(210)Bi - from interference to advantage in (210)Pb determination with liquid scintillation counter.

A novel method for determination of (210)Pb activity concentration using a liquid scintillation counter (LSC) in environmental samples is presented. After radiochemical separation of (210)Pb on Eichrom Sr Resin column, the decay product (210)Bi starts to in-grow and interfere with the (210)Pb during measurement with LSC. Instead of eliminating this interference, a novel method utilises (210)Bi in-growth to improve the detection efficiency and subsequently to lower the minimum detectable activity (MDA). This allows for substantial reduction of the MDA compared to conventional methods.

Radionuclides in the adriatic sea and related dose-rate assessment for marine biota.

Artificial and natural radionuclides were determined in the Adriatic Sea in the seawater and sediment samples in the period from 2007 to 2011. The sampling areas were coastal waters of Slovenia, Croatia and Albania, together with the deepest part of the Adriatic in South Adriatic Pit and Otranto strait. Sampling locations were chosen to take into account all major geological and geographical features of this part of the Adriatic Sea and possible coastal influences. After initial sample preparation steps, samples were measured by gamma-ray spectrometry. In the seawater 4°K activity concentrations were in the range from 6063 to 10519 Bq m⁻³, ¹³7Cs from 1.6 to 3.8 Bq m⁻³, ²²6Ra from 23 to 31 Bq m⁻³, ²²8Ra from 1 to 25 Bq m⁻³ and ²³8U from 64 to 490 Bq m⁻³. The results of sediment samples showed that 4°K was in the range from 87 to 593 Bq kg⁻¹, ¹³7Cs from 0.8 to 7.3 Bq kg⁻¹, ²²6Ra from 18 to 35 Bq kg⁻¹, ²²8Ra from 4 to 29 Bq kg⁻¹ and ²³8U from 14 to 120 Bq kg⁻¹. In addition, the ERICA Assessment Tool was used for the assessment of dose rates for reference marine organisms using the activity concentrations of the determined radionuclides in seawater. The assessment showed that for the most of the organisms, the dose rates were within the background levels, indicating that the determined values for seawater does not pose a significant risk for the most of marine biota. In the study, the results are critically discussed and compared with other similar studies worldwide. Generally, the activity concentrations of the examined radionuclides did not differ from those reported for the rest of the Mediterranean Sea.

Transfer of natural radionuclides from hay and silage to cow's milk in the vicinity of a former uranium mine.

After the closure of the former Zirovski Vrh uranium mine in Slovenia, mining and milling wastes were deposited on two waste piles, which are located close to the mine. These wastes contain elevated levels of natural radionuclides from the uranium decay chain. Due to different migration processes (erosion, aerial deposition, through groundwater), these radionuclides can be transported via fodder into cow's milk, which is an important foodstuff for Slovenian people. Therefore, natural radionuclides were analysed in the transfer food chain from soil to cow's fodder and cow's milk. After sampling, (238)U, (234)U, (230)Th, (226)Ra, (210)Pb and (210)Po were determined using radiochemical separation methods and alpha spectrometry or proportional counting. Hay and silage to milk concentration ratios (kg dry weight L(-1)) were calculated and were 0.260 for (238)U, 0.255 for (230)Th, 0.070 for (226)Ra, 0.021 for (210)Pb and 0.019 for (210)Po. The calculated annual ingestion dose due to milk consumption for the natural radionuclides analysed was 9 µSv/year for adults and 389 µSv/year for infants with the highest contribution of (210)Po (51% for adults and 63% for infants) and (210)Pb (36% for adults and 24% for infants). This study provides new data quantifying the transfer of natural radionuclides to milk, which is a parameter for which there have been very few previously reported values.

Estimation of sedimentation rate in the Middle and South Adriatic Sea using 137Cs.

