Comparative analysis of (239)Pu, (137)Cs, (210)Pb and (40)K spatial distributions in the top soil layer at the Baltic coast

This paper presents the results of an investigation into the spatial distribution of radionuclides of artificial ((239,240)Pu, (137)Cs) and natural ((210)Pb, (40)K) origins in the upper (0-5 cm) soil layers on the Baltic coastline of Lithuania ( approximately 5 km(2) area). The samples were analysed by gamma ray spectrometry and combined radiochemical procedures. The highest (210)Pb, (239,240)Pu and (137)Cs activity concentrations were determined in the forest samples, whereas (40)K activity was rather homogeneous across the study area. Relatively high (239,240)Pu and (40)K activity concentrations were determined along the surf zone. The (210)Pb and (137)Cs activity concentrations showed a gradual increase from the surf zone to the forest. The average activity concentrations of (239,240)Pu, (137)Cs, (210)Pb and (40)K in the beach and forest samples, respectively, were as follows: 0.32+/-0.08 and 0.74+/-0.14; 50+/-4 and 1190+/-50; 4.7+/-2.0 and 48+/-6; 186+/-15 and 216+/-17 Bq/kg.     

Analytical developments and preliminary assessment of human exposure to organophosphate flame retardants from indoor dust

A new and efficient analytical method was developed and validated for the analysis of organophosphorus flame retardants (OPFRs) in indoor dust samples. This method involves an extraction step by ultrasonication and vortex, followed by extract clean-up with Florisil solid-phase extraction cartridges and analysis of the purified extracts by gas chromatography-mass spectrometry (GC-MS). Method recoveries ranged between 76 and 127%, except for volatile OPFRs, such as triethyl phosphate (TEP) and tri-(n-propyl) phosphate (TnPP), which were partially lost during evaporation steps. The between day precision on spiked dust samples was <14% for individual OPFRs, except for TEP, tri-iso-butyl phosphate (TiBP) and tri (2-butoxyethyl) phosphate (TBEP). Method limit of quantifications (LOQ) ranged between 0.02 μg/g (TnPP and tris(1-chloro-2-propyl phosphate (TCPP)) and 0.50 μg/g (TiBP). The method was further applied for the analysis of indoor dust samples taken from Flemish homes and stores. TiBP, TBEP and TCPP were most abundant OPFR with median concentrations of 2.99, 2.03 and 1.38 μg/g in house dust and of 1.04, 3.61, and 2.94 μg/g in store dust, respectively. The concentration of all OPFRs was at least 20 to 30 times higher compared to polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs). Estimated exposure to OPFRs from dust ingestion ranged for individual OPFRs between <1 and 50 ng/kg body weight for adults and toddlers, respectively. The estimated body burdens were 1000 to 100 times below reference dose (RfD) values, except for the scenario with high dust ingestion and high concentrations of TBEP in toddlers, where intake was only 5 times below RfD. Exposure of non-working and working adults to OPFRs appeared to be similar, but in specific work environments, exposure to some OPFRs (e.g. TDCPP) was increased by a factor >5.     

Application of multivariate statistical analyses in the interpretation of geochemical behaviour of uranium in phosphatic rocks in the Red Sea,Nile Valley and Western Desert,Egypt

Factor and cluster analyses as well as the Pearson correlation coefficient have been applied to geochemical data obtained from phosphorite and phosphatic rocks of Duwi Formation exposed at the Red Sea coast. Nile Valley and Western Desert. Sixty-six samples from a total of 71 collected samples were analysed for SiO2, TiO2, Al203, Fe2O3, CaO, MgO, Na2O, K2O, P2O5, Sr, U and Pb by XRF and their mineral constituents were determined by the use of XRD techniques. In addition, the natural radioactivity of the phosphatic samples due to their uranium, thorium and potassium contents was measured by gamma-spectrometry. The uranium content in the phosphate rocks with P2O5 > 15% (average of 106.6 ppm) is higher than in rocks with P2O5 < 15% (average of 35.5 ppm). Uranium distribution is essentially controlled by the variations of P2O5 and CaO, whereas it is not related to changes in SiO2, TiO2, Al2O3, Fe2O3, MgO, Na2O and K2O concentrations.-Factor analysis and the Pearson correlation coefficient revealed that uranium belaves geochemically in different ways in the phosphatic sediments and phosphorites in the Red Sea, Nile Valley and Western Desert. In the Red Sea and Western Desert phosphorites, uranium occurs mainly in oxidized U6+ state where it seems to be fixed by the phosphate ion, forming secondary uranium phosphate minerals such as phosphuranylite. In the Nile Valley phosphorites, ionic substitution of Ca2+ by U4 is the main controlling factor in the concentration of uranium in phosphate rocks. Moreover, fixation of U6- by phosphate ion and adsorption of uranium on phosphate minerals play subordinate roles.     

