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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
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Volume 16, issue 20 | Copyright
Atmos. Chem. Phys., 16, 12849-12859, 2016
https://doi.org/10.5194/acp-16-12849-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 18 Oct 2016

Research article | 18 Oct 2016

Emissions of carbon tetrachloride from Europe

Francesco Graziosi1,2, Jgor Arduini1,2,3, Paolo Bonasoni3, Francesco Furlani1,2, Umberto Giostra1,2, Alistair J. Manning4, Archie McCulloch5, Simon O'Doherty5, Peter G. Simmonds5, Stefan Reimann6, Martin K. Vollmer6, and Michela Maione1,2,3 Francesco Graziosi et al.
  • 1Department of Pure and Applied Sciences, University of Urbino, 61029 Urbino, Italy
  • 2National Interuniversity Consortium for Physics of the Atmosphere and Hydrosphere (CINFAI), 00178 Rome, Italy
  • 3Institute of Atmospheric Sciences and Climate, National Research Council, 40129 Bologna, Italy
  • 4Hadley Centre, Met Office, Exeter, EX1 3PB, UK
  • 5School of Chemistry, University of Bristol, Bristol, BS8 1TH, UK
  • 6Laboratory for Air Pollution and Environmental Technology, Swiss Federal Laboratories for Materials Science and Technology (Empa), 8600 Dübendorf, Switzerland

Abstract. Carbon tetrachloride (CCl4) is a long-lived radiatively active compound with the ability to destroy stratospheric ozone. Due to its inclusion in the Montreal Protocol on Substances that Deplete the Ozone Layer (MP), the last two decades have seen a sharp decrease in its large-scale emissive use with a consequent decline in its atmospheric mole fractions. However, the MP restrictions do not apply to the use of carbon tetrachloride as feedstock for the production of other chemicals, implying the risk of fugitive emissions from the industry sector. The occurrence of such unintended emissions is suggested by a significant discrepancy between global emissions as derived from reported production and feedstock usage (bottom-up emissions), and those based on atmospheric observations (top-down emissions). In order to better constrain the atmospheric budget of carbon tetrachloride, several studies based on a combination of atmospheric observations and inverse modelling have been conducted in recent years in various regions of the world. This study is focused on the European scale and based on long-term high-frequency observations at three European sites, combined with a Bayesian inversion methodology. We estimated that average European emissions for 2006–2014 were 2.20.8)Ggyr−1, with an average decreasing trend of 6.9% per year. Our analysis identified France as the main source of emissions over the whole study period, with an average contribution to total European emissions of approximately 26%. The inversion was also able to allow the localisation of emission "hot spots" in the domain, with major source areas in southern France, central England (UK) and Benelux (Belgium, the Netherlands, Luxembourg), where most industrial-scale production of basic organic chemicals is located. According to our results, European emissions correspond, on average, to 4.0% of global emissions for 2006–2012. Together with other regional studies, our results allow a better constraint of the global budget of carbon tetrachloride and a better quantification of the gap between top-down and bottom-up estimates.

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Carbon tetrachloride is an ozone-depleting greenhouse gas banned under the Montreal Protocol. Measurements of atmospheric levels combined with global transport models indicate that it is still being emitted, in contrast to what is reported. In order to help solve the "mystery of carbon tetrachloride", we estimated European emissions during 2006–2014 using atmospheric observations and models. We identified emission hot spots and showed inconsistencies in national emission declarations.
Carbon tetrachloride is an ozone-depleting greenhouse gas banned under the Montreal Protocol....
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