Volcanic Formation of Halogenated Organic Compounds

Abstract

Volcanoes are very important halogen emitters. Currently observed levels of halogens in the ocean are the result of continuous volcanic degassing during Earth's history.Although the halogens are emitted almost exclusively as inorganic halides, volcanic production of organohalogens has also been observed in several studies. The range of compounds detected includes chlorofluorocarbons, methyl halides, short-chain halohydrocarbons as well as halogenated aromatics and heterocycles. The presence of halogenated hydrocarbons was a matter of controversy as it is in disagreement with thermodynamic considerations. Organic compounds detected in volcanic gases point to a non-equilibrium reaction mechanism including the thermal cracking of non-magmatic methane and subsequent halogenation reactions. Emission rate estimates for halocarbons result in very low global fluxes that are unlikely to have any significance for the global atmospheric budgets of relevant halogenated trace gases.

Volatile organic compounds (VOCs) in soil gases from Solfatara crater (Campi Flegrei, southern Italy): Geogenic source(s) vs. biogeochemical processes

“…Accordingly, Jordan (2003) suggested that reaction of light alkenes with FeS 2 and H 2 S is able to produce C 4 H 4 S in volcanic gases emitted from Mt. Etna (Italy).…”

Geogenic and atmospheric sources for volatile organic compounds in fumarolic emissions from Mt. Etna and Vulcano Island (Sicily, Italy)

“…Among VOCs, the origin and behavior of halogenated species in volcanic environment is of great interest due to their strong environmental impact and health effects related to i) the key role they play as primary agents of tropospheric and stratospheric ozone depletion [ Cicerone et al , 1974; Molina and Rowland , 1974; Farman et al , 1985; Rowland and Molina , 1994; Brune , 1996] and ii) their contribution to global warming [ Intergovernmental Panel on Climate Change , 2001; Harnisch and Hoehne , 2002; Harnisch et al , 2002]. The occurrence of halocarbons in volcanic plumes [ Cadle et al , 1979; Inn et al , 1981; Leifer et al , 1981; Cronn and Nutmagul , 1982a, 1982b; Brasseur and Granier , 1992] and gas emissions related to magmatic‐hydrothermal reservoirs [ Stoiber et al , 1971; Isidorov and Zenkevich , 1985; Isidorov et al , 1990, 1992; Gaffney , 1995; Wahrenberger et al , 1998, 2002; Jordan et al , 2000; Jordan , 2003; Schwandner et al , 2004; Frische et al , 2006] have been extensively studied.…”

“…However, the recent increase of halocarbon concentrations in air, especially that of chlorofluorocarbons (CFCs), is commonly ascribed to anthropogenic activities [ Gamlen et al , 1986; Butler et al , 1999; McCulloch et al , 2003]. In most cases, volcanic halocarbons were interpreted as related to an atmospheric source [ Stoiber et al , 1971; Rasmussen and Rasmussen , 1980; Inn et al , 1981; Rasmussen et al , 1981; Pereira et al , 1982; Fink , 1983; Brasseur and Granier , 1992; Gaffney , 1995; Jordan et al , 2000; Jordan , 2003; Frische et al , 2006]. However, Schwandner et al [2004] reported geochemical evidence supporting the idea of a natural volcanogenic source for halocarbons measured in the soil of La Fossa cone at Vulcano Island (Italy).…”

Origin and Distribution of Thiophenes and Furans in Gas Discharges from Active Volcanoes and Geothermal Systems

“…Production of C 4 H 4 S by reaction of light alkenes, such as C 2 H 4 , with FeS 2 and H 2 S was invoked to explain their presence in the volcanic gases emitted from Mt. Etna [52]. …”