title: Cosmogenic (7)Be and (22)Na in ground level air in Switzerland (1994-2011).
abstract: We report monthly averages of weekly (7)Be and (22)Na concentrations in aerosol samples collected with high volume aerosol filters at 5 sampling sites in Switzerland from 1994 to 2011 ((7)Be) and from 2000 to 2011 ((22)Na). Monthly average concentrations of the two cosmogenic isotopes varied between 2600 and 4600 μBq/m(3) for (7)Be and between 0.2 μBq/m(3) and 0.5 μBq/m(3) for (22)Na. The (22)Na concentration in ground level air strongly increased from March to May, while a corresponding (7)Be increase was seen from March until July. The observed variations of the (7)Be and (22)Na activities together with the changes in the (7)Be/(22)Na ratio indicate input of stratospheric air between March and May, increased mixing of upper tropospheric air from June to August, and less exchange between the upper and lower troposphere in autumn and winter. Additionally, the 11-year solar cycle is clearly seen in the annual averages of the (7)Be concentrations.
authors.affiliation: Federal Office of Public Health, Schwarzenburgstrasse 165, CH-3003 Bern, Switzerland. philipp.steinmann@bag.admin.ch
authors.forename: Philipp
authors.initials: P
authors.lastname: Steinmann
authors.forename: Michael
authors.initials: M
authors.lastname: Zeller
authors.forename: Pierre
authors.initials: P
authors.lastname: Beuret
authors.forename: Giovanni
authors.initials: G
authors.lastname: Ferreri
authors.forename: Sybille
authors.initials: S
authors.lastname: Estier
mesh_terms: D000396:Air Pollutants, Radioactive / Q000032:analysis* / Q000266:history; D001272:Atmosphere; D001608:Beryllium / Q000032:analysis* / Q000266:history; D003359:Cosmic Radiation; D049673:History, 20th Century; D049674:History, 21st Century; D011834:Radiation Monitoring; D011868:Radioisotopes / Q000032:analysis* / Q000266:history; D012979:Sodium Radioisotopes / Q000032:analysis* / Q000266:history; D019445:Solar Activity; D013557:Switzerland
chemical_list: D000396:Air Pollutants, Radioactive; D011868:Radioisotopes; D012979:Sodium Radioisotopes; D001608:Beryllium
keywords: Aerosol; Be-7; Na-22; Solar cycle; Stratosphere–troposphere exchange