北太平洋上エアロゾル中の^<210>Pb,^<210>Bi,^<210>Po

概要

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Atmospheric aerosol samples were collected on board a vessel over the North Pacific Ocean for the period from August to October, 1985, and were analyzed for the daughter nuclides of radon, ^<210>Ppb, ^<210>Bi and ^<210>Po. The concentrations of ^<210>Pb obtained during the cruise from Hawaii to Midway were about 5 dpm/1000m^3, corresponding to about one-eighth of the annual mean value observed at Okushiri Island (42°N) in Japan. On September 23, a cold front pass at a point of about 29°N, 177°W during the westward cruise. Before passing the cold front the concentration of ^<210>Pb was lower and the residence time of aerosols calculated from ^<210>Po/^<210>Pb was 48days and that from ^<210>Bi/^<210>Pb was about 14days, while the concentration of ^<210>Pb was increased and the residence time was largely shortered after the passing. These results suggest that there exists continental aerosols of longer residence time in the maritime air mass, which may be supplied from the upper atmosphere.
日本地球化学会の論文
1991-12-05