Environmental impact of the acid fumarolic plume of a passively degassing volcano (Vulcano Island, Italy)

This paper investigates the role played by the fumarolic plume of a passive degassing volcano in the genesis of rock coatings (RC) and in the introduction and re-distribution of metals and trace elements in the surficial environment. At La Fossa active volcano (Vulcano Island) and in the surrounding environment RC develop owing to exposure of the ground surface to the volcanic acid plume produced by the passive degassing of La Fossa. Significant positive anomalies of a wide variety of metals and trace elements (including Bi, Ag, Se, Te, Sb, Pb, As, Cu, Tl and Cd) were observed either in distal and proximal RC. Most of these anomalies are interpreted to be the result of the transport and subsequent deposition of trace elements, likely to form volatile compounds, in the fumarolic plume. Two main processes seem to control the geochemistry of RC: one is represented by the leaching and subsequent deposition of elements from the proximal toward the distal RC; the other is the direct input of trace elements carried by the emitted volcanic aerosol. The fact that most of the trace elements (particularly Pb, As, Tl, Bi, Te, Se, Cd) enriched in the RC of Vulcano are highly toxic and potentially dangerous to health in high concentration, indicates that the atmospheric metal injection by the quiescently degassing La Fossa volcano together with the subsequent deposition and remobilization by means of surficial waters may represent an environmental hazard that should be taken into account in evaluating the potential impact of volcanic air pollution on human health.