Aaron Packman, associate professor of civil and environmental engineering in the McCormick School of Engineering and Applied Science, is collaborating with ecologists and microbiologists from around the world to study how organic carbon is processed in rivers.
Packman, who specializes in studying how particles and sediment move around in rivers, is co-author of a paper on the topic published online in the journal Nature Geoscience.
The paper evaluates our current understanding of carbon dynamics in rivers and reaches two important conclusions: it argues that carbon processing in rivers is a bigger component of global carbon cycling than people previously thought, and it lays out a framework for how scientists should go about assessing those processes.
Much more is known about carbon cycling in the atmosphere and oceans than in rivers. Evaluating large-scale material cycling in a river provides a challenge -- everything is constantly moving, and a lot of it moves in floods. As a result, much of what we know about carbon processing in rivers is based on what flows into the ocean.
“But that’s not really enough,” Packman said. “You miss all this internal cycling.”
In order to understand how carbon cycles around the globe -- through the land, freshwater, oceans and atmosphere -- scientists need to understand how it moves around, how it’s produced, how it’s retained in different places and how long it stays there.
In rivers, carbon is both transformed and consumed. Microorganisms like algae take carbon out of the atmosphere and incorporate it into their own cells, while bacteria eat dead organic matter and then release CO2 back into the atmosphere.
“It’s been known for a long time that global carbon models don’t really account for all the carbon,” Packman said. “There’s a loss of carbon, and one place that could be occurring is in river systems.” Even though river waters contain a small fraction of the total water on earth, they are such dynamic environments because microorganisms consume and transform carbon at rapid rates.
“We’re evaluating how the structure and transport conditions and the dynamics of rivers create a greater opportunity for microbial processing,” Packman said.
Packman is the first to admit that studying microorganisms, carbon and rivers sounds more like ecology than engineering. But such problems require work from all different areas, he said.
“We’re dealing with such interdisciplinary problems, tough problems, so we have to put fluid mechanics, transport, ecology and microbiology together to find this overall cycling of carbon,” he said. “People might say it’s a natural science paper, but to me it’s a modern engineering paper. To understand what’s going on with these large-scale processes, we have to analyze them quantitatively, and the tools for getting good estimates have been developed in engineering.”
Packman was introduced to the co-authors of the paper -- ecologists who study how dead leaves and soil drive stream ecology and who come from as far away as Spain and Austria -- about 10 years ago through the activity of the Stroud Water Research Center in Pennsylvania.
Since then, they have collaborated on many similar projects around river structure and transport dynamics. They are currently working on a project funded by the National Science Foundation on the dynamics of organic carbon in rivers and trying to understand how carbon delivered from upstream areas influence the ecology of downstream locations.
“The broadest idea is really part of global change efforts to understand carbon cycling over the whole Earth, which is an enormous challenge,” Packman said.
Megan Fellman | EurekAlert!
Tiny satellites reveal water dynamics in thousands of northern lakes
15.02.2019 | Brown University
Artificial Intelligence to boost Earth system science
14.02.2019 | Max-Planck-Institut für Biogeochemie
For the first time, an international team of scientists based in Regensburg, Germany, has recorded the orbitals of single molecules in different charge states in a novel type of microscopy. The research findings are published under the title “Mapping orbital changes upon electron transfer with tunneling microscopy on insulators” in the prestigious journal “Nature”.
The building blocks of matter surrounding us are atoms and molecules. The properties of that matter, however, are often not set by these building blocks...
Scientists at the University of Konstanz identify fierce competition between the human immune system and bacterial pathogens
Cell biologists from the University of Konstanz shed light on a recent evolutionary process in the human immune system and publish their findings in the...
Laser physicists have taken snapshots of carbon molecules C₆₀ showing how they transform in intense infrared light
When carbon molecules C₆₀ are exposed to an intense infrared light, they change their ball-like structure to a more elongated version. This has now been...
The so-called Abelian sandpile model has been studied by scientists for more than 30 years to better understand a physical phenomenon called self-organized...
Physicists from the University of Basel have developed a new method to examine the elasticity and binding properties of DNA molecules on a surface at extremely low temperatures. With a combination of cryo-force spectroscopy and computer simulations, they were able to show that DNA molecules behave like a chain of small coil springs. The researchers reported their findings in Nature Communications.
DNA is not only a popular research topic because it contains the blueprint for life – it can also be used to produce tiny components for technical applications.
11.02.2019 | Event News
30.01.2019 | Event News
16.01.2019 | Event News
18.02.2019 | Interdisciplinary Research
18.02.2019 | Process Engineering
18.02.2019 | Studies and Analyses