Scavenging of sulphur, halogens and trace metals by volcanic ash: The 2010 Eyjafjallajökull eruption

The Eyjafjallajökull volcanic eruption in 2010 released considerable amounts of ash into the high troposphere-low stratosphere, leading to unprecedented disruption of air traffic over Europe. The role of such fine-grained tephra in adsorbing, and therefore rapidly scavenging, volcanogenic volatile elements such as sulphur and halogens, is explored here. We report on results (major to trace element chemistry) of leaching experiments carried out on 20 volcanic ash samples, taken from the deposits of the main phases of the eruption (March-April 2010), or directly while falling (5-9 May 2010). Ash leachate solutions from Eyjafjallajökull are dominated - among cations - by Ca and Na, and display nearly equal S:Cl:F abundances (mean S/Cl and S/F molar ratios of 0.95 and 0.34, respectively). Abundances of major elements on surface minerals from freshly fallen ash are found to increase linearly upon increasing distance from the eruptive vents (a proxy for in-plume residence times). This allows...