treatment plants or the urban channels They also tend to generate conditions rich in organic matter and oxygen poor that promote a high production and emission of methane.
Emily Stanleya researcher at the Center for Limnology at the University of Wisconsin-Madison and co-author of the article, stresses: “The research shows that, from a climate change perspective, we need to be more concerned with the systems in which humans create circumstances that produce methane that by natural cycles of production of this gas”.
Restoration of river ecosystems that have been modified by humans could be an approach to reduce methane emissions and their mitigation
The information provided by the study, confirming that rivers are an important source of methane in the global atmosphere and by identifying the main processes that drive emissions, you can help to intervene in the face of the climate change. The restoration of fluvial ecosystems that have been man-made could be an approach to reduce methane emissions and their mitigation.
The research has been possible thanks to the collaboration of scientists from Umeå University (Sweden), the Swedish University of Agricultural Sciences, the University of Wisconsin-Madison and Yale (USA). Thanks to this work, a new database has also been created, the Gloval River Methane Databasewith more than 24,000 records of methane concentrations.
Rocher-Ros, G. et al. “Global methane emissions from rivers and streams”. Nature (2023)
Rights: Creative Commons.
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