Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Earth's wobble 'fixes' dinner for marine organisms

16.09.2013
The cyclic wobble of the Earth on its axis controls the production of a nutrient essential to the health of the ocean, according to a new study in the journal Nature.

The discovery of factors that control this nutrient, known as "fixed" nitrogen, gives researchers insight into how the ocean regulates its own life-support system, which in turn affects the Earth's climate and the size of marine fisheries.


Researchers from Princeton University and the Swiss Institute of Technology in Zurich found that the wobble of the Earth on its axis controls the production of fertilizing nitrogen essential to the health of the ocean. The wobble, known as axial precession, causes an upwell of nitrogen-poor (but phosphorus-rich) water from the deep ocean roughly every 23,000 years. Blue-green algae such as Trichodesmium (above) feed on the phosphorous as they convert, or "fix," nitrogen in the air into a biologically active form that becomes part of the ocean's nitrogen cycle. (Image courtesy of the Center for Microbial Oceanography, University of Hawaii)

Researchers from Princeton University and the Swiss Institute of Technology in Zurich (ETH) report that during the past 160,000 years nitrogen fixation rose and fell in a pattern that closely matched the changing orientation of Earth's axis of rotation, or axial precession. Axial precession occurs on a cycle of roughly 26,000 years and arises because the Earth wobbles slightly as it rotates, similar to the wobble of a toy top.

Studies from the 1980s revealed that precession leads to a regular upwelling of deep water in the equatorial Atlantic Ocean roughly every 23,000 years. The upwelling in turn brings nitrogen-poor water to the surface where blue-green algae convert nitrogen drawn from the air into a form that is biologically usable.

The finding that nitrogen fixation is determined by precession-driven upwelling appears to indicate that the ocean's fixed nitrogen reservoir is resilient and that the ocean biosphere can recover from even the most dramatic ecological changes, said second author Daniel Sigman, Princeton's Dusenbury Professor of Geological and Geophysical Sciences.

"By studying the response of nitrogen fixation to different environmental changes in the Earth's past, we have found connections that may ensure that the ocean's fixed nitrogen level will always rebound," Sigman said. "This suggests that an ocean over time has a relatively stable nutrient reservoir, and thus stable productivity."

The rise of deep water spurs nitrogen fixation because that water is low in nitrogen but contains an excess of another key nutrient, phosphorus, Sigman said. The phosphorus fuels the fixing of nitrogen carried out by blue-green algae, also known as cyanobacteria.

"The phosphorus-rich, nitrogen-poor water is a boon to cyanobacteria that can fix their own nitrogen," Sigman said. "By growing more rapidly, the nitrogen-fixers 'top up' the fixed nitrogen to the levels needed by other phytoplankton."

Sigman collaborated on the study with Princeton graduate student Mathis Hain; first-author Marietta Straub, Alfredo Martínez-García, A. Nele Meckler and senior author Gerald Haug, all in the Department of Earth Sciences at ETH; and Haojia Ren of the Columbia University Lamont-Doherty Earth Observatory.

The researchers tracked changes in nitrogen fixation in the North Atlantic Ocean by measuring the fixed nitrogen contained in the shells of marine animals recovered from sediment in the Caribbean Sea. Working in Sigman's lab, the investigators measured the amount of two types of nitrogen known as 14N and 15N contained in the shells of tiny marine animal plankton called foraminifera. The ratio of 15N to 14N was then used to reconstruct the rate of nitrogen fixation.

The pattern of nitrogen fixation measured in foraminifera matched the historical record of axial precession and the resulting ocean upwelling. The investigators also compared the fluctuations in nitrogen fixation to historical records of water temperature and levels of iron — another crucial nutrient — both of which influence cyanobacteria survival and thus nitrogen fixation. No correlation was found.

"Our findings suggest that this upwelling was the dominant influence on nitrogen fixation," Sigman said.

Douglas Capone, a professor and chair of biological sciences at the University of Southern California, said that the research is notable both for understanding the nitrogen cycle and for providing a method to study it.

"I have long pondered and hoped for ways to reconstruct deeper historical trends in this important nitrogen-cycle process," Capone said. "The new study by the Sigman and Haug groups is a major breakthrough in providing a means to do this along with throwing light on the major forces of this key process over long time scales."

The paper, "Changes in North Atlantic nitrogen fixation controlled by ocean circulation," was published in Nature Sept. 12. The research was supported by the Swiss and U.S. National Science Foundations and Princeton's Grand Challenges Program.

Catherine Zandonella | EurekAlert!
Further information:
http://www.princeton.edu
http://www.princeton.edu/main/news/archive/S37/90/79G54/index.xml?section=topstories

More articles from Studies and Analyses:

nachricht Drone vs. truck deliveries: Which create less carbon pollution?
31.05.2017 | University of Washington

nachricht New study: How does Europe become a leading player for software and IT services?
03.04.2017 | Fraunhofer-Institut für System- und Innovationsforschung (ISI)

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

Im Focus: Optoelectronic Inline Measurement – Accurate to the Nanometer

Germany counts high-precision manufacturing processes among its advantages as a location. It’s not just the aerospace and automotive industries that require almost waste-free, high-precision manufacturing to provide an efficient way of testing the shape and orientation tolerances of products. Since current inline measurement technology not yet provides the required accuracy, the Fraunhofer Institute for Laser Technology ILT is collaborating with four renowned industry partners in the INSPIRE project to develop inline sensors with a new accuracy class. Funded by the German Federal Ministry of Education and Research (BMBF), the project is scheduled to run until the end of 2019.

New Manufacturing Technologies for New Products

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

New technique makes brain scans better

22.06.2017 | Medical Engineering

CWRU researchers find a chemical solution to shrink digital data storage

22.06.2017 | Life Sciences

Warming temperatures threaten sea turtles

22.06.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>