[1] Univ Florence, Dept Chem, Sesto Fiorentino, I-50019 Florence, Italy
[2] ENEA, Lab Observ & Anal Earth & Climate, I-90141 Palermo, Italy
[3] Univ Genoa, Dept Phys, I-16146 Genoa, Italy
[4] Univ Genoa, Ist Nazl Fis Nucl, I-16146 Genoa, Italy
[5] ARPAL Unita Operat CFMI PC, I-16129 Genoa, Italy
[6] Univ Florence, Dept Phys, I-50019 Florence, Italy
[7] INFN Firenze, Sesto Fiorentino, I-50019 Florence, Italy
[8] ENEA, Lab Observ & Analy Earth & Climate, I-00123 Rome, Italy
[9] Univ Valencia, Dept Earth Phys & Thermodynam, Valencia, Spain
[10] ENEA, Lab Observ & Anal Earth & Climate, I-92010 Lampedusa, Italy
[11] ISAC CNR, Via Gobetti 101, I-40129 Bologna, Italy