Active moss monitoring allows to identify and track distribution of metal(loid)s emitted from fumaroles on Vulcano Island, Italy

Volatile metal(loid)s are known to be emitted from volcanoes worldwide. We tested the suitability of active moss monitoring for tracking volatile metal(loid)s released from the fumarolic field on Vulcano Island, Italy, and differentiated fumaroles from other sources of gaseous and particulate trace elements such as sea spray and soil. Metal(loid) accumulation on the mosses per day did depend neither on the state of the exposed moss (dead or living) nor exposure time (3, 6, or 9 weeks). After collection, mosses were digested with either HNO3/H2O2 or deionized water and analyzed by ICP-MS. While for most elements both extraction methods yielded similar concentrations, higher concentrations were observed e.g. for Pb in the stronger HNO3/H2O2 extracts, indicating the presence of particles, which were not digested and removed by filtration in deionized water extracts. Due to their ubiquitous detection in comparable concentrations at all 23 moss monitoring stations all over the island, Li, Mg and Sr were attributed to sea spray origin. Iron, Co, W, V, Pb, Cr, Mo, and Ba occurred predominantly at the crater, where the soil was not covered by vegetation, and thus likely represent soil-borne particulate transport. Arsenic, Sb, S, Se, Tl, Bi, and I showed a clear concentration maximum within the fumarolic field. Concentrations gradually decreased along a transect in wind direction from the fumaroles, which confirms their volcanic origin. Active moss monitoring thus proved to be an inexpensive and easy-to-apply tool for investigations of volcanic metal(loid) emissions and distributions enabling differentiation of trapped elements by their source of origin.