The document summarizes seawater sampling data from off the coast of Fukushima, Japan following the Fukushima Daiichi nuclear disaster. Sampling was conducted by Japanese authorities MEXT and TEPCO at various distances from the coastline. The highest levels of radioactive iodine-131 and cesium-137 were found close to shore, with concentrations decreasing further offshore and over time. If no additional radioactive releases occur, concentrations measured 30 km offshore are expected to continue decreasing significantly through dilution and dispersion by ocean currents. An expert from the IAEA visited Japan to review marine sampling and measurements.

1. Marine Environment Monitoring Assessment of IAEA Environment Laboratories on Data provided by Japan Update 12 April IAEA Environment Laboratories, Monaco

5. Concentrations in sea water near discharge point of TEPCO 1-4