Rainwater Chemistry at Mt. Etna (Italy): Natural and Anthropogenic Sources of Major Ions

Authors: Aiuppa A.¹; Bonfanti P.²; D'Alessandro W.³

Source: Journal of Atmospheric Chemistry, Volume 46, Number 1, September 2003 , pp. 89-102(14)

Publisher: Springer

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Abstract:

Major ion content of 37 wet-only rainwater samples collected on the southern flank of Mount Etna volcano was investigated. Measured pH values range from 3.80 to 7.22 and display a positive correlation with Ca^{2 +} and an inverse correlation with NO₃^-, suggesting that anthropogenic NO_x are the most effective acidifying agents while Ca, likely as solid CaCO₃, is the prevailing proton acceptor. Na/Cl ratios indicate a dominant marine origin for both species, while K, mg and Ca contents point to additional sources (soil dust, fertilisers etc.). Nitrate and sulphate concentrations display a nearly constant ratio indicating a common anthropogenic origin, and only a few samples are characterised by sulphate excess. The analysis of time series reveals a good correlation between the excess sulphate in rainwater and SO₂ fluxes from the summit craters plume. Non sea salt chloride contents show also a significant correlation with volcanic activity indicating a magmatic sulphur and chloride contribution to rainwater. Meteoric flux estimations point to a prevailing magmatic origin for sulphur in the collected rainwaters while sea spray is the main source of chlorine.

Keywords: Etna; rainwater chemistry; major ions; volcanic activity; meteoric fluxes

Language: English

Document Type: Research article

Affiliations: 1: Dipartimento CFTA, Università di Palermo, via Archirafi 36, I-90123 Palermo, Italy 2: Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Palermo, via La Malfa 153, I-90146 Palermo, Italy 3: Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Palermo, via La Malfa 153, I-90146 Palermo, Italy, E-mail: walter@pa.ingv.it

Publication date: 2003-09-01