Mineral weathering generates great part of carbon dioxide in lakes and reservoirs
Nearly half of carbon dioxide (CO2) emissions from lakes all over the world are the result of a process that has not been considered until now: the weathering of minerals in the watershed. This is one of the conclusions of a scientific article published in the journal Nature Geoscience, signed by researchers in the Department of Ecology of the University of Barcelona (UB) Rafael Marcé, member of the Catalan Institute for Water Research (ICRA), Biel Obrador, Joan Lluís Riera, Pilar López, Joan Armengol, and Josep Anton-Morguí, member of the Catalan Institute of Climate Sciences (IC3).
Nearly half of carbon dioxide (CO2) emissions from lakes all over the world are the result of a process that has not been considered until now: the weathering of minerals in the watershed. This is one of the conclusions of a scientific article published in the journal Nature Geoscience, signed by researchers in the Department of Ecology of the University of Barcelona (UB) Rafael Marcé, member of the Catalan Institute for Water Research (ICRA), Biel Obrador, Joan Lluís Riera, Pilar López, Joan Armengol, and Josep Anton-Morguí, member of the Catalan Institute of Climate Sciences (IC3).
Why do lakes present CO2 supersaturation?
More than 90% worldʼs lakes and reservoirs have surface carbon dioxide concentrations that are supersaturated. Therefore, most aquatic ecosystems emit CO2 naturally to the atmosphere, a process that affects the carbon cycle which rules Earthʼs climate.
Rafael Marcé, first author of the study, says: “to date, it was thought that the main factor driving CO2 supersaturation in lakes was the activity of aquatic ecosystems, in other words, respiration, a process that generates CO2”. “The study —he points out— suggests that carbonate weathering in the watershed is as important as ecosystem carbon balance, and questions the traditional hypothesis that explains the origin of CO2 supersaturation in lakes”.
Weathering is a slow process that breaks down or dissolves rocks and minerals when they come into contact with the atmosphere. It is a chemical process that produces CO2, a molecule that water sweeps through the soil to rivers, lakes and reservoirs. Biel Obrador makes a comparison: “We could say that great part of emitted CO2 from lakes and reservoirs is like mineralsʼ breath”.
Weathering: a global phenomenon
This is the first study that quantifies the impact of weathering on CO2 emissions from lakes. It is focused on the role that lakes play in the destination of carbon from the watershed. Measurements were made in 101 reservoirs across Spain; they represent a wide range of geological and environmental conditions. Authors emphasize that the relevance of the study relies on the fact that it estimates the importance of this phenomenon in every lake all over the world.
According to conclusions, the phenomenon of watershed mineral weathering is particularly important in lakes located in tropical latitudes and temperate regions. Thus, the effects of weathering are not only significant in those areas where limestone predominates, but they are also relevant at the global level.
Further information:
Rafael Marcé, Biel Obrador, Josep-Anton Morguí, Joan Lluís Riera, Pilar López and Joan Armengol. "Carbonate weathering as a driver of CO2 supersaturation in lakes". Nature Geoscience, January 2015. DOI: 10.1038/ngeo2341