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 A promising target in the quest for a 1-million-year-old Antarctic ice core
24.05.2018 | University of Washington

nachricht Tropical Peat Swamps: Restoration of Endangered Carbon Reservoirs
24.05.2018 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

When corals eat plastics

24.05.2018 | Ecology, The Environment and Conservation

Surgery involving ultrasound energy found to treat high blood pressure

24.05.2018 | Medical Engineering

First chip-scale broadband optical system that can sense molecules in the mid-IR

24.05.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>