Navigation Links
Researchers document acceleration of ocean denitrification during deglaciation
Date:6/3/2013

CORVALLIS, Ore. As ice sheets melted during the deglaciation of the last ice age and global oceans warmed, oceanic oxygen levels decreased and "denitrification" accelerated by 30 to 120 percent, a new international study shows, creating oxygen-poor marine regions and throwing the oceanic nitrogen cycle off balance.

By the end of the deglaciation, however, the oceans had adjusted to their new warmer state and the nitrogen cycle had stabilized though it took several millennia. Recent increases in global warming, thought to be caused by human activities, are raising concerns that denitrification may adversely affect marine environments over the next few hundred years, with potentially significant effects on ocean food webs.

Results of the study have been published this week in the journal Nature Geoscience. It was supported by the National Science Foundation.

"The warming that occurred during deglaciation some 20,000 to 10,000 years ago led to a reduction of oxygen gas dissolved in sea water and more denitrification, or removal of nitrogen nutrients from the ocean," explained Andreas Schmittner, an Oregon State University oceanographer and author on the Nature Geoscience paper. "Since nitrogen nutrients are needed by algae to grow, this affects phytoplankton growth and productivity, and may also affect atmospheric carbon dioxide concentrations."

"This study shows just what happened in the past, and suggests that decreases in oceanic oxygen that will likely take place under future global warming scenarios could mean more denitrification and fewer nutrients available for phytoplankton," Schmittner added.

In their study, the scientists analyzed more than 2,300 seafloor core samples, and created 76 time series of nitrogen isotopes in those sediments spanning the past 30,000 years. They discovered that during the last glacial maximum, the Earth's nitrogen cycle was at a near steady state. In other words, the amount of nitrogen nutrients added to the oceans known as nitrogen fixation was sufficient to compensate for the amount lost by denitrification.

A lack of nitrogen can essentially starve a marine ecosystem by not providing enough nutrients. Conversely, too much nitrogen can create an excess of plant growth that eventually decays and uses up the oxygen dissolved in sea water, suffocating fish and other marine organisms.

Following the period of enhanced denitrification and nitrogen loss during deglaciation, the world's oceans slowly moved back toward a state of near stabilization. But there are signs that recent rates of global warming may be pushing the nitrogen cycle out of balance.

"Measurements show that oxygen is already decreasing in the ocean," Schmittner said "The changes we saw during deglaciation of the last ice age happened over thousands of years. But current warming trends are happening at a much faster rate than in the past, which almost certainly will cause oceanic changes to occur more rapidly.

"It still may take decades, even centuries to unfold," he added.

Schmittner and Christopher Somes, a former graduate student in the OSU College of Earth, Ocean, and Atmospheric Sciences, developed a model of nitrogen isotope cycling in the ocean, and compared that with the nitrogen measurements from the seafloor sediments. Their sensitivity experiments with the model helped to interpret the complex patterns seen in the observations.


'/>"/>

Contact: Andreas Schmittner
aschmittner@coas.oregonstate.edu
541-737-9952
Oregon State University
Source:Eurekalert

Related biology news :

1. Researchers design sensitive new microphone modeled on fly ear
2. Researchers help threatened wheat crops in Asia, Africa
3. U of A medical researchers ID genetic marker for sporadic breast cancer
4. UCI researchers find sea anemone venom-derived compound effective in anti-obesity studies
5. MU researchers develop radioactive nanoparticles that target cancer cells
6. Genetic predictors of postpartum depression uncovered by Hopkins researchers
7. U of M researchers develop model for better testing, targeting of MPNST
8. Widespread but neglected disease a health threat in Africa, Virginia Tech researchers say
9. Penn Medicine researchers identify 4 new genetic risk factors for testicular cancer
10. Non-inherited mutations account for many heart defects, Yale researchers find
11. Researchers discover a missing link in signals contributing to neurodegeneration
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:6/30/2017)... 30, 2017 Today, American Trucking Associations ... of face and eye tracking software, became the ... program. "Artificial intelligence and advanced ... monitor a driver,s attentiveness levels while on the ... to detect fatigue and prevent potential accidents, which ...
(Date:5/16/2017)... , May 16, 2017   Bridge ... health organizations, and MD EMR Systems , ... development partner for GE, have established a partnership ... Portal product and the GE Centricity™ products, including ... EMR. These new integrations will ...
(Date:4/17/2017)... , April 17, 2017 NXT-ID, Inc. ... company, announces the filing of its 2016 Annual Report on Form ... Exchange Commission. ... Form 10-K is available in the Investor Relations section of the ... on the SEC,s website at http://www.sec.gov . 2016 ...
Breaking Biology News(10 mins):
(Date:10/12/2017)... ... , ... AMRI, a global contract research, development and manufacturing ... and quality of life, will now be offering its impurity solutions as a ... requirements for all new drug products, including the finalization of ICH M7 earlier ...
(Date:10/11/2017)... ... October 11, 2017 , ... ... its endogenous context, enabling overexpression experiments and avoiding the use of exogenous expression ... guides is transformative for performing systematic gain-of-function studies. , This complement to ...
(Date:10/11/2017)... (PRWEB) , ... October 11, 2017 , ... ... pathology, announced today it will be hosting a Webinar titled, “Pathology is going ... Pathology Associates , on digital pathology adoption best practices and how Proscia improves ...
(Date:10/11/2017)... Tbilisi, Georgia (PRWEB) , ... October 11, 2017 , ... ... disaster, taking the lives of over 5.5 million people each year. Especially those living ... the greenovative startup Treepex - based in one of the most pollution-affected countries globally ...
Breaking Biology Technology: