Pb-210 in precipitation in Japan and its implication for the transport of continental aerosols across the ocean

Abstract

Total precipitation including rain or snow and dry fallout was collected once a month from February 1970 to March 1972 at five sampling stations in Hokkaido located from the coast of the Sea of Japan to inland. The monthly deposition rate of Pb-210 waa determined together with other chemical constituents. The results are summarized aa follows: (1) The deposition rate and the concentration of Pb-210 are remarkably high in winter.(2) A linear relation between the deposition rate of Pb-210 and the amount of rainfall is found in both summer and winter respectively. (3) As compared with the production rate of Pb-210, namely the exhalation rate of Rn-222 from the continent, the deposition rate of Pb-210 to the unit area at the coast of the Sea of Japan in winter is 2-4 times the exhalation rate of Rn-222 from the continent. (4) The budget calculation of Pb-210 in the atmosphere shows that about 40% of aerosols transported from the continent are caught by snow and deposited over the Sea of Japan and the Japan Islands in winter. Therefore, it is concluded that the Japan Islands play an important role as a collector of the continental aerosols in winter.Tellus XXVII (1975). 5

210Pb geochronology of sediments from Lake Shinji.

“…FUKUDA and TsUNOGAI (1975) have reported the 210Pb flux from atmosphere to land to be 1.5 ti 2.8 dpm/cm2y at Ha kodate, Japan, which is in a good agreement with the 210Pb flux at the sediment-water interface in Lake Shinji. This fact implies that the main source of 210Pb in lake sediments is atmospheric fallout, and 210Pb contribution from other sources such as river-borne solids is probably small to the sediments of Lake Shinji.…”

Radionuclide Limnochronology

“…The available data on the 21°Pb deposition flux at any given location seem to exhibit a positive correlation with local rainfall, with correlation coefficients ranging between 0.3 and 0.7 . Figure 4 shows the monthly 21°Pb deposition and rainfall for Hokkaido, Japan, where a significant seasonal variation in the 21°Pb concentration in rain water has been observed (Fukuda and Tsunogai , 1975) probably due to the influence of northwest monsoon. Such marked seasonal trends in the 2!OPb concentration in rain water have not been observed for several other stations for which data are available.…”

Settling model for the removal of insoluble chemical elements in seawater.

“…NOZAKI and TSUNOGAI used the larger value of the flux which was observed in Hokkaido by FUKUDA and TSUNOGAI (1975).…”