The contribution of volcanic emissions (Etna, Stromboli and Vulcano) to the atmospheric trace metals budget in the Mediterranean basin

Abstract

Volcanic emissions represent one of the major natural source for several trace metals (Cd, Cu, As, Pb, Hg and Zn) into the atmosphere both as gaseous and aerosol forms. The Mediterranean Sea can be considered a large geochemical sink for these elements whose source are the huge amounts of aerosols of different origin. The industrialized areas located in the northern part of the basin represent a nearly constant source of the anthropogenic-dominated aerosol. By contrast, the arid and desert regions located at the southern and eastern parts of the Mediterranean, are the sources of frequent dust “pulses” perturbing the “steady-state” conditions of the local atmosphere through the input of several millions of tons of desert dust. In this context, Mount Etna, Stromboli and Vulcano represent the biggest volcanic point-sources in the Mediterranean area by introducing several thousands of tons of gases and particles per day in the troposphere, both during eruptive and passive degassing periods. Comparison between estimated annual metal fluxes from the three Italian active volcanoes and the local emissions (Environmental Protection Agency - APAT), evidences the significant contribution of the volcanogenic trace metals (Cu, Se, Cr, As, Hg and Cd) to the metropolitan area of Catania and the whole Sicily. On a regional scale, volcanic degassing plays also an important role accounting for about 1 to 10% for the total European anthropogenic emissions of As, Cd, Cr, Hg, Ni and Pb (European Monitoring and Evaluation Programme - EMEP).