Assaying organochlorines in archived serum for a large, long-term cohort: implications of combining assay results from multiple laboratories over time

Conserving irreplaceable, archived serum samples may sometimes conflict with the objective of minimizing measurement error due to laboratory effects. We sought to determine whether we could successfully combine assay results for DDT-related compounds and polychlorinated biphenyls (PCBs) in serum from the same birth cohort obtained from different laboratories over time. Using the Child Health and Development Studies (CHDS) serum archive, we compared variability for assays of a quality control pool to variability for assays of subject serum. The quality control pool was created from native archived serum samples that were pooled, then aliquoted, blinded and inserted pair-wise into assay batches along with the subject serum for 5 studies using CHDS samples conducted over a 13year period by three different laboratories. We found that the variability between laboratory and over time within laboratory was small relative to inter-individual variability for p,p'-DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane), p,p'-DDE (1,1'-dichloro-2,2'-bis(p-chlorophenyl)ethylene) and o,p'-DDT (1,1,1-trichloro-2-(p-chlorophenyl)-2-(o-chlorophenyl)-ethane). Results were also consistent for most PCB congeners which were detectable in 85% or more of samples. Our results suggest that it is possible to combine assays for DDT and PCB congeners measured at positive levels as they are accumulated for cohort subjects without risking meaningful misclassification due to variation stemming from laboratory or time period. This has significant implications for future study costs, conservation of irreplaceable archived samples and for leveraging past investments for future research. For PCB congeners with very low levels, findings caution against pooling of assays without further exploration.     

Radioactivity in environmental samples: Calibration standards measurement methods,quality assurance,and data analysis

The numerous environmental radioactivity measurements made by and for the U.S. Environmental Protection Agency (U.S. EPA) include measurements on samples of water, urine, food, milk, and air filters. Calibration standards are listed which are available in the form of water solutions and soils for a wide range of radionuclides. Method validation procedures for U.S. EPA approval include protocol development and single-laboratory and multiple-laboratory evaluation for precision and accuracy. Interlaboratory comparison studies are conducted for both cross-check and performance evaluation samples and involve 295 federal, state, and local laboratories. For water samples, 80%–90% of the participating laboratories are within the control limits for most of the radionuclides measured; however, some problem areas exist, especially for radium-228 and strontium-89 and -90. For milk and food samples, more than 90% of the laboratories are within control limits for cobalt-60 and cesium-137 but some problems exist for the measurement of strontium-90, iodine-131, and potassium-40. For tritium, 91% of the laboratories are within the control limit for water samples and 87% are within the control limits for the urine samples. The laboratory performance for air filter samples shows some problems for gross beta, strontium-90 and cesium-137 measurements.     

Tissue radionuclide concentrations in water birds and upland birds on the Hanford Site (USA) from 1971-2009

Historical operations at the Hanford Site (Washington State, USA) have released a wide array of non-radionuclide and radionuclide contaminants into the environment. As a result, there is a need to characterize contaminant effects on site biota. Within this framework, the main purpose of our study was to evaluate radionuclide concentrations in bird tissue, obtained from the Hanford Environmental Information System (HEIS). The database was sorted by avian group (water bird vs. upland bird), radionuclide (over 20 analytes), tissue (muscle, bone, liver), location (onsite vs. offsite), and time period (1971-1990 vs. 1991-2009). Onsite median concentrations in water birds were significantly higher (Bonferroni P < 0.05) than those in onsite upland birds for Cs-137 in muscle (1971-1990) and Sr-90 in bone (1991-2009), perhaps due to behavioral, habitat, or trophic species differences. Onsite median concentrations in water birds were higher (borderline significance with Bonferroni P = 0.05) than those in offsite birds for Cs-137 in muscle (1971-1990). Onsite median concentrations in the earlier time period were significantly higher (Bonferroni P < 0.05) than those in the later time period for Co-60, Cs-137, Eu-152, and Sr-90 in water bird muscle and for Cs-137 in upland bird muscle tissue. Median concentrations of Sr-90 in bone were significantly higher (Bonferroni P < 0.05) than those in muscle for both avian groups and both locations. Over the time period, 1971-2009, onsite median internal dose was estimated for each radionuclide in water bird and upland bird tissues. However, a meaningful dose comparison between bird groups was not possible, due to a dissimilar radionuclide inventory, mismatch of time periods for input radionuclides, and lack of an external dose estimate. Despite these limitations, our results contribute toward ongoing efforts to characterize ecological risk at the Hanford Site.     

