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In this research radon concentrations in soil samples of some sites of the College of Education for Women, University of Tikrit, were measured using CR-39 nuclear impact detector. Soil samples were prepared according to classical protocols whereby they were irradiated for a period of 65 days in propagation chambers chemically treated and subjected to optical microscopy to calculate nuclear effects. The results show differences in the concentrations of radon gas in the samples collected from different sites ranging between a lowest value 161.600 x 103 Bq.m-3 in the location of the department of English and a highest value of 441.533 x 103Bq.m-3 in the location of the cafeteria of College compared to the radiation background of 161.158 x 103Bq.m-3 due to the geological factors that depend on the type and specifications of the soil, the amount of gases emitted from the soil, the amount of the emergence of radon from the granules of the soil and its spread through the pores of the soil to the outside. [ABSTRACT FROM AUTHOR]

The 238U, 226Ra, 210Pb, 228Ra, 228Th and 40K concentrations have been measured beside to radon emanation factor due to sample granulometric using γ-spectrometry. The radiological hazards of zeolitic rocks application in the environment as soil improvements, diet supplements and building materials have been studied. No γ-radiation hazards occur for soil improvements since up to 0.13 mSv year−1 estimate. No radiation hazards arise for diet supplements since 0.21 μSv day−1 g−1 of zeolite intake is estimated. Instead, the application as cement and bricks give external annual effective dose up to 1.19 mSv, while the internal radiation rises to 3.45 mSv. [ABSTRACT FROM AUTHOR]

Abstract Elevated indoor radon concentrations (222Rn) in dwellings pose generally a potential health risk to the inhabitants. During the last decades a considerable number of studies discussed both the different sources of indoor radon and the drivers for diurnal and multi day variations of its concentration. While the potential sources are undisputed, controversial opinions exist regarding their individual relevance and regarding the driving influences that control varying radon indoor concentrations. These drivers include (i) cyclic forced ventilation of dwellings, (ii) the temporal variance of the radon exhalation from soil and building materials due to e.g. a varying moisture content and (iii) diurnal and multi day temperature and pressure patterns. The presented study discusses the influences of last-mentioned temporal meteorological parameters by effectively excluding the influences of forced ventilation and undefined radon exhalation. The results reveal the continuous variation of the indoor/outdoor pressure gradient as key driver for a constant “breathing” of any interior space, which affects the indoor radon concentration with both diurnal and multi day patterns. The diurnally recurring variation of the pressure gradient is predominantly triggered by the day/night cycle of the indoor temperature that is associated with an expansion/contraction of the indoor air volume. Multi day patterns, on the other hand, are mainly due to periods of negative air pressure indoors that is triggered by periods of elevated wind speeds as a result of Bernoulli's principle. Highlights • The drivers of varying indoor radon concentrations are strongly interconnected. • Influences of the parameters ΔP, ΔT and wind speed were isolated and evaluated. • Varying indoor/outdoor pressure gradients trigger indoor Rn concentration variations. • Diurnal pressure gradient variations are predominantly temperature triggered. • Multi day pressure gradient variations are mainly due to the varying wind speed. [ABSTRACT FROM AUTHOR]

Abstract 236U, 239Pu and 240Pu are present in soils mainly as a result of the local- and global-fallout from the atmospheric nuclear weapons tests carried out mainly in the 1950's and 1960's. In this work we provide new data on the presence of 236U and 239,240Pu in surface soils (i.e. up to 5 cm depth) from Chile and Africa. The results were obtained by low-energy Accelerator Mass Spectrometry (AMS). In the case of the Chilean samples, 236U/239Pu atom ratios show a high variability and are in general higher than the reported value for the global fallout in the Northern Hemisphere, ranging from 0.2 to 1.5. The 236U atomic concentrations range from 3.5 × 106 to 9.1 × 106 atoms/g, and are at least two orders of magnitude lower than the reported values in the Northern Hemisphere. The measured 240Pu/239Pu atom ratio in soils from South-Africa and Mozambique are of about 0.17, in agreement with the expected one for global-fallout at those coordinates. To best knowledge of the authors the present work is the first publication on 236U concentrations and 236U/239Pu atom ratios in soils from South-America and Africa. Graphical abstract Image 1 Highlights • New data on the impact of nuclear tests to South-America, and Africa were reported. • This is the first publication on 236U concentrations in the Africa. • 236U/239Pu atom ratios of Chile are higher than the Northern Hemisphere. • 240Pu/Pu atom ratio in Africa are in agreement with the global fallout. • Traces of the plutonium from French test in Mururoa atoll were founded in Chile. [ABSTRACT FROM AUTHOR]

