Gaseous Elemental Mercury (GEM) from mining areas and volcanic and geothermal systems in some Mediterranean areas: a preliminary study Jacopo Cabassia, Orlando Vasellia,b,*, Franco Tassia,b, Sergio Calabresec, Matteo Nocentinia,b, b d e f Francesco Capecchiacci , Barbara Nisi , Oscar Matias Benavente Zolezzi , Daniele Rappuoli a
Dipartimento di Scienze della Terra, Via G. Pira 4, 50121 Firenze (Italy) b CNR-IGG Istituto di Geoscienze e Georisorse, Via G. Pira 4, 50121 Firenze (Italy) c Dipartimento di Scienze della Terra e del Mare, Via Archirafi 22, 90123 Palermo (Italy) d CNR-IGG Istituto di Geoscienze e Georisorse, Via Moruzzi 1, 56124 Pisa (Italy) e Departamento de Geología, Universidad de Chile, Plaza Ercilla 803, 8370450 Santiago (Chile) f Unione dei Comuni Amiata-Val D’Orcia, Via del Colombaio 98, 53023 Gallina, Castiglion d’Orcia, Siena (Italy) * Corresponding author. Email address:
[email protected]; Tel: +390552756289; Fax: +39055284571
Mercury has a strong environmental impact since both its organic and inorganic complexes are toxic and represent a pollutant of global concern. Liquid Hg is highly volatile and it can be released during natural and anthropogenic processes in the hydrosphere, biosphere and atmosphere. Hg in air is present in the oxidation states 0 and +2, the former being the dominant species with a residence time of 1-2 years due to its relatively low solubility and chemical inertness. In order to continuously and accurately determine concentrations of gaseous elemental mercury (GEM), a portable instrument (Lumex®; Fig. 1) based on the atomic absorption spectrometric technique with Zeeman effect, able to measured GEM concentrations from 2 to 50,000 ng m-3, was used. In this study, analytical results of GEM measurements from i) the Hg mining areas of Abbadia San Salvatore (Siena, central Italy) and ii) natural gas emissions of selected Mediterranean volcanic and geothermal systems (Mt. Etna, Vulcano Island, Phlegraean Fields, Italy; Santorini, Nisyros, Greece) are presented. In the Abbadia S.S. mining facilities (Fig. 2) and their surroundings, highly variable GEM concentrations were measured, ranging from background levels (3-5 ng m-3) to >50,000 ng m-3 (Fig. 4), the latter values being detected in the industrial edifices where cinnabar was converted to liquid Hg and where mine-waste calcines are still present. GEM values not exceeding the local limit concentrations for air quality (300 ng m-3), were measured in the urban area. Significant concentrations of GEM in volcanic and geothermal systems are carried up to the surface by uprising hot fluids. GEM concentrations up to 2,300 ng m-3, 1,800 ng m-3, 700 ng m-3, and 500 ng m-3 were measured at the close proximity of fumaroles from Mt. Etna (Bottoniera), Santorini (Nea Kameni), Phlegraean Fields (Pisciarelli) and Vulcano beach, respectively (Fig. 3-4). Anomalously high GEM concentrations (up to 80 ng m-3) were also measured within hot wells at about 20 cm from the water surface at Vulcano (Fig. 5) and Santorini islands. These results indicate that Lumex® is an highly efficient and effective instrument in providing reliable and reproducible GEM concentrations and it can be used to identify gaseous Hg-emitters in different environments such as mining areas and volcanic and geothermal systems. Continuous measurements of atmospheric mercury, also via an accumulation chamber in connection with Lumex® for the determination of Hg soil flux, can be programmed in order to better evaluate and compare the gathered scientific data and to assess the impact of measured air pollutants.
Fig. 1
Fig. 2
Abbadia S. Salvatore Fig. 3
Fig. 5 Fig. 4
Etna
Vulcano
Phlegrean Fields Santorini
