Scavenging of Chernobyl [sup 137]Cs and natural [sup 210]Pb in Lake Sempach, Switzerland

Journal Article · Thu Jul 01 04:00:00 EDT 1993 · Geochimica et Cosmochimica Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(93)90286-6· OSTI ID:6221852

Wieland, E ^[1]; Santschi, P H ^[2]; Hoehener, P ^[3]; Sturm, M ^[4]

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1. Stanford Univ., CA (United States)
2. Texas A M Univ., Galveston (United States)
3. Swiss Federal Inst. of Technology, Schlieren (Switzerland)
4. Swiss Federal Inst. for Water Resources and Water Pollution Control, Duebendorf (Switzerland)

Radioactive fallout from the burning Chernobyl nuclear reactor provided a pulsed release of [sup 137]Cs to Lake Sempach at the beginning of May 1986. The time-dependent removal of [sup 137]Cs from the water column into the sediments has been investigated by analyzing water samples, settling particles, and sediment cores. A flux balance has been established to determine and to quantify the removal processes in the epilimnion and hypolimnion of Lake Sempach. Between May 1986 and March 1988, removal residence times of [sup 137]Cs averaged 150 days in the epilimnion and 280 days in the hypolimnion. [sup 137]Cs accumulated in the hypolimnion during stratification, and its scavenging from the hypolimnion into the sediments was the rate-limiting step of the overall process of removing [sup 137]Cs from the water column. Resuspension of sedimentary [sup 137]Cs occurred during circulation periods in winter. Scavenging trap fluxes of [sup 137]Cs and [sup 210]Pb linearly correlated with increasing particle fluxes up to a maximum of about 2.5 g m[sup [minus]2] d[sup [minus]1]. Higher particle fluxes, likely due to calcite precipitation, did not enhance removal fluxes and scavenging efficiency for these nuclides. The distribution coefficient for the partition of [sup 137]Cs between lake water and settling particles, K[sub d], was determined to 7.0 [+-] 1.0 [times] 10[sup 4] cm[sup 3] g[sup [minus]1] for epilimnetic particles and to 5.3 [+-] 1.1 [times] 10[sup 4] cm[sup 3] g[sup [minus]1] for hypolimnetic particles. The distribution coefficient for [sup 210]Pb was estimated to 1.1 [times] 10[sup 6] cm[sup 3] g[sup [minus]1]. The possibility of postdepositional mobility of Chernobyl and nuclear weapons [sup 137]Cs and natural [sup 210]Pb in sediments was proved. 72 refs., 9 figs., 9 tabs.

• OSTI ID: 6221852
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Journal Name: Geochimica et Cosmochimica Acta; (United States) Vol. 57:13; ISSN GCACAK; ISSN 0016-7037
• Country of Publication: United States
• Language: English

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54 ENVIRONMENTAL SCIENCES
540330* -- Environment
Aquatic-- Radioactive Materials Monitoring & Transport-- (1990-)
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BETA-MINUS DECAY RADIOISOTOPES
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RADIONUCLIDE MIGRATION
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