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There are three primary objectives to this
proposed research. The first one is to improve our understanding
of the geological, hydrological, geochemical and geophysical properties of the
rapid vertical migration pathways associated
with the Chernobyl depression zones. This objective will be accomplished
through controlled field data acquisition, analysis, integration, and
interpretation to determine the
characteristics of these zones that influence the radionuclide migration from
land surface into the subsurface, with
particular emphasis on the aquifers. Field data acquisition will consist of instrumenting two depression zones where data are
currently being collected by the Radioecological Center,
NAS of Ukraine with automatic data recording devices for vertical soil moisture
and radionuclide flux in the vadose and
saturated shallow groundwater systems. The field instrumentation program
is fully described in the Research Approach description.
The second objective is to evaluate the quality
of the existing data sets on depression zone hydrogeologic
and geochemical behavior. We will compare newly acquired field data with those
data previously collected at each experiment
site (i.e., depression zone) by less sophisticated means. The quality
of the field data set developed over the several years that the Radioecological
Center has been studying depression zones is
a concern. The new field data, collected with improved instrumentation and
under more rigorous QA/QC guidelines than imposed in the past, will be used to
assess the quality of the previously
collected data and thereby the inferences based on this data set. The outcome of
this assessment will provide the basis for
any necessary modifications to the data acquisition program administered
by the Radioecological Center.
The third objective is to develop predictive
tools, i.e., numerical flow and transport models, for the
fluid and radionuclide flux through the depression zones. This component of the
research will facilitate extrapolation of the
results obtained from the detailed field investigations at two surface depression
to other depressions in order to estimate the overall contribution of surface
depressions to radionuclide loading of the
shallow groundwater system throughout the CEZ. Using these tools, the timing
and magnitude of the potential threat to the Kiev water supply from
Chernobyl-derived radionuclides can be
evaluated in more accurate and scientifically defensible terms. Also, the
resulting predictive capabilities will
enhance efforts to evaluate alternatives for containing and/or remediating the groundwater contamination occurring via the zones of
fast vertical flux.
Recent Interaction Between
University of South Carolina and Radioecological Center,
National Academy of
Sciences of Ukraine
The motivation for this research and the
resulting technical scope of effort are the culmination of three
trips during 1998 and 1999 by the University of South Carolina Co-Principal
Investigators to Kiev, Ukraine to meet with
the scientific staff of the Radioecological Center, NAS of Ukraine. Each trip
included travel within the Chernobyl Exclusion Zone to observe surface
depressions and the extent of the field
investigations currently conducted by the Radioecological Center. The trips were
sponsored by the Samuel Freeman Charitable
Trust with the express purpose of developing joint research and educational
opportunities in Ukraine. The Samuel Freeman Charitable Trust provides resources
to create scientific interchange, but expressly does not fund research. This
technical aspects of this proposal are based on the results of previous work by
the Radioecological Center scientists and several technical discussions among
the U.S. and Ukrainian co-principal investigators. It is within the scope of the
Ukrainian National Program for Minimization of the Chernobyl Accident
Consequences. Those initial projects were implemented with support from the INCO-Copernicus
Program and the CRDF Fund. From previous studies (e.g., Bublias, et al., 1999;
OECD, 1995) it was concluded that within the CEZ, radionuclide migration to
groundwater could contaminate drinking water above acceptable limits for the
next 10 to 100 years (Shestopalov, 1997).
Given this potential reality and the suspected
role played by depression zones within the CEZ, the Radioecological Center
identified the following research needs.
1) clarification of radionuclide distribution
within depression zones (soils, vadose, and shallow groundwater) and the
temporal and spatial variability associated with the redistribution
process.
2) hydrogeological, geophysical, and
geochemical characterization of the depression zones and how their
physical/chemical properties influence radionuclide redistribution.
3) assessment of the role of depression zones
in terms of redistribution of radionuclide contamination within the
geomorphology of the CEZ and migration of surface water into the
subsurface.
4) quantification, assessment, and prediction
of radionuclide vertical migration in depression zones.
5) assessment of the short-term versus
long-term and local versus regional threat to groundwater resources associated
with the fast vertical flux in depression zones.
The objectives of this collaborative research
project, previously described, are designed to specifically address these
identified research needs.
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