Volcanism global sulfur emission

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... 

Sulfur dioxide Is formed primarily from the Industrial and domestic combustion of fossil fuels. On a global scale, man-made emissions of SOj are currently estimated to be 160-180 million tons per year. These emissions slightly exceed natural emissions, largely from volcanic sources. The northern hemisphere accounts for approximately 90% of the man-made emissions (13-14). Over the past few decades global SOj emissions have risen by approximately 4%/year corresponding to the Increase In world energy consumption. 

Graf H.-F., Feichter J., and Langmann B. (1997) Volcanic sulfur emissions estimates of source strength and its contribution to the global sulfate distribution. J. Geophys. Res. 102, 10727-10738. 

Estimates of global volcanic sulfur emissions are summarized in Table 6. We have chosen a value of 9 X 10 t S yr as representative of the recent estimates. Therefore, by applying the determined Hg/S ratio, a global mercury flux from subaerial volcanism is estimated to be 45 t yr or 0.23 Mmol annually. These average emissions are only 5% of the natural flux of 5 Mmol yr estimated by Mason et al. (1994). Thus, and under long-term mean conditions, other types of terrestrial volatilization processes for mercury would dominate. Given this conclusion, it is important to place additional constraints on the validity of the 45 t yr estimate for subaerial volcanic mercury emissions. 

The effect of volcanic gas on global sulfur cycle is important. S concentration of volcanic gas from island arc is smaller than CO2 concentration. CO2 concentration of hot spot volcanic gas is similar to that of island arc volcanic gas, but amount of volcanic gas emission from hot spot volcanic activity (e.g., Hawaii) is small (Table 5.3). S concentration of volcanic gas from mid-oceanic ridges is similar to C concentration. Emission of S and C by volcanic gas from mid-oceanic ridge is small because solubility of gas into magma is high under high pressure condition at deep sea depth (3,000-4,000 m). Sulfur in basalt transfers to hydrothermal solution... 

Table 10-17 includes a global atmospheric sulfur budget based on the emission estimates discussed in this chapter and the flux diagrams shown in Figs. 10-8 and 10-9. The marine budget of 36 Tg S/yr supplied by the biosphere must be augmented by about 6.8 Tg S/yr from anthropogenic sources. In addition, about one-half of the sulfur from volcanic emissions... 

The only published estimate attempting to quantify NH3 emissions from a volcano appears to be that of Uematsu et al. (2004) for Mijahama volcano, in the south of Japan. They measured plume concentrations of NH3 up to 5 ppb ( 3 g m ) approximately 100 km downwind of the source, and reported an emission ratio of 1 ammonia 1 ammonium 1 sulfate 10 sulfur dioxide. Based on the estimate that NH , emissions were 15 % of SO2 emissions, they inferred an NH release of 340 kt NH3—N per year for the period since 2000. This is by far the largest NH3 point source emission ever reported, being similar to the total annual NH3 emission of the UK. Improved quantification of global volcanic NH3 and NH4 emissions must therefore be a priority (Sutton et al. 2008). 

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