Ambient air PM10 collected in the geothermal area of Piancastagnaio town, Siena province, Italy, was studied employing extensively Raman micro-spectroscopy with the help of scanning electron microscopy (SEM). Particulate matter was collected between the fall 2013 and the fall of 2014 according to the project Patos II of the Regione Toscana. In the area under investigation two geothermoelectric industrial plants of ENEL S.p.A are present along with natural wells and a pipeline system. This work represents a first effort aiming to understand the nature of ambient aerosol related to geothermal emissions and their deployment, and provides a useful starting point for taking into account the potential impact of such aerosol on human health. The nature of the solid fraction related to the geothermal emissions was studied collecting Raman spectra of more than a thousand particles, randomly selected, and identifying their mineralogical composition. On the total by number, the majority of particles belong to the group of sulphates (56.1%), followed by soot (21.8%), nitrates (5.0%), silicates (3.6%), oxides (3.6%), carbonates (3.0%) and others (6.9%). Among sulphates the 38.7%, by particles number, is due to mascagnite [(NH4)2SO4], 13.8% to a not well characterized phase “matteuccite-like” (NaHSO4·H2O), 13.8% to gypsum, 10.1% to Na2SO4(III), 8.9% to letovicite [(NH4)3H(SO4)2], and 3.9% to barite (BaSO4), being the ammonium and sodium cations largely abundant. Particles of sulphates exhibit dimensions typical of the secondary aerosol and, even if their presence is highly variable during the days of sampling, there is a rough inverse correlation between the pairs mascagnite plus letovicite and matteuccite-like plus Na2SO4(III). Even though the presence of mascagnite and letovicite has been detected in polluted urban areas the high amount of ammonium and sodium sulphates found in Piancastagnaio town, along with their peculiar proportions, represents a particular kind of aerosol strictly related to the geothermal emission.
PM10 emission near the Mt. Amiata geothermal field / Zoppi M., Pratesi G., Capecchiacci F., Cabassi J., Marchionni S., Tassi F., Vaselli O., Giannini L., Venturi S., Ulivi M., Forni F., Scodellini R., Tommasini S.. - ELETTRONICO. - (2015), pp. 0-0. (Intervento presentato al convegno Il Pianeta Dinamico: Sviluppi e prospettive a 100 anni da Wegener. Congresso congiunto SIMP-AIV-SoGeI-SGI).
PM10 emission near the Mt. Amiata geothermal field
Zoppi M.;Pratesi G.;Capecchiacci F.;Cabassi J.;Marchionni S.;Tassi F.;Vaselli O.;Giannini L.;Venturi S.;Ulivi M.;Scodellini R.;Tommasini S.
2015
Abstract
Ambient air PM10 collected in the geothermal area of Piancastagnaio town, Siena province, Italy, was studied employing extensively Raman micro-spectroscopy with the help of scanning electron microscopy (SEM). Particulate matter was collected between the fall 2013 and the fall of 2014 according to the project Patos II of the Regione Toscana. In the area under investigation two geothermoelectric industrial plants of ENEL S.p.A are present along with natural wells and a pipeline system. This work represents a first effort aiming to understand the nature of ambient aerosol related to geothermal emissions and their deployment, and provides a useful starting point for taking into account the potential impact of such aerosol on human health. The nature of the solid fraction related to the geothermal emissions was studied collecting Raman spectra of more than a thousand particles, randomly selected, and identifying their mineralogical composition. On the total by number, the majority of particles belong to the group of sulphates (56.1%), followed by soot (21.8%), nitrates (5.0%), silicates (3.6%), oxides (3.6%), carbonates (3.0%) and others (6.9%). Among sulphates the 38.7%, by particles number, is due to mascagnite [(NH4)2SO4], 13.8% to a not well characterized phase “matteuccite-like” (NaHSO4·H2O), 13.8% to gypsum, 10.1% to Na2SO4(III), 8.9% to letovicite [(NH4)3H(SO4)2], and 3.9% to barite (BaSO4), being the ammonium and sodium cations largely abundant. Particles of sulphates exhibit dimensions typical of the secondary aerosol and, even if their presence is highly variable during the days of sampling, there is a rough inverse correlation between the pairs mascagnite plus letovicite and matteuccite-like plus Na2SO4(III). Even though the presence of mascagnite and letovicite has been detected in polluted urban areas the high amount of ammonium and sodium sulphates found in Piancastagnaio town, along with their peculiar proportions, represents a particular kind of aerosol strictly related to the geothermal emission.
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