Pu-241 in samples of forest soil from Poland

Plutonium isotopes in the ground air layer in southern Poland (2010-2016): Source terms, seasonal variability and correlations with meteorological conditions

In this study, the results of the analysis of Pu-238 and Pu-239 + 240 activity concentrations on aerosol filters collected from 2010 to 2016 in Krakow (Southern Poland) are presented and discussed. For the first time, the temporal variation of Pu-239 + 240 activity concentration in surface air in Poland was studied using Fourier analysis. The analysis clearly showed that the Pu-239 + 240 content in the near-ground air layer is subject to seasonal variations and demonstrates annual periodicity. Pu analyses were performed using alpha spectrometry. The measured values ranged from 1.93∙10^-10 Bq/m³ to 1.31∙10^-8 Bq/m³ with an average of 2.07∙10^-9 Bq/m³ for Pu-239 + 240 and from 9.07∙10^-11 Bq/m³ to 1.27∙10^-9 Bq/m³ with the average 1.52∙10^-10 Bq/m³ for Pu-238. The analysis of the potential sources of plutonium isotopes in the air aerosols samples indicated that only two samples are uniquely characterized by the ratio corresponding to spent nuclear fuel: February 2012 (0.59 ± 0.18) and February 2015 (0.68 ± 0.19). The remaining samples showed mixed origins, with global radioactive fallout appearing to contribute more than spent nuclear fuel. To study the relationship between Pu-239 + 240 and meteorological conditions, Pearson's correlation and circulation pattern analyses were performed. The analyses showed that the Pu-239 + 240 activity concentration depends on air temperature (R = 0.51), the sum of ice and snowfall (R = -0.45), relative humidity (R = -0.54) and mean total cloud cover (R = -0.56). High concentrations of Pu-239 + 240 were positively correlated with air advection from the southern and eastern sectors, whereas low concentrations were observed during dynamic weather conditions with intense circulation from the western sector. In case of Pu-238 no significant correlation was observed.

Distribution of 241Am and Pu isotopes in the Curonian Lagoon and the south-eastern Baltic Sea seawater, suspended particles, sediments and biota

Distribution trends and temporal variations of 241Am and Pu isotopes in the south-eastern Baltic Sea during the study period of 1999-2001 and 2011-2015 were investigated with the aim to study temporal changes of radionuclide levels in seawater, suspended particles and sediment, to estimate 241Am and 239,240Pu levels in marine biota and to assess the radiation doses received by the biota. The activities of 241Am and 239,240Pu were measured by alpha spectrometry after radiochemical purification. 241Pu was determined radiometrically via the ingrown daughter 241Am after 10-12 years of storage, while the 240Pu/239Pu atom ratio of was measured by accelerator mass spectrometry. The 239,240Pu activities in suspended particles collected in the coastal waters of the Baltic Sea decreased by a factor of ∼3 during the study period, while they decreased about fourfold in the Curonian Lagoon. This could indicate a decrease in the influx of particles containing Pu isotopes into the Baltic Sea. While in the Curonian Lagoon, the 239,240Pu activities in the sediment samples varied insignificantly during the study periods, in the Baltic Sea, the maximum activity decreased by a factor of 6, and the mean/median values decreased by ∼4 times. The assessment tool ERICA was used to calculate the dose rates for biota. The total dose rate from all analysed radionuclides was <0.1 μGy/h, therefore no risk to organisms was identified.

Differentiating Fukushima and Nagasaki plutonium from global fallout using 241Pu/239Pu atom ratios: Pu vs. Cs uptake and dose to biota

