baseline survey of radionuclides in animal...
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BASELINE SURVEY OF RADIONUCLIDES IN ANIMAL TISSUES AT THE PROPOSED PINON RIDGE MILLSITE
By
F. Ward Whicker, Professor Emeritus Department of Environmental & Radiological Health Sciences
Colorado State University Fort Collins, CO 80523
August 27, 2008
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TABLE OF CONTENTS
Page Executive Summary 3 Introduction 5 Sampling and Sample Preparation 6 Radiochemical Analyses 7 Results and Discussion 8 References Cited 10 Tables 12 Table 1. List of tissues and analytes requested for analysis. 12 Table 2. Summary of tissue analysis results for natural uranium. 13 Table 3. Summary of tissue analysis results for 230Th. 14 Table 4. Summary of tissue analysis results for 226Ra. 14 Table 5. Summary of tissue analysis results for 210Po. 15 Table 6. Summary of tissue analysis results for 210Pb. 16 Figures 17 Fig. 1. Big sagebrush-dominated habitat within the mill site property. 17 Fig. 2. Rocky habitat at the big sagebrush-piñon/juniper interface. 17
Fig. 3. Havahart live trap near multi-entrance burrow system ---- 18 Fig. 4. Sherman live trap in erosion gully habitat. 18 Fig. 5. Victor snap trap near burrow entrance ---- 19
Fig. 6. Victor snap traps at multi-entrance burrow system ---- 19 Fig. 7. Cottontail rabbit photographed in erosion gully on site property. 20 Fig. 8. Levels of natural uranium measured in animal tissues. 20 Fig. 9. Levels of 230Th measured in animal tissues. 21 Fig. 10. Levels of 226Ra measured in animal tissues. 21 Fig. 11. Levels of 210Po measured in animal tissues. 22 Fig. 12. Levels of 210Pb measured in animal tissues. 22 Fig. 13. Comparison of 210Pb concentrations among rabbit tissues. 23
Appendices Appendix I. Geographic coordinates and map for rabbit collection sites 24 Appendix II. Basic chain of custody, QA/QC data and raw data (on CD) 26
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Executive Summary A baseline survey of naturally-occurring radionuclides in animals was performed in May 2008 to support the application by Energy Fuels Resources for a new uranium mill near Naturita, Colorado. Such a survey is required by State and Federal regulations as part of the permitting process, prior to the start of operations. The survey was designed in a manner that would allow comparison to similar measurements during and after any future mill operations. Such comparisons would facilitate an assessment of any radiological contamination of animals resulting from mill operations. Because uranium is radioactive, its decay leads to the formation of some 17 decay products that are also radioactive (Eisenbud and Gesell, 1997). A few of these are sufficiently abundant and long-lived that they have potential biological significance. Because of the ubiquitous presence of uranium in soil and rocks, some of these radionuclides can be measured in biological tissues anywhere on earth, even in the complete absence of uranium mining or milling activities. The potential Piñon Ridge uranium mill site is a natural landscape historically grazed by cattle and various wildlife species. The predominant vegetation is sagebrush and grass in the basin area, and piñon-juniper woodland along the southern boundary on the northeast-facing slope of Monogram Mesa. The dominant resident animals on the site include jack and cottontail rabbits, smaller mammals such as rodents, predators such as coyotes and foxes, and various reptilian and insect species. Mule deer, elk, and various bird species visit the site on a seasonal basis. Cattle are grazed in the area during winter months. My original intention was to sample mule deer, cottontail rabbits, smaller mammals, and cattle that had grazed the site the previous winter. The taking of wildlife required a scientific collection permit, which was approved by the Colorado Division of Wildlife, except for mule deer. The trapping effort for smaller mammals was unsuccessful, yielding only a single kangaroo rat. However, three cottontail rabbits, three jack rabbits, and tissues from three cows were obtained for radionuclide analysis.
The specific tissues obtained for analysis were lung, liver, muscle and bone. These tissues were carefully dissected, cleaned, bagged, and frozen. They were submitted to Paragon Analytics of Fort Collins, CO for analysis of uranium, 230Th, 226Ra, 210Po, and 210Pb. Some 37 different tissue samples were submitted and a total of 106 radionuclide-specific results were obtained and reported here. Wet (fresh) and dry weights of each sample were recorded, so that results can be expressed on either basis, but the wet weight basis was used for this report. Results reported here also include laboratory uncertainties and indication as to whether or not individual analyses were above the minimum detectable concentrations. Detailed information on chain of custody, QA/QC data and raw data were also provided by Paragon Analytics. These data are included in this report on a CD (see Appendix II).
In the case of the uranium measurements, of the 22 samples analyzed, only 12
exceeded the reporting limit. The other values are classified as “U”, or undetected. It is clear that the uranium contents of bone exceed those of muscle tissue, with 7 of the 12 samples containing detectable levels being bone. The error bars, representing variations
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among individual animals as well as laboratory uncertainties, were relatively large, with coefficients of variation (standard deviation/mean value) ranging from 0.16 to 0.62.
All sample results from the 230Th analyses were below the minimum detectable
concentrations. This is not surprising because thorium occurs in the environment in chemical forms that are extremely insoluble, and as a result its transport through food chains is very low or negligible. Thorium isotopes are not taken up to any significant degree by plants, and when it is ingested by animals, often in the form of dust particles, the absorption fraction is very low, typically < 10-4.
