Land Contamination & Reclamation / Volume 16 / Number 4 / 2008
selenium that can potentially be
Joachin Valley, one of the
leads a team of experts in
recovered from the process.
agriculturally most productive areas
subsurface geochemistry, hydrology
of the US (a comprehensive report
and microbiology. ‘But we believe
A study, ‘Biological Selenium
by the USGS is available at http://
this new approach will allow us to
Removal: The Solution to
pubs.usgs.gov/pp/p1646/pdf/
better understand the sources and
Pollution?’, funded by the European
pp1646.pdf).
migration behaviour of uranium in
Union, published in the September/ October issue of the Journal of
The abstract can be found at http://
Environmental Quality, by Markus
jeq.scijournals.org/cgi/content/
Lenz, Martijn Smit, Patrick Binder,
abstract/37/5/1691.
Adriaan C. van Aelst and Piet N. L.
Source: Soil Science Society of
Lens demonstrates that the
America
substantial amounts of selenate are converted to methylated selenium species or nano-sized elemental
Sophisticated monitoring array to address mystery of uranium plume Scientists have puzzled for years as
nano-sized selenium particles is
to why uranium contamination in
problematic, as these can become
groundwater continues to exceed
bioavailable by direct assimilation,
drinking-water standards in an area
or can reoxidize to selenite and
located at the south end of the
selenate. Dimethylselenide and
Hanford Site, WA.
with unknown ecotoxicological long-term effects, contributed substantially to selenium dissolved in the effluent. Their formation was induced by minor temperature changes during biological
Now, an innovative system has been
contaminated wastewater were disposed of. The waste originated from nuclear-fuel fabrication facilities.
experiments using waters of different temperature and
subsurface experimental system
and is a prerequisite for successful
containing nearly three dozen
removal in full-scale applications.
monitoring wells equipped with
character, no sustainable solution
location where large volumes of
decisions.
biotreatment systems for selenium,
volume – low-concentration’
35 monitoring wells is near the
and to support future clean-up
(PNNL) have developed a unique
implemented. Due to the ‘high-
contaminated ground, the array of
researchers to perform injection
the removal success of existing
reuse on the other, should be
approximately 100-metre plot of
The Hanford IFRC project allows
Northwest National Laboratory
hand, and selenium recovery and
chessboard within an
understanding of this complex site,
control might drastically increase
ecotoxicological risks on the one
Positioned like a triangular
experiments to arrive at a better
Scientists at DOE’s Pacific
aiming at minimizing
evaluations of the complex 300
installed to conduct field
reduction, thus careful process
Consequently, remediative systems
of the most comprehensive
more than 40 years.
selenium particles. The emission of
dimethyldiselenide, two species
The project promises to provide one
Area subsurface along the river in
biological treatment is indeed efficient for selenate reduction, and
the subsurface.’
sophisticated instrumentation. The entire subsurface surrounding the wells will be comprehensively characterized to enable a complete accounting of the processes occurring beneath the surface that contribute to the persistent groundwater contamination.
composition pumped from other locations in the 300 Area groundwater plume. The variability allows scientists to probe migration pathways through the subsurface, and to examine factors that control uranium release from the historically contaminated sediments. Time-based water-level and composition data gathered from the robust geophysical and geochemical monitoring system will enable researchers to develop three-
has been found yet to treat
‘The plume has baffled researchers
dimensional plume maps, helping
selenium-contaminated drainage
for more than a decade,’ said PNNL
to create improved uranium
waters originating from the San
Project Manager John Zachara, who
migration models.
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