Plutonium (Pu) has been released in Japan by two very different types of nuclear events - the 2011 Fukushima accident and the 1945 detonation of a Pu-core weapon at Nagasaki. Here we report on the use of Accelerator Mass Spectrometry (AMS) methods to distinguish the FDNPP-accident and Nagasaki-detonation Pu from worldwide fallout in soils and biota. The FDNPP-Pu was distinct in local environmental samples through the use of highly sensitive ²⁴¹Pu/²³⁹Pu atom ratios. In contrast, other typically-used Pu measures (²⁴⁰Pu/²³⁹Pu atom ratios, activity concentrations) did not distinguish the FDNPP Pu from background in most 2016 environmental samples. Results indicate the accident contributed new Pu of ~0.4%-2% in the 0-5 cm soils, ~0.3%-3% in earthworms, and ~1%-10% in wild boar near the FDNPP. The uptake of Pu in the boar appears to be relatively uninfluenced by the glassy particle forms of fallout near the FDNPP, whereas the ^134,137Cs uptake appears to be highly influenced. Near Nagasaki, the lasting legacy of Pu is greater with high percentages of Pu sourced from the 1945 detonation (~93% soils, ~88% earthworm, ~96% boar). The Pu at Nagasaki contrasts with that from the FDNPP in having proportionately higher ²³⁹Pu and was distinguished by both ²⁴⁰Pu/²³⁹Pu and ²⁴¹Pu/²³⁹Pu atom ratios. However, compared with the contamination near the Chernobyl accident site, the Pu amounts at all study sites in Japan are orders of magnitude lower. The dose rates from Pu to organisms in the FDNPP and Nagasaki areas, as well as to human consumers of wild boar meat, have been only slightly elevated above background. Our data demonstrate the greater sensitivity of ²⁴¹Pu/²³⁹Pu atom ratios in tracing Pu from nuclear releases and suggest that the Nagasaki-detonation Pu will be distinguishable in the environment for much longer than the FDNPP-accident Pu.

Sources and variation of isotopic ratio of airborne radionuclides in Western Arctic lichens and mosses

This research concerned radioactivity of lichens and mosses from coastal zones of the Canadian Arctic and Alaska. Over 50 samples were collected from 7 positions during two scientific expeditions in 2012 and 2013. The tundra contamination caused by anthropogenic radionuclides was relatively low, reaching mean values with SD's of: 17.4 ± 3.5 Bq/kg for ⁹⁰Sr, 14.0 ± 2.9 Bq/kg for ¹³⁴Cs, 38.4 ± 7.5 Bq/kg for ¹³⁷Cs, 0.86 ± 0.24 Bq/kg for ^239+240Pu, 0.065 ± 0.017 Bq/kg for ²³⁸Pu and 0.50 ± 0.13 Bq/kg for ²⁴¹Am. The increase of activity concentration with increasing latitudes was noticed mostly in regard to ⁹⁰Sr, Pu isotopes and ²⁴¹Am. The analysis of isotopic ratios exhibited dominant contribution of the global fallout (+SNAP 9A satellite re-entry fallout) for the presence of plutonium isotopes and ²⁴¹Am. The Fukushima fallout signature was identified in a few lichens from Alaska. However, the influence of additional unknown factor on the occurrence of ⁹⁰Sr and ¹³⁷Cs has been detected in western part of Canadian Arctic. Natural radioisotopes of thorium and uranium were found throughout the entire investigated region and the average values of activity concentration with SD's were as follows: 2.92 ± 0.47 Bq/kg for ²³⁰Th, 2.61 ± 0.48 Bq/kg for ²³²Th, 4.32 ± 0.80 Bq/kg for ²³⁴U and 3.97 ± 0.71 Bq/kg for ²³⁸U. Examined Western Arctic tundra was not affected with any technically enhanced natural radioactivity.

Plutonium and thorium isotopes in the bottom sediments of some Mazurian Lakes (Poland)

Presented are results on the Pu and Th isotopes activity concentration found in the upper part of bottom sediments collected from a deep part of 29 lakes in N-E Poland by diving in 2000. Analyses of Pu isotopic ratios allowed for the discussion of Pu origin. Maximum percentage of 239+240Pu activity from Chernobyl fallout was 24%. Surface deposition of 239+240Pu was calculated. No relationship was found between the plutonium and main chemical matrix components of sample nor with the trophic status of the lake. Pu activities were weakly correlated with measured previously 137Cs activities.

Variations in Pu isotopic composition in soils from the Spitsbergen (Norway): Three potential pollution sources of the Arctic region