The results for 226Ra analyses in bone samples were much more informative and
useful than for the other radionuclides. All bone samples contained 226Ra at sub-pCi/g levels when expressed on a wet mass basis, but well above the minimum detectable concentrations, and considerably higher than measurements for human bone summarized by Eisenbud and Gesell (1997). The coefficients of variation (CV) representing differences among individual animals and laboratory uncertainties were relatively small for the jack rabbits (0.15) and cows (0.14), but higher for the cottontails (0.50). The data indicate that rabbit bone was about three-fold higher in 226Ra than the cow bone samples.
Measurements of 210Po in animal tissues showed that 19 of the 27 sample analyses
were below the minimum analytical detection limits, and those that exceeded the detection limits were very low (< 1 pCi/g wet tissue). Although the data reflect very low and variable levels of 210Po in tissues, there was a tendency for the more detectable levels to occur in cow samples, particularly the liver and lung samples. The liver and kidney are known as main repositories of the small amounts of 210Po that might be found in the body.
Fifteen of 28 samples contained 210Pb at levels below the minimum detectable
concentration, while 13 were above. There were no apparent differences between species, but the differences between tissues were obvious. The pattern was for bone to contain the highest concentrations, lung to contain the lowest levels, while liver tissues contained intermediate amounts. Lead is well-known to be found primarily in bone, with intermediate levels in liver and kidney. Variability among individuals of the same species was relatively high, with CV values ranging from 0.34 to 1.76.
I am not aware of specific studies, published in the open literature, that have
reported levels of naturally-occurring radionuclides in animal tissues in the western U.S. Thus, this study did not have the benefit of previous, closely-related work to guide it. However, the findings here will be very beneficial for any future, follow-up work. For example, these findings can be used to make the argument that it would not likely be instructive to perform 230Th or 210Po analyses in biological samples. Monitoring for 210Pb in animals at the proposed mill site would be more instructive than for 230Th or 210Po, although for biological monitoring purposes, uranium and especially 226Ra should take precedence over the other radionuclides measured in this study.
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Based on the abundance of rabbits on the proposed mill site, the fact that they are resident yearlong, and the fact that 226Ra levels are readily measureable in bone with relatively small variability, I believe that this species and radionuclide should be targeted as probably the most sensitive and useful indicator of any future changes in radiobiological conditions. The radionuclide concentrations in animal tissues reflect intakes through ingestion and inhalation over the lifetime of the individuals sampled, not necessarily over the recent days, weeks or months immediately prior to collection. While tissues of cattle, mule deer and elk could be measured for relevant radionuclides, it is my opinion that these species would have very limited value because they do not reside permanently on the site. It would not be possible to know the location and diet history of any specific individual deer and elk taken, so one would never know how to compare or interpret the findings of such measurements. Introduction
State and federal regulations applicable to the construction of new uranium mills outline the need to develop baseline radiological surveys prior to construction and startup. Surveys required include biota, in addition to air, water and soil in the potentially impacted geographic area. Such media should be sampled in a manner that adequately characterizes the environs of the mill and that would allow robust comparisons with samples taken during and after plant operations. Radionuclides of interest include uranium and selected decay products. This report focuses on a survey of naturally occurring radionuclides in animals taken on the proposed site of the Piñon Ridge uranium mill, to be developed and operated by Energy Fuels Resources. The land parcel where the proposed mill would be located is private property that historically has been grazed by cattle during the winter months. Mule deer, elk, and birds are transitory depending on the various seasons. Based on recent surveys, local wildlife residents tend to be the smaller mammals i.e. rabbits, coyotes, fox, ground squirrels, etc. The radionuclides of interest include natural uranium and the specific progeny, 230Th, 226Ra, 210Po and 210Pb. The general goal of this work was to develop a characterization of the background, pre-operational levels of naturally-occuring radionuclides in selected animal tissues that will be included in an environmental report (ER) to the Colorado Department of Public Health and Environment (CDPHE). This effort has involved:
• A preliminary meeting with the CDPHE, Energy Fuels Resources, Kleinfelder, and other parties to define the scope of effort and specifically the sampling and analysis plan,
• Refinement of this initial proposed plan, based on the preliminary meeting, • Conduct of the actual sampling of animals in the relevant geographic area, • Dissection and preliminary preparation of the selected tissues at Colorado State
University (CSU), • Submission of tissues to Paragon Analytics, Inc. of Fort Collins, CO for assay of
selected radionuclides,
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• Analysis and interpretation of the data generated by Paragon Analytics, and • Preparation of a report on radionuclides in biota to be included in the ER.
