Signature of the 24th December 2018 eruption of Mt. Etna on the chemical composition of bulk deposition in the Siracusa area (Italy)

Risultato della ricerca: Conference contribution


Mt. Etna, in the eastern coast of Sicily (Italy), is one of the most active and most intenselymonitored volcanoes of the planet. It is widely recognized as a big source of volcanic gases, suchas CO2, SO2 and halogens, to the troposphere in the Mediterranean basin, and its gas emissionsaccount for a significant percentage respect to the worldwide average volcanic budget. The SO2flux from Mt. Etna’s plume has been routinely measured by the INGV since 1987. SO2 flux rangesbetween 600 to 25000 Mg/d; fluxes greater than 100000 Mg/d were prevalently measuredduring eruptive events. During eruptive periods, Etna’s emissions can be dispersed over longdistances and cover wide areas of the Mediterranean region.Mt. Etna is also considered a huge source of many trace elements to the atmosphere on regionaland global scale.On the morning of December 24th 2018, a moderate lateral eruption of the Mt. Etna started.This eruption was related to an intrusion of a magmatic dike on the high eastern flank of thevolcano, through a 2 kilometres long fracture in the NNW SSEdirection. At the same time,the summit craters produced a continuous strombolian activity generating a very dense ashplume, dispersed by the wind into the S/SE direction.From June 2018 to June 2019, atmospheric precipitations were collected in the area of Siracusa,a city on the east coast of Sicily, about 80 km SSE of Mt. Etna, and in the area of Milazzo, a cityon the northern coast of Sicily. Atmospheric precipitations were monthly collected through anetwork of 12 pluviometers; the collectors were open during the entire exposure time, receivingboth wet and dry deposition (bulk collectors). All the collected water samples were analysed formajor ion contents and for a large number of trace elements by ICPOESand ICPMS.During the eruptive period (from 24th to 27th December 2018), the prevailing winds blew fromthe North direction and there were light rainfalls in the monitored sites (between 0.2 mm inSiracusa and Augusta, and 1.6 mm in Palazzolo Acreide). As a consequence, gases and particlesof Etna’s plume were carried for long distance from the emission point, and they were depositedas dry and wet deposition also in the area of Siracusa. During the eruption event and in thefollowing days, the plume reached distances of more than 300 km from the emission point(island of Malta).The samples collected in the study area of Siracusa during the period straddling the eruptiveevent are characterized by high concentrations of some major ions, such as Fluoride (up to 0.88mg/l), Chloride (up to 124 mg/l) and Sulphate (23.1 mg/l). These ions derive mainly from theemitted volcanic gases (HF, HCl and SO2).The effect of the described eruption is also visible in the high concentrations of some traceelements, such as Aluminium, Thallium and Tellurium. The mean concentrations of the selectedtrace elements in the samples collected in the area of Siracusa, in the period before the eruptiveevent, are: 18.2 μg/l for Aluminium, 0.009 μg/l for Thallium, while Tellurium was always under the detection limit (0.004 μg/l); the concentrations of the same elements in the samplescollected during the eruptive event reach 152 μg/l for Aluminium, 0.16 Âg/l for Thallium and0.025 μg/l for Tellurium, therefore showing a strong enrichment.While Thallium and Tellurium are highly volatile elements typically enriched in volcanic emissions,Aluminium is a refractory element that was probably released by the dissolution of the relatedvolcanic ashes.The study area of Milazzo, due to the prevailing winds from the North direction during the
Lingua originaleEnglish
Titolo della pubblicazione ospiteAbstract Volume 4a Conferenza A. Rittmann Catania, 12-14 Febbraio 2020
Numero di pagine2
Stato di pubblicazionePublished - 2020

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