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 Value from wastewater
16.08.2017 | Hochschule Landshut

nachricht Species Richness – a false friend? Scientists want to improve biodiversity assessments
01.08.2017 | Carl von Ossietzky-Universität Oldenburg

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: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>