Fukushima radionuclides in Vilnius/Lithuania aerosols: Modelling of aerosol transport

Measurements of activity concentrations of ¹³¹I; ^129mTe, ¹³²Te, ¹³⁴Cs and; ¹³⁶Cs, ¹³⁷Cs in aerosol were carried out in daily samples after the Fukushima accident during the period of March–April, 2011 in Vilnius. The maximum activity concentrations of ¹³¹I and ¹³⁷Cs were found to be 3700 μBq m⁻³ and 1040 μBq m⁻³, respectively. Variations in activity ratios of ¹³²Te/^129mTe and ¹³⁷Cs/¹³⁶Cs observed after the accident were explained by the decay of the short-lived isotopes, while those in ¹³⁴Cs/¹³⁷Cs by the dilution effect of the Chernobyl-derived ¹³⁷Cs. It was found that different behaviours of highly volatile ¹³¹I and ¹³⁷Cs resulted in enrichment of ground level aerosol particles by ¹³¹I with respect to ¹³⁷Cs. Simulated activity concentrations of ¹³⁷Cs attached to aerosol particles for the Vilnius site reasonably agreed with measured activities in aerosol samples during the Fukushima accident.     

Distribution of radionuclides in soil samples from a petrified wood forest in El-Qattamia,Cairo, Egypt

The concentrations and distribution of radionuclides in a petrified wood forest in El-Qattamia have been determined using high-resolution gamma spectrometry to evaluate the environmental radioactivity. The mean activity concentrations of ²³⁸U, ²³²Th and ⁴⁰K were 65.26±12.99, 23.66±0.95 and 146.33±1.50 Bq kg⁻¹, respectively.Data of the soil samples show evidence of possible deposition and accumulation of ¹³⁷Cs. The mean activity concentration of ¹³⁷Cs in the soil samples was 4.37±0.16 Bq kg⁻¹ with a range of 0.00–35.70 Bq kg⁻¹. The measured activity concentration range of ¹³⁷Cs was compared with reported ranges in the literature from some of the other locations in the world. The radium-equivalent, dose rate in air and annual effective dose rate were evaluated. The mean activity concentrations of the γ-ray emissions from radionuclides in El-Qattamia petrified wood forest region were relatively low.     

How to assess the sensitivity and related uncertainty of a new solid state passive thoron measuring device

To test the sensitivity of our CR-39 alpha-track detector thoron passive device (ATD-TnPD), a closed-circuit exposure facility, composed by a new thoron source, a small exposure chamber and a new absolute ²²⁰Rn active monitor (TnM), was set up. ²²⁰Rn exposure was evaluated by assessing the TnM response and its combined uncertainty. The ATD-TnPD's sensitivity was determined by three thoron exposures, tested at different etching times. A non-linear relationship on etching conditions was obtained, with values in the range 1.54–1.76 (tracks cm²)(kBq h m⁻³)⁻¹.     

Presence of a radioactive gas in archaeological excavations,determination and mitigation

During recent archaeological discovery and excavation of a tunnel build approximately 2000 years ago by the Teotihuacans under the feathered serpent temple, in Mexico, abnormal radon concentrations up to 700 Bq m⁻³ were measured at several excavation stages. The tunnel is at 15 m below the earth surface with a vertical rectangular entrance of 4×4 m², a semi cylindrical shape of 3 m in diameter, with a probable length of 100 m.This study supports the assumption that at the opening of the tunnel radon concentration was around 5500 Bq m⁻³; however, although natural convection in the tunnel atmosphere naturally pups radon out, it build up to a maximum concentration of 2000 Bq m⁻³. This paper presents the identification of the radon problem in this archaeological site, dose determination, and the mitigation actions that reduced the radon concentration down to 40 Bq m⁻³ that ensure a negligible radon risk for archaeologist.     