Abstract The NE-OBT (Non-Exchangeable Organically Bound Tritium) in the soil plays a significant role in tritium migration and transformation. In order to further understand the NE-OBT activity in the soil, the particle size, vertical profile and spatial distribution of the NE-OBT activities in the soil were determined around the Qinshan Nuclear Power Plant (NPP) in China. The experimental results indicated that the NE-OBT preferred to concentrate in the soil particle sizes of 53–250 μm within the soil depth of 5 cm–25 cm. The NE-OBT activity showed significantly vertical variations, however, its largest activity did not appear at the surface soil (0–5 cm). Meanwhile, the NE-OBT had a significant spatial distribution, its activity decreased with the increasing distance from the NPP, especially from the HWRs. In this study, the NE-OBT activities have no significant relationship to the organic matter content in the soil. But the vertical profile distribution of the NE-OBT activity has a strong correlation with the NE-OBT/HTO ratio in the soil, which reflect the capability of living organisms converting HTO into NE-OBT. According to these analyses, we supposed that the NE-OBT in the soil may be derived from the microbial transformation of HTO. Highlights • The NE-OBT prefers to concentrate in medium soil particle sizes (53–250 μm) at the deeper soil depth of 5–25 cm. • The NE-OBT activities decreased with the increasing distance from the Nuclear Power Plant. • No apparent evidence shows that organic content has a correlation to the distribution of the NE-OBT in the soil. [ABSTRACT FROM AUTHOR]

Abstract Uranium contamination of soil has been a major concern with respect to its toxicity, accumulation in the food chain and persistence in the environment. Owing to these problems, remediation of uranium-contaminated soils has been investigated by various techniques. This review focuses on the challenges and complexities associated with the remediation of uranium-contaminated soil at field level. Therefore, laboratory studies have been excluded from this review. Challenges faced during remediation of uranium-contaminated soil using various techniques such as microbial/phyto/chemical/material based strategies have been discussed with suitable examples. Various factors that have a major influence on uranium decontamination process in soil such as soil type, uranium speciation, the presence of coexisting ions and organics, etc., have been highlighted. This review brings out the significance of the integrated role of various factors which determine the efficiency of the uranium decontamination process. Highlights • Uranium contamination of soil has been a major concern. • Remediation of uranium-contaminated soils investigated by various techniques. • Challenges faced and complexities in remediation discussed. • Significance of the integrated role of various factors in uranium decontamination process. [ABSTRACT FROM AUTHOR]

