Soil layer update (10/8)

10/8 (11:00am): Two more layers of soil have been tested from Oakland, and the results are posted on the Food Chain page. Cesium-134 was not detected in these samples, although the detection limits we reached were not quite low enough to rule out the tiny levels of Cesium-134 that had been measured in the top layer of soil. However, Cesium-137 was detected down to a depth of 6 cm. This Cs-137 is not from Fukushima for two reasons: (1) the cesium from Fukushima came in a one-to-one ratio of Cs-137 to Cs-134, and (2) cesium deposited earlier this year through rain could not yet have diffused down more than a centimeter or two into the soil (cesium diffuses very slowly through soil). As with our other "older" soil samples, this excess of Cs-137 must be due to previous fallout depositions, primarily from atmospheric weapons testing.

Two final layers down to a total depth of 14 cm will be finished next week.

Mark [BRAWM Team Member]