Natural gamma-ray spectrometry as a tool for radiation dose and radon hazard modelling

We reviewed the calibration procedures of gamma-ray spectrometry with particular emphasis to factors that affect accuracy, detection limits and background radiation in field measurements for dosimetric and radon potential mapping. Gamma-ray spectra were acquired in western Liguria (Italy). The energy windows investigated are centred on the photopeaks of ²¹⁴Bi (1.76 MeV), ²⁰⁸Tl (2.62 MeV) and ⁴⁰K (1.46 MeV). The inferred absorbed dose rate and the radon flux are estimated to be lower than 60 nGy h⁻¹ and 22 Bq m⁻² h⁻¹, respectively.     

The effect of uranium migration on radionuclide distributions for soil samples at the El-Gor area,Sinai, Egypt

The concentrations and distributions of the activity of natural radionuclides in soil samples were investigated in fifteen soil samples at El-Gor area representing two profiles (A and B) using a HP–Ge detector and alpha counting by SSNTD (CR-39), respectively. The average concentrations of the radionuclides ²³⁸U, ²²⁶Ra, ²³⁵U, ²³²Th and ⁴⁰K are 203.4, 177.23, 9.77, 43.33 and 386.22 Bq kg⁻¹ (dry weight), respectively, and profile A and ²³⁸U, ²²⁶Ra, ²³⁵U, ²³²Th and ⁴⁰K have average concentrations of 232.58, 246, 11.7, 31.7, and 277.07 Bq kg⁻¹ for profile B, respectively. The eTh and eU were estimated to detect the migration process of uranium into or out of an area or uranium to or from the studied profiles. The results indicate a migration of uranium by 29% for profile A and 65.37% for profile B. The activity ratio (²³⁸U/²²⁶Ra) was found to be 0.9 in profile A and 1.15 in profile B. These ratios coincide with the uranium migration processes. The responsible mass corresponding to the measured ²²⁶Ra activity was also calculated. The radon activity concentrations for the two profiles are nearly 300 Bq m⁻³. The emanation coefficient (η) was calculated from the ratio of the expected radon activity to the measured radon for the studied soil samples. The value of η was found to depend only on the radium activity regardless to soil formation.     

Measurement of natural radionuclides in phosphgypsum using an anti-cosmic gamma-ray spectrometer

Gamma-ray spectrometry measurements have been carried out to determine the activity of natural radionuclides in a phosphogypsum sample included in a specific tight container. The gamma spectrometer includes an N-type coaxial high-purity germanium (HPGe) detector equipped with an anti-cosmic system. This measurement required the determination of linear attenuation coefficients of phosphogypsum to calculate self-absorption correction between efficiency calibration conditions and measurement ones. The results are given for the three natural chains and for ⁴⁰K, in term of specific activity/g of dry material, ranging from a few Bq kg⁻¹ to a few hundreds Bq kg⁻¹. The equilibrium within the different families and the ²³⁵U/²³⁸U ratio are discussed.     

Radium-226 concentration in spring water sampled in high radon regions

Water ²²⁶Ra concentration in springs was measured in regions with high indoor radon: Ural, North Caucasus (Russia), Niska Banja (Serbia), Piestany (Slovakia), and Issyk-Kul (Kyrgyzstan). This paper presents the results for ²²⁶Ra concentration above 0.03 Bq l^–1. Radium in water could indicate indoor radon problem in the region and water investigation is useful at the initial stage of radon survey. Even low ²²⁶Ra concentration in water (0.1–0.6 Bq l^–1) caused high ²²⁶Ra activity in travertine (up to 1500 Bq kg^?1), which resulted in indoor radon concentration above 2000 Bq m^?3 (Niska Banja).     