湖南省经济增长的资源环境代价评估

应用“含资源与环境项目的社会会计矩阵”（SAMRE）方法及其数学模型计算湖南省1991～1999年资源净产值、环境净产值和真实储蓄值。结果显示,湖南省资源净产值与环境净产值每年损失幅度为4.00亿～99.01亿元,占全省每年GDP比重的0.48％～3.18％,平均占2.35％。真实国民储蓄比传统国民经济核算体系的净储蓄减少10.41亿～109.60亿元,占全省每年GDP比重的1.25％～3.52％,平均占2.84％。分析表明自然资源损失与环境污染已成为湖南省经济总量增长的沉重代价,其发展呈弱可持续性特征。分析结果还同时显示,近年来资源与环境净产值损失占全省GDP的比重总体呈下降趋势,真实储蓄比重逐渐上升。     

Seasonal variations in activity concentrations of 99Tc and 137Cs in the edible meat fraction of crabs and lobsters from the central Irish Sea

Discharges of most radionuclides into the Irish Sea from the BNFL site at Sellafield have decreased over the past 20 years or so. For a few radionuclides, however, discharges have peaked more recently. Notably, operation of the Enhanced Actinide Removal Plant (EARP) since 1994 has led to an increase in discharges of (99)Tc, as a result of the treatment of previously stored waste, with consequent increases in (99)Tc activity concentrations in a number of marine species, particularly in crustaceans such as lobsters. Previous research has considered the significance of factors such as sex and body weight on radionuclide concentrations. The current project set out to investigate whether seasonal variations in radionuclide concentrations in crabs and lobsters occur, with particular emphasis on the dynamics of (99)Tc and (137)Cs. Organisms were obtained from a site off the Isle of Man, where radionuclide concentrations were measurable but the site was sufficiently distant from Sellafield that the radionuclides were well mixed in the water column and not likely to be influenced by the pulsed nature of discharges of (99)Tc. Crab and lobster samples were collected monthly, between February 2000 and February 2001. Fifteen or 16 individuals (evenly split as male and female) of each species were collected on each occasion. Seawater samples were also collected over the 12-month period. Activity concentrations of (99)Tc in the edible meat fraction (both brown and white meat) ranged from 0.23 to 2.46 Bq kg(-1) (fresh weight (fw)) in crabs and 124 to 216 Bq kg(-1) (fw) in lobsters, with no observed seasonal variations. Activity concentrations of (137)Cs in both crab and lobster were lower, ranging from <0.16 to 0.85 Bq kg(-1) for crab meat (fw) and <0.3 to 3.3 Bq kg(-1) for lobster meat (fw). A statistically significant increase in activity concentrations of (137)Cs in the meat was observed in the summer months for both crab and lobster. The cause has not been investigated but may be related to the laying down of energy reserves during the active feeding period over the summer. At all times, uptake of (99)Tc is higher in the brown meat fraction of both crabs and lobsters, whilst (137)Cs is more uniformly distributed. These results are used to discuss the implications for sampling and monitoring programmes.     