Abstract The aim of this study is to comprehensively investigate radionuclide concentrations in surface soil and un-decayed vegetative litter along four stream systems (i.e. Fourmile Branch, Lower Three Runs, Pen Branch, and Steel Creek) at the Savannah River Site (SRS), Aiken, South Carolina. Soil and litter samples from systematically spaced 12 pairs (contaminated or uncontaminated) of plots along the four streams were analyzed for 16 distinct radionuclide activities. Lower radionuclide concentrations were observed in soil and litter samples collected along Pen Branch compared to the other 3 streams. The anthropogenic radionuclide with the highest activity was 137Cs in soil (10.6–916.9 Bq/kg) and litter (8.0–222.3 Bq/kg), while the naturally occurring radionuclides possessing the highest concentration in the samples were 40K (33.5–153.7 Bq/kg and 23.1–56.0 Bq/kg in soil and litter respectively) and 226Ra (55.6–159.9 Bq/kg and 30.2–101.8 Bq/kg in soil and litter respectively). A significant difference (p < 0.05) of radionuclide concentrations between paired-plots across four streams was observed for 241Am, 137Cs, 238Pu, 239Pu, and 226Ra in both contaminated and non-contaminated samples. 137Cs and uranium isotopes had the highest litter-to-soil correlation in contaminated (rho = 0.70) and uncontaminated plots (rho = 0.31–0.41), respectively. 90Sr was the only radionuclide with higher radioactive concentrations in litter (12.65–37.56 Bq/kg) compared to soil (1.61–4.79 Bq/kg). The result indicates that 1) historical discharges of anthropogenic 137Cs was the most important contributor of radiation contamination in the riparian environment at SRS, 2) 90Sr was the only radionuclide with higher concentration in litter than in soil, and 3) no apparent pattern in deposition density in soil or litter along downstream was observed for the radionuclides measured in this study. Highlights • The distribution of radionuclides in contaminated and uncontaminated plots along a riparian system was characterized. • 137Cs, 226Ra, and 40K were the radionuclides with the highest activity in the soil and litter along the streams. • 90Sr was the only radionuclide with a higher radioactivity in the litter than in the soil. • Correlation between soil and litter was observed for 137Cs in contaminated plots and U isotopes in uncontaminated plots. • No apparent spatial trend in deposition density of the radionuclides along the streams was observed. [ABSTRACT FROM AUTHOR]

Abstract Industrial activities involving radium sources, such as watchmaking, were still common up until the 1960s. They produced contaminations in building materials and the soil in a large variety of geometries. The potential remediation of such places requires instruments that are properly calibrated as well as adequate procedures. We have developed a model that estimates the rate of ambient dose equivalent H ˙ ∗ (10) at 10 cm and 1 m from a source of 226Ra and its progeny in both the soil or the building materials. Our model, described here, uses Monte Carlo (GEANT4) computed yield functions of H ˙ ∗ (10) per unit activity induced by point-like sources in different contaminated materials. Fit functions of the yield curve of H ˙ ∗ (10) are provided for outdoor contamination. The model can be used for any geometrical activity distribution and we present an example showing the dependency of H ˙ ∗ (10) on the diameter and the depth profile of the sources, for both outdoor and indoor contamination. Highlights • A model of ambient dose equivalent for radium contamination is presented. • The ambient dose equivalent can be computed for any shape of the 226Ra source. • Activity to dose rate conversion coefficients are provided for cylindrical 226Ra sources. • A method to assess the source activity from dose rate measurement is proposed. [ABSTRACT FROM AUTHOR]

Abstract Speciation of tritium (3Н) in soils from the “Balapan” site in Semipalatinsk are presented in this study. Three interrelated objects were chosen for further study: “Atomic” lake, the Shagan River and an external reservoir. The main speciation forms of 3Н in soil were: 3Н in surface-adsorbed water, 3Н in interlayer water, hydroxylic 3Н, organically bound 3Н and crystalline-bound 3Н. Results will allow an estimation of contamination mechanism to be made, and will also allow the potential for migration and bioavailability of 3Н to be assessed. Highlights • In this article we propose a method of phase definitions of the various forms of 3H in the soil. • Detailed consideration of the alleged speciation of 3H in the soil. • We investigated the distribution of speciation of 3H and in the soils of radiation-dangerous objects. • Revealed that the distribution of speciation form of 3H associated with the mechanism of formation of 3H in the study object. [ABSTRACT FROM AUTHOR]

For the first time the pollution of the paddy soil within 2 km around the uranium tailing reservoir was investigated. The concentrations of U, Cd, Cr, Pb, Cu, Zn, Hg and As were determined by ICP-MS. The study showed that there was severe pollution in the first area (within 0-1 km of the tailing reservoir), which was caused by Cd, As, U and Hg. The pollution level of the second area (within 1-2 km) was relatively low. Hg and As were the main pollutants. In the first area, the contamination degree and risk of elements were positively correlated with the distance from the tailing reservoir. The second area was less polluted and influenced by mining and human activities because of mountain barriers. [ABSTRACT FROM AUTHOR]

