Its sediments remain highly contaminated and tainted floodplain soils that wash up during storms and floods have now become a source of radioactive materials.
dict.youdao.com
在日本报道的放射性物质泄漏中,最令人担忧的主要是放射性碘和铯。
The big worries on the reported releases of radioactive material in Japan center on radioactive iodine and cesium.