Enrichment and vertical profiles of 210Po and 210Pb in monazite areas of coastal Karnataka

A study on radiation level and radionuclide distribution in the environment of coastal Karnataka has revealed the presence of low-level monazite deposit in the Ullal beach area. The paper presents systematic studies on the distribution, enrichment and vertical profiles of ²¹⁰Po and ²¹⁰Pb, important daughter products of ²³⁸U, in Ombattu Kere, Summer Sand and the Bhagavathi Temple region of the Ullal beach area of coastal Karnataka. Sand samples collected at different depths from these locations were analyzed for ²¹⁰Po and ²¹⁰Pb activities to understand the distribution, enrichment and vertical profiles of these radionuclides in monazite area. The activity of ²¹⁰Po in the Ullal region is found to vary from 1.7 to 43.2 Bq kg^?1 with a mean value of 11.2 Bq kg^?1 and that of ²¹⁰Pb varies from 1.0 to 66.7 Bq kg^?1 with a mean value of 19.1 Bq kg^?1. The mean ²¹⁰Po/²¹⁰Pb ratio was observed to be 0.6. The absorbed gamma dose rate in the region varies in the range 39–460 nGy h^?1 with a mean value of 193 nGy h^?1.     

The calibration and evaluation of a radioactive waste drum counting system

The drum counting system was calibrated in this study. For ¹³⁷Cs, the counting efficiencies were around 14–1% when the density of the waste of the drum was changed from 0.15 to 2.3 g cm⁻³. The effects of the background, hot spot, system linearity, sample density and weighing were also evaluated in this work. The combined standard uncertainty of the drum counting system for the ¹³⁷Cs in the density of 1 g cm⁻³ was around 12%. To verify the counting system, the drums containing radioactive solution were prepared by the NMI as the blind samples. A discrepancy below 15% was shown between the counting results and the reference values of the NMI.     

Results of an IAEA inter-comparison exercise to assess 137Cs and total 210Pb analytical performance in soil

Fallout radionuclides (FRNs) such as ²¹⁰Pb and ¹³⁷Cs have been widely used to assess soil erosion and sedimentation processes. It is of major importance to obtain accurate analytical results of FRNs by gamma analysis before any data treatment through conversion model and to allow subsequent comparison of erosion and sedimentation rates from different case studies.Therefore, IAEA organized an inter-comparison exercise to assess the validity and reliability of the analytical results of ¹³⁷Cs and total ²¹⁰Pb using γ-spectrometry in the various laboratories participating in the IAEA Co-ordinated Research Project on “Assess the effectiveness of soil conservation measures for sustainable watershed management using fallout radionuclides”.Reference materials were distributed to 14 participating laboratories and, using a rating system, their analytical results were compared to the reference values assigned.In the case of ¹³⁷Cs, the analytical results were satisfactory with 66% of the laboratories producing acceptable results. Only the sample with low ¹³⁷Cs activity (2.6±0.2 Bq kg⁻¹) gave less accurate results with more than 25% not acceptable results. The total ²¹⁰Pb analysis indicated a clear need for corrective actions in the analysis process as only 36% of the laboratories involved in the proficiency test was able to access total ²¹⁰Pb with occurrence (bias ⩽10%). This inter-laboratory test underlines that further inter-comparison exercises should be organized by IAEA or regional laboratories to ensure the quality of the analytical data produced in Member States. As a result of the above-mentioned proficiency test, some recommendations have been provided to improve accurate gamma measurement of both ¹³⁷Cs and total ²¹⁰Pb.     

Measurement of tritium with high efficiency by using liquid scintillation counter with plastic scintillator

The detection efficiencies of tritium samples by using liquid scintillation counter with hydrophilic plastic scintillator (PS) was approximately 48% when the sample of 20 μL was held between 2 PS sheets treated by plasma. The activity and count rates showed a good relationship between 400 Bq to 410 KBq mL⁻¹. The calculated detection limit of 2 min measurement by the PS was 13 Bq mL⁻¹ when a confidence was 95%. The plasma method for PS produces no radioactive waste.     