Radionuclide and chemical concentrations in mineral waters at Saratoga Springs, New York

A project to characterize the radionuclide and chemical components in natural spring waters in the vicinity of Saratoga Springs, New York (USA) has been completed. As a result of the measured radionuclide and chemical content, eight springs were labeled as mineral waters, whereas three springs contained very low concentrations of these components. The mineral waters were highly enriched in alkaline and alkaline-earth elements, as well as chloride ions. Three isotopes of radium ((224)Ra, (226)Ra, (228)Ra) were detected in the mineral waters and reached concentrations of 1, 20, and 2 Bq/L, respectively. Overall, the (226)Ra isotope constituted about 80% of the total radioactivity measured in the water samples. Dissolved uranium concentrations in the mineral waters were very low (mean approximately 50 mBq/L).     

Present status of 222Rn in groundwater in Extremadura

Radon-222 was measured in groundwater sources of Extremadura (Spain), analyzing 350 samples from private and public springs, wells, and spas by liquid scintillation counting (LSC) and gamma spectrometry. The (222)Rn activity concentrations ranged from 0.24 to 1168BqL(-1). The statistical analysis showed a log-normal distribution with a mean of (111+/-7)BqL(-1) and a median of (36+/-3)BqL(-1). A hydrogeological study revealed correlations between the activity concentration and the aquifer material's characteristics. A map of (222)Rn in groundwater was elaborated and compared with the natural gamma radiation map for this region. About 35% of the samples showed (222)Rn activity concentrations above the Euratom recommended limit of 100BqL(-1). Three uranium series radionuclides ((238)U, (234)U, and (226)Ra) were also assayed by alpha-particle spectrometry, estimating the annual effective dose due to the presence of these natural radionuclides in drinking water.     

Radioactivity and heavy metal composition of Nigerian phosphate rocks: possible environmental implications

Phosphate rock samples collected from the Dange Formation within the Sokoto basin were analyzed for trace element constituents using instrumental neutron activation analysis (INAA) and X-ray fluorescence analysis (XRFA) techniques, while natural activity concentrations due to 235U, 232Th, and 40K were determined by gamma-ray spectrometry. The analytical results show that the average concentrations of some toxic elements (As, Sb, Cr, and Zn) in phosphate rocks are not appreciably different from that in agricultural soils. However the U and Th contents are enriched significantly in comparison. The results were used to assess the environmental toxicity of heavy metals and radiation hazard attributable to the direct application of phosphate rock as fertilizer.     

Occupational exposure of phosphate mine workers: airborne radioactivity measurements and dose assessment

Under the Egyptian program for radiation safety and control, airborne radioactivity measurements and radiological dose assessment were conducted in some phosphate and uranium mines. Abu-Tartor mine is one of the biggest underground phosphate mines in Egypt. Airborne radioactivity, radon ((222)Rn) and its short-lived decay products (progenies) and thoron ((220)Rn), were measured in selected locations along the mine. The environmental gamma and workers dose equivalent rate (mSv/y) were measured inside and outside the mine using thermo-luminescence dosimeters (TLD). The results were presented and discussed. The calculated annual effective dose due to airborne radioactivity is the main source of occupational exposure and exceeding the maximum recommended level by ICRP-60 inside the mine tunnels. A number of recommendations are suggested to control the occupational exposures.     

Determination of technetium-99 using electrothermal vaporization inductively coupled plasma-mass spectrometry (ETV-ICP-MS) and NH4OH as chemical modifier

In recent years, developments in ICP-MS have led to improved methods for determination of long-lived radionuclides. This paper reports the use of NH(4)OH as a matrix modifier and ETV sample introduction for the determination of technetium-99 ((99)Tc) in a variety of environmental and biological samples, using Re as carrier and (99m)Tc as yield monitor in the chemical separation method. Addition of an excess of NH(4)OH led to a stable (99)Tc signal, reduced memory effect, better reproducibility and reduced detection limits. Following radiochemical separation of (99)Tc from the sample matrix, detection limits in the order of a few microBq have been achieved. ETV has also proved applicable for rapid, direct analysis of a number of environmental samples having relatively high concentrations of (99)Tc (sediment extracts and river water close to nuclear installations). However, in this case, control of matrix effects (signal reduction and enhancement) using standard additions is necessary.     

