Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study finds controlling phosphorus pollution in wetlands more important than believed

28.01.2003


A study led by a Duke University scientist suggests that the current emphasis on controlling upstream nitrogen pollution fails to adequately address the impacts on water quality of another potential contaminant, phosphorus. Thus, according to the scientists, current strategies used by environmental managers to control excessive nutrients in coastal wetlands may not achieve their intended goals.



The finding was published in a report in the Friday, Jan. 24, 2003, issue of the journal Science by Pallaoor Venkatesh Sundareshwar, a research associate and instructor at the Duke University Wetland Center in the Nicholas School of the Environment and Earth Sciences and co-authors James Morris and Brandon Fornwalt from the University of South Carolina at Columbia, and Eric Koepfler from Coastal Carolina University in Conway, S.C. The study was funded by the National Science Foundation and the National Oceanic and Atmospheric Administration.

Sundareshwar and his co-authors worked in a pristine wetland at the University of South Carolina’s Baruch Marine Field Laboratory, near Georgetown, where organisms’ natural interactions could be studied in the absence of human-caused pollution.


Both the phosphorus originating in upstream fertilizer applications, and the nitrogen derived from lawn and agricultural fertilizers or animal livestock operations can run off the land and flow downstream to shallow wetland estuaries, where they can cause algae blooms and fish kills that can threaten critical seafood nursery areas.

Managers have emphasized controlling nitrogen because that nutrient can lead to highly visible algae "blooms" in estuaries, which can turn the water green, Sundareshwar said in an interview. "People tend to be driven by what they see. But what we have shown is that’s not the whole truth; there is a major response to phosphorus by bacteria, which you can’t see."

By treating test plots with measured amounts of nitrogen and phosphorus, and comparing those results with untreated plots, the scientists learned that whereas plants visibly respond to nitrogen fertilization, bacteria in saturated wetland soils respond to phosphorus, not nitrogen. Bacterial responses to phosphorus pollution thus inconspicuously mimic the response of algae to nitrogen.

When nitrogen pollution leads to a surge of algae in coastal waters, subsequent algae die-offs release nutrients and carbon that the bacteria use for growth, and in doing so rob the water of needed oxygen, he added.

Extra phosphorus causes the bacteria to undergo a growth spurt and also consume any available organic matter, Sundareshwar said. In removing the carbon from the organic matter the bacteria take up oxygen as well. When coastal waters are over-enriched with phosphorus, bacteria can thus consume available carbon and remove enough oxygen from the water to potentially harm fish, even if there is no excess nitrogen in the water to cause algae blooms.

"Gone are the days of saying ’nitrogen, that’s the only thing,’ or ’phosphorus, that’s the only thing,’" Sundareshwar said. "I’m saying it’s high time we start looking at a more integrated approach to coastal management."

Not only do plants and bacteria in a coastal wetland respond to different nutrients; the tie between phosphorus supplies and bacterial growth also affects inputs and outputs of nitrogen in a wetland ecosystem, Sundareshwar and his co-authors report.

Among certain "legume" plants such as soybeans that grow on dry land, phosphorus fertilization increases nitrogen fixation by "symbiotic" bacteria residing in plant roots. These bacteria convert nitrogen from the air to a chemical form that acts as a plant fertilizer. Fixing that nitrogen is also an energy-intensive process requiring the symbiotic bacteria to use carbon from their host plants as an energy source.

In contrast to how symbiotic bacteria respond to phosphorus in dry land plants, Sundareshwar’s group found that adding extra phosphorus to a pristine coastal wetland can prompt the non-symbiotic bacteria that reside there to "shut down nitrogen fixation instead of promoting it," he said.

At Duke, Sundareshwar has designed a new course on the biogeochemistry of estuaries based on his personal studies. "As I teach this course, I always promote the integrated view, to get away from isolating-out nitrogen and phosphorus," he said.

Monte Basgall | EurekAlert!
Further information:
http://www.duke.edu/

More articles from Ecology, The Environment and Conservation:

nachricht Upcycling 'fast fashion' to reduce waste and pollution
03.04.2017 | American Chemical Society

nachricht Litter is present throughout the world’s oceans: 1,220 species affected
27.03.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

NASA's Fermi catches gamma-ray flashes from tropical storms

25.04.2017 | Physics and Astronomy

Researchers invent process to make sustainable rubber, plastics

25.04.2017 | Materials Sciences

Transfecting cells gently – the LZH presents a GNOME prototype at the Labvolution 2017

25.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>