131I and137Cs in the environment following the chernobyl reactor accident

The measured¹³¹I and¹³⁷Cs radioactivity in air, on the ground, and in milk at different places throughout the world were compared. It was found that the measured radioactivity can be explained assuming that the radioactive material released during the Chernobyl accident was transported primarily in two segments. The first part was transported at low altitudes, contaminated areas around Chernobyl and extended up to 2000–3000 km. The second part was injected into the troposphere. The radionuclides carried at high altitudes by the west-to-east winds traveled over continental Asia, Japan, Pacific Ocean, and North America. The time integrated radioactivity concentrations in nearground air particulates, the integral ground deposition densities and milk concentrations can be described by an exponential decrease as a function of the distance from Chernobyl. The intercept (values near the damaged reactor) and the slopes (describing dispersion conditions) were calculated. The deposition velocities for¹³¹I and¹³⁷Cs transported with the two altitude air masses are given.This work was supported in part by the Computer Center of the University of Maryland.