Navigation Links
Increasing nitrogen pollution overwhelms filtering capability of streams

MBL, WOODS HOLE, MAIncreasing nitrogen runoff from urban and agriculture land-use is interfering with our streams and rivers natural processes for reducing this pollutant before it endangers delicate downstream ecosystems, reports a nationwide team of 31 ecologists, including two from the MBL (Marine Biological Laboratory) Ecosystems Center.

The findings, published in the March 13 issue of Nature, are based on a major study of 72 streams in 8 regions across the U.S. and Puerto Rico. It was a collaborative effort by many leading aquatic ecologists working to solve a complex problem regarding the role of streams in reducing pollution, says lead author Patrick Mulholland of the Oak Ridge National Laboratory and University of Tennessee.

Just how important are streams" They are effective filters that can help prevent nitrate pollution from reaching lakes and coastal oceans, where it can cause noxious algal blooms and lead to oxygen depletion and death of fish and shellfish, as has been recently reported in the Gulf of Mexico, says Mulholland.

Building on an earlier study (Science, April 6, 2001) that demonstrated that even the smallest streams can filter up to half of the inorganic nitrogen that enters them, the scientists launched the new study to learn how increased nitrogen pollution is affecting this process. They analyzed data collected from a variety of waterways, including streams in urban and agricultural settings, where land-use dominates the landscape and degrades water quality.

Our findings demonstrate that streams containing excess nitrogen are less able to provide the natural nitrogen removal service known as denitrification, says Bruce Peterson, a senior scientist at the MBL Ecosystems Center and one of the studys authors. In denitrification, bacteria help convert nitrate in the water to nitrogen gases that then escape to the atmosphere.

The new research demonstrates that although denitrification rates increase as nitrate concentrations increase, the efficiency of denitrification and nitrate assimilation decline as nitrogen loading increases, adds Peterson. This means humans can easily overload stream and rivers networks to the point that nitrate removal is not sufficient to prevent eutrophication downstream, the scenario where algae grow out of the control and oxygen may fall to unhealthy levels.

To gauge the effects of high levels of nitrogen runoff on waterways, the scientists used the stable isotope 15N (nitrogen 15) to track nitrogen movement through each study stream. They also developed ecological models to study nitrate removal from water within river networks, which develop as small streams flow into larger streams and rivers. The models showed that the entire stream network is important in removing nitrogen from stream water.

The ecologists say these and other findings in the Nature study underscore the importance of controlling human-generated nitrogen runoff, and provide critical information to land-use managers contemplating large-scale land conversions for projects including corn farming for biofuels production.


Contact: Gina Hebert
Marine Biological Laboratory

Related biology news :

1. Toxic releases down from North American industry leaders, increasing from other facilities
2. Mountain summits in the Alps becoming increasingly similar
3. Nitrogen -- the silent species eliminator
4. Study reveals that nitrogen fertilizers deplete soil organic carbon
5. When accounting for the global nitrogen budget, dont forget fish
6. Bad news for coastal ocean: less fish out, means more nitrogen in
7. Nitrogen pollution boosts plant growth in tropics by 20 percent
8. Evolution of root nodule symbiosis with nitrogen-fixing bacteria
9. A common genetic mechanism discovered in nitrogen-fixing plants
10. Healthy rivers needed to remove nitrogen
11. ORNL study finds rivers play part in removing nitrogen
Post Your Comments:
(Date:10/8/2015)... , Oct. 8, 2015 Synaptics ... human interface solutions, announced today that it will ... fiscal 2016 on Thursday, October 22, 2015, after ... a corresponding conference call for analysts and investors ... which management may discuss forward-looking information.    ...
(Date:10/8/2015)... , October 8, 2015 ... or the "Company"), a biometric authentication company focused ... of the Wocket® smart wallet announces that revenues ... were approximately $410,000 compared with $113,00 for the ... the 9 months ended September 30, 2015 were ...
(Date:10/7/2015)... -- NXTD ) ("NXT-ID" or the "Company"), ... commerce market and creator of the Wocket® smart wallet ... term executive at American Express has been appointed to ... ("NXT-ID" or the "Company"), a biometric authentication company focused ... the Wocket® smart wallet announces Mr. Stanley E. ...
Breaking Biology News(10 mins):
(Date:10/9/2015)...  DePuy Synthes Trauma* announced today the U.S. launch ... Technology**, the only pre-hydrated demineralized cancellous bone tissue matrix ... ankle, hand and wrist), including fusion, and for filling ... 2015 Orthopaedic Trauma Association (OTA) Annual Meeting. ... bone growth) and osteoinductive 2,3 (stimulates new bone ...
(Date:10/9/2015)... ... October 09, 2015 , ... From blood to ... separating those cells from their surroundings for research, diagnostics, and cell therapy—also known ... address this, Ann Arbor-based startup Akadeum Life Sciences is developing a ...
(Date:10/8/2015)... CARDIFF, UK (PRWEB) , ... October 08, 2015 , ... ... to literally see inside the living brain, providing a new tool to study how ... work is reported by Woo June Choi and Ruikang Wang of the UW Department ...
(Date:10/8/2015)... 8, 2015  Sorrento Therapeutics, Inc. (NASDAQ:  SRNE; ... for cancer and associated pain, announced today that Dr. Henry ... presenting at the Aegis Capital Corporation 2015 Growth ... Capital Corporation 2015 Growth ConferenceDate:Friday, October 9, 2015Time:10:00 ... @ The Wynn in Las Vegas, NV , ...
Breaking Biology Technology: