Particle and solution phase depth distributions of transuranics and 55Fe in the North Pacific

In situ large volume filtration and chemisorption techniques were used to collect samples from the North Pacific for radiochemical analyses of fallout transuranics and ⁵⁵Fe in filterable and filtered phases. The data cover several locations for surface collections and a detailed depth profile north of Hawaii at 30°N. The observed partition of these nuclides between suspended particulate and filtered phases is directly linked to the rates at which they are moved downward through the water column in association with sinking particles. Particulate phases in open ocean surface waters contain higher Pu (12–35%) than subsurface particulates (which average about 6%). ²⁴¹Am was found to exhibit much stronger particle association—typically close to 50% in both surface and subsurface waters—in accord with its known greater particle reactivity. In the high Pu deep water layer, particle associated Pu dropped to close to 1% of total Pu concentration. Together with a correlated increase in the proportion of oxidized Pu in this layer close to the sediment-water interface, this is taken as clear evidence of remobilization Pu from particles at, or near to, the interface. ⁵⁵Fe distributions on filtered particulates indicate a much deeper depth distribution relative to the transuranics. This may reflect both a higher particle association reactivity in respect to scavenging and a longer exposure history to scavenging (especially relative to ²⁴¹Am—produced by in situ decay).     

The effect of acidification on abiotic interactions of dissolved humic substances, iron and phosphate in epilimnetic water from the humex Lake Skjervatjern

The responses to pH of abiotic interactions between dissolved humic substances, iron and phosphate were investigated by examining redistributions of ⁵⁵FeCl₃ and ³²PO₄³⁻ added to epilimnetic lakewater from Lake Skjervatjern. The simultaneous movement of ⁵⁵Fe and ³²P to fractions of 10 000–20 000 and > 100 000 Daltons nominal molecular weight, as indicated by Sephadex gel filtration, diminished in response to decreasing pH. Variations in transformations to larger molecular size fractions with incubation time revealed by gel filtration were erratic, but indicated that transformations of added ⁵⁵Fe and ³²P are complete after circa 24 h. Movement of ³²P to particle size fractions (>0.2 μm) was not dependent on pH, whilst transformations of ⁵⁵Fe to material of particle size increased as pH was lowered. Precipitation of added ⁵⁵Fe and ³²P was minimal at all pH values tested. Responses of precipitation losses to pH were not coincident for both radionuclides.     

The use of ultra filtration in trace metal speciation studies in sea water

During this work, size fractionation technique "ultra filtration" is used in speciation studies of trace elements in the coastal sea water. Filtration is the most commonly used method to fractionate trace metal species, but often only "dissolved" and "particulate" fraction. The purpose of the present study is to determine colloidal and suspended particulate concentrations of Fe, Zn, Cu, Ni, and Mn in sea water. Suspended particulate matter were separated in three different size groups namely (>2.7 microm, <2.7->0.45 microm and <0.45->0.22 microm) by suction filtration using cellulose acetate and nitrate filter membranes. Thereafter to concentrate the solution with colloidal particle <0.22 microm-1.1 nm (0.5 k Nominal Molecular Weight cut-off Limit {NMWL}), the solution obtained from filtration through <0.22 microm, is sequentially passed through the ultra-filtration membranes having pore diameters of 14 nm (300 k NMWL), 3.1 nm (50 k NMWL), 2.2 nm (30 k NMWL), 1.6 nm (10 k NMWL) and 1.1 nm (0.5 k NMWL) by using Stirred Ultra-filtration Cells, operating in concentration mode. The concentration of Fe, Zn, Cu, Ni, and Mn were measured in suspended and dissolved fraction by ion chromatography, ICP-AES and Atomic Absorption Spectrometer. The salinity of the solution in various dissolved fractions of sequential filtration varies between 30.89-34.22 parts per thousand. The maximum concentrations of colloidal Zn, Cu, Ni and Mn in dissolved fraction were in <2.2->1.6 nm fraction. In case of Fe, colloidal fractions <2.2->1.6 nm and <1.6-<1.1 nm shows higher concentration. The concentration of Zn, Cu, Ni and Mn increase with decrease in size in suspended particulate matter, while the reverse is observed in case of Fe. This size separation data that specifies the partitioning of metals between dissolved and suspended solid phases is necessary for developing physically based models of metal transport in aquatic system.     

Transport and distribution of artificial gamma-emitting radionuclides in the River Yenisei and its sediment

Discharges from the Krasnoyarsk Mining and Chemical Industrial Complex (KMCIC) near Krasnoyarsk resulted in radioactive contamination of sediments of the River Yenisei. Between 1999 and 2006, 16 sediment cores were collected at different positions 15-1500 km downstream from the discharge point. The concentration of artificial gamma-emitting radionuclides (¹³⁷Cs, ⁶⁰Co, ¹⁵²Eu, and ²⁴¹Am) was determined with the objective to analyze the migration processes leading to the transport of these radionuclides along the river and to their vertical distribution within the sediment. In cores taken in the vicinity of the reactors, the average activity concentration of ¹³⁷Cs, ¹⁵²Eu, and ⁶⁰Co was about 1000 Bq kg⁻¹, and the activity concentration of ²⁴¹Am was about 20 Bq kg⁻¹. Contamination levels of artificial radionuclides were decreasing with increasing distance downstream the KMCIC: The fastest decrease of average activity by a factor of 10 over a distance of 300 km was observed for ²⁴¹Am, whereas for ¹³⁷Cs this decrease occurred over a distance of 1100 km. Sequential extraction experiments revealed that in all depths and at all distances the studied radionuclides were tightly bound to the sediment.To investigate the mechanisms of transport of the ¹³⁷Cs and ⁶⁰Co contamination, mathematical models have been used to describe the contamination in the river water and within the sediments.     

Application of a magnetic extraction technique to assess radionuclide-mineral association in Cumbrian shoreline sediments

An assessment has been made of the association of (239+240)Pu, 241Am and 210Po (in secular equilibrium with 210Pb) with iron minerals using a magnetic extraction technique. Grab samples of beach sand from the Cumbrian (UK) coastline were subjected to successive extractions with an approximately 0.1 T ferrite magnet and an approximately 0.3 T rare-earth magnet procedure to separate magnetic iron oxide minerals. Radionuclide concentrations in the magnetic extracts were enhanced (by approximately 4-6-fold) relative to the residue. Those in the approximately 0.1 T magnet extracts were broadly similar to those in the antiferromagnetic material extracted by the approximately 0.3 T magnet, despite the very large differences in magnetic property values between the two fractions (one to two orders of magnitude). The percentage of magnetic material in terms of mass was small and therefore, the majority of these radionuclides (on average 88%) were associated with the residue. Removal of stable Fe was incomplete. Given that the radionuclides may also bind to paramagnetic (nonmagnetic) Fe minerals, the data were extrapolated by normalising the results to quantitative Fe removal. This yielded average values of 37%, 45% and 46% for (239+240)Pu, 241Am and 210Po(210Pb), respectively, as upper limits for the fraction associated with magnetic + nonmagnetic Fe minerals. There are significant uncertainties inherent in quantifying data from this extraction technique. Nevertheless, it seems reasonable to conclude that radionuclide association with Fe minerals is unlikely to have a significant impact upon the physical dispersion of sediment contaminated by Sellafield discharges in the Irish Sea. However, it may be an important factor in governing Pu redox and redissolution behaviour.     

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

As a result of former uranium mining and milling activities at ?irovski vrh, Slovenia, 0.6 million tons of uranium mill tailings (UMT) were deposited onto a nearby waste pile Boršt. 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 ²³⁸U, ²³⁴U, ²³⁰Th and ²²⁶Ra 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, ²³⁸U and ²³⁴U are the most mobile. Mobility of ²²⁶Ra is suppressed by high sulphate concentrations and is similar to mobility of ²³⁰Th.     

Pre-assessment of the speciation of 60Co, 125Sb, 137Cs and 241Am in a contaminated aquifer

A sample of contaminated groundwater was analyzed using a combination of wet techniques to obtain geochemical information on the mobile species of 60Co, 125Sb, 137Cs and 241Am. The techniques were combined in a scheme to determine the predominant character of the radionuclides in negative or positive fractions, size separation by ultrafiltration, and their association with natural organic matter (NOM). The analyses indicated that the radionuclides of interest were predominantly in the negative fraction. Most of the 60Co and 125Sb were in the small size fraction (<5000 Da), and 137Cs and 241Am were found with the larger, colloidal-sized material. Antimony-125 and 60Co were predominantly in the hydrophilic fraction, while 137Cs and 241Am were found in hydrophobic fractions. Our analysis indicated that 137Cs is found in the same fraction as the large-sized colloidal (hydrophobic) material, suggesting an association with NOM. The results suggested that 60Co and 241Am were associated with NOM, in different size fractions, suggesting that these two nuclides are bound to different sites. Finally, the 125Sb results were inconclusive, whether this nuclide is associated with NOM, or it is inorganic.     

