Carbon emissions from dams considerably underestimated so far
Researchers re-evaluate the role of dams in the global carbon cycle
2021-05-13
(Press-News.org) Among other things, dams serve as reservoirs for drinking water, agricultural irrigation, or the operation of hydropower plants. Until now, it had been assumed that dams act as net carbon stores. Researchers from the Helmholtz Centre of Environmental Research (UFZ) together with Spanish scientists from the Catalan Institute for Water Research (ICRA) in Girona and the University of Barcelona showed that dams release twice as much carbon as they store. The study has been published in Nature Geosciences.
Whether leaves, branches, or algae - streams transport large amounts of carbon-containing material. If the water is dammed, the material gradually settles and accumulates at the bottom of the body of water. "Because of the lack of oxygen, the degradation processes are much slower down there. As a result, less carbon dioxide is released. The carbon contained is stored in the sediment of the dam for a longer time", explains Dr Matthias Koschorreck, a biologist in the Department of Lake Research at the UFZ. "It had been assumed that dams store about the same amount of carbon than they release as greenhouse gases".
However, for the carbon balance of bodies of water, not only the zones covered by water - but also those that temporarily dry out because of a drop in the water level - play a role. Koschorreck's working group had demonstrated this in previous studies. If the carbon-containing material previously covered by water comes into contact with atmospheric oxygen, degradation processes and thus the formation of carbon dioxide are strongly driven. "Areas of water that are drying out thus release considerably more carbon than areas covered by water", says Philipp Keller, a former PhD student in the Department of Lake Research at the UFZ. "If large amounts of water are released by a dam, large areas are suddenly exposed. But these areas had not been considered when calculating the carbon balance. This is the knowledge gap that we close with our work".
For their investigations, the researchers used a database based on satellite imagery. This contains monthly data on the size of water surface areas from around 6,800 dams worldwide between 1985 and 2015. For these 30 years, the scientists were thus able to determine exactly when, where, and for how long the dams were not completely filled and how large the dry areas were. On average, 15% of the total reservoir surface was not covered by water. The scientists used this figure to further calculate the carbon release from these areas. "Our calculations show that carbon emissions from dams had been significantly underestimated. On a global average, they release twice as much carbon as they store", says Koschorreck. "Their image as a net carbon store in the global carbon cycle must be reconsidered".
The data also show that the magnitude of water level fluctuations of dams depends on both their use and their geographic location. "Fluctuations were more pronounced in dams used for irrigation than in those used for hydropower generation", say Keller. "And in places where the annual precipitation pattern is more uniform - such as near the poles and around the equator - there were fewer large fluctuations in water levels than in the intermediate latitudes, where larger areas of the dams were often dry for much longer periods".
Using the example of dams, the research team demonstrates the influence of areas that are drying out on the global carbon balance of bodies of water. "We hope that our study raises the awareness that areas that are drying out must also be considered when balancing carbon fluxes of natural inland waters", says Koschorreck. The new findings could also be incorporated into a more climate-friendly management of dams. If, for example, the water has to be drained for maintenance, it makes sense to consider the best timing with respect to carbon release. If the work is done in the cold season instead of the summer, the degradation processes of the exposed carbon-containing material are much slower, and the carbon emission is much lower.
In order to better understand the carbon balance of dams, Koschorreck's research team plans to take a closer look at the release of both carbon dioxide and methane as well as the role of vegetation on the carbon cycle of areas that have become dry.
INFORMATION:
[Attachments] See images for this press release:
ELSE PRESS RELEASES FROM THIS DATE:
2021-05-13
Cooperation as a successful strategy has evolved in both nature and human society, but understanding its emergence can be a difficult task. Researchers have to abstract interactions between individuals into mathematical formulas to be able to create a model that can be used for predictions and simulations.
In the field of evolutionary game theory, they often investigate strategies of players in a simple game of giving and receiving benefits. Such strategies tell players how to behave in a given interaction. The scientists' findings counter the narrative that only the strongest and most selfish flourish and survive. Instead, they show how cooperation can be a successful and stable strategy.
Researchers, spearheaded by Laura Schmid ...
2021-05-13
The majority of children infected with SARS-CoV-2 may not show typical symptoms such as fever, cough or shortness of breath, according to a study published in Scientific Reports, which examined data on 12,306 children with laboratory-confirmed COVID-19 across the United States.
Pakaj Arora and colleagues found that 18.8% of the children included in the study were recorded as having symptoms such as fever, malaise, muscle or joint pain, and disturbances of smell or taste. . 16.5% of children had respiratory symptoms including cough and shortness of breath, 13.9% had gastrointestinal symptoms such as nausea, vomiting and diarrhea, 8.1% had dermatological symptoms (rash), and 4.8% had headaches.