Sampling and Sample Preparation Originally, I proposed to sample mule deer, range cattle, cottontail rabbits and deer mice in locations as near as practical to the site of the proposed mill. At least three individual animals of each species were to be taken. The taking of mule deer and other wildlife requires a scientific collection license from the Colorado Division of Wildlife (CDOW). I applied for the collection license in early April, 2008, and received it May 19, 2008. However, approval to take mule deer was not given. The CDOW wanted us to first attempt to collect road-killed animals, and failing that, to take animals during the normal big-game hunting season with a regularly-purchased license. The scientific collection license received (No. 08TR2013), did include jack and cottontail rabbits and other small mammals. The cattle tissues were provided by a local rancher. These animals were allowed to graze the proposed mill site property the previous winter. The main collection effort occurred during the week of May 19, 2008, and it was completely restricted to the proposed mill site property (see Appendix I for geo-coordinates of sampling locations and a map). The trapping effort for ground squirrels and mice was not successful. Five different habitats were trapped using various trap designs (Figs. 1-6). Baits included peanut butter mixed with rolled oats, and small apple pieces. Focus was placed on areas that exhibited burrow systems, often with numerous entrances. Only those burrow entrances that appeared active, based on tracks and the lack of spider webs, were used for trap sets. Over a three day period with 36 individual trap sets, we caught only one animal, a kangaroo rat. This was quite disappointing. The reasons for the poor success are not clear. It could have been the lack of time for the animals to adjust to the presence of the traps, a lack of animals (we did not actually see any squirrels or mice, despite being in the field at nearly all hours), the bait, or other factors. The carcass of the kangaroo rat was processed and analyzed, but results from this single animal have very limited value.
The original plan was to collect only one rabbit species, but given the poor success in collecting smaller mammals, I decided to collect both jack and cottontail rabbits (Fig. 7). These species appear to represent the dominant herbivorous mammals on the site, and both could be hunted and consumed by people. These species, being resident to the site yearlong, provide a much better representation of the local radiological conditions than would large game such as deer or elk that mainly use the site during seasonal migration periods. Another advantage of rabbits as indicators is that they are large enough to provide ample tissue for reasonably accurate radionuclide analysis. Smaller mammals would have required pooling of tissues from several individuals in order to have sufficient tissue for a reliable analysis.
Both rabbit species were plentiful and relatively easy to take by 22-caliber rifle in
the early morning and late evening hours. The cottontails were most numerous along the southern boundary of the site near the piñon-juniper woodland, while the jack rabbits
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appeared more numerous toward the northern and central portions of the site, which are dominated by sagebrush and grass. Geographic coordinates were recorded for each kill location (see Appendix I). We killed three individuals of each species in representative habitats across the site and did preliminary tissue dissections in the field. Liver, lung, hind leg and shoulder were dissected in the field, doubly bagged, labeled, and placed on ice. Care was taken to keep the samples clean. This involved the use of clean plastic sheeting on which to work, the use of disposable gloves, rinsing of tissues with water, and cleaning of tools between each tissue dissection. Samples were placed in a freezer the evening after collection, and kept in a frozen state until they were more carefully prepared in the laboratory.
Tissue samples from three cows were taken through arrangements between
Energy Fuels and a local rancher. The tissues included liver, lung, muscle, and bone (scapula). These samples were located in a freezer at Energy Fuels headquarters in Nucla, CO, and were transported in a frozen state to Fort Collins along with the frozen rabbit tissues on May 23, 2008. The cattle were slaughtered April 7, 12 and 13, 2008. They were reportedly grazed on the proposed mill site property the previous winter/early spring. More precise rabbit and cattle tissue dissections were completed in the laboratory. Lung and liver samples were thoroughly isolated from other tissues, rinsed with clean water, patted dry with paper towel, re-bagged, and re-labeled. Muscle tissues were carefully separated from bone, fat or other tissue, rinsed with clean water, patted dry with paper towel, re-bagged, and re-labeled. Bone samples (scapula) were dissected from flesh and scrapped free of muscle or other tissue. In the case of rabbit bone, the entire scapula was bagged for analysis, while a roughly 20 g sample of cow scapula was sawed out of the thinner section for analysis. Where possible, extra tissue not needed for analysis was bagged, labeled and placed in a freezer. These samples, mainly cattle bone, liver, lung and muscle, and rabbit muscle and bone (femur & humerus), will serve as an archive in case there is a need for additional analyses at a later date. After consultation with Paragon Analytics, I decided for the rabbit tissues, to add leg bone to the scapula samples (which were quite small) to provide a greater mass, which in turn would improve the radionuclide detection and measurement capability of the laboratory procedures. This was not necessary for the cattle bone samples. Radiochemical Analysis All tissue samples were delivered to Paragon Analytics on May 27, 2008. The specific radionuclide analyses requested for each tissue sample are listed in Table 1. Soft tissue samples were weighed wet (fresh), dried at 90 deg. Celsius to a constant mass, then reweighed. This allowed the expression of concentrations on a dry or wet mass basis. Sample results shown in this report are expressed as pCi/g wet (fresh) tissue because this is the typical practice in monitoring studies of this kind. However, dry masses tend to be more consistent than wet masses due to often differing degrees of moisture loss in the latter case. Therefore, the wet/dry tissue mass ratios are provided in the basic data tables to allow results to be expressed either way. Sample masses used for analysis varied
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among tissue types and specific analyses. Approximately 5 g fresh tissue were used for uranium, 230Th and 210Pb in soft tissues (liver, lung and muscle). About 0.5 g fresh tissue was used for 210Po in soft tissues. Aliquots in the range of 2-5 grams were used for 226Ra, 230Th, and uranium in bone. Approximately 0.5 -1 g aliquots were used for 210Pb in bone. These sample masses were expected to provide a reasonable balance between the cost of digesting the samples, the ability to chemically isolate the basic elements from interfering substances, and having sufficient analyte to obtain reasonable measurement accuracy. Individual sample aliquot masses used in each case are provided in the basic data tables. Similar aliquot masses should be used in subsequent studies to provide data that can be credibly compared to the data set prepared in this report.