The aim of this study is to determine the soil radioactivity levels and assess the possible relevant health hazards for the inhabitants of Ankara province. Total of 341 samples were collected from predetermined locations and outdoor gamma dose rate measurements were carried out. The mean activity of 40K, 226Ra, 232Th, and 137Cs with the ranges were determined as 454 (23-1355), 27 (6-186), 33 (2-181) and 3.3 (0.5-20.9) Bq kg−1, respectively. The average annual effective dose equivalent was found to be 71.8 µSv y−1 for public exposure and the average excess lifetime cancer risk value was calculated as 2.69E−04. [ABSTRACT FROM AUTHOR]

Naturally Occurring Radionuclide Materials (NORM) such as fertilizers, agricultural soils fertilized and wheat grain cultivated at those soils were studied regarding the radiation hazard to the public and workers. Activity of 238U, 226Ra, 232Th and 40K was measured hermitical sealing the marinelli beaker using the Stopaq FN 2100L material that prevent 222Rn escape from the baker. The phosphate fertilization of soil did not affect natural radioactivity in comparison with non-fertilized soils and also did not affect natural radioactivity of wheat grain cultivated since only 40K was measured. The high mean value of D air 211 nGy h−1 for fertilizers compared to soils fertilized 53 nGy h−1 highlights the raising concern about radioprotection of workers occupied with tasks involving fertilizers. The maximum external dose rate 1.15 mSv y−1 calculated for truck drivers involved to transportation section is similar to annual external effective dose limit 1 mSv. Real concerns rise for workers in the fertilizers storage and supply department since the maximum dose rate estimated is 1.98 mSv y−1, while the mean value is 0.89 mSv y−1. [ABSTRACT FROM AUTHOR]

The activity concentrations of natural 40K, 232Th, and 238U in 89 soil and 84 sediment samples collected over the entire Egyptian Nile River basin including the Nile delta are reported based on the results of epithermal neutron activation analysis. The average activity concentrations of 40K, 232Th, and 238U equal to 15.3 ± 6.6, 15.6 ± 11.1 and 220 ± 31 Bq/kg, respectively, are significantly lower than those reported for the Upper Continental Crust, World Average Sediments as well as World Average Soils, suggesting the presence of a considerable portion of mafic material, most probably originating from the Ethiopian High Plateau. Their average activity concentrations are statistically the same in soil and sediments, indicating that the Nile sediments and soil material are of the same origin. The main goal of this study was not only to estimate the radiological hazards but also to show the influence of sedimentary material transportable by the Blue Nile from the Ethiopian High Plateau. The different hazard indices like the radium equivalent, gamma index, external hazard as well as the internal hazard show a low radiological exposure either on direct contact or if local mud bricks are used in the construction of dwellings. [ABSTRACT FROM AUTHOR]

In this work a hand-held spectrometer InSpector 1000 with NaI (Tl) 2″ x 2″ detector has been adapted to fast in situ gamma-ray spectroscopy. Two specially designed mounting stands with shielding have been built, allowing conducting measurements in different geometries. Three particular geometries (NW, IS50, IS00) have been chosen for efficiency calibration and further study. The first one (NW) is intended for small environmental samples (volume ca 140 cm 3 ) collected on site. IS50 geometry is a typical in situ geometry meant for radioactivity measurements in soil with detector pointed towards the ground. In this geometry the probe is shielded and mounted 50 cm above the soil surface. The new proposed geometry IS00 is designed in the way that the detector is inserted directly into the soil in order to increase the counting efficiency. The methods of efficiency calibration involved using calibration standards (in NW geometry) and the results obtained in previous in situ measurements with InSpector 2000 portable spectrometer with HPGe detector and ISOCS™ Shield Systems, which is routinely used in environmental measurements. NW geometry turned out to be useful for natural radioisotopes concentrations (K-40, U-238 and Th-232), which significantly exceed typical values of those concentrations observed in Poland. Both IS50 and IS00 geometries are applicative for quick (2 h long measurement) evaluation of typical concentrations of K, U and Th in soils. The newly proposed geometry IS00 is superior as it showed lower detection limits and uncertainties as well as its handling was far easier than of IS50. Authors have proven that hand-held spectrometer InSpector 1000, together with mounting stands and shielding, can be successfully used for fast in situ gamma-spectroscopy. Its relatively small weight and good mobility are additional assets. Moreover, detailed procedures for measurements in each geometry have been developed to conduct such analyses properly. [ABSTRACT FROM AUTHOR]

