7Be, 210Pb, and 210Po in the surface air from the Arctic to Antarctica

Abstract

In the present study we have investigated the activity concentrations of 210Pb, 210Po as well as 7Be in surface air of the North and South Atlantic (1988–1989), the Arctic Ocean (1991), and along the coastline of Siberia (1994) during succeeding expeditions in the Swedish Polar Research program.During the cruises in the Arctic Ocean during 1991-07-28 to 1991-10-04 the average air concentrations of 7Be was 0.6 ± 0.4 mBq/m3, 210Pb 40 ± 4 μBq/m3 and 210Po-38 ± 10 μBq/m3. During the Swedish-Russian Tundra Ecology-94 expedition along the Siberian coastline the average air concentrations of 7Be and 210Pb measured during May–July were 11 ± 3, and 2.4 ± 0.4 mBq/m3, and during July–September they were 7.2 ± 2 and 2.7 ± 1.1 mBq/m3 respectively. The results from measurements of the activity concentration of 210Pb in the air over the Arctic Ocean vary between 75 and 176 μBq/m3. In the air close to land masses, however, the activity concentration of 210Pb in the air increases to 269–2712 μBq/m3.The activity concentration of 7Be in the South Atlantic during the cruise down to Antarctica varied between 1.3 and 1.7 with an average of 1.5 ± 0.8 mBq/m3. The activity concentration of 210Pb in the South Atlantic down to Antarctica varied between 6 and 14 μBq/m3. At the Equator the activity concentration recorded in November 1988 was 630 μBq/m3 and in April 1989 it was 260 μBq/m3. The average activity concentration of 210Pb during the route Gothenburg–Montevideo in 1988 was 290 and on the return Montevideo–Gothenburg it was 230 μBq/m3. The activity concentration of 210Po in the South Atlantic down to Antarctica varied between 15 and 58 μBq/m3. At the Equator the activity concentration in November 1988 was 170 and in April 1989 it was 70 μBq/m3. The average activity concentration of 210Po during the route Gothenburg–Montevideo in 1988 was 63 and on the return Montevideo–Gothenburg it was 60 μBq/m3. The average of the activity concentrations in the Antarctic air of 210Pb was 27 ± 10 μBq/m3 and of 210Po it was 12 ± 7 μBq/m3.All our results were compiled together with other published data, and the global latitudinal distribution of 210Pb was converted to total annual deposition (Bq/m2/a) and fitted to a 4th degree polynomial. By using the global latitudinal distribution of 210Po/210Pb-activity ratio from our own results the global latitudinal distribution of 210Po annual deposition was derived.