Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Rivers great and small can fight pollution, if given chance

13.03.2008
Big rivers typically get the credit for being powerful and mighty, but a sweeping national study released today shows that when it comes to pollution control, even little streams can pack a punch.

Stephen Hamilton, an aquatic ecologist at Michigan State University, studied nine streams that flowed through cities, forests and agricultural land in the Kalamazoo River watershed of southwestern Michigan as part of a nationwide team seeking to understand what happens to the nitrogen that is washed into the water.

The results, published in this week’s issue of Nature, provide the most comprehensive understanding yet of how the complex network of rivers and streams – mighty and small – naturally process nitrogen from the waters before it ends up causing trouble downstream.

“This study presents a picture of unprecedented detail of the extent to which streams can remove nitrate,” Hamilton said. “We also now have a better idea of what makes one stream more efficient at nitrate removal than another.”

The stakes are high. Nitrogen gets into the water as runoff from fertilizers and wastes from human activities. Too much nitrogen can cause noxious algal blooms and lead to oxygen depletion and death of fish and shellfish, as has been recently reported in the Gulf of Mexico.

Rivers and streams naturally can act as the “kidneys of our landscape,” according to lead author Patrick Mulholland of the Oak Ridge National Laboratory and University of Tennessee. They can significantly improve the quality of water, thereby reducing the potential for problems in downstream environments.

Hamilton and his team from MSU and the University of Notre Dame spent three years conducting experiments in which they added small amounts of a harmless, nonradioactive isotope of nitrogen, N-15, into streams. They then were able to track the isotope as it traveled downstream and record what processes removed it from the water.

What they found, which was supported by experiments across 72 streams in eight regions across the United States and Puerto Rico, was that the nitrate was taken up from stream water by tiny organisms such as algae, fungi and bacteria. In addition, a considerable fraction was permanently removed from streams by a bacterial process known as denitrification, which converts nitrate to nitrogen gas that then escapes harmlessly into the atmosphere.

Hamilton said they also learned that not all streams are created equal. Streams that are allowed to meander naturally through a complex channel were more efficient at filtering pollutants than streams that had been engineered to quickly convey water away from farmland or developments.

“What we often do to streams to make them more like drains diminishes their ability to reduce pollutants,” Hamilton said. “Complexity – both biological and physical – helps streams be more effective at removing nitrogen.”

In addition, the effectiveness of streams to remove nitrate was greatest if the streams were not overloaded by nitrogen sources such as fertilizers and wastes from human activities. If overloaded, a stream or river passes nitrogen downstream, where it can cause problems in oceans and coastal waterways.

This appears to put two imperatives at odds – removing water quickly from urban areas or agricultural fields versus trying to reduce pollutants. But Hamilton said there are ways to satisfy both goals, such as directing waters into wetland ponds or buffer strips that allow nature time to gobble the nitrates.

The study, Hamilton said, now presents a comprehensive picture that can help guide stream and river management and land-use planning.

Stephen Hamilton | EurekAlert!
Further information:
http://www.msu.edu

More articles from Studies and Analyses:

nachricht New model connects respiratory droplet physics with spread of Covid-19
21.07.2020 | University of California - San Diego

nachricht Risk of infection with COVID-19 from singing: First results of aerosol study with the Bavarian Radio Chorus
03.07.2020 | Klinikum der Universität München

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: ScanCut project completed: laser cutting enables more intricate plug connector designs

Scientists at the Fraunhofer Institute for Laser Technology ILT have come up with a striking new addition to contact stamping technologies in the ERDF research project ScanCut. In collaboration with industry partners from North Rhine-Westphalia, the Aachen-based team of researchers developed a hybrid manufacturing process for the laser cutting of thin-walled metal strips. This new process makes it possible to fabricate even the tiniest details of contact parts in an eco-friendly, high-precision and efficient manner.

Plug connectors are tiny and, at first glance, unremarkable – yet modern vehicles would be unable to function without them. Several thousand plug connectors...

Im Focus: New Strategy Against Osteoporosis

An international research team has found a new approach that may be able to reduce bone loss in osteoporosis and maintain bone health.

Osteoporosis is the most common age-related bone disease which affects hundreds of millions of individuals worldwide. It is estimated that one in three women...

Im Focus: AI & single-cell genomics

New software predicts cell fate

Traditional single-cell sequencing methods help to reveal insights about cellular differences and functions - but they do this with static snapshots only...

Im Focus: TU Graz Researchers synthesize nanoparticles tailored for special applications

“Core-shell” clusters pave the way for new efficient nanomaterials that make catalysts, magnetic and laser sensors or measuring devices for detecting electromagnetic radiation more efficient.

Whether in innovative high-tech materials, more powerful computer chips, pharmaceuticals or in the field of renewable energies, nanoparticles – smallest...

Im Focus: Tailored light inspired by nature

An international research team with Prof. Cornelia Denz from the Institute of Applied Physics at the University of Münster develop for the first time light fields using caustics that do not change during propagation. With the new method, the physicists cleverly exploit light structures that can be seen in rainbows or when light is transmitted through drinking glasses.

Modern applications as high resolution microsopy or micro- or nanoscale material processing require customized laser beams that do not change during...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“Conference on Laser Polishing – LaP 2020”: The final touches for surfaces

23.07.2020 | Event News

Conference radar for cybersecurity

21.07.2020 | Event News

Contact Tracing Apps against COVID-19: German National Academy Leopoldina hosts international virtual panel discussion

07.07.2020 | Event News

 
Latest News

Rare Earth Elements in Norwegian Fjords?

06.08.2020 | Earth Sciences

Anode material for safe batteries with a long cycle life

06.08.2020 | Power and Electrical Engineering

Turning carbon dioxide into liquid fuel

06.08.2020 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>