Performing in-situ measurements of gamma radiation originating from soil requires adequate detection efficiency curves, which can be obtained by Monte-Carlo simulations. In simulations, soil density of 1.046 g/cm 3 was used, with the following elemental composition of soil in which gamma radiation was generated: O - 47%, Si −35%, Al - 8%, Fe - 3.9%, C - 2.1%, Ca - 1.4%, K - 1.3%, N - 0.6%, Mg - 0.6%, N - 0.1%. Soil matrix was represented by cylindrical volume of 1.5 m diameter and 0.5m thickness, while germanium detector was placed at 1 m height above the soil. The simulated gamma spectrum, originated from K-40, as well as from members of Th-232 chain, and daughters of Ra-226, was obtained. Homogeneous distribution of various radionuclides (Ra-226, Th-232, K-40) in soil matrix is considered in this work. Gamma spectra obtained in simulations were analyzed, and together with simulated detection efficiency data they provide comparison with real experimental measurements and practical application of results derived by Monte-Carlo simulations. As a result of this work, the corresponding detection efficiency curve for HPGe detector was obtained, which can be applied for in-situ measurements of radionuclide concentration in soil, assuming uniform radionuclide distribution. In order to validate our simulation results regarding detection efficiency, we performed in-situ measurements of soil radioactivity and compared the obtained activity concentrations with laboratory measurements. We found a good agreement, within activity concentration uncertainty, between in-situ measurement results and average values of activity concentrations obtained by laboratory measurements. [ABSTRACT FROM AUTHOR]

In petroleum engineering, the produced drilling mud sometimes contains elevated amounts of natural radioactivity. In this study, a remediated Hungarian drilling mud depository was investigated from a radiological perspective. The depository was monitored before and after a clay layer was applied as covering. In this study, the ambient dose equivalent rate H*(10) of the depository has been measured by a Scintillator Probe (6150AD-b Dose Rate Meter). Outdoor radon concentration, radon concentration in soil gas, and in situ field radon exhalation measurements were carried out using a pulse-type ionization chamber (AlphaGUARD radon monitor). Soil gas permeability (k) measurements were carried out using the permeameter (RADON-JOK) in situ device. Geogenic radon potentials were calculated. The radionuclide content of the drilling mud and cover layer sample has been determined with an HPGe gamma-spectrometer. The gamma dose rate was estimated from the measured radionuclide concentrations and the results were compared with the measured ambient dose equivalent rate. Based on the measured results before and after covering, the ambient dose equivalent rates were 76 (67–85) nSv/h before and 86 (83–89) nSv/h after covering, radon exhalation was 9 (6–12) mBq/m 2 s before and 14 (5–28) mBq/m 2 s after covering, the outdoor radon concentrations were 11 (9–16) before and 13 (10–22) Bq/m 3 after covering and the soil gas radon concentrations were 6 (3–8) before and 24 (14–40) kBq/m 3 after covering. Soil gas permeability measurements were 1E-11 (7E-12-1E-11) and 1E-12 (5E-13-1E-12) m 2 and the calculated geogenic radon potential values were 6 (3–8) and 12 (6–21) before and after the covering. The main radionuclide concentrations of the drilling mud were C U-238 12 (10–15) Bq/kg, C Ra-226 31 (18–40) Bq/kg, C Th-232 35 (33–39) Bq/kg and C K-40 502 (356–673) Bq/kg. The same radionuclide concentrations in the clay were C U-238 31 (29–34) Bq/kg, C Ra-226 45 (40–51) Bq/kg, C Th-232 58 (55–60) Bq/kg and C K-40 651 (620–671) Bq/kg. According to our results, the drilling mud depository exhibits no radiological risk from any radiological aspects (radon, radon exhalation, gamma dose, etc.); therefore, long term monitoring activity is not necessary from the radiological point of view. [ABSTRACT FROM AUTHOR]