A soil sampling intercomparison exercise for the ALMERA network

Soil sampling and analysis for radionuclides after an accidental or routine release is a key factor for the dose calculation to members of the public, and for the establishment of possible countermeasures. The IAEA organized for selected laboratories of the ALMERA (Analytical Laboratories for the Measurement of Environmental Radioactivity) network a Soil Sampling Intercomparison Exercise (IAEA/SIE/01) with the objective of comparing soil sampling procedures used by different laboratories. The ALMERA network is a world-wide network of analytical laboratories located in IAEA member states capable of providing reliable and timely analysis of environmental samples in the event of an accidental or intentional release of radioactivity. Ten ALMERA laboratories were selected to participate in the sampling exercise. The soil sampling intercomparison exercise took place in November 2005 in an agricultural area qualified as a “reference site”, aimed at assessing the uncertainties associated with soil sampling in agricultural, semi-natural, urban and contaminated environments and suitable for performing sampling intercomparison. In this paper, the laboratories sampling performance were evaluated.     

1991－2001年南昌市土地利用/覆被变化特征研究

土地利用/覆被变化是区域变化的重要组成部分，是短时期内人类活动对自然环境改造的显著表现形式。南昌市地处京广线和沿海地区之间，属于经济欠发达地区的省会城市。近年来，社会经济发展迅速，城镇化进程明显加快，土地利用变化显著。文章利用1991—2001年南昌市土地详查和变更数据，分析南昌市土地利用/覆被变化特征，其基本结论有： （1）土地利用类型构成以耕地、水域和林地为主；（2）建设用地增幅显著，而耕地数量则呈下降态势，土地利用结构的变化与城镇的发展密切相关；（3）从土地利用程度看，不论是单项指标指数还是综合指数，南昌市均高于全国平均水平；（4）从时间序列看，南昌市土地利用/覆被的多样性指数和均匀度指数逐渐增大，而优势度指数逐渐减小，指数变化的趋势还表现为前一时期（1991—1996年）比后一时期（1996—2001年）要大，这表明土地利用/覆被的破碎化程度持续加强，但后期的加强程度呈弱化趋势。     

A rapid method for 90Sr determination in the presence of 137Cs in environmental samples

A rapid method for the determination of 90Sr in the presence of 137Cs using the Cherenkov radiation technique is described. The contribution of 137Cs to gross Cherenkov radiation (90Y + 137Cs) was examined for 137Cs /90Sr ratios ranging from 0.09 to 2.50 for 137Cs activities ranging from 2 to 1,211 Bq. Results from direct Cherenkov radiation measurement and results after radiochemical separation of 90Y from 90Sr for samples containing both 90Sr and 137Cs were compared. Errors below 5% were obtained for 137Cs /90Sr ratios lower than 1, when no separation was performed, independently of the activity level. However, errors between 10% and 35% were obtained for 137Cs/90Sr ratios higher than 1. In order to determine 90Sr activity in the presence of 137Cs using the Cherenkov technique, a multiple linear regression analysis model was established to correct the data for 137Cs content. The mathematical correction proposed was validated using 66 artificially contaminated lettuce samples in a laboratory experiment by taking into account the activity levels of 137Cs and 90Sr and the radionuclide ratios. Comparison of mathematically corrected radionuclide ratios with the results obtained without correction shows that, for radionuclide ratios higher than 1, error values for measuring 90Sr activity using the mathematical model were much smaller than when no radiochemical separation was performed. On the other hand, for ratios lower than 1, error values when measuring 90Sr activity with radiochemical separation were smaller than when mathematical correction was performed. In spite of this, the mathematical correction is an appropriate way of reducing the time needed to determine radiostrontium using the Cherenkov radiation technique. The method proposed could be a powerful tool for environmental research whenever the contents of 90Sr and 137Cs have to be determined.     

