Remobilisation of uranium from contaminated freshwater sediments by bioturbation
Benthic macro-invertebrate bioturbation can influence the remobilisation of uranium (U) initially associated with freshwater sediments, resulting in a high release of this pollutant through the overlying water column. Given the potential negative effects on aquatic biocenosis and the global ecologic...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2014-06-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/11/3381/2014/bg-11-3381-2014.pdf |
| Summary: | Benthic macro-invertebrate
bioturbation can influence the remobilisation of uranium (U) initially
associated with freshwater sediments, resulting in a high release of this
pollutant through the overlying water column. Given the potential negative
effects on aquatic biocenosis and the global ecological risk, it appears
crucial to improve our current knowledge concerning the biogeochemical
behaviour of U in sediments. The present study aimed to assess the
biogeochemical modifications induced by <i>Tubifex tubifex</i> (Annelida,
Clitellata, Tubificidae) bioturbation within the sediment in order to explain
such a release of U. To reach this goal, U distribution between solid and
solute phases of a reconstructed benthic system (i.e. in mesocosms) inhabited
or not by <i>T. tubifex</i> worms was assessed in a 12-day laboratory
experiment. Thanks notably to fine-resolution (mm-scale) measurements (e.g.
"diffusive equilibrium in thin-films" DET gel probes for porewater,
bioaccumulation in worms) of U and main chemical species (iron, sulfate,
nitrate and nitrite), this work (i) confirmed that the removal of bottom
sediment particles to the surface through the digestive tract of worms
greatly favoured oxidative loss of U in the water column, and (ii)
demonstrated that both U contamination and bioturbation of <i>T.
tubifex</i> substantially influenced major microbial-driven biogeochemical
reactions in sediments (e.g. stimulation of denitrification, sulfate
reduction and iron dissolutive reduction). This study provides the first
demonstration of biogeochemical modifications induced by bioturbation in
freshwater U-contaminated sediments. |
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| ISSN: | 1726-4170 1726-4189 |