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Investigation of chlorine radical chemistry in the Eyjafjallajökull volcanic plume using observed depletions in non‐methane hydrocarbons
Author(s) -
Baker Angela K.,
RautheSchöch Armin,
Schuck Tanja J.,
Brenninkmeijer Carl A. M.,
van Velthoven Peter F. J.,
Wisher Adam,
Oram David E.
Publication year - 2011
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2011gl047571
Subject(s) - methane , plume , volcano , chlorine , environmental chemistry , environmental science , atmospheric sciences , chemistry , earth science , geology , meteorology , geochemistry , physics , organic chemistry
As part of the effort to understand volcanic plume composition and chemistry during the eruption of the Icelandic volcano Eyjafjallajökull, the CARIBIC atmospheric observatory was deployed for three special science flights aboard a Lufthansa passenger aircraft. Measurements made during these flights included the collection of whole air samples, which were analyzed for non‐methane hydrocarbons (NMHCs). Hydrocarbon concentrations in plume samples were found to be reduced to levels below background, with relative depletions characteristic of reaction with chlorine radicals (Cl). Recent observations of halogen oxides in volcanic plumes provide evidence for halogen radical chemistry, but quantitative data for free halogen radical concentrations in volcanic plumes were absent. Here we present the first observation‐based calculations of Cl radical concentrations in volcanic plumes, estimated from observed NMHC depletions. Inferred Cl concentrations were between 1.3 × 10 4 and 6.6 × 10 4 Cl cm −3 . The relationship between NMHC variability and local lifetimes was used to investigate the ratio between OH and Cl within the plume, with [OH]/[Cl] estimated to be ∼37.