One such product linked to these activities,
isosaccharinic acid (ISA), causes much concern as
it can react with a wide range of radionuclides -
unstable and toxic elements that are formed during
the production of nuclear power and make up the
radioactive component of nuclear waste. If the ISA
binds to radionuclides, such as uranium, then the
radionuclides will become far more soluble and
more likely to flow out of the underground vaults to
surface environments, where they could enter
drinking water or the food chain. However, the
researchers' new findings indicate that
microorganisms may prevent this becoming a
problem.
Working on soil samples from a highly alkaline
industrial site in the Peak District, which is not
radioactive but does suffer from severe
contamination with highly alkaline lime kiln wastes,
they discovered specialist "extremophile" bacteria
that thrive under the alkaline conditions expected in
cement-based radioactive waste. The organisms
are not only superbly adapted to live in the highly
alkaline lime wastes, but they can use the ISA as a
source of food and energy under conditions that
mimic those expected in and around intermediate
level radwaste disposal sites. For example, when
there is no oxygen (a likely scenario in underground
disposal vaults) to help these bacteria "breath" and
break down the ISA, these simple single cell
microorganisms are able to switch their metabolism
to breath using other chemicals in the water, such
as nitrate or iron.
The fascinating biological processes that they use
to support life under such extreme conditions are
being studied by the Manchester group, as well as
the stabilizing effects of these humble bacteria on
radioactive waste. The ultimate aim of this work is
to improve our understanding of the safe disposal
of radioactive waste underground by studying the
unusual diet of these hazardous waste eating
microbes.
One of the researchers, Professor Jonathan Lloyd
of The University of Manchester School of Earth,
Atmospheric & Environmental Sciences said: "We
are very interested in these Peak District
microorganisms. Given that they must have
evolved to thrive at the highly alkaline lime-kiln site
in only a few decades, it is highly likely that similar
bacteria will behave in the same way and adapt to
living off ISA in and around buried cement-based
nuclear waste quite quickly. Nuclear waste will be
remain buried deep underground for many
thousands of years so there is plenty of time for the
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