The impact of the Chernobyl accident on a river/groundwater aquifer

The radionuclides 99mTc, 103Ru, 131I, 132Te, 134Cs and 137Cs, resulting from fallout from the damaged nuclear power plant at Chernobyl (USSR) were measured several times between May 2nd and 20th, 1986, in the River Glatt (Zurich, Switzerland) and in the adjacent shallow ground water stream. Samples from the river and from different groundwater wells were filtered (0.45, 0.20, 0.05 μm). The resulting water and the filters were assayed by γ-ray spectroscopy. For all these nuclides the main radioactivity (> 75%) of the river water was found in the water passing the 0.05 μm-filter. The fraction > 0.45 μm contained the main particulate activity. Upon infiltration of river water into the groundwater stream iodine, ruthenium and tellurium are not, or only slightly sorbed, probably due to the formation of anionic or neutral species, whereas cesium is completely retained by the sediments. Particulate (> 0.05 μm) infiltration from the river into the groundwater is a negligible process. (orig.)