Dosimetry for 131Cs and 125I seeds in solid water phantom using radiochromic EBT film

PurposeTo measure the 2D dose distributions with submillimeter resolution for ¹³¹Cs (model CS-1 Rev2) and ¹²⁵I (model 6711) seeds in a Solid Water phantom using radiochromic EBT film for radial distances from 0.06 cm to 5 cm. To determine the TG-43 dosimetry parameters in water by applying Solid Water to liquid water correction factors generated from Monte Carlo simulations.MethodsEach film piece was positioned horizontally above and in close contact with a ¹³¹Cs or ¹²⁵I seed oriented horizontally in a machined groove at the center of a Solid Water phantom, one film at a time. A total of 74 and 50 films were exposed to the ¹³¹Cs and ¹²⁵I seeds, respectively. Different film sizes were utilized to gather data in different distance ranges. The exposure time varied according to the seed air-kerma strength and film size in order to deliver doses in the range covered by the film calibration curve. Small films were exposed for shorter times to assess the near field, while larger films were exposed for longer times in order to assess the far field. For calibration, films were exposed to either 40 kV (M40) or 50 kV (M50) x-rays in air at 100.0 cm SSD with doses ranging from 0.2 Gy to 40 Gy. All experimental, calibration and background films were scanned at a 0.02 cm pixel resolution using a CCD camera-based microdensitometer with a green light source. Data acquisition and scanner uniformity correction were achieved with Microd3 software. Data analysis was performed using ImageJ, FV, IDL and Excel software packages. 2D dose distributions were based on the calibration curve established for 50 kV x-rays. The Solid Water to liquid water medium correction was calculated using the MCNP5 Monte Carlo code. Subsequently, the TG-43 dosimetry parameters in liquid water medium were determined.ResultsValues for the dose-rate constants using EBT film were 1.069±0.036 and 0.923±0.031 cGy U⁻¹ h⁻¹ for ¹³¹Cs and ¹²⁵I seed, respectively. The corresponding values determined using the Monte Carlo method were 1.053±0.014 and 0.924±0.016 cGy U⁻¹ h⁻¹ for ¹³¹Cs and ¹²⁵I seed, respectively. The radial dose functions obtained with EBT film measurements and Monte Carlo simulations were plotted for radial distances up to 5 cm, and agreed within the uncertainty of the two methods. The 2D anisotropy functions obtained with both methods also agreed within their uncertainties.ConclusionEBT film dosimetry in a Solid Water phantom is a viable method for measuring ¹³¹Cs (model CS-1 Rev2) and ¹²⁵I (model 6711) brachytherapy seed dose distributions with submillimeter resolution. With the Solid Water to liquid water correction factors generated from Monte Carlo simulations, the measured TG-43 dosimetry parameters in liquid water for these two seed models were found to be in good agreement with those in the literature.     

Dose-response between frequency of breaks in sedentary time and glucose control in type 2 diabetes: A proof of concept study

