Detection of bromine monoxide in a volcanic plume

Abstract

The emission of volcanic gases usually precedes eruptive activity, providing both a warning signal and an indication of the nature of the lava soon to be erupted. Additionally, volcanic emissions are a significant source of gases and particles to the atmosphere, influencing tropospheric and stratospheric trace-gas budgets. Despite some halogen species having been measured in volcanic plumes (mainly HCl and HF), little is known about bromine compounds and, in particular, gas-phase reactive bromine species. Such species are especially important in the stratosphere, as reactive bromine-despite being two orders of magnitude less abundant than chlorine-accounts for about one-third of halogen-catalysed ozone depletion. In the troposphere, bromine-catalysed complete ozone destruction has been observed to occur regularly during spring in the polar boundary layers as well as in the troposphere above the Dead Sea basin. Here we report observations of BrO and SO2 abundances in the plume of the Soufrière Hills volcano (Montserrat) in May 2002 by ground-based multi-axis differential optical absorption spectroscopy. Our estimate of BrO emission leads us to conclude that local ozone depletion and small ozone 'holes' may occur in the vicinity of active volcanoes, and that the amount of bromine emitted from volcanoes might be sufficiently large to play a role not only in the stratosphere, but also in tropospheric chemistry.

Volcano remote sensing with ground-based spectroscopy

“…This is highly significant, as anthropogenic sulphate is presently considered to be the most important factor offsetting the anthropogenic greenhouse effect. Recently, USB2000s have been adapted for remotely sensed measurements of two other volcanogenic gases: NO 2 and BrO (Bobrowski et al 2003). The former observation supports a recent report that volcanoes may have played a significant role in generating biologically available forms of nitrogen, via thermal fixation, during the evolution of the early Earth (Mather et al 2004).…”

Retrieval of sulfur dioxide from a ground-based thermal infrared imaging camera

“…Fourier-transform interferometers (FT-IRs) have become a very valuable device for volcanic gas studies (Love et al, 1998;Oppenheimer et al, 1998;Burton et al, 2000;Horrocks, 2001), including measurements of gas ratios reported by Oppenheimer et al (2002). Systems using ultraviolet light as a source have recently been developed for volcanic SO 2 measurements (McGonigle, 2005;Horton et al, 2006), for volcanic BrO measurements (Bobrowski et al, 2003), and also for CO 2 slantpath columns (Goff et al, 2001). More recently Stremme et al (2013) and Krueger et al (2013) presented measurements of volcanic emissions using a scanning FT-IR, showing two-dimensional visualisations of SO 2 based on thermal emission spectroscopy.…”

Reactive halogen chemistry in volcanic plumes

“…In this article we focus on a third potentially significant source of halogens to the atmosphere: volcanic emissions. BrO was detected in a volcanic plume for the first time at Soufriere Hills volcano on Montserrat [Bobrowski et al, 2003], and has subsequently been measured at other volcanoes (a brief description of BrO levels and emissions of five different volcanoes is given by N. Bobrowski and U. Platt (Bromine monoxide studies in volcanic plumes, submitted to Journal of Volcanology and Geothermal Research, 2006, hereinafter referred to as Bobrowski and Platt, submitted manuscript, 2006)). So far BrO has been detected at all volcanoes where the authors carried out measurements at distances exceeding about 1 km.…”