Particle size distribution and its elemental composition in the ambient air of Delhi

This study examines the chemical composition of PM10, the thoracic fraction of the atmospheric particulate matter. An eight-stage Anderson impactor is used to separate the PM10 from other fractions with different aerodynamic behaviour at three different area representative sites in Delhi from February to May 1998. PM10 particulate are subdivided into two fractions, coarse (> 2.1-10 microns) and fine (< 2.1 microns). The concentrations of major heavy metals such as Pb, Zn, Cd, Ni, and Fe are determined by atomic absorption spectrophotometer. The average concentration of coarse fraction of PM10 is found to be 68.3 +/- 17 micrograms/m3 while the fine fraction of PM10 is 71.3 +/- 15 micrograms/m3 for Delhi. Metal concentration (except Fe) in fine fraction exceeds by a factor of up to 6, as compared to that in the coarse fraction. In order to identify the major sources of fine and coarse fraction of PM10, principle component analysis (PCA) was undertaken and three major sources were identified, namely vehicular emissions, industrial emission, and soil resuspension.     

Dynamic model for radionuclide uptake in lichen

Samples of atmospheric particulate material and terrestrial plants, including lichens, were collected in New Brunswick, Canada between 1980 and 1983 and analyzed for a wide range of artificial and naturally-occuring radionuclides, including fission products (¹⁴¹Ce, ¹⁴⁴Ce, ¹⁰³Ru, ¹⁰⁶Ru, ⁹⁵Zr and ¹³⁷Cs) derived from the 16 October 1980 Chinese nuclear test. Activity ratios of some of the short-lived fission products in air particulates and lichens are in reasonable agreement with those predicted from fission product yields for nuclear weapons tests, indicating that only minor fractionation occurred for these radionuclides during their transport through air particulate and lichen environmental phases. The ⁷Be inventories measured in a suite of lichen (Cladonia rangiferina) samples were used to calibrate each lichen plant for its collection efficiency for atmospheric particulates and fallout radioactivity.A lichen model has been developed to predict lichen inventories of radioactivity for different lichen growth functions and bio-elimination rates. Assuming that lichen growth results in a linear increase in surface area with time, the experimental results yield biological residence times of 1–2 years for ²¹⁰Pb and Pu and 5–8 years for ¹³⁷Cs. The more efficient retention of ¹³⁷Cs is probably due to its physiological uptake in lichen plants as a proxy for potassium, as evidenced by an observed, inverse relationship between ¹³⁷Cs and ⁴⁰K activities in lichen.     

Distribution of organic carbon, selected stable elements and artificial radionuclides among dissolved, colloidal and particulate phases in the Rhône River (France): preliminary results

The behaviour of radionuclides discharged from nuclear facilities in the Rh?ne River depends on their distribution among the dissolved, colloidal and particulate phases. A large water sample was fractionated using sequential ultrafiltration. Size distributions of organic carbon, Fe, Al, Si, Ca, Mg, Cu, Zn, 137Cs, 60Co and 106Ru were obtained. Our results show that organic colloids account for 11% of the total organic carbon content. Approximately 20% of the dissolved (< 450 nm) Fe and Al are in colloidal classes. 137Cs is not significantly transferred by the colloidal phase while 25% of 60Co or 106Ru is associated with organic and inorganic colloids.     

Occurrence and behaviour of radionuclides in the Moselle River—Part III: Dispersion of radionuclides along the river course

Knowledge about propagation of radionuclides from nuclear power plants (NPPs) along the course of a river is of great interest in radioecological assessments. By use of a model previously applied in the cases of the Rhine and Weser Rivers, the distribution of various radionuclides released into the Moselle from the NPP Cattenom at normal operation is described with ⁵⁸Co, ⁶⁰Co and ^110mAg as tracers. A comparison of field measurements with calculated values revealed that the radionuclide concentrations in suspended matter and nuclide loads calculated from emission rates agreed with the measured data by a factor of less than two on average.Radionuclide concentrations and loads along the river course decrease mainly due to deposition of particulate radioactive matter in high-sedimentation areas and due to dilution with uncontaminated material from tributaries and other sources. The rate constants of both processes were evaluated, and the mean range of suspended radioactive particles in the Moselle was estimated. Moreover, this study showed anew that suspended matter has to be considered as the main carrier by which the radionuclides from NPPs may be transported over long distances.     

