High levels of molecular chlorine found in Arctic atmosphere

Jan 13, 2014
Jin Liao checks the instrumentation in Barrow, Alaska, during a research trip to measure molecular chlorine in the atmosphere. Liao is the first author of the study, published January 12 in the Advance Online Publication of Nature Geoscience.

(Phys.org) —Scientists studying the atmosphere above Barrow, Alaska, have discovered unprecedented levels of molecular chlorine in the air, a new study reports.

Molecular chlorine, from sea salt released by melting , reacts with sunlight to produce . These chlorine atoms are highly reactive and can oxidize many constituents of the including methane and , as well activate bromine chemistry, which is an even stronger oxidant of elemental mercury. Oxidized mercury is more reactive and can be deposited to the Arctic ecosystem.

The study is the first time that molecular chlorine has been measured in the Arctic, and the first time that scientists have documented such high levels of molecular chlorine in the atmosphere.

"No one expected there to be this level of chlorine in Barrow or in polar regions," said Greg Huey, a professor in the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology in Atlanta.

The study was published January 12 in the journal Nature Geoscience and was supported by the National Science Foundation (NSF), part of the international multidisciplinary OASIS program.

The researchers directly measured molecular chlorine levels in the Arctic in the spring of 2009 over a six-week period using chemical ionization mass spectrometry. At first the scientists were skeptical of their data, so they spent several years running other experiments to ensure their findings were accurate.

The level of molecular chlorine above Barrow was measured as high as 400 parts per trillion, which is a high concentration considering that chlorine atoms are short –lived in the atmosphere because they are strong oxidants and are highly reactive with other atmospheric chemicals.
Molecular chlorine concentrations peaked in the early morning and late afternoon, and fell to near-zero levels at night. Average daytime molecular chlorine levels were correlated with ozone concentrations, suggesting that sunlight and ozone may be required for molecular chlorine formation.

Previous Arctic studies have documented high levels of oxidized mercury in Barrow and other polar regions. The major source of elemental mercury in the Arctic regions is coal-burning plants around the world. In the spring in Barrow, ozone and elemental mercury are often depleted from the atmosphere when halogens—chlorine and bromine—are released into the air from melting sea ice.

"Molecular chlorine is so reactive that it's going to have a very strong influence on atmospheric chemistry," Huey said.

Chlorine atoms are the dominant oxidant in Barrow, the study found. The area is part of a region with otherwise low levels of oxidants in the atmosphere, due to the lack of water vapor and ozone, which are the major precursors to making oxidants in many urban areas.

In Barrow, snow-covered ice pack extends in every directly except inland. The ultimate source of the molecular chlorine is the sodium chloride in sea salt, Huey said, most likely from the snow-covered ice pack. How the sea salt is transformed into molecular chlorine is unknown.

"We don't really know the mechanism. It's a mystery to us right now," Huey said. "But the sea ice is changing dramatically, so we're in a time where we have absolutely no predictive power over what's going to happen to this chemistry. We're really in the dark about the chlorine."

Scientists do know that sea ice is rapidly changing, Huey said. The sea ice that lasts from one winter to the next winter is decreasing. This has created a larger area of melted ice, and more ice that comes and goes with the seasons. This seasonal variation in ice could release more molecular chlorine into the atmosphere.

"There is definite climate change happening in the Arctic," Huey said. "That's changing the nature of the ice, changing the volume of the ice, changing the surface area and changing the chemistry of the ."

Explore further: NASA reveals new results from inside the ozone hole

More information: Jin Liao, et al., "High levels of molecular chlorine n the Arctic atmosphere," (Nature Geoscience, January 2014). dx.doi.org/10.1038/NGEO2046

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Returners
2.6 / 5 (8) Jan 13, 2014
The study is the first time that molecular chlorine has been measured in the Arctic, and the first time that scientists have documented such high levels of molecular chlorine in the atmosphere.


Don't go into panic mode yet. Remember the Methane Torches? I bet most of this is all-natural. Discovering it a few years ago for the first time means nothing since you don't have a historical data set for comparison.

"We don't really know the mechanism. It's a mystery to us right now... ...We're really in the dark about the chlorine."


Suggest taking sea ice cores of various ages, and hit it with light emulating the sun (including infrared, uv, etc,) and watch what happens.

Suggest testing the ice cores via mass spectrometry for unknown catalysts appearing in trace amounts.

Normally chlorine should react with sodium, but perhaps a certain type of radiation breaks the bond, or perhaps there is a catalyst in the ice/water which reverses the normal reaction..
Returners
2.3 / 5 (6) Jan 13, 2014
Hypothesis:

Sodium and Potassium are metallic in their molecular form. Chlorine is a gas in it's molecular.

For this reason, it is conceivable that in the ionic form in solution in water or water-ice, the Chlorine has a certain chance, however small, of escaping the liquid while the potassium or sodium remains behind. I think it need not even be a matter of other chemistry. For example, if you think about it probabilistically, or in terms of QM, there must be a chance of the two Chlorine atoms interacting to form molecular Chlorine temporarily, and then there must be a chance of this molecule (or else the two atoms independently,) vibrating or tunnel out of the liquid or solid.

Because the Chlorine is a gas, when this happens it would totally escape, but since Sodium and Potassium are solids, even if they vibrated onto the surface of the water(or ice) they'd just sit there, or sink back in, or react with the water itself.

