Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Drop in acid rain altering Appalachian stream water

14.12.2006
Appalachian hardwood forests may be getting a respite from acid rain but data from a long-term ecological study of stream chemistry suggests that the drop in acid rain may be changing biological activity in the ecosystem and hiking dissolved carbon dioxide in forest streams.

"These are unexpected results," says David DeWalle, professor of forest hydrology at Penn State. "Rising amounts of carbon dioxide in streams and soil could have implications for the forest ecosystem, and the carbon balance in general."

DeWalle and his colleagues have been monitoring stream water chemistry in the Appalachians since 1990. They are studying the effect of reduced sulfur emissions – required under the Clean Air Act – on the water quality of five streams in Pennsylvania.

"These streams are as pristine as you can get, and we have been sampling them nearly every month over the past 15 years," he says.

Some expected changes in stream chemistry are already showing. Water quality in the streams is gradually improving from the reduced sulfur emissions, and researchers are also seeing less nitrogen from the atmosphere and in the streams.

"This reduction in nitrogen deposition is yet to be seen in many parts of New England," DeWalle says. "We are probably seeing it earlier than others because we are pretty close to the sources of these emissions."

There have also been some unexpected changes. DeWalle and his Penn State colleagues Bryan Swistock, extension specialist, and Anthony Buda and Sarah MacDougall, graduate students, say they are recording rising amounts of dissolved carbon dioxide in all five streams.

DeWalle, whose work is funded by the U.S. Environmental Protection Agency, thinks that by reducing pollutants emitted to the atmosphere, we are creating a different set of conditions for organisms in the soil. The rising dissolved carbon dioxide in the streams, he suggests, might be traced to increased respiration by these organisms.

He explains that organic matter broken down by these organisms generates byproducts such as carbon dioxide, water and residual dissolved organic matter. The increased respiration, he adds, may be gradually increasing soil carbon dioxide and reducing the amount of residual organic matter. As the organisms break down more of the organic matter, there is less of it leaving as dissolved organic matter in stream water.

"There have been some experiments where they added nitrogen to the soil and saw a reduction in soil respiration. We have of course, reduced the nitrogen, and indicators of stream chemistry suggest that this may have caused the opposite reaction and stepped up the respiration," says DeWalle.

Though the stream chemistry data suggests increased respiration in the soil, researchers caution that the hypothesis needs to be tested with experiments that mimic reduced amounts of nitrogen in the atmosphere.

Penn State researchers are already seeing increasing amounts of silica and sodium in streams which may be from the weathering of minerals and sandstone bedrock, caused presumably by the increased carbonic acid in soil and groundwater.

"If you have higher carbon dioxide in the soil, you get more carbonic acid in the groundwater, which increases the weathering of minerals. You would not normally expect weathering rates to increase with reduced acid rain," DeWalle told attendees at the American Geophysical Union conference today (Dec. 12) in San Francisco.

Appalachian forests play a crucial role in maintaining a healthy ecosystem, and support thousands of jobs through the hardwood industry.

"This area is a region bigger than Pennsylvania, where we see declines in both sulfur and nitrogen emissions.

Although that is a positive thing, it is having an influence, it appears, on the forest ecosystem. Higher amounts of carbon dioxide in the soil means more of it ultimately may be emitted back to the atmosphere as a greenhouse gas," adds the Penn State researcher.

Amitabh Avasthi | EurekAlert!
Further information:
http://www.psu.edu

More articles from Earth Sciences:

nachricht Predicting unpredictability: Information theory offers new way to read ice cores
07.12.2016 | Santa Fe Institute

nachricht Sea ice hit record lows in November
07.12.2016 | University of Colorado at Boulder

All articles from Earth Sciences >>>

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 >>>