Although the polar regions have not been industrialised, numerous contaminants originating from human activity are detectable in the Arctic environment. This study reports evidence of ²⁴⁰Pu/²³⁹Pu atomic ratios in the tundra and initial soils from different parts of west and central Spitsbergen and recognizes possible environmental inputs of non-global fallout Pu. The average atomic ratio of ²⁴⁰Pu/²³⁹Pu equal to 0.179 (ranging between 0.129 and 0.201) in tundra soils are comparable to the characteristic ratio for global fallout (0.180). However, the ²⁴⁰Pu/²³⁹Pu atomic ratios in the initial soils from proglacial zone of glaciers change within wide range between 0.1281 and 0.234 with the mean value of 0.169. By combining alpha and mass spectrometry, the three-sources model was used to identify the Pu sources in initial soils. Our study indicated that the main source of Pu is nuclear tests and that a second source with lower Pu ratio may come from weapons grade Pu (unexploded weapons grade Pu ie. material from bomb which didn't undergo nuclear explosions for example for security tests). Additionally, we found samples with high ²³⁸Pu/^239+240Pu activity ratios and with typical global fallout ²⁴⁰Pu/²³⁹Pu atomic ratios, which are associated with separate sources of pure ²³⁸Pu from the SNAP-9A satellite burn up in the atmosphere.

Characterization of (241)Pu occurrence, distribution, and bioaccumulation in seabirds from northern Eurasia

The paper presents unique data of plutonium (241)Pu study in seabirds from northern Eurasia, permanently or temporally living at the southern Baltic Sea coast. Together, ten marine birds species were examined, as follows: three species that permanently reside at the southern Baltic, four species of wintering birds, and three species of migrating birds; 366 samples were analyzed. The obtained results indicated plutonium was non-uniformly distributed in organs and tissues of analyzed seabirds. The highest (241)Pu content was found in the digestion organs and feathers, the lowest in muscles. Also, the internal radiation doses from (241)Pu were evaluated.

241Pu concentrations in water, plankton and fish from the southern Baltic Sea

The aim of the work was to determine 241Pu activities in different components (water, plankton and fish) of the southern Baltic Sea ecosystem. Measurement of 241Pu in the samples was done indirectly by determining the increment in 241Am from the decay of the β-emitting 241Pu in samples collected 10–15 years after the Chernobyl accident.

Enhanced levels of 241Pu were observed in all analyzed Baltic samples. The highest 241Pu concentrations in fish were found in Perciformes: benthic round goby (0.863 ± 0.066 mBq/g ww) and pelagic perch (0.666 ± 0.001 mBq/g ww). Plutonium is also non-uniformly distributed in the organs and tissues of the analyzed fish; especially pelagic herring and cod as well as benthic flounder. Most of 241Pu in flounder, herring and cod is located in soft tissues, especially digestive organs (stomach, intestine, liver). The annual individual effective doses calculated on the basis of 241Pu concentrations in fish indicated that the impact of the consumption of 241Pu containing Baltic fish on the annual effective dose for a statistical inhabitant of Poland was very small.

241Pu in the biggest Polish rivers

In the paper the results of ²⁴¹Pu activity concentration determination in the biggest Polish rivers are presented. The analysis of more than 100 river water samples showed the Vistula and the Odra as well as three Pomeranian Rivers are important sources of ²⁴¹Pu in the southern Baltic Sea. There were differences in ²⁴¹Pu activities depending on season and sampling site and the plutonium contamination came mainly from the global atmospheric fallout as well as the Chernobyl accident, which is confirmed by plutonium activity ratios of ²⁴¹Pu/^239+240Pu and ²³⁸Pu/^239+240Pu.

Determining 241Pu in environmental samples: case studies in alpine soils

A procedure was developed for determining 241Pu activity in environmental samples. This beta emitter isotope of plutonium was measured by ultra low level liquid scintillation, after several separation and purification steps that involved the use of a highly selective extraction chromatographic resin (Eichrom-TEVA). Due to the lack of reference material for 241Pu, the method was nevertheless validated using four IAEA reference sediments with information values for 241Pu. Next, the method was used to determine the 241Pu activity in alpine soils of Switzerland and France. The 241Pu/239,240Pu and 238Pu/239,240Pu activity ratios confirmed that Pu contamination in the tested alpine soils originated mainly from global fallout from nuclear weapon tests conducted in the fifties and sixties. Estimation of the date of the contamination, using the 241Pu/241Am age-dating method, further confirmed this origin. However, the 241Pu/241Am dating method was limited to samples where Pu-Am fractionation was insignificant. If any, the contribution of the Chernobyl accident is negligible.