I'd say it's a physical/mechanical process, not chemistry.
deatopmg
2.8 / 5 (9) Jan 13, 2014
OMG, it's worse than we thought!

It's common knowledge that sea ice and snow are composed of essentially pure water, so where does the NaCl in the ice pack come from? The small coating of salt water or sea water itself? When sun light is at it's strongest sea water, not ice, is the dominant salt source.

Blaming Arctic warming, i.e. fresh water ice melting, as the root cause promotes the political agenda and increases the likelihood of further funding. It's blind to the facts & does nothing to advance the science.

Indigestion
1 / 5 (3) Jan 13, 2014
This was a while back, 30 years, 85?....think I'm an old fart now, but not much wiser... but I had a physical chem professor at the U of U where this discussion came up in class over the ozone layer, CFCs, and molecular chlorine in the atmosphere. It was his opinion that molecular chlorine contributed more to ozone depletion than the CFCs since so much more was used in, or the result of, the chlorination of public water. I wondered when an article like this would show up ever since then....never really saw one until now, but never looked really hard either.

Of course, conspiracy wise, and we must go there because this is a phys.org comment section, Dupont's patents may have been running out....
mosahlah
1 / 5 (3) Jan 13, 2014
Yet another surprise in global atmospheric chemistry. I wonder what the effect will be concerning long term global temperature and CO2 predictions.
Returners
2 / 5 (4) Jan 13, 2014
Yet another surprise in global atmospheric chemistry. I wonder what the effect will be concerning long term global temperature and CO2 predictions.


There may be a regulating mechanism in the biosphere. There are some cave bacteria and other microbes which metabolize Chlorine compounds, but as I recall, the by-product is hydrochloric acid. Depending on the cave geology, this acid could become concentrated deeper in the cave, and react with rocks. Perhaps this could serve as a mechanism of natural sequestration of the Chlorine, assuming it doesn't leak back into oceans or rivers.
radek
1 / 5 (2) Jan 13, 2014
http://arxiv.org/...6844.pdf

everybody should be satisfied - AGW apologets because of CFC emmision and naturalists bec of CR driven mechanism.
baudrunner
1.8 / 5 (6) Jan 13, 2014
Methinks that the unexpected levels are not all the result of natural processes. Old-fashioned industrial fertilizer manufacturing techniques used in China, for example, and chlorinated water releasing chlorine vapor into the atmosphere etc.
Mimath224
1 / 5 (3) Jan 13, 2014
baudrunner yes. Where I live sometimes the chlorinated water odour is pungent and stings when in contact with recent skin breaks. (I add that this water is NOT for consumption and drinking water has to be bought from trucks separately.) So it seems that some countries still over chlorinate water supplies.
Howhot
4.2 / 5 (5) Jan 14, 2014
Chlorine is very reactive and will bind with just about anything it meets. So for there to be a spike in chlorine readings in one area of Alaska, would indicate a localized event. As the article suggest, melting of sea ice is the major cause. Nothing else makes sense. If the chlorine levels correlate with melting sea-ice, then there must be a lot of sea ice melting to create "Unprecedented levels" of chlorine. It fits with known AGW facts.

It's an AGW global warming effect.
Restrider
5 / 5 (2) Jan 14, 2014
Hypothesis:

Sodium and Potassium are metallic in their molecular form. Chlorine is a gas in it's molecular.



You also have to consider the change of the acidity in the sea water.
If you generate Cl2 and metallic Na out of NaCl, the metallic Na would instantly react with H2O forming OH- and thus this mechanism would increase the pH value.

Maybe it is some sort of counter reaction to acidification of sea water due to higher CO2 concentrations.
However, the proposed mechanism just seems too simple and improbable (NaCl ist quite stable).
Probably there is more to it.
EnricM
not rated yet Jan 14, 2014
The study is the first time that molecular chlorine has been measured in the Arctic, and the first time that scientists have documented such high levels of molecular chlorine in the atmosphere.


Don't go into Conspiracy mode yet. I bet that all is done by Evil Dr. No and SPECTRA who everybody know is allied with the IPCC (Illuminati Pokemon Collectors Club).

Let's call 007 to clean off all these evil Climate scientists!
Dug
not rated yet Jan 14, 2014
"Molecular chlorine, from sea salt released by melting sea ice, reacts with sunlight to produce chlorine atoms." It's also a common reaction that goes on continually anywhere there is seawater+wind = sea spray and sunlight. It would be really difficult to distinguish molecular chlorine coming from open ocean spray reactions carried by arctic winds = with salt ice reactions once the wind carried the spray over the ice. Obviously, more grants needed to further study this well known chemical phenomena.
kienhoa68
5 / 5 (1) Jan 14, 2014
A most ineresting theory. Somewhat better than simply dissing the idea so soon. The change we are undergoiing will reveal phenomena previously unkown in both kind and rate. We are already witnessing unusual Jet Stream behavior. For some a direct assult on their existence is required to reach a level of awareness and concern for the matters at hand. Just human nature at its best.

Hypothesis:

Sodium and Potassium are metallic in their molecular form. Chlorine is a gas in it's molecular.



You also have to consider the change of the acidity in the sea water.
If you generate Cl2 and metallic Na out of NaCl, the metallic Na would instantly react with H2O forming OH- and thus this mechanism would increase the pH value.

Maybe it is some sort of counter reaction to acidification of sea water due to higher CO2 concentrations.
However, the proposed mechanism just seems too simple and improbable (NaCl ist quite stable).
Probably there is more to it.

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