A team of international scientists known as the NICOPP (Nitrogen Cycle in the Ocean, Past and Present) working group, led by Dalhousie oceanographer Markus Kienast and Eric Galbraith of McGill University, use these cylinders to measure isotopes of nitrogen on the seafloor that arise from nitrogen-rich phytoplankton sinking and collecting in the mud.
“Over thousands of years, this slow accumulation builds up a vertical record of past changes that can be sampled by taking a sediment core using a specialized ship,” says Dr. Kienast. “As you go down in the core, you go back in time.”
In a new paper, published last week in Nature Geoscience, the NICOPP working group presented the first global synopsis of available sedimentary nitrogen isotope records from throughout the world’s oceans, spanning the past 30,000 years.
“The results confirm the ocean is an effective self-regulator with respect to nitrogen, a major nutrient,” says Dr. Kienast, “but reaching equilibrium after a disturbance such as the last glacial-interglacial warming can take hundreds or thousands of years.”
That’s a concern, given the scale and speed of current anthropogenic changes. In recent years, human activity, rather than natural causes, has become the main factor in oceanic change around the world. Global warming, along with the heavy use of nitrogen-based fertilizers for agriculture, is pushing the natural ocean nitrogen cycle off balance.
“Despite its importance for all marine life, we don’t really have a good handle on how the global ocean will react to these changes,” said Dr. Galbraith. “With too little nitrogen, the ecosystem would starve. Too much, and the decay of sinking phytoplankton would use up the oxygen dissolved in ocean water, suffocating fish and other marine animals.”
This highlights the importance of research on the interplay between climate change and ocean biogeochemistry.
Previous studies on nitrogen isotopes in marine sediment records had shown signs of changes in denitrification at the end of the ice age, in some localized places. But the nitrogen isotope records are difficult to interpret from individual sites alone.
“Our research was driven by our need to provide quantitative constraints of climate change effects on the global ocean,” says Dr. Kienast.
After three years of research, the international team, composed of 35 ocean researchers, completed their goal of assembling a global network of sediment records to see the full picture clearly and compare the results with computer models of the ocean.
“This publication is not the end of it,” says Dr. Kienast. “We have a great group of enthusiastic scientists and we are looking to broaden our group and expand our research. Stay tuned.”
On his recent trip collecting sediment samples in the western tropical Pacific, Dr. Kienast was accompanied by Dalhousie MSc student Liz Kerrigan.
“If you like getting muddy, then you’ll love sediment work,” says Kerrigan. “Ultimately, this information from the sediment helps us reveal a little bit more about what’s happening in the ocean, both today and in the past”.
It is not a rare occasion for Dalhousie Oceanography graduate students to spend time at sea — it’s a key program requirement.
“A requirement that they are usually more than happy to fulfill,” says Dr. Kienast.
Regis Dudley, Communications, Faculty of Science, Dalhousie University, (902) 494-4105, firstname.lastname@example.org
Regis Dudley | Newswise
Large-Mouthed Fish Was Top Predator After Mass Extinction
26.07.2017 | Universität Zürich
Strength of tectonic plates may explain shape of the Tibetan Plateau, study finds
25.07.2017 | University of Illinois at Urbana-Champaign
Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers
Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...
Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.
At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...
3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects
A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...
Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.
For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...
What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.
To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...
21.07.2017 | Event News
19.07.2017 | Event News
12.07.2017 | Event News
26.07.2017 | Health and Medicine
26.07.2017 | Life Sciences
25.07.2017 | Physics and Astronomy