The reactor accident at chernobyl: A possibility to test colloid-controlled transport of radionuclides in a shallow aquifer

• Published in: Journal of contaminant hydrology 1988-07, Vol.2 (3), p.237-247
• Main Authors: Von Gunten, Hans R, Waber, Ursula E, Krähenbühl, Urs
• Format: Article
• Language: English
• Subjects: aquifers; drinking water; groundwater; radioactive pollution; radionuclides; river water; water pollution
• ISSN: 0169-7722; 1873-6009
• DOI: 10.1016/0169-7722(88)90024-1

Radioactive fall-out from the damaged nuclear power station at Chernobyl (USSR) has been measured in May 1986 in the River Glatt (Zürich, Switzerland) and in a shallow groundwater stream. This aquifer is hydraulically connected to the river and recharged by river water. Ruthenium-103, I-131, Te-132, Cs-134 and Cs-137 were measured several times using gamma-ray spectroscopy. By filtration through 0.45 μm, 0.2 μm and 0.05 μm filters the radionuclides were partitioned between solution (filtrate < 0.05 μm) and particles/colloids. In the river, the main radioactivity for all the investigated nuclides was found in the water passing the 0.05 μm filter. Among the particulates the highest radioactivity was detected in the fraction > 0.45 μm, the two smaller sizes contributing only little. In the water infiltrating into the groundwater Ru-103, I-131 and Te-132 were found almost exclusively in the filtrate (< 0.05 μm). No Cs-134, 137 was detected in this fraction indicating complete sorption on the aquifer material during infiltration. Only a very small radioactivity was found on colloids > 0.05 μm suggesting their retention by the heterogeneous glaciofluvial outwash deposits (stones, gravel, sand, clays).