Radioecological consequences of radioactive discharges into the Techa River on the Southern Urals

The sources and levels of radioactive contamination of the Techa River are analyzed. Dose assessments are made for humams and biota. The highest radionuclide concentrations in the river water were observed in the period 1950–1951. In 1951, at a distance of 78 km from the site of radioactive discharges, the content of ⁹⁰Sr in the water was 2.7 × 10⁴ Bq l⁻¹ and that of ¹³⁷Cs was 7.5 × 10³ Bq l⁻¹. Subsequently, the radionuclide activity in the river water decreased considerably. In the period 1991–1994, the average annual content of ⁹⁰Sr in the water varied between 6 and 20 Bq l⁻¹. The average annual content of ¹³⁷Cs in the river water varied from 0.06 to 0.23 Bq l⁻¹, i.e. was lower than that of ⁹⁰Sr approximately by two orders of magnitude. The concentration of ^239,240Pu in the water varied between 0.004 and 0.019 Bq l⁻¹. The radioactive contamination of the Techa floodplain is highly nonuniform. With increasing distance from the river sources, the contamination density of the floodplain decreases, remaining, however, considerably higher than the background values.At present, the average annual dose rates in contaminated areas are (0.1–2) × 10⁻³ Sv year⁻¹, which is considerably lower than in the periods of ‘acute’ exposure (1950–1951). The doses to aquatic biota were much higher than those to humans.     

Radioactivity concentration in liquid and solid phases of scale and sludge generated in the petroleum industry

Scales and sludge generated during oil extraction and production can contain uranium, thorium, radium and other natural radionuclides, which can cause exposure of maintenance personnel. This work shows how the oil content can influence the results of measurements of radionuclide concentration in scale and sludge. Samples were taken from a PETROBRAS unit in Northeast Brazil. They were collected directly from the inner surface of water pipes or from barrels stored in the waste storage area of the E&P unit. The oil was separated from the solids with a Soxhlet extractor by using aguarras at 90+/-5 degrees C as solvent. Concentrations of 226Ra and 228Ra in the samples were determined before and after oil extraction by using an HPGe gamma spectrometric system. The results showed an increase in the radionuclide concentration in the solid (dry) phase, indicating that the above radionuclides concentrate mostly in the solid material.     

Radionuclides from past uranium mining in rivers of Portugal

During several decades and until a few years ago, uranium mines were exploited in the Centre of Portugal and wastewaters from uranium ore milling facilities were discharged into river basins. To investigate enhancement of radioactivity in freshwater ecosystems, radionuclides of uranium and thorium series were measured in water, sediments, suspended matter, and fish samples from the rivers Vouga, D?o, Távora and Mondego. The results show that these rivers carry sediments with relatively high naturally occurring radioactivity, and display relatively high concentrations of radon dissolved in water, which is typical of a uranium rich region. Riverbed sediments show enhanced concentrations of radionuclides in the mid-section of the Mondego River, a sign of past wastewater discharges from mining and milling works at Urgeiri?a confirmed by the enhanced values of (238)U/(232)Th radionuclide ratios in sediments. Radionuclide concentrations in water, suspended matter and freshwater fish from that section of Mondego are also enhanced in comparison with concentrations measured in other rivers. Based on current radionuclide concentrations in fish, regular consumption of freshwater species by local populations would add 0.032 mSv a(-1) of dose equivalent (1%) to the average background radiation dose. Therefore, it is concluded that current levels of enhanced radioactivity do not pose a significant radiological risk either to aquatic fauna or to freshwater fish consumers.     

Erosion of atmospherically deposited radionuclides as affected by soil disaggregation mechanisms

The interactions of soil disaggregation with radionuclide erosion were studied under controlled conditions in the laboratory on samples from a loamy silty-sandy soil. The fate of 134Cs and 85Sr was monitored on soil aggregates and on small plots, with time resolution ranging from minutes to hours after contamination. Analytical experiments reproducing disaggregation mechanisms on aggregates showed that disaggregation controls both erosion and sorption. Compared to differential swelling, air explosion mobilized the most by producing finer particles and increasing five-fold sorption. For all the mechanisms studied, a significant part of the contamination was still unsorbed on the aggregates after an hour. Global experiments on contaminated sloping plots submitted to artificial rainfalls showed radionuclide erosion fluctuations and their origin. Wet radionuclide deposition increased short-term erosion by 50% compared to dry deposition. A developed soil crust when contaminated decreased radionuclide erosion by a factor 2 compared to other initial soil states. These erosion fluctuations were more significant for 134Cs than 85Sr, known to have better affinity to soil matrix. These findings confirm the role of disaggregation on radionuclide erosion. Our data support a conceptual model of radionuclide erosion at the small plot scale in two steps: (1) radionuclide non-equilibrium sorption on mobile particles, resulting from simultaneous sorption and disaggregation during wet deposition and (2) later radionuclide transport by runoff with suspended matter.     