All samples required chemical digestion in strong acids to obtain the samples in solution form. The different elements were then isolated chemically, prior to further processing. Uranium was measured using ICP mass spectrometry. This provided the total uranium content in μg, and was not isotope-specific. However, the isotopes of natural uranium include 238U, 235U and 234U, and the normal abundances of these are well-known. This allowed the calculation of the natural uranium in activity units (pCi/g) representing the sum of activities of the three uranium isotopes. It can be shown from basic physical principles that 1 μg Unat/kg tissue equals 6.83 x 10-4 pCi/g. After chemical isolation and plating on a disk, 230Th and 210Po were measured by alpha spectrometry. Liquid scintillation counting was used to measure 210Pb. 226Ra was measured by emanation of 222Rn, allowing in-growth of the progeny, and counting of the progeny using gamma spectrometry.
Laboratory results, which were received June 27, 2008, provided minimum
detection limits and total propagated uncertainties in addition to the basic data on radionuclide concentrations in tissues. The detection limits are affected primarily by the sample masses analyzed, the concentration of the analyte in the samples, and counting times for the radionuclides analyzed by radiation event counting (alpha and gamma spectrometry and liquid scintillation). Total propagated uncertainties include counting error, determined by count rate and count time, as well as other laboratory error such as weighing, chemical recovery, accuracy of standards, etc. Detailed information on chain of custody, QA/QC data and raw data were also provided by Paragon Analytics. These data are included in this report on a CD (see Appendix II). Results and Discussion Uranium, in general, is relatively “low” in its tendency to be transported in food chains (Whicker and Schultz, 1982). The fraction of uranium ingested that is assimilated after ingestion is generally < 10-4, and approximately 85% of that which accumulates in the body is expected to be found in bone (ICRP Committee II, 1960). Basic data for natural uranium in animal tissues from the present study are provided in Table 2, and mean values in μg/kg with error bars are illustrated in Fig. 8. Of the 21 samples listed in Table 2, only 12 exceeded the reporting limit. The other values are classified as “U”, or undetected. The reporting limits, which are sample-specific and represent the ability of the ICP mass spectrometry analysis procedure to detect and measure uranium, were used
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to represent the upper-bound of the actual uranium present in those samples flagged with a “U”. The actual uranium contents of these samples are very likely to be lower than the reporting limits. It is clear that the uranium contents of bone exceed those of muscle and liver tissue, with 7 of the 12 samples containing detectable levels being bone. The error bars (Fig. 8) are relatively large, with coefficients of variation (standard deviation/mean value) ranging from 0.16 to 0.62. Such large variations are not unexpected when the levels are very low and near or below the limit of detection. Any true differences between species are likely to be relatively low, and certainly not demonstrable in this case, given the low uranium levels, the small sample size in terms of animal numbers (3), and the relatively high variation among individual animals. The results of the 230Th analyses are shown in Table 3 and Fig. 9. All samples were below the minimum detectable concentrations. This is not surprising because thorium occurs in the environment in chemical forms that are extremely insoluble, and as a result, its transport through food chains is very low or negligible (Whicker and Schultz, 1982). Thorium isotopes are not taken up to any significant degree by plants, and when it is ingested by animals, often in the form of dust particles, the absorption fraction is very low, typically < 10-4 (ICRP Committee II, 1960). In the future, and with respect to monitoring radionuclides around the Piñon Ridge uranium mill, these findings can be used to bolster the argument that it would not likely be instructive to perform 230Th analyses in biological samples. Radium-226 is a well-known “bone-seeking” radionuclide that accumulates in calcareous tissues because of its chemical similarity to calcium (Whicker and Schultz, 1982). Its movement through food chains is “moderate”, and some 99 % of the total body content is expected to be found in bone (ICRP Committee II, 1960). I fully expected that 226Ra would be present in bone tissues because it tends to be moderately soluble in the environment. It is taken up by vegetation from the soil and it is assimilated fairly efficiently from the gut when ingested by animals (NCRP, 1999). Its retention in bone is high, thus it accumulates over time under conditions of chronic intake. Levels measured in human bone from a few mostly urban locations have ranged from about 0.001 to 0.01 pCi/g (Eisenbud and Gesell, 1997).
