They made a quantitative study of the origin and evolution of nitrogen compounds in the Arctic atmosphere, in order to understand their environmental impact on this region. These findings are published in the 31 October 2008 issue of the journal Science.
In the Arctic, the snow that covers the land mass and the pack ice is a constant source of new surprises for researchers. One of the major players in climate change, it is also closely monitored by atmospheric chemists, who suspect it of being behind fundamental alterations in atmospheric composition in spring, when sunshine returns.
The researchers had already studied episodes of total destruction of ozone at the surface of the Arctic snow cover  as well as the role played by this cover in the dangerous mercury 'rain' that pollutes ecosystems . This time they were interested in the ability of the arctic snow cover to interact with nitrogen compounds such as nitrogen oxides and atmospheric nitrate.
At temperate latitudes nitrogen oxides are produced not only by natural phenomena such as lightning and forest fires, but also by human activity, such as combustion in engines and industrial activity. They are the cause of the peaks in ozone concentration observed on the outskirts of cities during episodes of high pollution. Nitrogen oxides are rapidly oxidized to nitrate, which, incorporated into atmospheric particulate matter, is transported by air currents, bringing surplus nitrogen to distant ecosystems.
In the Arctic, in autumn, winter and spring, the nitrate is deposited onto the snow cover. Then, when the snow is exposed to solar radiation, the nitrate turns into nitrogen oxides that are emitted to the atmosphere, causing disturbances in Arctic atmospheric chemistry. However, the extent of this phenomenon remained to be quantified.
By measuring the isotopic composition of the nitrogen and oxygen in the atmospheric nitrate collected in the Canadian Arctic (Alert station, Nunavut), the researchers have shown that the 'recycling' of nitrate deposited on the snow of the Arctic pack ice returns nitrogen oxides to the atmosphere in substantial quantities. For instance, in spring, nearly one third of the Arctic atmospheric nitrate comes from emissions of nitrogen oxides from the snow cover, while the rest comes directly from atmospheric transport from middle latitudes. The researchers also show that there are strong chemical interactions between the nitrogen oxides emitted by the snow cover and the halogenated compounds (in particular BrO radicals) that are involved in the phenomena of ozone destruction in the lower levels of the atmosphere in spring.
This study highlights the close links between the climate system (ice surfaces, snow-covered surfaces, temperatures, and percentage of solar radiation reaching the Earth's surface) and the presence of highly reactive pollutants in the Arctic atmosphere (nitrogen oxides, ozone, and particulate matter emitted by human activity). It shows the need for a global approach to environmental problems, calling for long-term monitoring and the use of new techniques for analyzing processes.
The work was funded by CNRS's National Institute of Earth Sciences and Astronomy (INSU), the Institut Polaire - Paul Émile Victor (IPEV) and by a European Science Foundation program (EUROCORE-EuroCLIMATE).
 Laboratoire de glaciologie et de géologie de l’environnement (CNRS/Université Joseph Fourier), Laboratoire d’étude des transferts en hydrologie et environnement (CNRS/Université Joseph Fourier/Institut polytechnique de Grenoble), Service d'aéronomie (CNRS/Université Pierre et Marie Curie/Université Versailles Saint Quentin)
 by the Meteorological Service of Canada ( Global Atmospheric Watch program, coordinated by the World Meteorological Organization).
Win-win strategies for climate and food security
02.10.2017 | International Institute for Applied Systems Analysis (IIASA)
The personality factor: How to foster the sharing of research data
06.09.2017 | ZBW – Leibniz-Informationszentrum Wirtschaft
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
20.10.2017 | Information Technology
20.10.2017 | Materials Sciences
20.10.2017 | Interdisciplinary Research