ISOCS (In Situ Counting Object System) from Canberra is applied in laboratory for creating efficiency calibrations of good quality without using radioactive standards. Besides of typical sample containers used in laboratory, ISOSC system also allows modelling containers and objects of almost any shape and elemental composition. The study was based on gamma spectrometry with HPGe semiconductor detector with electronics and software spectrum analysis GENIE 2000 + ISOCS. Measuring set is equipped with portable shield system with set of collimators ISOCS Shield Systems Model ISOXSHLD from Canberra. This shielding system provides attenuation of gamma background radiation with average value 33 (for gamma energies from 186 keV to 2615.5 keV). The portable shield system can be used for low-background laboratory measurements. For this purpose a measuring vessel of new geometry was constructed: the polystyrene cylinder with a height of 40 mm and a diameter of 70 mm. The efficiency calibration for this container was performed using both ISOCS system and classical calibration standard in the same geometry. In order to verify the correctness of performed calibration procedures, the measurements of radioactive standard CBSS 2 were made. The results of both calibrations were compared with the data from the standard certificate. Satisfactory agreement was achieved. Mean percentage difference between results from ISOCS calibration compared to reference values is 6% for all isotopes activities in CBSS 2 standard. The set of collimators was used to develop efficiency calibration for in situ measurements of the soil surface. Test measurements were carried out at the area of the Institute of Nuclear Physics Polish Academy of Sciences in Kraków, Poland (IFJ PAN). Two measurement methods were compared: in situ and laboratory gamma spectroscopy. The obtained average results (from all 10 measuring points) are consistent within the range of measurement uncertainty. [ABSTRACT FROM AUTHOR]

In situ gamma spectrometry is a widely applied analysis technique for the determination of radioactivity levels in soil. Compared to traditional laboratory analysis of soil samples, in situ techniques offer a quick and low-cost way of obtaining accurate results from on-site measurements. However, although the technique is well-known, the dependence of in situ gamma spectrometry on complex and time-consuming calibration procedures as well as in-depth knowledge of the geometric distribution of the source in the ground deters many potential users from employing it in their routine work. Aiming to alleviate this issue, a software tool named InSiCal ( In Situ gamma spectrometry Calculator) has been developed to make in situ gamma spectrometry more accessible to both experts and non-experts in the field. This is done by simplifying and streamlining both calibration and activity calculation through a simple and intuitive graphical user interface. Testing in real field conditions show that InSiCal is capable of yielding results which are in very good agreement with soil sample analyses, and that the results may be obtained using different detector types (HPGe, NaI, LaBr and CZT). Overall, InSiCal, provides results which are comparable in accuracy to laboratory measurements, indicating that it fulfills its purpose successfully. [ABSTRACT FROM AUTHOR]

This study was performed in order to investigate gamma dose rates, radon exhalation rates and soil radioactivity with respect to geology. Fifteen locations in three Serbian spas were under investigation. Gamma dose rate was measured by Radex RD1503+ monitor. GIS technology was applied for the interpretation of the results. HPGe detector was used for gamma-spectrometry determination of soil radioactivity. Radon exhalation rate was determined using RAD7 device. The correlation was examined between radon exhalation rate and 226Ra. No correlation was found between calculated effective dose from radionuclides in soil and measured ambient gamma dose rate. [ABSTRACT FROM AUTHOR]