In the present study, results for 226Ra analyses in bone samples were much more informative and useful than data for the other radionuclides (Table 4 and Fig. 10). All bone samples contained 226Ra at sub-pCi/g levels when expressed on a wet mass basis, but well above the minimum detectable concentrations, and considerably higher than measurements for human bone summarized by Eisenbud and Gesell (1997). The level in the kangaroo rat carcass was not detectable because of the small sample size and the fact that muscle tissue was present, causing a dilution in the concentration. The coefficients of variation (CV) were relatively small for the jack rabbits (0.15) and cows (0.14), but higher for the cottontails (0.50). The data indicate that the rabbit bone was about three-fold higher in 226Ra than the cow bone samples. With a sample size of only three, it would not be particularly meaningful to try and draw any inference to the population of rabbits vs. cows. The specific dietary history of the cows is not known to me, other than the statement that the cattle were grazed on the site property for a period of time prior to
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slaughter. Appendix I provides locations of rabbit kills and external gamma radiation levels at those and other locations along access roads within the site. There was no correlation between gamma radiation levels at collection sites and 226Ra concentrations in rabbit bone. This was not surprising because of the variable home ranges of the animals and other factors that affect tissue concentrations. Based on the abundance of rabbits on the proposed mill site, and the fact that 226Ra levels are readily measureable in bone with relatively small variability, I believe that this animal and radionuclide should be targeted as perhaps the most sensitive and useful indicator of any future changes in radiobiological conditions. Concentrations of 210Po measured in animal tissues are summarized in Table 5 and illustrated in Fig. 11. Nineteen of the 27 sample analyses were below the minimum analytical detection limits, and those that exceeded the detection limits were very low in 210Po (< 1 pCi/g wet tissue). Although the data reflect very low and variable levels of 210Po in tissues, there was a tendency for the more detectable levels to occur in cow samples, particularly the liver and lung samples. The liver and kidney are known as main repositories of the small amounts of 210Po that might be found in the body (ICRP Committee II, 1960). The very low levels of 210Po, and the substantial degree of variability between individual animals (CV values ranged from 0.37 to 3.01, with most exceeding 1.0), makes comparisons somewhat meaningless. Overall, my opinion is that future sampling and analysis considerations for monitoring the Piñon Ridge uranium mill should raise doubts about the utility of performing tissue analyses for 210Po. Results for 210Pb in animal tissues are provided in Table 6 and illustrated in Fig. 12. Fifteen of 28 samples contained 210Pb at levels below the minimum detectable concentration, while 13 were above. There were no apparent differences between species, but the differences between tissues were obvious (Fig. 12). The pattern was for bone to contain the highest concentration, lung to contain the lowest level, and liver was intermediate (Fig. 13). Lead is well-known to be found primarily in bone, with intermediate levels in liver and kidney (ICRP Committee II, 1960). Variability among individuals of the same species was relatively high, with CV values ranging from 0.34 to 1.76. It appears that monitoring for 210Pb in animals at the proposed mill site would be more instructive than for 210Po, although for biological monitoring purposes, uranium and especially 226Ra should take precedence over the other radionuclides measured in this study. References Cited Eisenbud, M. and T. Gesell. 1997. Environmental radioactivity from natural, industrial and military sources, Fourth edition. Academic Press, New York. ICRP Committee II. 1960. Report of Committee II on permissible dose for internal radiation (1959). Health Physics 3: 217-226. NCRP. 1999. Recommended screening limits for contaminated surface soil and review
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of factors relevant to site-specific studies. NCRP Report No. 129. National Council on Radiation Protection and Measurements. Bethesda, MD 20814-3095.
Whicker, F.W. and V. Schultz. 1982. Radioecology: Nuclear energy and the environment, Vol. I. CRC Press, Inc. Boca Raton, FL.
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Tables Table 1. List of tissues and analytes requested for analysis. Analytes requested
Sample # species tissue
Collection Date U-nat Th-230 Ra-226 Po-210 Pb-210
