Plumes 196 INDEX

Adjust values for the averaging time correction for plume predictions with Eq. (23-77). Note that the index p for use in the averaging time correction depends on the model used. If the hazard time scale th is different from the model averaging time scale (10 min for plumes), then the predicted concentration should be adjusted to but only if ts> t if ts < t then adjust the predicted concentration to ts. 

The volume of entrained air was found to be proportional to the drop height raised to the power of approximately 5/3. This is in contrast to Eq. (1) where the expected index is 2/3 [3]. This is an important result and suggests that a better approach to modelling of the air entrainment process might come from the use of a modified plume theory. 

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... 

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