Kinetics of the adsorption and desorption of radionuclides of Co, Mn, Cs, Fe, Ag and Cd in freshwater systems: experimental and modelling approaches

The sorption and release kinetics of 54Mn, 58Co, 59Fe, 109Cd, 110mAg and 134Cs by freshwater suspended particles were investigated to better identify the biogeochemical processes involved and to obtain suitable data for improving models describing radionuclide migration in freshwater streams. In order to observe any seasonal variability in the interaction of radionuclides with natural particles, experiments were performed both in winter and in summer during a phytoplanktonic bloom. Two kinetic models are compared in this paper: the "one-step reversible" model, based on the hypothesis that the transfer of radionuclides between water and suspended solids is governed by a reversible reaction, and the "two-successive-step reversible" model, which assumes two distinct types of sites or reactions on the solid phase. The "one-step reversible" model is generally unable to describe properly the exchange kinetics; this result shows that at least two processes are generally involved in radionuclide exchange between water and suspended particles. On the contrary, a model involving the existence of two successive reversible reactions properly simultes both the sorption and release kinetics. The determination of the kinetic coefficients allows quantitative assessment of the relative importance and kinetics of the processes. In particular, it has been shown that, except for Cs and Cd, major fractions of the radionuclides are associated at equilibrium with particulate sites involving strong interactions. The kinetics to reach this equilibrium depend on seasonal conditions, especially for Co and Mn: the transfer of Co and Mn to particulate sites involving strong interactions is much slower in winter. The distribution of the radionuclides between water and particulate sites involving weak interactions also shows seasonal variations for Co, Mn, Fe and Ag: the capacity to associate radionuclides is much higher in summer for Co and Mn, while the inverse tendency is observed for Fe and Ag. For Cs and Cd, no significant seasonal differences were observed.     

Variation of radiation level and radionuclide enrichment in high background area

Significantly high radiation level and radionuclide concentration along Quilon beach area of coastal Kerala have been reported by several investigators. Detailed gamma radiation level survey was carried out using a portable scintillometer. Detailed studies on radionuclides concentration in different environmental matrices of high background areas were undertaken in the coastal areas of Karunagapalli, Kayankulam, Chavara, Neendakara and Kollam to study the distribution and enrichment of the radionuclides in the region. The absorbed gamma dose rates in air in high background area are in the range 43-17,400 nGyh⁻¹. Gamma radiation level is found to be maximum at a distance of 20 m from the sea waterline in all beaches. The soil samples collected from different locations were analysed for primordial radionuclides by gamma spectrometry. The activity of primordial radionuclides was determined for the different size fractions of soil to study the enrichment pattern. The highest activity of ²³²Th and ²²⁶Ra was found to be enriched in 125-63 μ size fraction. The preferential accumulation of ⁴⁰K was found in <63 μ fraction. The minimum ²³²Th activity was 30.2 Bq kg⁻¹, found in 1000-500 μ particle size fraction at Kollam and maximum activity of 3250.4 Bq kg⁻¹ was observed in grains of size 125-63 μ at Neendakara. The lowest ²²⁶Ra activity observed was 33.9 Bq kg⁻¹ at Neendakara in grains of size 1000-500 μ and the highest activity observed was 482.6 Bq kg⁻¹ in grains of size 125-63 μ in Neendakara. The highest ⁴⁰K activity found was 1923 Bq kg⁻¹ in grains of size <63 μ for a sample collected from Neendakara. A good correlation was observed between computed dose and measured dose in air. The correlation between ²³²Th and ²²⁶Ra was also moderately high. The results of these investigations are presented and discussed in this paper.     

Effect of americium-241 on luminous bacteria. Role of peroxides

The effect of americium-241 (²⁴¹Am), an alpha-emitting radionuclide of high specific activity, on luminous bacteria Photobacterium phosphoreum was studied. Traces of ²⁴¹Am in nutrient media (0.16-6.67 kBq/L) suppressed the growth of bacteria, but enhanced luminescence intensity and quantum yield at room temperature. Lower temperature (4 °C) increased the time of bacterial luminescence and revealed a stage of bioluminescence inhibition after 150 h of bioluminescence registration start. The role of conditions of exposure the bacterial cells to the ²⁴¹Am is discussed. The effect of ²⁴¹Am on luminous bacteria was attributed to peroxide compounds generated in water solutions as secondary products of radioactive decay. Increase of peroxide concentration in ²⁴¹Am solutions was demonstrated; and the similarity of ²⁴¹Am and hydrogen peroxide effects on bacterial luminescence was revealed. The study provides a scientific basis for elaboration of bioluminescence-based assay to monitor radiotoxicity of alpha-emitting radionuclides in aquatic solutions.     