CSUPR-1 CTAIL liver 5/20/2008 X X X CSUPR-2 CTAIL lung 5/20/2008 X X CSUPR-3 CTAIL muscle 5/20/2008 X X CSUPR-4 CTAIL bone 5/20/2008 X X X X CSUPR-5 CTAIL liver 5/20/2008 X X X CSUPR-6 CTAIL lung 5/20/2008 X X CSUPR-7 CTAIL muscle 5/20/2008 X X CSUPR-8 CTAIL bone 5/20/2008 X X X X CSUPR-9 CTAIL liver 5/20/2008 X X X CSUPR-10 CTAIL lung 5/20/2008 X X CSUPR-11 CTAIL muscle 5/20/2008 X X CSUPR-12 CTAIL bone 5/20/2008 X X X X CSUPR-13 JACK liver 5/19/2008 X X X CSUPR-14 JACK lung 5/19/2008 X X CSUPR-15 JACK muscle 5/19/2008 X X CSUPR-16 JACK bone 5/19/2008 X X X X CSUPR-17 JACK liver 5/19/2008 X X X CSUPR-18 JACK lung 5/19/2008 X X CSUPR-19 JACK muscle 5/19/2008 X X CSUPR-20 JACK bone 5/19/2008 X X X X CSUPR-21 JACK liver 5/19/2008 X X X CSUPR-22 JACK lung 5/19/2008 X X CSUPR-23 JACK muscle 5/19/2008 X X CSUPR-24 JACK bone 5/19/2008 X X X X CSUPR-25 K-RAT carcass 5/20/2008 X X X X CSUPR-26 COW liver 4/7/2008 X X X X CSUPR-27 COW lung 4/7/2008 X X CSUPR-28 COW muscle 4/7/2008 X X CSUPR-29 COW bone 4/7/2008 X X X X CSUPR-30 COW liver 4/12/2008 X X X X CSUPR-31 COW lung 4/12/2008 X X CSUPR-32 COW muscle 4/12/2008 X X CSUPR-33 COW bone 4/12/2008 X X X X CSUPR-34 COW liver 4/13/2008 X X X X CSUPR-35 COW lung 4/13/2008 X X CSUPR-36 COW muscle 4/13/2008 X X CSUPR-37 COW bone 4/13/2008 X X X X
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Table 2. Summary of tissue analysis results for natural uranium. Results given in wet (fresh) tissue mass basis. Multiply by column 5 to get results on dry mass basis. Sample ID
Species
Tissue
Wet aliquot mass (g)
Ratio: wet/drymass
μg/kgwet
pCi/g wet
Flaga
Reportinglimitb
CSUPR-3 CTail-1 muscle 5.06 4.29 0.47 0.0003 U 0.47 CSUPR-4 bone 1.37 1.64 7.4 0.005 6.2 CSUPR-7 CTail-2 muscle 5.09 4.02 1.3 0.0009 0.37 CSUPR-8 bone 1.44 1.67 16 0.011 5.9 CSUPR-11 CTail-3 muscle 5.08 4.22 0.65 0.0004 0.37 CSUPR-12 bone 1.31 1.93 6.5 0.004 U 6.5 CSUPR-15 Jack-1 muscle 5.04 4.18 0.31 0.0002 0.3 CSUPR-16 bone 3.06 1.69 4 0.003 3.3 CSUPR-19 Jack-2 muscle 5.11 4.01 0.23 0.0002 U 0.23 CSUPR-20 bone 2.99 1.60 3.6 0.002 U 3.6 CSUPR-23 Jack-3 muscle 5.32 4.23 0.23 0.0002 U 0.23 CSUPR-24 bone 3.06 1.51 6.1 0.004 2.6 CSUPR-25 K-rat carcass 2.00 4.11 1.2 0.001 U 1.2 CSUPR-28 Cow-7 muscle 5.23 8.19 0.38 0.0003 U 0.38 CSUPR-29 bone 1.98 1.21 6.9 0.005 5.4 CSUPR-26 liver 12.5 4.60 0.63 0.0004 0.42 CSUPR-32 Cow-45 muscle 5.17 4.91 0.5 0.0005 U 0.5 CSUPR-33 bone 2.93 1.32 4.5 0.003 3.7 CSUPR-30 liver 9.43 3.79 0.50 0.0003 U 0.50 CSUPR-36 Cow-524 muscle 5.16 4.91 0.39 0.0003 U 0.39 CSUPR-37 bone 2.25 1.23 6 0.004 4.8 CSUPR-34 liver 3.05 4.84 0.97 0.0007 0.72 ______________________________________________________________________ aFlag: U = Sample analyzed but not detected. bValues in column = Reporting limits for specific samples based on uranium mass.
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Table 3. Summary of tissue analysis results for 230Th. Results given in wet (fresh) tissue mass basis. Multiply by column 5 to get results on dry mass basis. Sample ID
Species
Tissue
Wet aliquot mass (g)
Ratio: wet/dry
mass
pCi/g wet
TPUa +/-
Flagb
CSUPR-4 CTail-1 bone 2.26 1.64 0 0.018 U CSUPR-1 liver 5.03 3.79 0.0048 0.0093 U CSUPR-8 CTail-2 bone 2.36 1.67 -0.014 0.016 U CSUPR-5 liver 5.00 3.83 0.0015 0.0083 U CSUPR-12 CTail-3 bone 2.15 1.93 0.003 0.02 U CSUPR-9 liver 3.70 4.23 -0.0069 0.0091 U CSUPR-16 Jack-1 bone 5.04 1.69 0.004 0.016 U CSUPR-13 liver 5.03 3.81 -0.0054 0.0072 U CSUPR-20 Jack-2 bone 4.97 1.60 0.002 0.018 U CSUPR-17 liver 5.08 3.89 -0.0006 0.007 U CSUPR-24 Jack-3 bone 5.17 1.51 0.015 0.019 U CSUPR-21 liver 5.14 3.91 -0.0004 0.0073 U CSUPR-25 K-rat carcass 2.00 4.11 0 0.017 U CSUPR-29 Cow-7 bone 3.29 1.21 0.038 0.032 U CSUPR-26 liver 5.18 4.60 0.0029 0.0077 U CSUPR-33 Cow-45 bone 4.87 1.32 0.006 0.017 U CSUPR-30 liver 5.02 3.79 -0.002 0.0089 U CSUPR-37 Cow-524 bone 3.73 1.23 -0.003 0.02 U CSUPR-34 liver 5.14 4.84 -0.0057 0.0075 U aTPU = Total propagated uncertainty (2 standard deviations). bU = Result is less than minimum detectable concentration. Table 4. Summary of tissue analysis results for 226Ra. Results given in wet (fresh) tissue mass basis. Multiply by column 5 to get results on dry mass basis. Sample ID
Species
Tissue
Wet aliquot mass (g)
Ratio: wet/dry
mass
pCi/gwet
TPUa +/-
Flagb CSUPR-4 CTail-1 bone 4.03 1.64 0.222 0.052 LT CSUPR-8 CTail-2 bone 4.22 1.67 0.63 0.13 LT CSUPR-12 CTail-3 bone 3.84 1.93 0.69 0.14 LT CSUPR-16 Jack-1 bone 5.04 1.69 0.81 0.16 LT CSUPR-20 Jack-2 bone 4.97 1.60 0.67 0.13 LT CSUPR-24 Jack-3 bone 5.17 1.51 0.6 0.12 LT CSUPR-25 K-rat carcass 2.00 4.11 0.029 0.045 U CSUPR-29 Cow-7 bone 3.29 1.21 0.332 0.076 LT CSUPR-33 Cow-45 bone 4.87 1.32 0.182 0.047 LT CSUPR-37 Cow-524 bone 3.73 1.23 0.095 0.034 LT aTPU = Total propagated uncertainty (2 standard deviations). bFlags: LT = Result greater than minimum detectable concentration. U = Result is less than minimum detectable concentration.
