of activity concentrations in the proximity of Fukushima
Daiichi NPP and at 10 to 30 km distance from the coastline.
Fig. 5 shows the measured concentrations of 137Cs
at two different locations. High concentrations of cesium
and iodine could be observed in March and at the beginning
of April. These values had a high potential for high
concentrations in fish, mussels, and algae. By mid-May,
the concentrations of cesium in seawater were below the
limiting value.