Measurements of 60Co in spoons activated by neutrons during the JCO criticality accident at Tokai-mura in 1999

Neutron activated items from the vicinity of the place where the JCO criticality accident occurred have been used to determine the fluence of neutrons around the facility and in nearby residential areas. By using underground laboratories for measuring the activation products, it is possible to extend the study to also cover radionuclides with very low activities from long-lived radionuclides. The present study describes gamma-ray spectrometry measurements undertaken in a range of underground laboratories for the purpose of measuring (60)Co more than 2 years after the criticality event. The measurements show that neutron fluence determined from (60)Co activity is in agreement with previous measurements using the short-lived radionuclides (51)Cr and (59)Fe. Limits on contamination of the samples with (60)Co are evaluated and shown to not greatly affect the utility of neutron fluence determinations using (60)Co activation.     

The use of extraction chromatography resins to concentrate actinides and strontium from soil for radiochromatographic analyses

An analytical technique utilizing selective extractant resins to concentrate strontium and actinides from soil followed by separation with radiochromatography was evaluated. The technique was tested using uncontaminated soil samples spiked with a radionuclide tracer solution that were either microwave-aided acid digested or leached with a strong acid. Extraction of the strontium and actinides from the acidified solution was accomplished using a serial arrangement of Sr-Resin and TRU-Resin columns. The combined eluate solutions from the extraction resins were treated with HNO(3) and H(2)O(2) to oxidize residual extractant and eluates prior to separation and analysis of the radionuclides by radiochromatography. Chromatograms obtained with larger soil mass loadings resulted in either incomplete peak resolution of the tracers or had highly variable peak elution times, indicative of an ionic interfering constituent(s). Better separations (e.g., chromatograms that resolved all radioactive constituents) were obtained when the sample mass loading was decreased, but with a concurrent decreased sensitivity for the radionuclides. Elemental analyses of the soil were conducted to provide data on the ionic constituents in unprocessed soil and post-processed soil samples. These results identified aluminum as an interfering contributor to the poor performance exhibited by the radiochromatographic separations.     

A study of radionuclides, metals and stable lead isotope ratios in sediments and soils in the vicinity of natural U-mineralisation areas in the Northern Territory

Australian guidelines recommend that tailings materials from uranium (U) mining and milling be contained without any detrimental impact on the environment for at least 1000 years. Natural analogue sites are being investigated to determine if they can provide data on the rates of natural erosion processes which occur over these timescales, for input into predictive geomorphic computer models. This paper presents radionuclide, metal and stable lead (Pb) isotope data from sediment cores and surface soils in the vicinity of two mineralised areas in the Alligator Rivers Region.Surface scrapes from the natural Anomaly #2, south of the Ranger mineral lease, exhibit radiogenic ²⁰⁶Pb/²⁰⁷Pb and ²⁰⁸Pb/²⁰⁷Pb ratios, and elevated U and metal concentrations typical for a near surface U anomaly. In contrast, samples taken from the Koongarra mineral lease (KML) show radionuclide activity and metal concentrations similar to natural areas elsewhere in the Alligator Rivers Region and Pb isotope ratios are closer to present day average crustal ratios (PDAC), as the orebodies at KML are covered by surficial sand. A sediment core collected from Anbangbang Billabong, downstream of KML, exhibits small variations in Pb isotope ratios that indicate that approximately 1% of the upper sediments in the sediment core may be derived from material originating from the U anomaly at Koongarra.     

