Criegee intermediates and atmospheric cleansing

these molecules

At first glance, Criegee biradicals or intermediates seem to hold a ray of hope for atmospheric clean up, at least of nitric oxide, nitrogen dioxide and sulphur dioxide.

This article appeared this morning in the UK press. So I thought I would check out other articles. The National Post tells us that by converting some pollutants into compounds that can lead to cloud formation, the earth may be somewhat shielded from the sun as things hot up.

Of course news reports are hyped so I turned to more science based reports. Live Science (this is a great article) had a more useful amount of information. Now we all know that I am no chemist, organic or otherwise but I do like a working knowledge of things hitherto unknown to me.

I found that the name of the molecule is named after a German chemist Rudolf Criegee who first hypothesised its existence in 1949. I had not heard of him until today.

 In 1949, the chemist Criegee proposed that biradicals — reactive molecules missing two chemical bonds — could form when ozone reacts with hydrocarbons like alkenes. These biradicals would presumably play a substantial role in both removing pollutants from the lower atmosphere (a process called oxidation) and producing secondary organic aerosols (primary aerosols come from such sources as sea spray and wind-blown dust, whereas secondary aerosols form from the reactions of atmospheric gases). (From LiveScience)

Apparently they are short lived molecules that form in the atmosphere when ozone reacts with a family of hydrocarbons called alkenes. Then I thought I should check out alkenes. And I did, here. These molecules contain at least one carbon-to-carbon double bond. Now, we all know that as a species we pump vast amounts of hydrocarbons into the atmosphere simply by living on our planet so any help in neutralising them is welcome. Here’s another alkene introductory article.

But before we get over confident and assume that we don’t have to do anything and the earth will look after its own (yet again), the British scientists who published these findings in Science, headed by Carl Percival

Carl Percival

from U of Manchester herald a warning.

Given that 90 percent of the alkenes in the atmosphere that produce these intermediates come from Earth’s ecosystems, the results suggest that “the ecosystem is negating climate change more efficiently than we thought it was,” said study co-author Carl Percival, an atmospheric chemist at the University of Manchester in the United Kingdom. “The most important message here is that we need to protect the ecosystems we have left.”  (From LiveScience)

His co-author

Prof. Dudley Shallcross

Dudley Shallcross from U of Bristol echoes this warning and points out that chemicals are released naturally by vegetation which helps the production of Criegee biradicals. These remaining ecological areas in the world need protecting, he says.

One of the things I have noticed about human beings is that we all share the capacity to be embarrassingly blind to uncomfortable information, especially if a change in our behaviour could help to minimise the inevitable result of the information we prefer to ignore.

It seems to me that it is always business as usual whether you are an individual or a corporation, or a government, except their rhetoric discombobulates the rest of us.

We have to clean up our act but will we do it? I doubt it. As I have said before, this is most probably our last century.

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2 comments on “Criegee intermediates and atmospheric cleansing

  1. Rosie says:

    I’m not sure that our problem is that we might become ‘over confident’, more that we human beings need to be less arrogant and more respectful of nature. Nature has been practicing for a lot longer than we have, and seems remarkably efficient at self-regulating, although overcoming the increased speed of interferences by humans may just be too much to deal with. Like you, V, I’m not convinced that we have all the answers necessary to keep the planet able to support life as we know it.

    • Veronique says:

      I can’t even count the number of people I have met who are deniers of our impact on the planet, Rosie. Likewise those who have no idea what ‘treading as lightly as possible’ on the earth means.

      The Indians of North America and the Aborigines of Australia knew how to look after their habitat. The remnants of both peoples have lost a lot of what made their ancestors so aware of their surroundings.

      My father always looked to science to fix the woes of the planet. I have never been convinced that science can fix what we wilfully unfix:-)

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