FOREnSic Innovations to constrain GreenHouse Trace gas budgets

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A halocarbon is an organic molecule containing at least one halogen atom, i.e. fluorine, chlorine, bromine or iodine. Halocarbons can be found almost everywhere: in refrigerators, in TVs, in fire extinguishers, in plants and - in small traces - in air. Usually there is less than one molecule of halocarbons in a billion air molecules. But despite these low abundances halocarbons both act as powerful greenhouse gases and are potent depleters of stratospheric ozone. They presently account for more than 20% of the anthropogenic greenhouse effect, and this fraction could potentially increase in the future. The aim of this project is to explore the capabilities of a number of highly innovative analytical tools to enhance the present level of understanding of important halocarbons and their origins, distributions and fate in the atmosphere in the past, present and future. Firstly, the isotope ratios of halogens in halocarbon gases will be used as a wholly novel tool to identify and quantify the sources and sinks of very persistent compounds such as the chlorofluorocarbons (CFCs). CFCs have been banned in most countries. But because they break down so slowly, it will take at least many decades before they disappear from the atmosphere. A very important question is, how long? One part of the answer could lie in the stratosphere, which is the only place where CFCs do break down. I am investigating the isotopes of halogens in CFCs and these contain information about the exact manner and speed of their stratospheric breakdown. The second part of the answer relies on how much CFC is still being released to the atmosphere (e.g. from old cars, landfills or illegal use). To distinguish in the atmosphere between CFC released years ago and CFC released now, one could again benefit from isotopic information. This is because the different molecules contain an isotopic 'fingerprint' which is often characteristic for the manufacturing process and also changes over time in the atmosphere. Consequently, the aim is to detect as many 'fingerprints' as possible and to identify and quantify the remaining emissions. Secondly, pioneering work on the detection of the rapidly growing number of industrial halocarbon compounds in the atmosphere will be continued and extended. There is an emerging threat from halocarbons with respect to global warming. The replacement compounds for CFCs are increasing rapidly in the atmosphere, and many of them are strong greenhouse gases. The variety of compounds used in industrial processes is increasing so fast, that scientists are struggling to keep up. Within this project new techniques to scan the atmosphere and track down these 'novel' halocarbons will be investigated. Consequently the threat posed by these compounds both to climate and to stratospheric ozone will be estimated. Finally, the promising methodologies of adapting two-dimensional gas chromatography and time-of-flight mass spectrometry for atmospheric trace gas studies will be explored and will build upon the outcomes of the first two activities. This project will contribute to improved predictions of the recovery of the ozone layer and serve as an early-warning system for emerging threats from halocarbons in the atmosphere. Society will benefit from all of these activities as it will help to predict, when the ozone layer - and thus the protection from skin-cancer-causing UV radiation - will fully recover. Moreover, this project will help to better understand the risks arising from halocarbons with regard to climate change. It will also develop innovative new tools with which to study the chemistry of the atmosphere.