Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Atmospheric bromine, which attacks ozone layer, is decreasing

14.08.2003


Researchers have discovered that total bromine in the lower atmosphere has been decreasing since 1998 and is now more than five percent below the peak reached that year. Bromine is one of the most active destroyers of the stratospheric ozone layer, which forms an invisible shield around the Earth, protecting it from the biologically damaging ultraviolet rays of the Sun.



Stephen A. Montzka and colleagues from the National Oceanic and Atmospheric Administration’s Climate Monitoring and Diagnostics Laboratory in Boulder, Colorado, attribute the decline of total bromine primarily to international restrictions on industrial production of methyl bromide. Their report will be published August 15 in the journal Geophysical Research Letters.

"The decrease is driven by a large and rapid decline in methyl bromide, a brominated gas that is regulated internationally by the Montreal Protocol," said Montzka. The surprisingly large drop in atmospheric methyl bromide, about 13 percent since 1998, has more than offset the small increases still observed for bromine from fire-extinguishing agents known as halons. Bromine is about 50 times more efficient than chlorine at destroying stratospheric ozone.


"This is welcome news for stratospheric ozone because it means that less bromine and chlorine have been entering the upper atmosphere [stratosphere], where the ozone layer resides, for a number of years now," said Montzka. Furthermore, while chlorine’s decline in the lower atmosphere had been slowing in recent years, these new data suggest that the overall threat posed to stratospheric ozone from all halogenated gases continues to steadily diminish, Montzka said.

Methyl bromide is produced industrially for use as a fumigant in agriculture and in the shipment of commercial goods. It is unique among ozone-depleting substances regulated by the Montreal Protocol, in that it also has substantial natural sources, including the oceans, wetlands, some plants, and burning vegetation.

Global industrial production of methyl bromide has declined in recent years in response to restrictions outlined in the amended Montreal Protocol, say the researchers. The Montreal Protocol, which limits production of ozone-damaging compounds, was originally signed by 23 nations in 1987 and has been strengthened through revisions and amendments since then.

Methyl bromide and halons together account for nearly all of the human-released bromine that reaches the stratosphere. The NOAA scientists were able to discern the reversal in the long-term upward trend for bromine based on their ground-based measurements of methyl bromide and halons over the past eight years at 10 stations around the globe, including Cape Grim, Tasmania; the South Pole; Mauna Loa, Hawaii; and Barrow, Alaska.

The decrease in bromine is large compared to the decline documented earlier for chlorine. With this new result, the authors determined that overall ozone-depleting gases are declining faster than previously thought. International efforts to reduce industrial production of methyl bromide have had a noticeable impact on overall atmospheric levels of ozone-depleting substances, they say.

This good news must be tempered, however, because bromine from halons is still increasing slowly. But, says Montzka, "the surprisingly large decline observed for methyl bromide now dominates the overall trend for bromine." Full recovery of the ozone layer is still expected to take several decades, provided atmospheric levels of both bromine and chlorine continue to drop.

The researchers note that these encouraging trends could change. "Decreases in ozone-depleting substances are a direct result of international limits on production," said Montzka. "Without continued worldwide adherence to the restrictions outlined in the Protocol, these trends could slow and delay the recovery of stratospheric ozone."

The research was funded by NOAA.

Harvey Leifert | AGU

More articles from Earth Sciences:

nachricht Researchers reveal how microbes cope in phosphorus-deficient tropical soil
23.01.2018 | DOE/Oak Ridge National Laboratory

nachricht Radioactivity from oil and gas wastewater persists in Pennsylvania stream sediments
22.01.2018 | Duke University

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Optical Nanoscope Allows Imaging of Quantum Dots

Physicists have developed a technique based on optical microscopy that can be used to create images of atoms on the nanoscale. In particular, the new method allows the imaging of quantum dots in a semiconductor chip. Together with colleagues from the University of Bochum, scientists from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute reported the findings in the journal Nature Photonics.

Microscopes allow us to see structures that are otherwise invisible to the human eye. However, conventional optical microscopes cannot be used to image...

Im Focus: Artificial agent designs quantum experiments

On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Researchers reveal how microbes cope in phosphorus-deficient tropical soil

23.01.2018 | Earth Sciences

Opening the cavity floodgates

23.01.2018 | Life Sciences

Siberian scientists suggested a new method for synthesizing a promising magnetic material

23.01.2018 | Materials Sciences

VideoLinks Science & Research
Overview of more VideoLinks >>>