National monitoring of PCDD/DFs in environmental media around incinerators in Korea

To examine the levels of PCDD/DFs pollution in environmental samples in the vicinity of various incinerators, the levels of PCDD/DFs in air and soil samples collected near 17 incinerators and stack emission gases were investigated between 2003 and 2006. A total of 434 soil, 28 stack emission gas, and 38 air samples were analyzed for their PCDD/DFs concentrations. The PCDD/DFs concentrations in the flue gas samples ranged from 0.02 to 16.41 ng I-TEQ/Sm(3), with an arithmetical mean value of 3.13 ng I-TEQ/Sm(3). The PCDD/DFs concentrations in the air samples ranged from 0.032 to 0.965 pg I-TEQ/Sm(3). The soil samples contained between N.D. and 153.23 pg I-TEQ/g-dry, with an average of 7.36 pg I-TEQ/g-dry. These levels were generally consistent with or lower than many previous studies. The average PCDD/DFs levels in the soil samples decrease with increasing distance from the incinerator. From the PCDD/DFs level gradient from each plant, a distance of 500 m is suggested as being under the influence of an incinerator.     

Vertical migration of 60Co, 137Cs and 226Ra in agricultural soils as observed in lysimeters under crop rotation

In most studies quantifying the migration parameters - apparent migration velocity and apparent dispersion coefficient - of radionuclides in the soil by model calculations, these parameters are determined for undisturbed soils. For soils disturbed by ploughing, however, no such data are available in the literature. Therefore, in the present study, the migration parameters of (137)Cs, (60)Co and (226)Ra were estimated for ploughed soils by means of a convection-dispersion model. The depth distributions of the radionuclides were determined in four lysimeters (area: 1m(2), depth of soil monolith: 0.75m) filled with artificially contaminated soils of different types in July 1990. The lysimeters were cropped with agricultural plants. The soil in each lysimeter was ploughed manually once a year until 1996 (plough depth 20cm). In July 1999, soil samples were collected from three pits in each lysimeter. The depth distributions of all radionuclides proved to be very similar in each soil pit. The spatial variability of the depth distributions of a given radionuclide within the lysimeters was about the same as their variability between the four lysimeters. Evaluation of the migration parameters revealed that the convective transport of the radionuclides was always rather small or even zero, while the dispersive transport caused a "melting" process of the initially sharp activity edge at the lower border of the Ap horizon. These results are explained by the high evapotranspiration (80-90% of the total precipitation plus irrigation) and the small amounts of seepage water during the observation period of 9 years.     

Chemical availability of 137Cs and 90Sr in undisturbed lysimeter soils maintained under controlled and close-to-real conditions

Chemical availability of 137Cs and 90Sr was determined in four undisturbed soils in a lysimeter study three and four years after deposition to the soil surface. The study was part of a larger project on radionuclide soil-plant interactions under well-defined conditions. The soil types were loam, silt loam, sandy loam and loamy sand, and were representatives of important European soil and climatic conditions. The lysimeters were installed in greenhouses with climatic and hydrological control, and were contaminated with 137Cs and 90Sr in an aerosol mixture simulating fallout from a nuclear accident. Soil samples were taken from several depths in each soil in 1997 and 1998 and the samples were sequentially extracted with H2O, NH4Ac, NH2OH.HCl, H2O2 and HNO3. Extractability of 137Cs decreased in the order: HNO3 > R-esidual > or = NH4Ac > H2O2 > or = NH2OH.HCl > or = H2O. More than 80% was found in the acid digestible or residual fractions, and 11-17% in labile fractions. Soil type differences were small. Extractability of 90Sr decreased in the order: NH4Ac > NH2OH.HCl > HNO3 > H2O2 approximately H2O. 31-58% was found in easily available fractions. Differences between soil types were quite small. The results suggest that availability of 137Cs for plant uptake and migration is low, whereas availability of 90Sr is rather high.