Comparative trends and seasonal variation of 7Be, 210Pb and 137Cs at two altitude sites in the central part of France

• Published in: Journal of environmental radioactivity Vol. 102; no. 3; pp. 294 - 301
• Main Authors: Bourcier, L., Masson, O., Laj, P., Pichon, J.M., Paulat, P., Freney, E., Sellegri, K.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-03-2011; Elsevier
• Subjects: 137Cs; 210Pb; 7Be; Altitude; Applied sciences; Atmospheric pollution; Beryllium - analysis; Carbon Isotopes - analysis; Environmental Monitoring; Environmental Sciences; Exact sciences and technology; France; Lead Radioisotopes - analysis; Pollutants physicochemistry study: properties, effects, reactions, transport and distribution; Pollution; Seasons; Vertical transport; Auvergne; France; Europe; Puy-de-Dome; Vertical transport; 7Be; 210Pb; 137Cs; Altitude; Radioactive pollution; Troposphere; Cosmogenic factor; Radioisotope; Modeling; Transport process; Cs; Pb; Seasonal variation; Natural origin pollution; Cesium 137; Be; Pollutant behavior; Mixing process; Lead 210; Stratosphere; Beryllium 7; Radioactivity measurement; Air mass; Long range pollutant transport; Trend analysis; Pollution source; Air pollution
• ISSN: 0265-931X; 1879-1700
• DOI: 10.1016/j.jenvrad.2010.12.005

The atmospheric concentrations of
137Cs,
210Pb, and
7Be were measured over a three-year period at two research stations located less than 12
km apart and at different altitudes (puy de Dôme, 1465
m a.s.l. and Opme, 660
m a.s.l., France). Seasonal trends in all radionuclides were observed at both stations, with high concentration measured during the summer and low concentrations during the winter. The
210Pb concentrations at both stations were similar to each other. Higher concentrations of both
7Be and
137Cs were measured at puy de Dôme than at Opme. These observations can be explained by the stratospheric and upper tropospheric sources of
7Be and the long-range transportation of
137Cs at high altitudes. Air mass origins during sampling periods were classified into several groups by their route to the stations (marine, marine modified, continental and mediterranean). We observed that
7Be concentrations were constant regardless of the air mass origins, unlike
137Cs and
210Pb concentrations that increased when influenced by continental air masses. Higher
7Be concentrations were observed when air masses were arriving from the upper troposphere than from the boundary layer, the opposite was observed for
137Cs. The temporal trend in concentrations of
7Be shows good agreement with previous modelling studies suggesting that there is a good understanding of its sources and the atmospheric vertical mixing of this radionuclide. The sources and mixing of
210Pb, however, seem to be more complex than it appeared to be in previous modelling studies.