137Cs and 40K in fruiting bodies of different fungal species collected in a single forest in southern Poland

Fruiting bodies of fungi belonging to more than 70 species were collected within a few thousand square meter area of one forest during 2006 and 2007. The soil profile was collected to check the cumulative deposition of (137)Cs, which was relatively high, equal to 64 +/- 2 kBq/m(2) (calculated for October 2006). The majority of this activity was in the first 6 cm. Fruitbodies were analyzed for radiocesium and (40)K by means of gamma-spectrometry. The highest (137)Cs activity was 54.1 +/- 0.7 kBq/kg (dry weight) for a sample of Lactarius helvus collected in 2006. The results for 2006 were higher than those for 2007. In a few cases the traces of short-lived (T(1/2) = 2.06 a) (134)Cs were still found in samples. The importance of mycorrhizal fungi for radiocesium accumulation is confirmed. The differences in activity among the species are discussed in relation to observations and predictions from previous studies, where the change in relative accumulation between fruiting bodies of different species was at least partially explained by the differences in the depth of the mycelium localization in a litter/soil system. It is concluded that in some cases, such as Boletus edulis and Xerocomus badius, this prediction is fulfilled and therefore this explanation confirmed.

Application of microprecipitation on membrane filters for Alpha Spectrometry, liquid scintillation counting and Mass Spectrometric determination of plutonium isotopes

For the determination of plutonium isotopes in environmental samples, chemical separation of plutonium together with a suitable sample preparation method for measurement is necessary. In this work, a combined method for the determination of238Pu,239Pu,240Pu and241Pu based on alpha spectrometry, Liquid Scintillation Counting (LSC) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) is presented. For the alpha spectrometric determination of238Pu and239(40)Pu, sample preparation by coprecipitation of Pu with NdF3on a membrane filter after separation by anion exchange, using242Pu as tracer, is widely used. This sample preparation method was also applied as a preconcentration step for the determination of240Pu/239Pu ICP-MS after wet ashing of a part of the membrane filter.241Pu was measured with LSC after dissolving a part of the same membrane filter in a suitable cocktail and using the total alpha activity of the filter for determination of the chemical yield.

The use of this approach gives the advantage of combining the strengths of both radiometric and mass spectrometric methods for plutonium determination after chemical separation from environmental samples.

Results from the measurement of reference materials and from sediment samples from the Irish Sea are presented and the applied methods are compared with respect to their detection limits for the investigated nuclides.

Vertical distribution of 238Pu, 239(40)Pu, 241Am, 90Sr and 137Cs in Austrian soil profiles

The occurrence of 238Pu, 239(40)Pu, 241Am, 90Sr and 137Cs in the region of Nassfeld (Salzburg, Austria) is discussed at four different locations by evaluating a depth profile for each radionuclide. Furthermore, the plutonium separated from the soil samples was measured by Accelerator Mass Spectrometry (AMS) to get information on the isotope ratio 240Pu/ 239Pu. The radiochemical procedure consisted of a Pu separation step from Am and Sr by anion exchange in 8 M HNO3 after oxidation state adjustment to Pu(IV). Am and Sr were coprecipitated with calcium oxalate. Am was separated from Sr by extraction chromatography using TRU-resin. The Sr separation was performed also by extraction chromatography using Sr-resin; after coprecipitation as oxalate, 90Sr was measured in a gas proportional counter. For the determination of 239(40)Pu and 241Am by α-spectrometry thin sources were prepared by microprecipitation with NdF3.

With the respective Pu isotope ratios, it was possible to identify the global fallout as source of the contamination. This was confirmed by the ratio 241Am/239(40)Pu. From the activity ratio 90Sr/ 137Cs, it could be shown that most of these radionuclides stem from the reactor accident in Chernobyl.

Sample preparation methods for the determination of plutonium and strontium in environmental samples by low level liquid scintillation counting and α-spectrometry

Two different methods – leaching and microwave assisted total dissolution – have been exploited for the treatment of environmental samples for the determination of plutonium and strontium. Leaching applied to reference materials demonstrated the procedure to be applicable for the recovery of technogenic Pu and Sr from environmental samples.

For the measurement of the alpha emitters of plutonium, co-precipitation with calcium oxalate and ferric hydroxide and separation with anion exchange has been used. For preparation of α-spectrometry sources, co-precipitation with NdF3on a membrane filter or electro-deposition using the (NH4)2C2O4/HCl method have been tested. The beta emitter241Pu was measured by liquid scintillation counting. Pu isotope concentrations determined in the reference materials agreed well with the certified concentrations.

