Volcanic gas and particle monitoring using moss-bags on Vulcano Island, Italy
Julia Arndt (03/2012-12/2012)
Support: Britta Planer-Friedrich
Emissions and depositions of the active geothermal system Vulcano, Italy, were investigated by active moss monitoring in spring 2012. Sphagnum moss bags were exposed covered and uncovered for periods of 3 days, 3, 6 and 9 weeks. Soil samples and meteorologic data were collected. After exposure, mosses were oven-dried, grinded and extracted in HNO3 or deionized water. Extraction solutions were analyzed by ICP-MS for total concentrations of Li, Mg, Sr, Ba, Cr, Mn, S, Fe, Co, Cu, Zn, Mo, W, Tl, As, Sb, Bi, I, and Se. Soil and rain water were analyzed for the same trace elements. The HNO3 extraction efficiency of most elements was higher than that for deionized water extraction, especially for particles, and was therefore used for further data evaluation. Uncovered moss bags accumulated higher concentrations of each element than covered moss bags. Apparently covered moss bags accumulated predominantly emissions, while uncovered moss bags accumulated emissions and depositions. Washout of uncovered moss bags by rain water washout obviously only had a minor effect. Distribution patterns of emissions and depositions over the whole island of Vulcano allowed to classify all elements into four major groups. Lithium was ubiquitous on the island. The elements Mg, Fe, Sr, Mn, Zn, Co, and W were found predominantly on the crater where bare soil was present, and were grouped as “soilborne elements”. Elements with higher concentrations at the fumarolic field were grouped by their transport characteristics. The elements I, Se, Tl, Bi, Sb, As and S were assigned as true volatiles being transported further away from the fumarolic field than Pb, Cr, Mo, and Ba which were interpreted to be predominantly emitted as particles. For investigation of volcanic emissions and depositions in the close environment of volcanoes, active moss monitoring proved to be an effective tool which also allows a classification of accumulated elements on the moss by their origin and distribution patterns.