An assessment of radon concentrations at Khan Alzabib was implemented using two different approaches; the radon exhalation approach and the subsoil approach. The measurements were analyzed in view of two parameters, uranium concentration levels and the presence of fault zones. Radon measurements from the radon exhalation approach were related to the uranium concentration in the collected samples and a positive correlation was observed showing higher exhalation rates of radon for higher uranium concentration. Radon measurements from the subsoil approach showed the effect of fault zones in promoting the migration process of radon. [ABSTRACT FROM AUTHOR]

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Transfer of radiocesium from soil to crops is an important pathway for human intake. In the period from one to two years after the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, food monitoring results showed that radiocesium concentrations in soybean (a legume) were higher than those in other annual agricultural crops; in these crops, root uptake is the major pathway of radiocesium from soil to plant. However, it was not clear whether or not leguminous and non-leguminous herbaceous plants have different Cs uptake abilities from the same soil because crop sample collection fields were different. In this study, therefore, we compared the concentrations of 137 Cs in seven herbaceous plant species including two leguminous plants ( Trifolium pratense L. and Vicia sativa L.) collected in 2012–2016 from the same sampling field in Chiba, Japan that had been affected by the FDNPP accident fallout. Among these species, Petasites japonicus (Siebold & Zucc.) Maxim. showed the highest 137 Cs concentration in 2012–2016. The correlation factor between all concentration data for 137 Cs and those for 40 K in these seven plants was R = 0.54 (p < 0.001) by t -test, thus potassium uptake ability by species would affect radiocesium uptake; however, for each species, no correlation between 137 Cs and 40 K was found. Interestingly, 40 K concentrations in T. pratense , V. sativa and Poaceae family plants did not differ significantly, but 137 Cs data in the Poaceae family plants were significantly lower than those in T. pratense (p < 0.001) and V. sativa (p = 0.017). The results indicated that leguminous species would have higher 137 Cs uptake ability than Poaceae family plants. [ABSTRACT FROM AUTHOR]

Large-scale deforestation, intensive land use and unfavourable rainfall conditions are responsible for significant continuous degradation of the Haitian uplands. To develop soil conservation strategies, simple and cost-effective methods are needed to assess rates of soil loss from farmland in Haiti. The fallout radionuclide caesium-137 ( 137 Cs) provides one such means of documenting medium-term soil redistribution rates. In this contribution, the authors report the first use in Haiti of 137 Cs measurements to document soil redistribution rates and the associated pattern of erosion/sedimentation rates along typical hillslopes within a traditional upland Haitian farming area. The local 137 Cs reference inventory, measured at an adjacent undisturbed flat area, was 670 Bq m −2 (SD = 100 Bq m −2 , CV = 15%, n = 7). Within the study area, where cultivation commenced in 1992 after deforestation, three representative downslope transects were sampled. These were characterized by 137 Cs inventories ranging from 190 to 2200 Bq m −2 . Although, the study area was cultivated by the local farmers, the 137 Cs depth distributions obtained from the area differed markedly from those expected from a cultivated area. They showed little evidence of tillage mixing within the upper part of the soil or, more particularly, of the near-uniform activities normally associated with the plough layer or cultivation horizon. They were very similar to that found at the reference site and were characterized by high 137 Cs activities at the surface and much lower activities at greater depths. This situation is thought to reflect the traditional manual tillage practices which cause limited disturbance and mixing of the upper part of the soil. It precluded the use of the conversion models normally used to estimate soil redistribution rates from 137 Cs measurements on cultivated soils and the Diffusion and Migration conversion model frequently used for uncultivated soils was modified for application to the cultivated soils of the study area, in order to take account of the unusual local conditions. The model was also modified to take account of the fact that cultivation in the study area commenced in 1992, rather than predating the period of weapons test fallout which extended from the mid 1950s to the 1970s. Erosion rates on the upper parts of the hillside involved in the study were found to be relatively high and ca. −23 t ha −1 y −1 with low spatial variability. In the lower, flatter areas at the bottom of the slope, deposition occurred. Deposition rates were characterized by high spatial variability, ranging from 6.0 to 71 t ha −1 y −1 . Soil redistribution rates of this magnitude are a cause for concern and there is an urgent need to implement soil conservation measures to ensure the longer-term sustainability of the local agricultural practices. [ABSTRACT FROM AUTHOR]