90Sr was measured in the leachate solutions from environmental samples collected close to a nuclear facility and from reference materials, after separation from the other leached elements, by liquid scintillation counting and Cherenkov counting. The90Sr-concentrations determined in the reference materials agreed well with the certified concentrations. In the samples collected close a nuclear facility (soil, grass and sheep faeces),90Sr was found at higher levels, which could also be correlated with the location of the sampling.

Plutonium isotopes in the Hungarian environment

More than 50 soil samples were analysed from different parts of the country, the activity concentration of 239+240Pu was in the range of 0.01-0.84 Bq/kg dry soil with the average of 0.10 Bq/kg. 238Pu could be detected only in few moss samples and 238Pu/239+240Pu ratio determines the origin of plutonium. 241Pu was determined by liquid scintillation spectrometry. The activity concentration of this isotope in the soil is between 0.04 and 3.74 Bq/kg with the average of 0.82 Bq/kg, while in the moss is also similar 0.01-2.07 Bq/kg fresh mass with the average of 0.43 Bq/kg. Significant difference could not be observed between the different types of soils occurring in the country, but the results could be sorted according to the sampling carried out on undisturbed or cultivated area. The isotope ratios 241Pu/239+240Pu prove that the origin of the plutonium in Hungary is the global fallout determined by the atmospheric nuclear weapon tests.

Retrospective estimation of the concentration of 241Pu in air sampled at a Belgrade site following the Chernobyl accident

The surface air activity concentration of 241Pu for the period May 01-15, 1986, for a monitoring site in Vinca, Belgrade was retrospectively estimated. The results were obtained by re-measurement of plutonium fraction alpha-spectrometric sources, with 236Pu as a tracer, used almost 13 years earlier for the determination of (239,240)Pu concentration in surface air immediately after the Chernobyl accident. The estimated 241Pu concentration, based on the 241Am in-growth method for air samples, ranged from 240 to 7800 microBq/m3. The average activity ratio 241Pu/(239,240)Pu originating from the Chernobyl accident at Belgrade site was approximately 100 at the collection time.

Determination of plutonium in environmental samples by AMS and alpha spectrometry

Environmental samples from nuclear weapons test sites at the atolls of Mururoa and Fangataufa (French Polynesia, south Pacific) have been analyzed for their content of plutonium isotopes by applying the independent techniques of decay counting (Alpha Spectrometry) and accelerator mass spectrometry (AMS). Here, we propose the combination of both techniques which results in a maximum of information on the isotopic signature of Pu in environmental samples. Plutonium was chemically separated from the bulk material by anion exchange. (242)Pu was used as an internal standard for both AMS and alpha spectrometry. The samples for alpha spectrometry were prepared by micro-precipitation with NdF(3). After alpha spectrometry, the samples were reprocessed for AMS. Pu was co-precipitated with Fe(OH)(3) and finally, solid samples were prepared. At the VERA (Vienna Environmental Research Accelerator) facility, the various Pu isotopes were separated by their isotopic masses and quantified by the AMS technique. A good agreement of the results obtained from the AMS measurements was found with those obtained from Alpha Spectrometry. Overall, the data agree on average within 10% of each other. Isotope ratios for (238)Pu, (239)Pu and (240)Pu can be extracted from our investigations. Alpha spectrometry delivers data for the (238)Pu and the combination of ((239+240))Pu concentrations in those samples. In addition, the AMS technique provides information on the individual concentrations of (240)Pu and (239)Pu.

Resolving Chernobyl vs. global fallout contributions in soils from Poland using Plutonium atom ratios measured by inductively coupled plasma mass spectrometry

