Long - term tropospheric trend of octafluorocyclobutane (c-C4F8 or PFC-318)

Oram, D.E. and Mani, Francis S. and Laube, J.C. and Newland, M.J. and Reeves, C.E. and Sturges, W.T. and Penkett, S.A. and Brenninkmeijer, C.A.M. and R, T. and Fraser, P.J. (2012) Long - term tropospheric trend of octafluorocyclobutane (c-C4F8 or PFC-318). Atmospheric Chemistry and Physics, 12 . pp. 261-269. ISSN 1680-7316

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Abstract

Air samples collected at Cape Grim, Tasmania between 1978 and 2008 and during a series of more recent aircraft sampling programmes have been analysed to determine the atmospheric abundance and trend of octafluorocyclobutane
(c-C4F8 or PFC-318). c-C4F8 has an atmospheric lifetime in excess of 3000 yr and a global warming potential (GWP) of 10 300 (100 yr time horizon), making it one of the most potent greenhouse gases detected in the atmosphere to date. The abundance of c-C4F8 in the Southern Hemisphere has risen from 0.35 ppt in 1978 to 1.2 ppt in 2010, and is currently increasing at a rate of around 0.03 ppt yr"121. It is the third most abundant perfluorocarbon (PFC) in the present day atmosphere, behind CF4 (�75 ppt) and C2F6 (�4 ppt). Although a number of potential sources of c-C4F8 have been reported, including the electronics and semi-conductor industries, there remains a large discrepancy in the atmospheric
budget. Using a 2-D global model to derive top-down global
emissions based on the Cape Grim measurements yields a recent (2007) emission rate of around 1.1 Gg yr"121 and a cumulative emission up to and including 2007 of 38.1 Gg. Emissions reported on the EDGAR emissions database for the
period 1986 132005 represent less than 1% of the top-down
emissions for the same period, which suggests there is a large unaccounted for source of this compound. It is also apparent that the magnitude of this source has varied considerably over the past 30 yr, declining sharply in the late 1980s before increasing again in the mid-1990s.

Item Type:	Journal Article
Subjects:	Q Science > QD Chemistry
Divisions:	Faculty of Science, Technology and Environment (FSTE) > School of Biological and Chemical Sciences
Depositing User:	Francis Mani
Date Deposited:	15 Dec 2013 23:58
Last Modified:	24 Apr 2017 04:06
URI:	https://repository.usp.ac.fj/id/eprint/7036

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