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 Successful calculation of human and natural influence on cloud formation
04.11.2016 | Goethe-Universität Frankfurt am Main

nachricht Invasive Insects Cost the World Billions Per Year
04.10.2016 | University of Adelaide

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: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

NTU scientists build new ultrasound device using 3-D printing technology

07.12.2016 | Health and Medicine

The balancing act: An enzyme that links endocytosis to membrane recycling

07.12.2016 | Life Sciences

How to turn white fat brown

07.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>