Investigating incorporation and distribution of radionuclides in trinitite

Most of the surface explosions in nuclear tests have released radioactivity to the environment in the form of bulk glassy materials originating from the melting of sandy soil in the neighbourhood of ground zero. In view of clarifying issues concerning the mechanism of formation and the radiological impact of these materials, we investigated incorporation and volume distribution of radionuclides in a typical fragment of trinitite, the glassy substance generated following the first nuclear test (Trinity Site, New Mexico, 1945). Specific activities were determined by γ-spectrometry for the most significant fission and activation products. In particular, ¹⁵²Eu activity was used to estimate the original point of collection of the sample with respect to ground zero. After embedding in an epoxy resin, the sample was then sliced to perform cross-sectional β- and α-autoradiograph. α-spectrometry was also carried out on a fine powder obtained by surface abrasion. In the β-autoradiography, hot spots were distinguishable in the proximity of the blast side, over a 1000 times less intense background of sand activation products. Also α-contamination (from ^239+240Pu and ²⁴¹Am) was mostly concentrated within the superficial layer, in a fraction of only 20% of the overall volume of the sample, exhibiting a discontinuous, droplet-like distribution. This evidence would partially support a recent hypothesis on trinitite formation according to which most of the glass layer was formed not on the ground but by a rain of material injected into the fireball that melted, fell back, and collected on a bed of already fused sand.     

Direct comparison of 210Po, 234Th and POC particle-size distributions and export fluxes at the Bermuda Atlantic Time-series Study (BATS) site

Particle-reactive, naturally occurring radionuclides are useful tracers of the sinking flux of organic matter from the surface to the deep ocean. Since the Joint Global Ocean Flux Study (JGOFS) began in 1987, the disequilibrium between ²³⁴Th and its parent ²³⁸U has become widely used as a technique to measure particle export fluxes from surface ocean waters. Another radionuclide pair, ²¹⁰Po and ²¹⁰Pb, can be used for the same purpose but has not been as widely adopted due to difficulty with accurately constraining the ²¹⁰Po/²¹⁰Pb radiochemical balance in the ocean and because of the more time-consuming radiochemical procedures. Direct comparison of particle flux estimated in different ocean regions using these short-lived radionuclides is important in evaluating their utility and accuracy as tracers of particle flux. In this paper, we present paired ²³⁴Th/²³⁸U and ²¹⁰Po/²¹⁰Pb data from oligotrophic surface waters of the subtropical Northwest Atlantic and discuss their advantages and limitations. Vertical profiles of total and particle size-fractionated ²¹⁰Po and ²³⁴Th activities, together with particulate organic carbon (POC) concentrations, were measured during three seasons at the Bermuda Atlantic Time-series Study (BATS) site. Both ²¹⁰Po and ²³⁴Th reasonably predict sinking POC flux caught in sediment traps, and each tracer provides unique information about the magnitude and efficiency of the ocean's biological pump.     

Anthropogenic radionuclides in sediment in the Japan Sea: distribution and transport processes of particulate radionuclides

Distributions of anthropogenic radionuclides (⁹⁰Sr, ¹³⁷Cs and ^239+240Pu) in seabed sediment in the Japan Sea were collected during the period 1998–2002. Concentration of ⁹⁰Sr, ¹³⁷Cs and ^239+240Pu in seabed sediment was 0.07–1.6 Bq kg⁻¹, 0.4–9.1 Bq kg⁻¹ and 0.002–1.9 Bq kg⁻¹, respectively. In the northern basin of the sea (Japan Basin), ^239+240Pu/¹³⁷Cs ratios in seabed sediment were higher and their variation was smaller compared to that in the southeastern regions of the sea. The higher ^239+240Pu/¹³⁷Cs ratios throughout the Japan Basin were considered to reflect production of Pu-enriched particles in the surface layer and substantial sinking of particulate materials in this region. In the southern regions of the Japan Sea (<38°N), both inventories and ^239+240Pu/¹³⁷Cs ratios in sediment were larger than those in the other regions. In the southern Japan Sea, observations suggested that supply of particulate radionuclides by the Tsushima Warm Current mainly enhanced accumulation of the radionuclides in this region.     