A prognostic estimation of the area contaminated with alpha-emitting transuranium isotopes in Belarus following the Chernobyl accident

As a result of the Chernobyl accident, some regions of Belarus have been contaminated with the plutonium isotopes (238,239,240,241)Pu. Considering the importance of the environmental impact of the alpha-emitting radionuclides we have carried out a prognostic estimation of the area contaminated with (238,239,240)Pu and (241)Am (the latter being a decay product of (241)Pu) in Belarus. The calculations were made using measurements of (238,239,240)Pu activity concentrations in soil samples from about 600 settlements in the affected region, together with the estimated activity ratio A((241)Am)/A((238,239,240)Pu). The area contaminated with alpha-emitting transuranium isotopes predicted for the year 2006 has been compared with that estimated for 1986. The results show that by 2006, the area of inhabited districts where contamination with (238,239,240)Pu and (241)Am exceeds the threshold level of 740 Bq/m(2), will be 3.7 times larger, reaching approximately 3.5 x10(3)km(2). Of this, almost 20% will have a contamination level of 1850--3700 Bq/m(2).     

Distribution of natural radionuclides in the production and use of phosphate fertilizers in Brazil

The Brazilian phosphate fertilizer is obtained by wet reaction of igneous phosphate rock with concentrated sulphuric acid, giving as final product, phosphoric acid and dehydrated calcium sulphate (phosphogypsum) as by-products. Phosphoric acid is the starting material for triple superphosphate (TSP), single superphosphate (SSP), monoammonium phosphate (MAP) and diammonium phosphate (DAP). The phosphate rock used as raw material presents in its composition radionuclides of the U and Th natural series. Taking this into account, the main aim of this paper is to evaluate the fluxes of natural radionuclides and radioactive disequilibria involved in the Brazilian industrial process of phosphoric acid production; to determine the content of radioactivity in several commercial fertilizers produced by this industry; to estimate their radiological impact in crop soils and the long term exposure due to their application. Radiological characterization of phosphate rock, phosphogypsum and phosphate fertilizers was performed by alpha and gamma spectrometry. The fertilizer samples, which are derived directly from phosphoric acid, MAP and DAP, presented in their composition low activity concentrations for 226Ra, 228Ra and 210Pb. As for U and Th, the concentrations found in MAP and DAP are more significant, up to 822 and 850Bqkg(-1), respectively. SSP and TSP, which are obtained by mixing phosphoric acid with different amounts of phosphate rock, presented higher concentrations of radionuclides, up to 1158Bqkg(-1) for (238)U, 1167Bqkg(-1) for (234)U, 1169Bqkg(-1) for 230Th, 879Bqkg(-1) for 226Ra, 1255Bqkg(-1) for 210Pb, 521Bqkg(-1) for 232Th, 246Bqkg(-1) for 228Ra and 302Bqkg(-1) for 228Th. Long term exposure due to successive fertilizer applications was evaluated. Internal doses due to the application of phosphate fertilizer for 10, 50 and 100 years were below 1mSvy(-1), showing that the radiological impact of such practice is negligible.     

Multi-compartmental environmental surveillance of a petrochemical area: levels of micropollutants

Since 2002, the chemical/petrochemical industrial zone of Tarragona County (Catalonia, Spain) is being annually monitored. As part of the environmental surveillance program, in this study the levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs), polycyclic aromatic hydrocarbons (PAHs), and metals (As, Cd, Cr, Hg, Mn, Pb and V) were determined in soil and vegetation samples collected in 4 areas of Tarragona County (chemical, petrochemical, urban/residential, and unpolluted). Moreover, the airborne concentrations of the same micropollutants were determined in each area. In soil samples, significant higher levels of PCNs and higher concentrations of PCDD/Fs and PAHs were found in the urban zone. PCDD/F levels in vegetation samples significantly decreased from 2002. The concentrations of Cr in soil samples, as well as V levels in vegetation samples collected in the vicinity of an oil refinery were significantly higher than those found in the unpolluted zones. A significant and progressive increase in V concentrations was also noted. The current results clearly indicate that the petrochemical industry is still being an important focus of inorganic pollution for the surrounding environment. In air, the higher amount of the 7 carcinogenic PAHs suggests a relatively greater impact on the petrochemical and urban areas. The temporal trend of the global pollution was also studied an Integral Risk Index was applied.     

