Lakes across eastern Japan are being contaminated with radioactive cesium from the crippled Fukushima No. 1 nuclear power plant, and scientists are warning of a growing problem in Tokyo Bay.
In March, a maximum cesium concentration of 9,550 becquerels per kilogram was detected in mud on the bottom of the Bizengawa river, 1.65 kilometers from where it flows into Japan’s second-largest lake, Lake Kasumigaura in Ibaraki Prefecture.
A month later, the highest reading was 800 meters closer to the lake and had increased to 9,980 becquerels per kilogram.
Since April, cesium levels over 100 becquerels per kilogram have also been found in fish and shellfish in Lake Numazawako, Lake Inawashiroko and Lake Akimotoko in Fukushima Prefecture, Hinuma marsh in Ibaraki Prefecture, Teganuma marsh in Chiba Prefecture and Lake Chuzenjiko in Tochigi Prefecture.