Deposition of artificial radionuclides from atmospheric Nuclear Weapon Tests estimated by soil inventories in French areas low-impacted by Chernobyl

Soil inventories of anthropogenic radionuclides were investigated in altitudinal transects in 2 French regions, Savoie and Montagne Noire. Rain was negligible in these 2 areas the days after the Chernobyl accident. Thus anthropogenic radionuclides are coming hypothetically only from Global Fallout following Atmospheric Nuclear Weapon Tests. This is confirmed by the isotopic signatures (²³⁸Pu/^239+240Pu; ¹³⁷Cs/^239+240Pu; and ²⁴¹Am/^239+240Pu) close to Global Fallout value. In Savoie, a peat core age-dated by ²¹⁰Pb_ex confirmed that the main part of deposition of anthropogenic radionuclides occurred during the late sixties and the early seventies. In agreement with previous studies, the anthropogenic radionuclide inventories are well correlated with the annual precipitations. However, this is the first time that a study investigates such a large panel of annual precipitation and therefore of anthropogenic radionuclide deposition. It seems that at high-altitude sites, deposition of artificial radionuclides was higher possibly due to orographic precipitations.     

Invariance of isotope ratios of lithogenic radionuclides: more evidence for their use as sediment source tracers

Activities of radionuclides in the 238U (230Th, 226Ra, 210Pb) and 232Th (232Th, 228Th, 228Ra) decay series were determined in sediments from an east Texas watershed and examined with isotope ratios and compared to particulate organic carbon (POC), % fines (<63 microm) and total concentrations of Al, Fe and Mn. The objective was to elucidate the presence or absence of relationships affecting the effectiveness of these radionuclides in modeling sediment transport. Strong positive correlations were observed between radionuclides and Mn (Th) and % fines (Ra and Th). Isotope ratios effectively reduce these influences, supporting the contention that isotope ratios offset extrinsic variability in terrestrial sediments. Strong associations of 210Pbxs (excess 210Pb) and 226Ra/230Th with POC agree with data from marine and terrestrial settings, indicating that the role of POC in isotope fractionation, transport and sequestration merits further investigation.     

Americium,plutonium and uranium contamination and speciation in well waters,streams and atomic lakes in the Sarzhal region of the Semipalatinsk Nuclear Test Site,Kazakhstan

New data are reported on the concentrations, isotopic composition and speciation of americium, plutonium and uranium in surface and ground waters in the Sarzhal region of the Semipalatinsk Test Site, and an adjacent area including the settlement of Sarzhal. The data relate to filtered water and suspended particulate from (a) streams originating in the Degelen Mountains, (b) the Tel′kem 1 and Tel′kem 2 atomic craters, and (c) wells on farms located within the study area and at Sarzhal. The measurements show that ²⁴¹Am, ^239,240Pu and ²³⁸U concentrations in well waters within the study area are in the range 0.04–87 mBq dm⁻³, 0.7–99 mBq dm⁻³, and 74–213 mBq dm⁻³, respectively, and for ²⁴¹Am and ^239,240Pu are elevated above the levels expected solely on the basis of global fallout. Concentrations in streams sourced in the Degelen Mountains are similar, while concentrations in the two water-filled atomic craters are somewhat higher. Suspended particulate concentrations in well waters vary considerably, though median values are very low, at 0.01 mBq dm⁻³, 0.08 mBq dm⁻³ and 0.32 mBq dm⁻³ for ²⁴¹Am, ^239,240Pu and ²³⁸U, respectively. The ²³⁵U/²³⁸U isotopic ratio in almost all well and stream waters is slightly elevated above the ‘best estimate’ value for natural uranium worldwide, suggesting that some of the uranium in these waters is of test-site provenance. Redox analysis shows that on average most of the plutonium present in the microfiltered fraction of these waters is in a chemically reduced form (mean 69%; 95% confidence interval 53–85%). In the case of the atomic craters, the proportion is even higher. As expected, all of the americium present appears to be in a reduced form. Calculations suggest that annual committed effective doses to individual adults arising from the daily ingestion of these well waters are in the range 11–42 μSv (mean 21 μSv). Presently, the ground water feeding these wells would not appear to be contaminated with radioactivity from past underground testing in the Degelen Mountains or from the Tel′kem explosions.