Liquid discharges from the use of radionuclides in medicine (diagnosis)

The production and discharge of liquid radioactive wastes as excreta from patients undergoing Nuclear Medicine Diagnostic (NMD) in a hospital were studied. Instantaneous and accumulated activity, discharged from the hospital to the sewage system, has been estimated keeping in mind radionuclide decay. This study would enable estimation of the environmental impact due to NMD procedures. Annual accumulated activities of 2.2GBq ((131)I), 1.847GBq ((99m)Tc), 0.743GBq ((123)I), 0.337GBq ((67)Ga), 0.169GBq ((111)In) and 0.033GBq ((201)Tl) result from our model when applied to a European hospital. A comparison is made with calculations by other authors that do not consider the radionuclide decay and who overestimate by two orders of magnitude. Doses to critical people as sewage treatment workers are also significantly reduced. So, our results stress the importance of including the decay in the calculations.     

Arbuscular mycorrhiza reduces phytoextraction of uranium, thorium and other elements from phosphate rock

Uptake of metals from uranium-rich phosphate rock was studied in Medicago truncatula plants grown in symbiosis with the arbuscular mycorrhizal fungus Glomus intraradices or in the absence of mycorrhizas. Shoot concentrations of uranium and thorium were lower in mycorrhizal than in non-mycorrhizal plants and root-to-shoot ratio of most metals was increased by mycorrhizas. This protective role of mycorrhizas was observed even at very high supplies of phosphate rock. In contrast, phosphorus uptake was similar at all levels of phosphate rock, suggesting that the P was unavailable to the plant-fungus uptake systems. The results support the role of arbuscular mycorrhiza as being an important component in phytostabilization of uranium. This is the first study to report on mycorrhizal effect and the uptake and root-to-shoot transfer of thorium from phosphate rock.     

Natural radioactivity in phosphates, phosphogypsum and natural waters in Morocco

The contents of natural radionuclides (uranium, actinium and thorium series) were measured in sedimentary phosphate rock samples using high-resolution gamma spectrometry. Data obtained for uranium content (ppm) were compared with the results obtained by a method based on the measurements using solid-state nuclear track detectors (SSNTD) in the same samples. The potential leaching of radionuclides from sedimentary phosphate rock during the industrial production of the phosphoric acid was studied. The process of leaching of the radioisotopes from phosphogypsum was discussed. A method for the direct alpha counting of 226Ra thin source, elaborated by the deposition of Ra from aqueous solutions on manganese oxides film deposited on polyvinyl support, have been developed and applied for the determination of 226Ra in natural water samples. The results show that only the water sample from the mine area reveals the presence of 226Ra at a level of about 0.2 Bq l-1.     

Activity concentration of caesium-137 in agricultural soils

In this study, we measured 137Cs activity concentrations in the soil samples taken from agricultural lands in the Buyuk Menderes Basin in Turkey in 1997 and 1998. The soil samples were collected from 42 sites in this Basin. The activity concentration of 137Cs was found to range between 2.81+/-0.17 Bq.kg(-1) and 20.75+/-0.29 Bq.kg(-1). The effect of organic matter, clay, silt and sand contents and pH of the soil on the relative adsorption of the 137Cs on the soil surface were also studied.     

(90)Sr, (210)Po and (210)Pb in lichen and reindeer in Norway

Concentrations of (90)Sr, (210)Po and (210)Pb in lichen and reindeer were studied in central (?stre Namdal) and southern Norway (V?g?) during 2000-2003. The study focussed on potential differences in concentrations of these nuclides in reindeer of different ages. Concentrations of (90)Sr in bones of approximately 10 year old adult females were about 40% higher than those in calves' antlers ((90)Sr concentrations in antlers and bones of calves are similar), while the available data from V?g? suggest that (90)Sr concentrations in reindeer calves decreased with an effective ecological half-time of 9.03+/-0.06 years during 1988-2002. Furthermore, (90)Sr concentrations were 50-80% higher in bone of reindeer of a similar age from V?g? compared to those from ?stre Namdal. Concentrations of (210)Po and (210)Pb in muscle and liver tissues were comparable to those reported for reindeer in other Nordic areas, with no significant difference in (210)Po and (210)Pb concentrations between adults and calves or between reindeer from the two different study areas.     