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Table 5. Summary of tissue analysis results for 210Po. Results given in wet (fresh) tissue mass basis. Multiply by column 5 to get results on dry mass basis. Sample ID
Species
Tissue
Wet aliquot mass (g)
Ratio: wet/dry
mass
pCi/g wet
TPUa +/-
Flagb CSUPR-1 CTail-1 liver 0.56 3.79 0.027 0.034 LT CSUPR-2 lung 0.46 4.47 0.016 0.072 U CSUPR-3 muscle 0.63 4.29 -0.022 0.046 U CSUPR-5 CTail-2 liver 0.50 3.83 0.021 0.035 U CSUPR-6 lung 0.37 4.99 0.051 0.08 U CSUPR-7 muscle 0.54 4.02 -0.024 0.03 U CSUPR-9 CTail-3 liver 0.31 4.23 -0.055 0.066 U CSUPR-10 lung 0.55 5.13 0.026 0.032 U CSUPR-11 muscle 0.54 4.22 0.025 0.03 U CSUPR-13 Jack-1 liver 0.54 3.81 0.044 0.051 U CSUPR-14 lung 0.51 4.51 0 0.035 U CSUPR-15 muscle 0.67 4.18 0.025 0.024 LT CSUPR-17 Jack-2 liver 0.56 3.89 0.029 0.054 U CSUPR-18 lung 0.57 4.36 -0.006 0.029 U CSUPR-19 muscle 0.85 4.01 -0.005 0.038 U CSUPR-21 Jack-3 liver 0.55 3.91 0.062 0.059 U CSUPR-22 lung 0.62 4.84 0.019 0.032 U CSUPR-23 muscle 0.89 4.23 0 0.019 U CSUPR-26 Cow-7 liver 0.71 4.60 0.74 0.017 LT CSUPR-27 lung 0.60 4.42 0.29 0.1 LT CSUPR-28 muscle 0.52 8.19 0.094 0.072 LT CSUPR-30 Cow-45 liver 0.60 3.79 0.141 0.066 LT CSUPR-31 lung 0.63 5.10 0.166 0.081 LT CSUPR-32 muscle 0.60 4.91 0.027 0.033 LT CSUPR-34 Cow-524 liver 0.56 4.84 0.025 0.06 U CSUPR-35 lung 0.60 5.25 0.014 0.033 U CSUPR-36 muscle 0.52 4.91 0.043 0.079 U _____________________________________________________________ aTPU = Total propagated uncertainty (2 standard deviations). bFlags: LT = Result greater than minimum detectable concentration. U = Result is less than minimum detectable concentration.
16
Table 6. Summary of tissue analyses results for 210Pb. Results given in wet (fresh) tissue mass basis. Multiply by column 5 to get results on dry mass basis. Sample ID
Species
Tissue
Wet aliquot mass (g)
Ratio: wet/dry
mass
pCi/gwet
TPUa +/-
Flagb CSUPR-4 CTail-1 bone 0.40 1.64 1.44 0.73 LT CSUPR-1 liver 5.03 3.79 0.172 0.07 LT CSUPR-2 lung 4.14 4.47 0.058 0.072 U CSUPR-8 CTail-2 bone 0.42 1.67 0.53 0.62 U CSUPR-5 liver 5.00 3.83 0.097 0.058 LT CSUPR-6 lung 3.37 4.99 0.023 0.083 U CSUPR-12 CTail-3 bone 0.38 1.93 1.17 0.73 LT CSUPR-9 liver 3.70 4.23 0.102 0.08 U CSUPR-10 lung 5.02 5.13 0.045 0.064 U CSUPR-16 Jack-1 bone 1.07 1.69 0.54 0.29 LT CSUPR-13 liver 5.03 3.81 0.189 0.072 LT CSUPR-14 lung 5.06 4.51 0.013 0.05 U CSUPR-20 Jack-2 bone 0.99 1.60 0.44 0.29 LT CSUPR-17 liver 5.08 3.89 0.058 0.055 U CSUPR-18 lung 5.03 4.36 0.038 0.053 U CSUPR-24 Jack-3 bone 1.15 1.51 1.19 0.4 LT CSUPR-21 liver 5.14 3.91 0.102 0.057 LT CSUPR-22 lung 5.10 4.84 -0.01 0.053 U CSUPR-25 K-rat carcass 2.00 4.11 0.14 0.14 U CSUPR-29 Cow-7 bone 0.66 1.21 1.47 0.61 LT CSUPR-26 liver 5.18 4.60 0.191 0.078 LT CSUPR-27 lung 5.11 4.42 0.011 0.06 U CSUPR-33 Cow-45 bone 0.97 1.32 1.43 0.47 LT CSUPR-30 liver 5.02 3.79 0.097 0.063 LT CSUPR-31 lung 5.03 5.10 0.045 0.058 U CSUPR-37 Cow-524 bone 0.74 1.23 0.44 0.41 U CSUPR-34 liver 5.14 4.84 0.104 0.079 U CSUPR-35 lung 5.09 5.25 0.003 0.059 U ____________________________________________________________ aTPU = Total propagated uncertainty (2 standard deviations). bFlags: LT = Result greater than minimum detectable concentration. U = Result is less than minimum detectable concentration.
17
Figures
Fig. 1. Big sagebrush-dominated habitat within the mill site property.
Fig. 2. Rocky habitat at the big sagebrush-piñon/juniper interface.
