Fumarolic emission

The transport of copper and lead in the vapour phase under such volcanic conditions is well documented. While the Cu3Clj trimer might be important for the former, abundant evidence for CuCl(g) has accrued. It has been observed spectrographically in volcanic flames at Kilaue,158 and in high-temperature volcanic gases by other workers.159,160 The sublimation of CuCl from lavas leading to the crystallization of primary atacamite, Cu3(OH)3Cl, upon condensation has also been reported.161 Zinc may also be transported as the volatile chloride under the same conditions and has been noted in fumarolic emissions from the Showashinzan volcano, Japan.162... 

Studies of volcanoes (Vulcano, Mt. Etna, Kuju, and Satsuma-Iwojima) have found CH3Br in the fumarolic emissions (216, 217). 

Nevertheless, high SO2 fluxes remain a reliable indicator of the presence of magma during new episodes of unrest at volcanoes (e.g., seismicity, changes in fumarole emissions), and help to discriminate between magmatic, and tectonic or... 

Gerlach T. M. and Casadevall T. J. (1986) Fumarole emissions at Mount St Helens volcano, June 1980 to October 1981 degassing of a magma-hydrothermal system. J. Volcanol. Geotherm. Res. 28, 141—160. 

CO/S02 = 0.02, for H2S/SO2 = 0.15, with estimated error of 0.01. These measurements show that under the reduced magmatic conditions of this fumarolic emission, reduced gases (such as H2, H2S and CO) are relatively abundant so as to be detectable. The general correlation with plume tracer SO2 suggests limited in-plume chemistry of these species between their emission and detection ( minutes). Details of electrochemical sensor data analysis methodology are now discussed. 

Fig. 15.4 ScatlCT plots of the gas mixing ratios derived from the electrochemical sensor data of Fig. 15.3, shown as X vctsus SO2 where X is H2, CO or H2S. The estimate of H2S from N02-A1 sensor is preferred over that of H2S-A1 sensor which exhibits enhanced scatter see text for explanation. Linear regression is used to determine the characteristic gas ratios in the Aso volcano fumarole emission...

Helens emissions An estimation of the magma reservoir volume. J Volcanol Geotherm Res 28 85-89 Le Cloarec M-F, Allard P, Ardouin B, Giggenbach WF, Sheppard DS (1992) Radioactive isotopes and trace elements in gaseous emissions from White Island, New Zealand. Earth Planet Sci Lett 108 19-28 Le Cloarec M-F, Pennisi M, Corazza E, Lambert G (1994) Origin of fumarolic flnids emitted from a nonerapting volcano Radionuchde constraints at Vulcano (Aeolian Islands, Italy). Geochim Cosmochim Acta 58 4401-4410... 

Goodwin (1961, 1973b) considers the BIF of the Canadian shield to be the products of chemical precipitation in submarine volcanic regions as a result of extensive development of hot springs and fumarolic activity. A typical feature of the Archean crust was the production of volcano-tectonic basins with exhalative-clastic-effusive filling. Universal emission of basic effusives, rhythmic eruption of acid pyroclastic material, and extensive development of exhalative activity were observed in their formation. After the ore components arrived in the sea water they were deposited mainly near springs, but substantial amounts of SiOj and part of the Fe were widely disseminated. 

Fumaroles represent a gentler and more continuous source of sulfur. The sources can be dispersed and quite small, so the total emissions from this source are not easy to estimate. Some of them are dominated by H2S. The sulfur gases, SO2, H2S, Sg, have been found in a range of fumaroles (Montegrossi et al., 2001). Although present Sg remains a minor component several orders of magnitude below SO2 and H2S. The production of sulfuric acid through aerial oxidation of sulfur(IV) is the most familiar process but it can readily be produced by disproportionation in fumarolic systems (Kusakabe et al, 2000) ... 

The volcanoes of Hawaii emit large quantities of fumarolic sulfur dioxide which causes widespread damage to human health and vegetation downwind. These emissions often take the appearance of widespread hazes and are locally known as vogs. The primarily component is of sulfuric acid and sulfate formed through oxidation of the sulfur dioxide. The vog particles also contain trace elements selenium, mercury, arsenic. 

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... 

Eruptions from volcanoes are spasmodic rather than continuous. Between eruptions, activity may still be witnessed in the form of steam and vapours issuing from small vents named fumaroles or solfataras. But, in some volcanoes, even this form of surface manifestation ceases, and such a dormant state may continue for centuries. To all intents and purposes, these volcanoes appear extinct. In old age, the activity of a volcano becomes limited to emissions of gases from fumaroles and hot water from geysers and hot springs. 

Deployment of a multi-gas system to analyse gas emissions from the fumaroles of La Fossa crater, Vulcano, Italy, is illustrated in Fig. 15.2a. To make in situ... 

McGonigle et al. presented the first study to use an in situ electrochemical sensor deployed on an unmanned aerial vehicle alongside an infra-red spectrometer to characterise CO2 and SO2 in the plume <200 m downwind of La Fossa, Vulcano, Italy. This study demonstrated the advantages of UAV-based sensing not only from a safety perspective (obtaining plume measurements with minimal personal gas exposure), but also to quantify the bulk plume emission arising from individual fumarole sources. 

Witt M, Fischer TP, Pyle DM, Yang TF, Zelhner GF (2008) Fumarole compositions and mercury emissions from the Tatun Volcanic Field, Taiwan results from multi-component gas analyser, portable mercury spectrometer and direct sampling techniques. J Volcanol Geotherm Res 178(4) 636-643... 

---