New Ozone Depleting Substances Discovered in Atmosphere

Scientists from the University of East Anglia have identified four new ozone depleting substances (ODS) in the atmosphere above Antarctica. Even with protocols set in place, including the Montreal Protocol, which banned the use of chloroflurocarbons (CFCs)/hydrochloroflurocarbons (HCFCs) and set phase-out limits for developed/developing countries -- the four new ozone depleting substances (ODS) that have been detected in the atmosphere, total 74,000 tonnes. Questions are being raised regarding the possible source of each compound. As stated above, the Montreal Protocol prohibits the production and release of CFCs/HCFCs and as of 2010, nearly every country should have phased them out of production. Yet, there is mounting evidence that the pollutants are being emitted even at present-day. As noted in previous weeks, there are still exemptions and products that are allowed to emit the compounds.

The scientists collected air samples from relatively unpolluted and fairly remote regions, namely in Tasmania. They were then able to reconstruct the lifetime emissions of the compounds by examining air extracted from polar firn (perennial snowpack) from Greenland, which allows for an accurate construction of abundance from the past century. Based on the time that these four compounds began to be detected (after the 1960s), it has been concluded that they are likely anthropogenic sources. Researcher Johannes Laube states, "In late 2012, CFC-113a was the most abundant of the four gases at 0.48 parts per trillion molar (ppt), followed by CFC-112 at 0.44 ppt, HCFC-133a at 0.37 ppt and CFC-112a at 0.07 ppt." He goes on to state, "The identification of these four new gases is very worrying as they will contribute to the destruction of the ozone layer. We don't know where new gases are being emitted from and this should be investigated. Possible sources include feedstock chemicals for insecticide production and solvents for cleaning electronic components." Interestingly enough, based on the lag behind Tasmania and the polar firn from Greenland, which can be seen in the Figure below, scientists are certain that the lag suggests that the source of these gases is in the Northern Hemisphere, where most developed countries are located. It's worth mentioning that while the Nature article specified the likely origin of the compounds, the ScienceDaily article did not mention such information; a curious tidbit to leave out.

Chemical structure for the compounds: CFC-112 (CFCl2CFCl2), CFC-112a (CF2ClCCl3), CFC-113a (CF3CCl3) and HCFC-133a (CF3CH2Cl)
Source: Nature Geoscience

The question remains: Who is responsible for governing the management of the phase out? Currently, production of exempted chemicals is reported to the United Nations Environment Programme (UNEP) Ozone Secretariat, but nearly no public data is available. There are many loopholes, as both the article and journal article point out: granted exemptions, no reporting on fugitive emissions or trace amounts released during the production of such ODS and more. As noted in Nature, "CFC-113a, for example, has been listed as an 'agrochemical intermediate for the manufacture of synthetic pyrethroids' in a list of Montreal Protocol exemptions in 2003. This is possibly related to its use in the production of the insecticides cyhalotrin and tefluhrin. There have however been no publicly accessible reports of actual CFC-113a production to UNEP." It is worth mentioning that the Nature article could not conclusively state that the observed ODS are due to the aforementioned emissions, yet the article urges for an investigation on the origins of the compounds.

Overall, the ScienceDaily article did a decent job conveying the findings from the Nature article in a clear and concise manner, but almost to a fault. The article itself was fairly short (both from Nature and ScienceDaily) and concluded that more investigation is needed to corroborate these findings. The methods mentioned in the ScienceDaily article were rather vague, namely focusing on the findings from the article rather that going into detail on how the polar firn and other air samples were analyzed. I would give the article a 6/10 because it left out key information regarding the possible sources for each new chemical, it did not specify that they are likely released from industrialized countries, and the methodology was glossed over.

ScienceDaily: http://www.sciencedaily.com/releases/2014/03/140309150534.htm
Nature: http://www.nature.com.proxy.lib.umich.edu/ngeo/journal/v7/n4/full/ngeo2109.html