Evidence for crustal degassing of CF4 and SF6 in Mojave Desert groundwaters

Residence time, mineralization processes and groundwater origin within a carbonate coastal aquifer with a thick unsaturated zone

“…Indeed, within the Bonifacio aquifer, groundwater from the LA and the G displays SF 6 contents largely higher than those resulting from atmospheric chronicles. The high SF 6 values are probably due to the presence of pegmatite veins in the surrounding fractured granites, source of terrigenous SF 6 (Deeds et al, 2008;Friedrich et al, 2013;Harnisch and Eisenhauer, 1998). Terrigenic SF 6 can thus affect the groundwater dating (Koh et al, 2007).…”

Inverse modelling of CF<sub>4</sub> and NF<sub>3</sub> emissions in East Asia

“…Other emission sources for CF4 include release during the production of SF6 and HCFC-22, but emissions from these sources are estimated to be small compared to the emissions from the aluminium production and semiconductor manufacturing industries 55 (EC-JRC/PBL, 2013; Mühle et al, 2010). There is also a very small natural emission source of CF4, sufficient to maintain the preindustrial atmospheric burden (Deeds et al, 2008).…”

“…The Advanced Global Atmospheric Gases Experiment (AGAGE) has been monitoring the global atmospheric trace gas budget for decades (Prinn et al, 2018). Most recently, AGAGE's 'Medusa' pre-concentration GC-MS (gas chromatography-mass spectrometry) system has been able measure a full suite of the long-lived halogenated GHGs (Arnold et al, 2012;Miller et al, 2008 Korea, eastern China, and surrounding countries (Fang et al, 2015;Kim et al, 2010;Li et al, 2011 areas. The technology for abating emissions of these gases from such discrete sources exists and could be used (Chang and Chang, 2006;Purohit and Höglund-Isaksson, 2017;Illuzzi and Thewissen, 2010;Yang et al, 2009;Raoux, 2007;Wangxing et al, 2016).…”

“…A Medusa GC-MS system was installed at GSN in 2007 and has been operated as part of the AGAGE network to take automated, high-precision measurements for a wide range of CFCs, HCFCs, HFCs, PFCs, Halons and other halocarbons; all significant synthetic GHG and/or stratospheric ozone depleting gases as well as many naturally occurring halogenated compounds (Miller et al, 2008;Arnold et al, 2012;Kim et al, 2010 gases is given elsewhere (Arnold et al, 2012;Mühle et al, 2010;Miller et al, 2010;Prinn et al, 2018).…”

Spectrometric monitoring of atmospheric carbon tetrafluoride (CF<sub>4</sub>) above the Jungfraujoch station since 1989: evidence of continued increase but at a slowing rate

“…The only known but poorly quantified natural sources of CF 4 are of lithospheric origin (e.g., Gassmann, 1974;Cicerone, 1979;Harnisch et al, 1996a;Harnisch and Eisenhauer, 1998;Harnisch, 2000). Recently, Deeds et al (2008) presented the first in situ evidence for this lithospheric flux, which leads to a background contribution to atmospheric carbon tetrafluoride that lies between 35 and 45 ppt (parts per trillion dry air mole fraction) with the lower value favored on the basis of reported accuracies and precisions (for an overview, see Table 2 of Mühle et al, 2010).…”