Plutonium in Polish forest soils and the Bór za Lasem peat bog is resolved between Chernobyl and global fallout contributions via inductively coupled plasma mass spectrometric measurements of 240Pu/230Pu and 241Pu/239Pu atom ratios in previously prepared NdF3 alpha spectrometric sources. Compared to global fallout, Chernobyl Pu exhibits higher abundances of 240Pu and 241Pu. The ratios 240Pu/230Pu and 241Pu/239Pu co-vary and range from 0.186 to 0.348 and 0.0029 to 0.0412, respectively, in forest soils (241Pu/239Pu = 0.2407 x [240Pu/239Pu] - 0.0413; r2 = 0.9924). Two-component mixing models are developed to apportion 239+240Pu and 241Pu activities; various estimates of the percentage of Chernobyl-derived 239+240Pu activity in forest soils range from < 10% to > 90% for the sample set. The 240Pu/230Pu - 241Pu/239Pu atom ratio mixing line extrapolates to estimate 241Pu/239Pu and the 241Pu/239+240Pu activity ratio for the Chernobyl source term (0.123 +/- 0.0007; 83 +/- 5; 1 May 1986). Sample 241Pu activities, calculated using existing alpha spectrometric 239+240Pu activities, and the 240Pu/230Pu and 241Pu/239Pu atom ratios, agree relatively well with previous liquid scintillation spectrometry measurements. Chernobyl Pu is most evident in locations from northeastern Poland. The 241Pu activities and/or the 241Pu/239Pu atom ratios are more sensitive than 240Pu/239Pu or 238Pu/239+240Pu activity ratios at detecting small Chernobyl 239+240Pu inputs, found in southern Poland. The mass spectrometric data show that the 241Pu activity is 40-62% Chernobyl-derived in southern Poland, and 58-96% Chernobyl in northeastern Poland. The Bór za Lasem peat bog (49.42 degrees N, 19.75 degrees E), located in the Orawsko-Nowotarska valley of southern Poland, consists of global fallout Pu.

Transuranic isotopes and 90Sr in attic dust in the vicinity of two nuclear establishments in northern Germany

Attic dust was chosen as the test medium in order to search for traces of man-made bone seeking alpha and beta emitters. The samples were taken from 5 houses in the community of Elbmarsch situated at the river Elbe, adjacent to the Krümmel nuclear power plant and the nuclear research center of Geesthacht. Five houses in other regions of northern Germany were taken as a control. 238Pu, (239,240)Pu, 241Am, and 244Cm were measured by alpha spectrometry after chemical separation. Additionally, 241Pu was measured by liquid scintillation spectrometry, and the fission product 90Sr was measured in a separate investigation. All nuclides except 244Cm showed activities above the detection limit in the Elbmarsch samples and an elevated mean concentration compared to the control. It can be concluded from the activity ratio 241Am/(239,240)Pu that the Elbmarsch contamination cannot be accounted for by the background levels of transuranic nuclides resulting from weapons fallout. The derived release of alpha emitters is assumed to have contributed to the induction of a leukemia cluster in children, which was observed in Elbmarsch between 1990 and 1996.

Bioaccumulation and distribution of plutonium in fish from Gdansk Bay

In this paper, the results of 238Pu and 239 + 240Pu determinations in four representative species of Baltic fish collected in Gdansk Bay; flounder, herring, cod and sprat, are presented and discussed. The plutonium isotopes are amongst the more radiotoxic nuclides. In the marine environment, the highest concentrations of plutonium are found in the sediments, but the complex biogeochemical cycle of the element means that it is also found in all other compartments. The activities of the fish samples were measured using alpha spectrometry and the concentrations of plutonium 238Pu and 239 + 240Pu were estimated for particular organs and tissues and the whole body. The 239 + 240Pu concentrations for fish species were: flounder 0.94 mBq kg-1 w.w., herring 2.22 mBq kg-1 w.w., cod 2.35 mBq kg-1 w.w. and sprat 0.33 mBq kg-1 w.w. On the basis of the 238Pu/239 + 240Pu activity ratio in the organs and tissues, the proportion of Chernobyl-derived plutonium in the Baltic Sea was calculated. The lowest values of Chernobyl plutonium were accumulated in flounder stomach, herring skin, cod intestine, the highest in cod gills and skin.

Plutonium and other alpha-emitters in bones of wild, herbivorous animals from north-eastern Poland

The results of the investigation of (239+240)Pu, 241Am and thorium isotope activity concentrations in bones of wild herbivorous animals (deer, roe-deer, boars, elks) from north-eastern Poland are presented. The area on which the animals were living had relatively high Chernobyl plutonium fallout. Possible traces of plutonium were seen only in four samples, but only for one it was it 3sigma above background, at 6.2 +/- 2.4 mBq/kg (ash). The 241Am activity concentration was below the detection limits in all samples. The maximum 228Th concentration in the samples was 7.81 +/- 0.44 Bq/kg (ash), calculated under the assumption of 100% thorium recovery. This isotope seems to originate in bones not from direct incorporation but from the decay of 228Ra. Large variations in activity concentration wose observed, as well as some differences between boars and the chewing animals.