Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study: Source of organic matter affects Bay water quality

24.04.2013
Persistence of “urban” organics downstream favors dead-zone formation
Each time it rains, runoff carries an earthy tea steeped from leaf litter, crop residue, soil, and other organic materials into the storm drains and streams that feed Chesapeake Bay.

A new study led by researchers at the Virginia Institute of Marine Science reveals that land use in the watersheds from which this “dissolved organic matter” originates has important implications for Bay water quality, with the organic carbon in runoff from urbanized or heavily farmed landscapes more likely to persist as it is carried downstream, thus contributing energy to fuel low-oxygen “dead zones” in coastal waters.

The study appears in this month’s issue of the Journal of Geophysical Research, and was highlighted by the journal’s publisher, the American Geophysical Union, as an “AGU Research Spotlight” in their print and online channels.

The study was authored by VIMS post-doctoral researcher Dr. Yuehan Lu (now at the University of Alabama), VIMS Professor Elizabeth Canuel, Professor Jim Bauer of Ohio State University, Associate Professor Youhei Yamashita of Hokkaido 
University in Japan, Professor Randy Chambers of the College of William & Mary, and Professor Rudolf Jaffé of Florida International University.

Low-oxygen dead zones are a growing problem in Chesapeake Bay and coastal ecosystems worldwide. While most management practices focus on reducing inputs of nitrogen and other nutrients known to fuel dead zones, Canuel says “organic matter from the watershed may also contribute. One goal of our study was to examine the quality of organic matter derived from streams and its potential to contribute to dead-zone formation.”

Sunlight & bacteria

As streams and rivers carry dissolved organic matter downstream, bacteria or sunlight can modify it into compounds and forms that are more difficult for organisms to use. While the team’s research showed no significant difference in bacterial degradation of organic matter from cleared or forested watersheds, Canuel says it did show that “organic carbon in runoff from watersheds affected by 
human activity is less 
susceptible to solar degradation than that from forested watersheds.”

“Urban organics” thus remain at higher 
levels longer, says Canuel, “delivering more organic material to the river mouth and increasing the likelihood that low-oxygen conditions will develop in downstream locations such as estuaries and the coastal ocean.”

The research team conducted their study using samples taken from seven small streams that flow into the James and York rivers, major tributaries of Chesapeake Bay. Three of these streams drain forested watersheds, with 87 to 100% tree cover, while the other four drain watersheds largely converted by human activity into pasture, cropland, or pavement and buildings.

The authors aren’t yet sure why the
 organic carbon from the more developed watersheds is less vulnerable to breakdown by sunlight in rivers and streams, but suggest that it might be because it has already been exposed to appreciable sunlight in the less shady urban and agricultural environment.
Says Canuel, “Urban organics may persist downstream because their more photoreactive compounds have already been degraded due to greater light exposure in urban areas, farm fields, and pastures, leaving only the more photo-resistant, refractory compounds to wash into the coastal zone.”

The team’s findings provide one possible mechanism for an observed increase in the concentration of dissolved organic carbon in the surface waters of North America and Europe during the last few decades, and have implications for management of water quality in coastal zones worldwide.

“Our results show that future studies should assess not only the quantity of dissolved organic carbon entering our rivers and streams, but also its source,” says Canuel. “Understanding how organic matter from developed and undeveloped watersheds behaves in the aquatic environment will contribute to the development of more effective watershed management practices and hopefully more successful efforts to reduce the number, extent, and duration of low-oxygen dead zones.”

David Malmquist | EurekAlert!
Further information:
http://www.vims.edu

More articles from Earth Sciences:

nachricht Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center

nachricht NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>