Rapid release of metal salts and nutrients from the 2011 Grímsvötn, Iceland volcanic ash

We exposed the pristine ash to ultrapure deionised (MilliQ) water in a single pass, plug, flow through reactor and the effluent was analyzed for 73 elements using inductively coupled plasma sector field mass spectroscopy (ICP-SFMS) and ion chromatography (IC). High release rates of mainly S, Na, Ca, Mg, F and Cl were observed during the first 10 min but after 12 h, the most abundant element released was Si. The effluent was alkaline. Secondary phases of mainly Al and Fe precipitated on the ash surfaces and these were suspected of scavenging As, Ba, Cr, Co, Cu, Ga, Mn, Mo, Ni, P, Te, V and Zn. The maximum total of surface salts containing F, Cl and S, carried by the erupted ash, was 11, 13 and 117 kilotonne. The flux of nutrient and toxic elements from the Grímsvötn ash was low compared with that from other eruptions and would not have been expected to cause poisoning of mammals or aquatic life. The elements most likely to affect sensitive biota were F, Se, Cu and Zn.