Concentrations and environmental fate of Ra in cation-exchange regeneration brine waste disposed to septic tanks and accumulation in sludge, New Jersey Coastal Plain, USA

Concentrations of Ra in liquid and solid wastes generated from 15 softeners treating domestic well waters from New Jersey Coastal Plain aquifers (where combined Ra ((226)Ra plus (228)Ra) concentrations commonly exceed 0.185 Bq L(-1)) were determined. Softeners, when maintained, reduced combined Ra about 10-fold (<0.024 Bq L(-1)). Combined Ra exceeded 0.185 Bq L(-1) at 1 non-maintained system. Combined Ra was enriched in regeneration brine waste (maximum, 81.2 Bq L(-1)), but concentrations in septic-tank effluents receiving brine waste were less than in the untreated ground waters. The maximum combined Ra concentration in aquifer sands (40.7 Bq kg(-1) dry weight) was less than that in sludge from the septic tanks (range, 84-363 Bq kg(-1)), indicating Ra accumulation in sludge from effluent. The combined Ra concentration in sludge from the homeowners' septic systems falls within the range reported for sludge samples from publicly owned treatment works within the region.     

Natural radioactivity in farm soil and phosphate fertilizer and its environmental implications in Qena governorate, Upper Egypt

Samples of phosphate fertilizers and farm soils, taken to a depth of up to 30 cm in cultivated land, were collected over the Qena governorate, Upper Egypt. Activity concentration of background radionuclides such as (226)Ra, (232)Th and (40)K of these samples were determined by gamma-ray spectrometry. The results show that these radionuclides were present in concentrations of 366+/-10.5, 66.7+/-7.3 and 4+/-2.6 Bq/kg for phosphate fertilizers. For farm soil and Nile island's soil the corresponding values were 13.7+/-7, 12.3+/-4.6, 1233+/-646 and 11.9+/-6.7, 10.5+/-6.1, 1636+/-417 Bq/kg, respectively. The radium equivalent activity (Ra(eq)), the representative level index, I(gamma r), and absorbed dose in air for all samples were calculated. The data were discussed and compared with those given in the literature.     

The derivation of radionuclide transfer parameters for and dose-rates to an adult ringed seal (Phoca hispida) in an Arctic environment

Radionuclide transfer parameters and dose-rates for an adult ringed seal from Svalbard have been determined based on empirical and estimated tissue activity concentrations and detailed dietary and habitat information. Whole-body equivalent concentration factors determined for anthropogenic radionuclides ranged from 10(1) ((90)Sr) to 10(2) ((137)Cs, (238)Pu and (239,240)Pu), while natural radionuclides ranged from 10(2) ((210)Pb) to 10(4) ((210)Po). Employing a dietary composition of 40% fish, 40% zooplankton and 20% benthic invertebrates, a whole-body biological half-life of 29 days was derived for (137)Cs. A total dose-rate of approximately 0.19microGyh(-1) (1.7mGya(-1)) was derived for an adult ringed seal; this dose-rate is virtually entirely attributable to the internal components of (210)Po and (40)K. The dose-rates associated with the presence of anthropogenically derived radionuclides in the present assessment fall many orders of magnitude below the dose-rates at which any biological effects would be expected.     

Distribution and mobilization of U, Th and 226Ra in the plant-soil compartments of a mineralized uranium area in south-west Spain

The activity concentrations of natural uranium isotopes (238U and 234U), thorium isotopes (232Th, 230Th and 225Th) and 226Ra were studied in soil and vegetation samples from a disused uranium mine located in the Extremadura region in the south-west of Spain. The results allowed us to characterize radiologically the area close to the installation and one affected zone was clearly manifest as being dependent on the direction of the surface water flow from the mine. The activity concentration mean values (Bq/kg) in this zone were: 10,924, 10,900, 10,075 and 5,289 for 238U, 234U, 230Th and 226Ra, respectively, in soil samples and 1,050, 1,060, 768 and 1,141 for the same radionuclides in plant samples. In an unaffected zone, the activity concentration mean values (Bq/kg) were: 184, 190, 234 and 7251 for 235U, 234U, 230Th and 226Ra, respectively, in soil samples and 28. 29, 31 and 80 in plant samples. The activity concentrations obtained for 232Th and 228Th showed that the influence of the mine was only important for the uranium series radionuclides. The relative radionuclide mobilities were determined from the activity ratios. Correlations between radionuclide activity concentrations and stable element concentrations in the soil samples helped to understand the possible distribution paths for the natural radionuclides.