ObjectivesThis study aimed to investigate dose-response between frequency of breaks in sedentary time and glucose control.DesignRandomised three-treatment, two-period balanced incomplete block trial.MethodsTwelve adults with type 2 diabetes (age, 60 ± 11 years; body mass index, 30.2 ± 4.7 kg/m²) participated in two of the following treatment conditions: sitting for 7 h interrupted by 3 min light-intensity walking breaks every (1) 60 min (Condition 1), (2) 30 min (Condition 2), and (3) 15 min (Condition 3). Postprandial glucose incremental area under the curves (iAUCs) and 21-h glucose total area under the curve (AUC) were measured using continuous glucose monitoring. Standardised meals were provided.ResultsCompared with Condition 1 (6.7 ± 0.8 mmol L⁻¹ × 3.5 h⁻¹), post-breakfast glucose iAUC was reduced for Condition 3 (3.5 ± 0.9 mmol L⁻¹ × 3.5 h⁻¹, p ˂ 0.04). Post-lunch glucose iAUC was lower in Condition 3 (1.3 ± 0.9 mmol L⁻¹ × 3.5 h⁻¹, p ˂ 0.03) and Condition 2 (2.1 ± 0.7 mmol L⁻¹ × 3.5 h⁻¹, p ˂ 0.05) relative to Condition 1 (4.6 ± 0.8 mmol L⁻¹ × 3.5 h⁻¹). Condition 3 (1.0 ± 0.7 mmol L⁻¹ × 3.5 h⁻¹, p = 0.02) and Condition 2 (1.6 ± 0.6 mmol L⁻¹ × 3.5 h⁻¹, p ˂ 0.04) attenuated post-dinner glucose iAUC compared with Condition 1 (4.0 ± 0.7 mmol L⁻¹ × 3.5 h⁻¹). Cumulative 10.5-h postprandial glucose iAUC was lower in Condition 3 than Condition 1 (p = 0.02). Condition 3 reduced 21-h glucose AUC compared with Condition 1 (p < 0.001) and Condition 2 (p = 0.002). However, post-breakfast glucose iAUC, cumulative 10.5-h postprandial glucose iAUC and 21-h glucose AUC were not different between Condition 2 and Condition 1 (p ˃ 0.05).ConclusionsThere could be dose-response between frequency of breaks in sedentary time and glucose. Interrupting sedentary time every 15 min could produce better glucose control.     

Spatial distributions of 137Cs and 239+240Pu in surface seawater within the Exclusive Economic Zone of East Coast Peninsular Malaysia

The studies of ¹³⁷Cs and ^239+240Pu distributions in surface seawater at South China Sea within the Exclusive Economic Zone (EEZ) of Peninsular Malaysia were carried out in June 2008. The analysis results will serve as additional information to the expanded baseline data for Malaysia’s marine environment. Thirty locations from extended study area were identified in the EEZ from which large volumes of surface seawater samples were collected. Different co-precipitation techniques were employed to concentrate cesium and plutonium separately. A known amount of ¹³⁴Cs and ²⁴²Pu tracers were used as yield determinant. The precipitate slurry was collected and oven dried at 60 ^oC for 1–2 days. Cesium precipitate was fine-ground and counted using gamma-ray spectrometry system at 661.62 keV, while plutonium was separated from other radionuclides using anion exchange, electrodeposited and counted using alpha spectrometry. The activity concentrations of ¹³⁷Cs and ^239+240Pu were in the range of 3.40–5.89 Bq/m³ and 2.3–7.9 mBq/m³, respectively. The ^239+240Pu/¹³⁷Cs ratios indicate that there are no new inputs of these radionuclides into the area.     

Modelling the relationships between volume,intensity and injury-risk in professional rugby league players

ObjectiveThis study aimed to: (a) identify the association between external-workloads and injury-risk in the subsequent week; and (b) understand the effectiveness of workload variables in establishing injury-risk.DesignRetrospective cohort study.MethodsWorkload and injury data (soft-tissue) were collected from forty-eight professional male rugby league players. Load variables included duration (min), total distance (m), relative distance (m min⁻¹), high speed distance ([m]>20 km h⁻¹), very-high speed distance ([m]>25 km h⁻¹), acceleration and deceleration efforts (count) and PlayerLoad (Arbitrary Unit: AU). Cumulative two-, three- and four-weekly loads; Acute:Chronic Workload Ratio (ACWR); Mean-Standard Deviation Workload Ratio (MSWR) and strain values were calculated and divided into three equally-sized bins (low, moderate and high). Generalised Estimating Equations analysed relationships between workload variables and injury probability in the subsequent week.ResultsInjury-risk increased alongside increases in the ACWR for duration, total distance and PlayerLoad. Conversely, injury-risk decreased (Area Under Curve: 0.569–0.585) with increases in the four-weekly duration, total distance, accelerations, decelerations and PlayerLoad. For relative distance, high four-weekly workloads (high: >60 m min⁻¹) demonstrated a positive association with injury-risk, whilst high two-weekly loads (high: >82 m min⁻¹) were negatively associated.ConclusionsA range of external workload metrics and summary statistics demonstrate either positive or negative associations with injury-risk status. Such findings provide the framework for the development of decision-support systems in which external workload metrics (e.g. total or high speed distance) can be uniquely and routinely monitored across a range of summary statistics (i.e. cumulative weekly loads and ACWR) in order to optimise player performance and welfare.     

