Radioactive strontium exceeding normal levels has been detected in
sediment from atop an apartment building in Yokohama, some 250 km from
the Fukushima No. 1 nuclear power plant, city officials said Wednesday.
While the discovery of 195 becquerels of strontium-90 in the rooftop
sediment fueled concerns that leaked radiation may have spread farther
than the central government expected, the officials said the city is
carefully examining where the isotope came from. If the substance is
from the Fukushima plant, it will be the first time strontium at a
concentration of more than 100 becquerels per kilogram has been found
beyond 100 km from the troubled plant. (Japan Times )