Volcanic plume

Recently GOME measurements have been used to observe tropospheric SO2 from both volcanic plumes and fossil fuel burning (Eisinger et al., 1998 Eisinger and Burrows, 1998a,b). 

Eisinger, M. and J.P. Burrows (1998a) Observations of SO] from volcanic plumes. Earth Observation Quarterly 58 16-18. 

Bobrowski N, Honninger G, Galle B, Platt U (2003) Detection of Bromine Monoxide in a Volcanic Plume. Nature 423 273... 

Tiesi A, Villani MG, D Isidoro M, Praia AJ, Maurizi A, Tampieri E (2006) Estimation of dispersion coefficient in the troposphere from satellite images of volcanic plumes. Atmos Environ 40 628-638. doi 10.1016/j.atmosenv.2005.09.079 Villani MG, Mona L, Maurizi A, Pappalardo G, Tiesi A, Pandolfi M, D Isidoro M, Cuomo V, Tampieri F (2006) Transport of volcanic aerosol in the troposphere the case study of the 2002 Etna plume. JGeophys Res 111 D21102. doi 10.1029/2006JD00712... 

Stratospheric Chemistry and Radiative Impacts of Volcanic Plumes... 

The more soluble volatile components of volcanic plumes (e.g., halogens) can be removed from eruption clouds rapidly by adsorption on to tephra, or deposition in hydrometeors. The estimates of atmospheric burdens of volcanic volatiles in eruption clouds, therefore, depend on the time after eruption that the measurements were made, and can, in general, be lower than the total volatile release. Surprisingly, little work has been undertaken to quantify the total volatile budgets of eruptions (see De Hoog et al., 2001, for an exception). 

Various meteorological and proxy records do indicate regional climate anomalies inl783-1784 (e.g., Brififa et al., 1998), but the patterns are not yet well understood or modeled. More generally, it is not clear how readily volcanic plumes generated by fissure and flood basalt emptions can reach, and entrain sulfur into, the stratosphere, and considerable work is still required to understand the circumstances by which effusive activity can compete in the climate stakes with explosive emptions. 

Thanks largely to the work following Pinatubo, there is now a good understanding of the stratospheric chemistry of volcanic emption clouds, at least for emissions on this scale (Section 3.04.6.1). In contrast, the tropospheric chemistry of volcanic plumes is rather poorly known. This partly stems... 

Increasing interest in the impacts of tropospheric volcanic emissions on terrestrial and aquatic ecology and on human and animal health is driving more research into the tropospheric chemistry and transport of volcanic plumes. This will be of particular importance in understanding the long-range pollution impacts of volcanic clouds (that might be expected from future emptions like that of Laki 1783-1784). 

Andres R. J. and Rose W. 1. (1995) Remote sensing spectroscopy of volcanic plumes and clouds. In Monitoring Active Volcanoes Strategies, Procedures and Techniques (eds. B. McGuire, C. Kilburn, and J. Murray). UCL Press, London, pp. 301-314. 

Hoff R. M. (1992) Differential SO2 column measurements of the Mt. Pinatubo volcanic plume. Geophys. Res. Lett. 19, 175-178. 

Oppenheimer C., Francis P., and Stix J. (1998b) Depletion rates of sulfur dioxide in tropospheric volcanic plumes. Geophys. Res. Lett. 25, 2671-2674. 

Watson I. M. and Oppenheimer C. (2001) Particle-size distributions of ash-rich volcanic plumes determined by sun photometry. Atmos. Environ. 35, 3561-3572. 

Pinto et al. (1989) list an HBr/HCl ratio of 4.3 X 10"" for high temperature, i.e., explosive emptions. If the Br/Cl ratio is not much higher for more quiescent volcanoes or fumaroles, then volcanoes are a small source for bromine in the troposphere and stratosphere as well. Very recent measurements, however, found up to 1 nmol mol" BrO in a volcanic plume at Montserrat and the authors concluded that this might be a substantial global source of BrO (Bobrowski et al. 2003). 

Bobrowski N., Honninger G., Galle B., and Platt U. (2003) Detection of bromine monoxide in a volcanic plume. Nature 423, 273 -276. 

When we consider of the heterogeneous oxidation of SO2, it has to include not only the oxidation of the SO2 within the droplet phase, but the transfer of further SO2 into the droplet and the overall depletion of the gas in the air mass as a whole. In general the overall oxidation in the remote atmosphere is rather slow and takes 2-4 d, but under some conditions it can be much faster. The depletion rates of sulfur dioxide in volcanic plumes can sometimes be very fast with residence times of as little as 15 min in moist plumes, where catalytic mechanisms similar to urban air masses probably occur. 

In summary, it has been demonstrated that Hg/S ratios measured for a variety of volcanic plumes and fumaroles, when indexed to estimates of global sulfur emissions from volcanism, yield a mean volcanic mercury flux of 0.23 Mmol (45 t), which is consistent with other estimates and observations. Accordingly, average yearly mercury emission from volcanoes is small... 

While many natural processes produce chlorine at ground level (including for example, sea salt and volcanic emissions of HC1), these compounds are efficiently removed in precipitation (rain and snow) due to high solubility. The removal of HC1 emitted, for example, in volcanic plumes (which contain a great deal of water and hence form rain) is extremely efficient (see, e.g., Tabazadeh and Turco, 1993). This renders even the most explosive volcanic plumes ineffective at providing significant inputs of chlorine to the stratosphere. Observations... 

The eruption of a volcano is accompanied by emissions of water vapour (>70% of the volcanic gases), CO2 and SO2 plus lower levels of CO, sulfur vapour and CI2. Carbon dioxide contributes to the greenhouse effect, and it has been estimated that volcanic eruptions produce 112 million tonnes of CO2 per year. Levels of CO2 in the plume of a volcano can be monitored by IR spectroscopy. Sulfur dioxide emissions are particularly damaging to the environment, since they result in the formation of acid rain. Sulfuric acid aerosols persist as suspensions in the atmosphere for long periods after an eruption. The Mount St Helens eruption occurred in May 1980. Towards the end of the eruption, the level of SO2 in the volcanic plume was 2800 tonnes per day, and an emission rate of p 1600 tonnes per day was measured in July 1980. Emissions of SO2 (diminishing with time after the major eruption) continued for over two years, being boosted periodically by further volcanic activity. 

Chuan RL, Palais J, Rose WI, Kyle PR (1986) Huxes, sizes, morphology, and compositions of particles in the Mt. Erebus volcanic plume, December 1983. J Atmos Chem 4 467-477 Clague DA, Frey FA (1982) Petrology and trace element geochemistry of the Honolulu Volcanics, Oahu Implications for the oceanic mantle below Hawaii, J. Petrol. 23(3) 447-504 Cole JW, Ewart A (1968) Contributions to the volcanic geology of the Black Island, Brown Peninsula, and Cape Bird areas, McMurdo Sound, Antarctica. New Zealand J Geol Geophys ll(4) 793-828... 

Both HBr and BrO (see problem 17.23) are present in volcanic plumes. A model for reactions in the plume involves the following sequence ... 

Fig. 6.75, Passive doas recordiug using blue sky radiation as the illumination source. Sky spectra recorded through the volcanic plume of Mt. Etna (a) and at the side of the plume (b) are shown together with a divided spectrum clearly showing the SO2 signature [6.176]...

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