Abstract
135Cs is among the most important radionuclides in the
long-term safety assessments of spent nuclear fuel, due
to its long half-life of 2.3 My and large inventory in
spent nuclear fuel. Batch sorption experiments were
conducted to evaluate the sorption behavior of
radiocesium (134Cs) in the surface moss, peat, gyttja,
and clay layers of 7-m-deep profiles taken from a
nutrient-poor boreal bog. The batch distribution
coefficient (Kd) values of radiocesium increased as a
function of sampling depth. The highest Kd values, with a
geometric mean of 3200 L/kg dry weight (DW), were
observed in the bottom clay layer and the lowest in the
0.5-1.0 m peat layer (50 L/kg DW). The maximum sorption
in all studied layers was observed at a pH between 7 and
9.5. The in situ Kd values of 133Cs in surface Sphagnum
moss, peat and gyttja samples were one order of magnitude
higher than the Kd values obtained using the batch
method. The highest in situ Kd values (9040 L/kg DW) were
recorded for the surface moss layer. The sterilization of
fresh surface moss, peat, gyttja and clay samples
decreased the sorption of radiocesium by 38%, although
the difference was not statistically significant.
However, bacteria belonging to the genera Pseudomonas,
Paenibacillus, Rhodococcus and Burkholderia isolated from
the bog were found to remove radiocesium from the
solution under laboratory conditions. The highest
biosorption was observed for Paenibacillus sp. V0-1-LW
and Pseudomonas sp. PS-0-L isolates. When isolated
bacteria were added to sterilized bog samples, the
removal of radiocesium from the solution increased by an
average of 50% compared to the removal recorded for pure
sterilized peat. Our results demonstrate that the
sorption of radiocesium in the bog environment is
dependent on pH and the type of the bog layer and that
common environmental bacteria prevailing in the bog can
remove cesium from the solution phase.
Original language | English |
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Pages (from-to) | 22-32 |
Journal | Journal of Environmental Radioactivity |
Volume | 147 |
DOIs | |
Publication status | Published - 2015 |
MoE publication type | A1 Journal article-refereed |
Keywords
- sorption
- cesium
- peat
- bacteria
- radionuclides
- radioactive waste