HR: 17:00h
AN: V12H-05    [PDF]
TI: The Impact of Etna's Volcanic Gas Emissions on Soils and Vegetation
AU: * D'Alessandro, W
EM: walter@pa.ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia - Sez. PA, via U. La Malfa, 153, Palermo, 90146 Italy
AU: Aiuppa, A
EM: aiuppa@pa.ingv.it
AF: University of Palermo - Dipartimento CFTA, via Archirafi, 36, Palermo, Ita 90123 Italy
AU: Bellomo, S
EM: sbellomo@pa.ingv.it
AF: University of Palermo - Dipartimento CFTA, via Archirafi, 36, Palermo, Ita 90123 Italy
AU: Parello, F
EM: parello@unipa.it
AF: University of Palermo - Dipartimento CFTA, via Archirafi, 36, Palermo, Ita 90123 Italy
AB: Mt. Etna is considered to be at present, on long time average, the major volcanic gas emitter in the world, accounting for about 10 percent of world-wide average volcanic emissions of CO$_{2}$ and SO$_{2}$. Hydrogen Chloride and HF emissions are proportionally high with measured values of 750 and 190 tons day respectively. Such huge emissions, significantly overwhelming the regional anthropogenic mass output, have a strong impact at least on local scale. Its strong influence has been assessed for example on rainwater chemistry, which display increasing contents of F (up to 227 mg/l), Cl (up to 1410 mg/l) and SO$_{4}$ (up to 481 mg/l) with decreasing distances from the summit craters. The corresponding high wet deposition values (up to 72 mg/m$^{2}$ day for SO$_{4}$, 226 mg/m$^{2}$ day for Cl and 21 mg/m$^{2}$ day for F) are comparable or even higher than those measured in heavily polluted areas of central Europe. Dry deposition, estimated with a network of passive samplers, represents an additional load on the local environment especially for sulfur. The geographical pattern of wet and dry deposition reflects the dilution of the volcanic plume with increasing distance and its prevailing displacement to the east by atmospheric circulation. To study the impact on Etnean soils, 52 soil-sampling sites were chosen all around Mt Etna in areas with minor anthropic disturbance, at distances from the summit craters between 3.7 and 16 km. At each sampling site, a composite sample of the first 5 cm of the soil profile of at least 4 points within an area of about 100 m$^{2}$ was collected. Samples were analyzed for bulk chemical composition and for leachable anion and cation content. Although the results display a large variability, the strong impact of crater emissions can be seen especially in fluorine content and in pH of soil solutions, which closely resemble the deposition pattern. But despite the huge acidic deposition, Etnean soils do not show the adverse effects noted in the heavily polluted areas of Central Europe because of the high acid buffering capacity of these young volcanic soils. Furthermore about 60 samples of leaves and needles of 6 different plant species were collected for the study of the impact of Etna gaseous emissions on its vegetation cover. Preliminary results indicate fluorine and sulfur content, which are sometimes higher than in heavily polluted areas, and with generally higher contents in conifers with respect to broad-leaved species. But the effects on vegetation at Etna seem significantly low, likely because: i) the acidity of the emitted sulfur and halogen compounds is buffered by the presence of large quantities of volcanic silicate ash and/or carbonate dust; ii) local vegetation species has developed some kind of resistance to the "volcanic pollution".
DE: 0322 Constituent sources and sinks
DE: 0330 Geochemical cycles
DE: 0370 Volcanic effects (8409)
DE: 8400 VOLCANOLOGY
DE: 9335 Europe
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting