In order to determine the physical location of contaminants in soil, two solidified soil "thin" sections, which preserve the undisturbed structural characteristics of the original soil, containing weapons-grade plutonium from the Rocky Flats Environmental Test Site were prepared. Two autoradiographic methods were used in radionuclide mapping: contact autoradiography using CR-39�� plastic alpha track detectors and neutron-induced autoradiography that produced fission fragment tracks in Lexan�� plastic detectors. The combination of the two autoradiographic methods distinguished alpha-emitting particles of natural U, from ������������������Pu and non-fissile alpha-emitters. The locations of 990 alpha "stars" caused by plutonium "hot particles" in two soil sections were recorded, particles were sized, their size-frequency and depth distributions were analyzed. Several large colloidal conglomerates of "hot particles" were found in soil profiles. One such conglomerate with a geometric size of about 500 ��m contained over 94% of the total recorded contaminant alpha activity in the sample. It was found that the upper 6.5 cm of soil contained 20% of all recorded particles (mean equivalent size 0.35 ��m). The deeper portion of the surface 6.5 cm soil layer contained 80% of the particles (with mean equivalent size 0.25 ��m). The average specific activity (SA) for 989 hot particles (with the conglomerate of the particles excluded) with equivalent diameters over 80 nm was found to be greater than 23.9 Bq g����� (about 90% of the overall average SA). For dissolved and defragmented (below 80 nm of equivalent diameter) actinide particles, SA was found smaller than 2.9 Bq g�����. Over 99% of the total actinide contaminant activity in the analyzed soil sample (with the conglomerate of the particles included) was found in particles with equivalent diameters over 0.08 ��m. it suggests that larger particles of plutonium oxide moved down more slowly than smaller ones and no significant breakup of plutonium oxide particles occurred since the original plutonium soil deposition. Both profiles of the depth contaminant activity and number of actinide particles have distinctive peaks at the same depth, about 10 cm. Independent from nuclear track analysis, this pattern of the actinides depth distribution was observed in the measured gamma activity depth profile of �������Am (daughter product of �������Pu beta decay) in solidified soil blocks. / Graduation date: 2001

Soil that is contaminated with radioactive elements poses an exposure hazard to those whom may take up temporary or permanent residence on such a site. Of particular interest is the internal exposure from ingestion of this radioactive soil. Although most ingestion of soil is inadvertent, usually being attached to foodstuffs that are not properly cleaned, it is possible that a person might consume a larger quantity. Childhood soil ingestion from simple hand-to-mouth activities is one explanation for this larger intake, as well as geophagia (eating dirt) or pica (craving and eating non-food items). The assumption that any person might consume a "mouthful" of dirt is a rare but possible occurrence that, when analyzed, will help with decisions about safe contamination levels of soil. Samples of soils contaminated with radium-226 were sent from an engineering and environmental firm to Oregon State University's Department of Nuclear Engineering and Radiation Health Physics for assessment. The analysis of the samples was aimed at the determination of bioavailability and bioaccessibility of the radioactive species found in the soils. Subsequent site remediation actions for the New Jersey-based project would be partially dictated by the results of Oregon State University's testing. Initially, the soils were tested for the presence of carbonates, for leachability of radioactivity in water and in acid, and for particle size distribution, i.e., soil type. Each of the eight samples was then subjected to a stomach/intestinal analogue to determine how much of the radioactivity would be transferred to solution upon human ingestion, (bioaccessibility). Mass balance and gamma spectrometry outputs for the soil samples before and after the digestion was one way the loss to solution was assessed. Another method to determine the loss of radioactivity to solution was to count aliquots of the digestive fluids in a high purity germanium detector, using a library of only radium isotopes and their progeny to locate peaks. The combination of results from mass balance and gamma spectrometry outputs allowed for OSU's researchers to determine the bioaccessibility of each soil's radioactive components. Using the determined bioaccessibility and previous animal models, the determination of bioavailability varied between the samples, from zero to 28% of the total initial radioactivity in the samples. A hot particle estimation of the dose from the non-bioavailable portion of the samples yielded a high dose to a small number of cells. Assuming ingestion of the most radioactive sample, (Sum-03a), the amount of damaged (killed) tissue in each section of the gastrointestinal tract was estimated to be less than 0.0407 cm³. This small volume of tissue is not likely to result in evident damage as the healthy human gastrointestinal tract regenerates all surface cells approximately every six days and most items are resident in the digestive system for less than 48 hours. / Graduation date: 2006

Thesis (Ph. D.)--Lehigh University, 2002. / Includes vita. Includes bibliographical references (leaves 128-134).

Following the Chernobyl accident in 1986, a range of countermeasures has been developed to reduce the transfer of 137Cs from soil to plant and from the plant into grazing animals. One such countermeasure is the application of potassium to the soil. However, little is known of any side-effects such an application may have on the ecosystem, the longevity of the application and the effectiveness in a range of soil types. An application of potash (KCl) was made to four organic upland soils in Cumbria. England at two application rates of 100 and 200 kg K ha-1 in June 1997 and at a single site in June 1998. Following application. a range of parameters within the ecosystem were recorded, through the collection of monthly samples of sail, vegetation and water samples over a period of fifteen months. The results indicate that the application was effective for at least one year following application, that a lag phase existed between potash application and any effect within each ecosystem and that the duration of this phase was site specific. The results also showed that the countermeasure was effective at all sites and there was little apparent difference between the two application rates. The parameters measured which included soil pH, plant biomass, changes in Cu, K, Mg, Mn and Ca concentrations within the soil and vegetation indicated only a relatively small effect of the application on the ecosystem as a whole. The application can be considered as a viable option for reducing the transfer of 137Cs from soil to plant. The study also shows that the effectiveness of the application is dependent on the measurement used. i.e. concentration ratios, Tag values or a total flux approach. It is argued that the flux approach is the most appropriate basis for comparing the effectiveness of potash as a countermeasure between several sites.

Thesis (M. Phil.)--University of Hong Kong, 2010. / Includes bibliographical references (leaves 139-[147]). Also available in print.

Thesis (M. Phil.)--University of Hong Kong, 2010. / Includes bibliographical references (leaves 139-[147]). Also available online.

Thesis (Ph. D.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on September 4, 2007) Vita. Includes bibliographical references.

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 52-54). Also available on the World Wide Web.

The human health effects of acute exposure to high levels of ionizing radiation are well understood; however, when these irradiations occur at low levels, there is controversy as to their potential health threat (BEIR V, 1990). For individuals living in areas where the level of naturally occurring background radiation is relatively high, the issue of additional exposure to anthropogenically derived sources of ionizing radiation may be of some concern. This study investigates the presence of radionuclides in surface soils near a United States Environmental Protection Agency (EPA) Superfund site near Pocatello, Idaho, where two phosphorus production facilities have operated for more than fifty years. It is hypothesized that airborne particulates from these facilities are migrating into a residential community, and are accumulating in the uppermost soil layers. Soil samples were collected from seven sites located between 1.3 and 6.7 km along a transect aligned with the prevailing downwind direction. The transect origin lies at the northern boundary of the Superfund site, and the sites were selected for their ease of public access. Samples were collected at four different 2.5 cm depths (10 cm total) for each site, and these samples were analyzed for their gamma emissions. Statistical evaluations of the sample data yielded results of no significant difference in nuclide concentrations between soil layers, or between sample sites (��=0.05). This investigation corroborates the EPA discovery that nuclide concentrations in surface soils decrease rapidly beyond 1 km from the site boundary. This study extends the available information regarding the presence of radionuclides in off-site surface soils by approximately 4 km in the prevailing downwind direction. Additionally, these data appear to contradict the EPA's conclusion that no residential exposure is occurring via a surface soil pathway. This investigation finds that surface soil exposures, at locations such as public parks and schools, may be occurring from radionuclide concentrations that are as high as 4 times that of published background radiation levels. / Graduation date: 2002

The Hanford nuclear reservation in Washington state was initially created during World War II for the production of plutonium to be used in atomic bombs. A perceived need for a large increase in the number of nuclear weapons spurred expansions in production facilities at Hanford through the 1960's, and production was continued through the mid 1980's. The production process included irradiation of uranium fuel in reactors followed by chemical separation of the plutonium from the other fuel constituents, and finally transformation of plutonium nitrate to plutonium metal. The various steps in the process produced large amounts of radioactive as well as chemical hazardous waste. Some of this waste was released to the environment either through deliberate disposal methods or by leaks in transfer and storage systems. As a result, the soil at many areas of Hanford is contaminated to a point at which it would be unsafe for human contact for more than a short period of time. The current focus of efforts at Hanford is cleanup of the environment as well as decommissioning of the facilities. As part of the cleanup process, future land use must be determined which will then affect the scale of the remediation effort. The proposed land use will determine the residual contamination which will be left after all remediation is complete and access is allowed to the site. This document details the process for determining the residual contamination levels associated with various land use options. Some possible land use options are explained in the form of exposure scenarios. These scenarios give data in the form of exposure factors which describe the possible exposure level of an individual to contaminated media. Once the exposure factors are determined, they can be used in the equations outlined in the Hanford Site Risk Assessment Methodology to calculate preliminary remediation goals. These goals are presented as contaminant concentrations in environmental media which are the maximum allowable in order to meet regulatory limits. The limits are expressed either as a risk for carcinogens, or as a hazard quotient for non-carcinogens. / Graduation date: 1997