Comment on “Scavenging of sulfur, halogens and trace metals by volcanic ash: The 2010 Eyjafjallajökull eruption” by Bagnato et al. (2013)

Bagnato et al. (2013) report leachate measurements of volcanic ash samples collected following the 2010 eruption of Eyjafjallajökull, Iceland. Their data purport to show increased interaction between ash particles and gases in the eruption plume with longer residence time in the atmosphere. Based on this apparent relationship, the authors derive the rates of formation of sulfur- and halogen-bearing salts on the ash surface. They further infer average rates of ash dissolution consequent on exposure of the ash particles to sulfur and halogen acid gases and aerosols in the volcanic cloud. Bagnato et al. introduce a number of errors and inconsistencies in the data processing and interpretation which invalidate these calculations and thus, the conclusions reached in the paper.