5.5% (672) of children included in the study were hospitalized. Of those, 118 (17.6%) and ...
2021-05-13
CHICAGO --- For men physicians, the professional perks of networking on social media, like being asked to give a talk, are abundant, a new Northwestern Medicine study reports.
For women physicians, the benefits are far less plentiful, the study found.
What's more, women physicians are more than twice as likely to be sexually harassed on social media than men physicians, according to an earlier study, published in January, of this same group of study participants.
The findings mirror the struggles women physicians face in person when trying to advance their careers, ...
2021-05-13
New research led by the University of Kent has found that adolescents and older adults pay less attention to social cues in real-world interactions than young adults.
The findings published by Nature Human Behaviour show that social attention undergoes age-related change, which has potential implications for how successfully we can interpret social interactions in daily life and throughout the lifespan.
Interpreting the facial expression, tone of voice and gestures of others is a vital element of social interaction that allow us to make rapid inferences about others' mental states, such as their intentions, emotions, desires and beliefs. Successful social interaction prompts perspective-taking and empathy along with other essential ...
2021-05-13
Multiple studies have shown that African American women with breast cancer have lower survival rates than white women with the disease. But the association between race or ethnicity and treatment outcomes in triple-negative breast cancer -- an aggressive type of tumor that does not respond to hormonal or other targeted therapies -- has not been well defined.
Now, new research from Washington University School of Medicine in St. Louis shows that non-Hispanic African American women with triple-negative breast cancer also do not fare as well as non-Hispanic white women with this type of breast cancer. The study demonstrates the need for additional research to address disparities in cancer care and understand whether tumor biology or nonbiological reasons such as systemic racism -- ...
2021-05-13
University of Massachusetts Amherst neuroscientists examining genetically identified neurons in a songbird's forebrain discovered a remarkable landscape of physiology, auditory coding and network roles that mirrored those in the brains of mammals.
The research, published May 13 in Current Biology, advances insight into the fundamental operation of complex brain circuits. It suggests that ancient cell types in the pallium - the outer regions of the brain that include cortex - most likely retained features over millions of years that are the building blocks for advanced cognition in birds and mammals.
"We as neuroscientists are catching on that birds can do sophisticated things and they have sophisticated circuits to do those things," ...
2021-05-13
The Antarctic ice sheet was even more unstable in the past than previously thought, and at times possibly came close to collapse, new research suggests.
The findings raise concerns that, in a warmer climate, exposing the land underneath the ice sheet as it retreats will increase rainfall on Antarctica, and this could trigger processes that accelerate further ice loss.
The research is based on climate modelling and data comparisons for the Middle Miocene (13-17 million years ago) when atmospheric carbon dioxide and global temperatures reached levels similar to those expected by the end of this century.
The study was carried out by ...
2021-05-13
A new discovery led by Princeton University could upend our understanding of how electrons behave under extreme conditions in quantum materials. The finding provides experimental evidence that this familiar building block of matter behaves as if it is made of two particles: one particle that gives the electron its negative charge and another that supplies its magnet-like property, known as spin.
"We think this is the first hard evidence of spin-charge separation," said Nai Phuan Ong, Princeton's Eugene Higgins Professor of Physics and senior author on the paper published this week in the journal Nature Physics.
The experimental results fulfill a prediction made decades ago to explain one of the most mind-bending states ...
2021-05-13
The chemical compound glyphosate, the world's most widely used herbicide, can weaken the immune systems of insects, suggests a study from researchers at the Johns Hopkins Bloomberg School of Public Health. Glyphosate is the active ingredient in Round Up™, a popular U.S. brand of weed killer products.
The researchers investigated the effects of glyphosate on two evolutionarily distant insects, Galleria mellonella, the greater wax moth, and Anopheles gambiae, a mosquito that is an important transmitter of malaria to humans in Africa. They found that ...
2021-05-13
People who work nontraditional work hours, such as 11 p.m.-7 p.m., or the "graveyard" shift, are more likely than people with traditional daytime work schedules to develop a chronic medical condition -- shift work sleep disorder -- that disrupts their sleep. According to researchers at the University of Missouri, people who develop this condition are also three times more likely to be involved in a vehicle accident.
"This discovery has many major implications, including the need to identify engineering counter-measures to help prevent these crashes from happening," said Praveen Edara, department chair and professor of civil and environmental ...
LAST 30 PRESS RELEASES:
[Press-News.org] Carbon emissions from dams considerably underestimated so far
Researchers re-evaluate the role of dams in the global carbon cycle