(137)Cs activity concentrations were studied in the sediment profiles collected at five locations in the Middle and South Adriatic. In the sediment profiles collected from the South Adriatic Pit, the deepest part of the Adriatic Sea, two (137)Cs peaks were identified. The peak in the deeper layer was attributed to the period of intensive atmospheric nuclear weapon tests (early 1960s), and the other to the Chernobyl nuclear accident (1986). Those peaks could be used to estimate sedimentation rates by relating them to the respective time periods. Grain-size analysis showed no changes in vertical distribution through the depth of the sediment profile, and these results indicate uniform sedimentation, as is expected in deeper marine environments. It was not possible to identify respective peaks on more shallow locations due to disturbance of the seabed either by trawlers (locations PalagruZa and Jabuka) or by river sediment (location Albania). The highest sedimentation rates were found in Albania (∼4 mm y(-1)) and Jabuka (3.1 mm y(-1)). For PalagruZa, the sedimentation rate was estimated to be 1.8 mm y(-1), similar to the South Adriatic Pit where the sedimentation rate was estimated to be 1.8±0.5 mm y(-1). Low sedimentation rates found for the Middle and South Adriatic Sea are consistent with previously reported results for the rest of the Mediterranean.

Natural radionuclides in trees grown on a uranium mill tailings waste pile.

OBJECTIVE: The purpose of the study was to investigate natural radionuclide uptake and allocation by trees. MATERIALS AND METHODS: Samples from six Scots pines (P. sylvestris), six Norway spruces (Picea abies) and one sycamore maple (Acer pseudoplatanus) tree, growing on the Borst uranium mill tailings waste pile in Slovenia were collected. (238)U, (230)Th, (226)Ra and (210)Pb activity concentrations in wood, shoots and 1-year-old needles or leaves were determined. Particular radionuclides were separated from the samples by appropriate radiochemical procedures and their activity concentrations measured with an alpha spectrometry system. In addition, concentration ratios for different plant parts were calculated. RESULTS AND CONCLUSIONS: Results showed that for all radionuclides, the highest activity concentrations were found in foliage, followed by shoots and wood. The activity concentrations in trees were from 0.01 to 5.4 Bq kg(-1) for (238)U, 0.03-11.3 Bq kg(-1) for (230)Th, 2.7-2,728 Bq kg(-1) for (226)Ra and 5.1-321 Bq kg(-1) for (210)Pb. All activity concentrations were calculated on dry weight basis. The calculated concentration ratios were from 1.05E-5 to 5.39E-3 for (238)U, 7.65E-6-2.88E-3 for (230)Th, 3.10E-4-3.16E-1 for (226)Ra and 6.70E-4-4.22E-2 for (210)Pb.

Levels of ²¹°Po and ²¹°Pb in fish and molluscs in Slovenia and the related dose assessment to the population.

²¹°Po and ²¹°Pb activity concentrations in fish from the Slovenian part of Adriatic Sea, in the vicinity of a former uranium mine at Zirovski vrh and from the Slovenian market were determined. In addition, ²¹°Po and ²¹°Pb activity concentrations in squid from the Slovenian market and in mussels from the Slovenian part of the Adriatic Sea were also determined. Fish, squid and mussel consumption in Slovenia was assessed from the data available from Eurostat and Food and Agriculture Organisation (FAO) and the data used for the corresponding dose calculation. Fish species with the highest activity concentrations were grilled to assess possible loss of ²¹°Po during the food preparation process. Samples were freeze dried and radiochemical separation of ²¹°Po and ²¹°Pb was performed. Measurements of ²¹°Po were performed by alpha spectrometry and ²¹°Pb by a low background gas-flow proportional counter. ²¹°Po activity concentrations in fish, squid and mussels were from 0.039 to 35.0 Bqkg⁻¹ fresh weight and ²¹°Pb activity concentrations were from 0.08 to 3.03 Bqkg⁻¹ fresh weight. Grilling of fish resulted in no significant loss of ²¹°Po at 90°C. The assessed combined annual effective ingestion dose due to ²¹°Po and ²¹°Pb for fish, squid and mussels consumed in Slovenia is 47.6 µSv year⁻¹.

Fractionation of natural radionuclides in soils from the vicinity of a former uranium mine Zirovski vrh, Slovenia.