18
Fig. 3. Havahart live trap near multi-entrance burrow system in shortgrass- dominated habitat.
Fig. 4. Sherman live trap in erosion gully habitat.
19
Fig. 5. Victor snap trap near burrow entrance at edge of grass-sagebrush gully.
Fig. 6. Victor snap traps at multi-entrance burrow system in grass-dominated habitat.
20
Fig. 7. Cottontail rabbit photographed in erosion gully on site property.
0
2
4
6
8
10
12
14
16
Cot
tont
ails
(bon
e)
Cot
tont
ails
(mus
cle)
Jack
Rab
bits
(bon
e)
Jack
Rab
bits
(mus
cle)
All
Rab
bits
(bon
e)
All
Rab
bits
(mus
cle)
Cow
s (b
one)
Cow
s (m
uscl
e)
Cow
s (li
ver)
Mea
n U
-nat
(± σ
, uG
/kg)
Fig. 8. Levels of natural uranium measured in animal tissues, in units of μg/kg. Error bars represent one standard deviation based on three samples.
21
0.000
0.005
0.010
0.015
0.020
0.025
0.030
0.035
0.040
Cot
tont
ails
(bon
e)
Cot
tont
ails
(liv
er)
Jack
Rab
bits
(bon
e)
Jack
Rab
bits
(liv
er)
All
Rab
bits
(bon
e)
All
Rab
bits
(liv
er)
Cow
s (b
one)
Cow
s (li
ver)
K-R
at (c
arca
ss)
Mea
n Th
-230
(± σ
, pC
i/g)
Fig. 9. Levels of 230Th measured in animal tissues, in units of pCi/g. Error bars represent one standard deviation based on three samples. All results were less than minimum detectable concentrations.
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Cot
tont
ails
(bon
e)
Jack
Rab
bits
(bon
e)
All
Rab
bits
(bon
e)
Cow
s (b
one)
K-R
at(c
arca
ss)
Mea
n R
a-22
6 (±
σ, p
Ci/g
)
Fig. 10. Levels of 226Ra measured in animal tissues, in units of pCi/g. Error bars represent one standard deviation based on three samples.
22
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Cot
tont
ails
(liv
er)
Cot
tont
ails
(lun
g)
Cot
tont
ails
(mus
cle)
Jack
Rab
bits
(liv
er)
Jack
Rab
bits
(lun
g
Jack
Rab
bits
(mus
cle)
All
Rab
bits
(liv
er)
All
Rab
bits
(lun
g)
All
Rab
bits
(mus
cle)
Cow
s (li
ver)
Cow
s (lu
ng)
Cow
s (m
uscl
e)
K-R
at (c
arca
ss)
Mea
n Po
-210
(± σ
, pC
i/g)
Fig. 11. Levels of 210Po measured in animal tissues, in units of pCi/g. Error bars represent one standard deviation based on three samples.
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
Cot
tont
ails
(bon
e)
Cot
tont
ails
(liv
er)
Cot
tont
ails
(lun
g)
Jack
Rab
bits
(bon
e)
Jack
Rab
bits
(liv
er)
Jack
Rab
bits
(lun
g)
All
Rab
bits
(bon
e)
All
Rab
bits
(liv
er)
All
Rab
bits
(lun
g)
Cow
s (b
one)
Cow
s (li
ver)
Cow
s (lu
ng)
K-R
at (c
arca
ss)
Mea
n Pb
-210
(± σ
, pC
i/g)
Fig. 12. Levels of 210Pb measured in animal tissues, in units of pCi/g. Error bars represent one standard deviation based on three samples.
23
Pb-210 in Rabbits by Tissue
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
bone liver lung
Pb-2
10 (p
Ci/g
)Cottontail-1
Cottontail-2
Cottontail-3
Jack Rabbit-1
Jack Rabbit-2
Jack Rabbit-3
Fig. 13. Comparison of 210Pb concentrations among rabbit tissues.
24
Appendix I. Geo-coordinates (in decimal degrees) for animals collected and trap locations on the Piñon Ridge site. Species & trap location
Field I.D. number
Lab control numbers for Species/tissue
Collection or trap location (Lat, DD North)
Collection or trap location (Long, DD West)
PR-CT-1 CSUPR-1 to CSUPR-4 38.24408 108.77359 PR-CT-2 CSUPR-5 to CSUPR-8 38.23894 108.76731
Cottontail rabbit
PR-CT-3 CSUPR-9 to CSUPR-12 38.24131 108.77082 PR-J-1 CSUPR-13 to CSUPR-16 38.25482 108.76395 PR-J-2 CSUPR-17 to CSUPR-20 38.25268 108.76800
Jack rabbit
PR-J-3 CSUPR-21 to CSUPR-24 38.25147
108.76918
Kangaroo rat
PR-K-1 CSUPR- 25 38.24787
108.76397
Trap area PR-1 38.24787
108.76397
Trap area PR-2 38.26097
108.77847
Trap area PR-3 38.25163
108.76857
Trap area PR-4 38.24441
108.76981
Trap area PR-5 38.24047
108.76994
25
Appendix I. Map of trapping locations, rabbit collection locations and access roads on the Piñon Ridge site. External gamma ray exposure rates (in μR/hr), measured with a calibrated NaI detector, are shown along each road and collection location.
26
Appendix II. Basic chain of custody, QA/QC information and raw data (on CD).