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
A new dead zone in the Indian Ocean could impact future marine nutrient balance
06.12.2016 | Max-Planck-Institut für marine Mikrobiologie
NASA's AIM observes early noctilucent ice clouds over Antarctica
05.12.2016 | NASA/Goddard Space Flight Center
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:...
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...
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...
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...
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,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
06.12.2016 | Materials Sciences
06.12.2016 | Medical Engineering
06.12.2016 | Power and Electrical Engineering