Strontium-90 and cesium-137 in sea sediments (from Jul. 1983 to Sept. 1983)

Results are presented for the determination of strontium-90 and cesium-137 in coastal sea sediments of 12 sampling points all over Japan from Hokkaido to Okinawa in July, August and September, 1983. Sampling of the sea sediments was carried out under the following criteria: place of more than 1 meter of water depth at low tide, no significant sediment movement observation in the vicinity of concern, and preferable sampling of mud, silt, and fine sands. After removing foreign substances, radiochemical pretreatment for separation of strontium-90 was carried out and also for cesium. Radioactivity of strontium-90 or cesium-137 was determined with a low background beta counter normally for 60 minutes. As for strontium-90 contents, they were ranged from 0.0 +- 3.0 pCi/kg-dry (off Niigata Port, Niigata Prefecture) to 15.0 +- 3.9 pCi/kg-dry (at Mutsu Bay, Aomori Prefecture) and the average value was 3 pCi/kg-dry. As for cesium-137 contents, their variance was large and the value ranged from 8.0 +- 2.6 pCi/kg-dry to 190.0 +- 8.0 pCi/kg-dry (both at Mutsu Bay) and the average value was 65 pCi/kg-dry. Seasonal variance or differences among sampling points were not clarified both for strontium-90 and cesium-137, and it is speculated that the determined values were not abnormal in general. (Takagi, S.)