137Cs tracing dynamics of soil erosion,organic carbon and nitrogen in sloping farmland converted from original grassland in Tibetan plateau

There is a shortage of research concerning the relationships between land-use change, soil erosion, and soil organic carbon (SOC) and nitrogen (N) dynamics in alpine environments such as those found in the Tibetan plateau. In this paper, typical sloping farmlands converted from grassland 50 years ago in eastern Tibet were selected to determine dynamics of soil erosion, SOC, and total N associated with land-use change. Soil samples were collected from sloping farmland and control fields (grassland). The ¹³⁷Cs, SOC, total N contents, and soil particle size fractions were analyzed in these samples. As compared with the control fields, ¹³⁷Cs, SOC, and total N inventories in the sloping farmlands decreased by 30%, 27%, and 33%, respectively. Meanwhile variations in the three parameters were enhanced in the sloping farmlands, with coefficients of variation (CVs) of 38%, 23%, and 20%, respectively, for ³⁷Cs, SOC, and total N. In addition, SOC and total N inventories significantly decreased with increasing soil erosion in the sloping farmland. In a sloping farmland with a steep 24° gradient, the ¹³⁷Cs inventory gradually increased along a downslope transect with its lowest value at 0 Bq m^?2 in the top-slope position (0 m). The soil clay (<0.002 mm) content in such an area increased with decreasing elevation (r=?0.95, p=0.001). Significant correlations between ¹³⁷Cs and clay (r=0.92, p=0.003), SOC (r=0.96, p=0.001), or total N (r=0.95, p=0.001) were also found in the farmland. These results showed that converting alpine grassland to sloping farmland accelerates soil erosion, losses in SOC and N, and increases the soil’s spatial variability. The combined impacts of tillage and water erosion contributed a significant decrease in the soil’s organic carbon and N storages. Particularly in steep sloping farmlands, tillage erosion contributed for severe soil loss, but the soil redistribution pattern was dominated by water erosion, not tillage erosion, due to the lack of boundaries across the field patches. It was also found that ¹³⁷Cs, SOC, and total N moved along the same pathway within these sloping farmlands, resulting in net C and N losses during soil redistribution. The negative influences of land-use conversion from grassland to farmland in sloping areas in the Tibetan plateau should be addressed.     

Overground vs. treadmill walk-to-run transition

Determination of the walk-to-run transition (WRT) speed is a crucial aspect of gait transition research, which has been conducted on treadmill as well as overground. Overground WRT-speeds were reported to be higher than on treadmill.Part of this difference could be related to the lower acceleration magnitudes on treadmill. In this study, spontaneous WRT overground was compared to WRT at a comparable acceleration on treadmill. In addition, calculation procedures correcting for movement in the lab reference frame on treadmill were implemented. As such, this study was, in contrast to previous treadmill studies, able to detect a speed jump. This speed jump was until now a typical feature of overground WRT and contributed to the higher transition speed.By incorporating horizontal movements of the COM, a speed jump was also detected on treadmill. Yet, treadmill WRT-speed (2.61 m s⁻¹) remained lower than overground (2.85 m s⁻¹). Nevertheless, this difference was much smaller than assumed in the literature. The remaining difference could be explained by a larger speed jump (treadmill: 0.40 m s⁻¹; overground: 0.51 m s⁻¹), and a higher speed at the start of the transition step overground (treadmill: 2.21 m s⁻¹; overground: 2.34 m s⁻¹).In conclusion, even when controlling for effects of acceleration and movement in the lab reference frame a treadmill influence on WRT was visible.