As a result of former uranium mining and milling activities at Zirovski vrh, Slovenia, 0.6 million tons of uranium mill tailings (UMT) were deposited onto a nearby waste pile Borst. Resulting enhanced levels of natural radionuclides in UMT could pose threat for the surrounding environment. Therefore, sequential extraction protocol was performed to assess mobility and bioavailability of (238)U, (234)U, (230)Th and (226)Ra in soils from the waste pile and its surrounding. The radionuclides associated with exchangeable, organic, carbonate, Fe/Mn oxides and residual fraction, respectively, were determined. Results showed that the highest activity concentrations for the studied radionuclides were on the bottom of the waste pile. In non-contaminated locations, about 80% of all radionuclides were in the residual fraction. Considering activity concentrations in the UMT, (238)U and (234)U are the most mobile. Mobility of (226)Ra is suppressed by high sulphate concentrations and is similar to mobility of (230)Th.

Investigation of trace element atmospheric pollution by nuclear analytical techniques at a global scale: harmonized approaches supported by the IAEA.

In the framework of the IAEA programmes, Member States involved in air pollution studies using nuclear analytical techniques have harmonized their methodologies. Participants characterising chemical composition of size fractionated airborne particulate matter based their methodology on a common type of air sampler, centralised data collection and evaluation, and the same kind of data processing. Institutions involved in biomonitoring air pollution identified appropriate organisms to be applied at a regional scale, and harmonized procedures for sample preparation and analysis, as well as data processing and presentation. Both metrology approaches have been validated and disseminated in many Member States.

Preparation and characterization of a soil reference material from a mercury contaminated site for comparability studies.

The preparation and characterization of a soil reference material (SOIL-1) from a site polluted with mercury due to the past mercury mining in Idrija, Slovenia is reported. Homogeneity tests and intercomparison exercises for total (T-Hg) and methylmercury (MeHg) were performed. In addition, selective sequential extraction was applied for Hg fractionation, and multielemental analyses were performed by k(0) standardization neutron activation analysis (k(0)-INAA) and inductively coupled mass spectrometry (ICP-MS) for other trace elements. Comparison of different analytical methods, as well as the distribution of data were critically evaluated using descriptive statistics and analysis of variance (ANOVA). Due to the nugget effect (cinnabar particles representing more than 90% of the mercury), homogeneity for T-Hg determination was difficult to achieve. The intercomparison exercise indicated that in order to obtain comparable results for total mercury (T-Hg) sample decomposition by HF must be performed. These data are then in good agreement with non-destructive methods such as k(0)-INAA. Accepted reference values calculated taking into account the results obtained by six and three laboratories, respectively, were 67.1+/-11.3 mg kg(-1) for T-Hg and 4.0+/-1.3 ng g(-1) for MeHg (95% confidence intervals). However, the results obtained for Hg fractionation displayed significant differences in the organically bound fraction and elemental Hg. Results obtained by two laboratories using totally different analytical protocols for other elements showed excellent agreement for most elements. In summary, the results obtained for the SOIL-1 sample were of sufficient quality to suggest its use for quality control in laboratories dealing with mercury contaminated soils.

Internationally harmonized approach to biomonitoring trace element atmospheric deposition.

The International Atomic Energy Agency (IAEA) has been systematically supporting work on biomonitoring air pollution using plants since 1997. Such studies are presently being supported by the IAEA in 14 countries within a co-ordinated research project. The main emphasis of this project is on (1) identification of suitable biomonitors of atmospheric pollution for local and/or regional application, and (2) their validation for general environmental monitoring, whenever possible. Although the participants are using different plants as biomonitors in their research in geographically and climatically diverse parts of the world, they are harmonising sampling approaches and analytical procedures. In this paper, an overview of these activities is given, along with the details, where possible. In all of these activities, proficiency testing and analytical quality assurance are important issues, which merit special attention. Within the scope of an intercomparison exercise, two lichen materials were distributed among the participating laboratories and a proficiency test was organised. The results obtained proved satisfactory performance for most participating laboratories.