Atmospheric nuclear weapons tests carried out by the United States, the former Soviet Union, the United Kingdom, France and China between 1945 and 1980 resulted in radioactive fallout over the earth's surface of long-lived radionuclides, such as 137 Cs, 239+240 Pu and 238 Pu that could be detected more than 50 years after their production. In addition, the burnup in the upper atmosphere of a thermoelectric generator fueled by 238 Pu, SNAP-9A, contributed to the inventory of 238 Pu deposited on the ground. In order to estimate the deposition densities of 137 Cs, 239+240 Pu and 238 Pu in French Polynesia, we collected undisturbed soil samples up to 30 cm deep at eight sites in two islands (Hiva Oa, 139°W - 10°S and Raivavae, 148°W - 24°S) in 2015–2016. The top 0–10 cm of the soil cores were sliced into five 2-cm layers and the bottom 10–30 cm into four 5-cm layers for gamma spectrometry and alpha spectrometry measurements. We found that more than 50% of the radioactive inventories are still contained within the first 10 cm and that the average vertical migration velocities of 137 Cs and Pu are less than 0.2 cm y −1 . The average accumulated depositions, deduced from the profile measurements, are 236 ± 11 Bq.m −2 and 313 ± 39 Bq.m −2 for 137 Cs, 12.1 ± 1.5 Bq.m −2 and 22.1 ± 1.7 Bq.m −2 for 239+240 Pu, and 1.23 ± 0.46 Bq.m −2 and 1.58 ± 0.60 Bq.m −2 for 238 Pu, in Hiva Oa and Raivavae, respectively. The 238 Pu/ 239+240 Pu ratios are 0.102 ± 0.050 at Hiva Oa and 0.072 ± 0.033 at Raivavae. Both values are higher than the ratio in nuclear weapons tests fallout estimated to be 0.016 in 2016 (Hardy et al., 1973), because of the contribution of 238 Pu fallout from SNAP-9A, which is latitude dependent. The 137 Cs/ 239+240 Pu ratios, 19.5 ± 3.2 at Hiva Oa and 14.2 ± 2.8 at Raivavae are in the lower part of the range of values observed in other regions of the world. [ABSTRACT FROM AUTHOR]

The relative discrepancies between the gamma spectrometry efficiency of RGU, RGTh, RGK reference materials and some soil samples have been studied using a MCNP model of a real HPGe detector. It has been shown that, in a specified geometry, efficiencies differences depend on the sample elemental composition. The elemental compositions of RGU-1, RGTh-1 reference materials and a soil sample have been evaluated using X-Ray fluorescence (XRF) method and used in the MCNP simulation along with RGK-1 and six other soil samples with different elemental compositions to calculate their efficiencies in different gamma ray energies. To estimate the maximum relative efficiencies differences between soil samples and reference materials, five soil samples with higher attenuation properties were selected from a large data set of soils elemental compositions. The results show that the efficiency differences between soil samples and reference materials are almost ignorable for more than 100 KeV gamma energies. It strongly depends on the sample attenuation factor in the lower energies, so use of a self-attenuation correction is essential for radionuclide counting in low energies gamma rays. Results show about 8 percent discrepancy between RGU and two soil samples efficiencies in 63.2 KeV energy. [ABSTRACT FROM AUTHOR]

90 Sr specific activity in the teeth of young cattle that were abandoned in Kawauchi village and Okuma town located in the former evacuation areas of the Fukushima-Daiichi Nuclear Power Plant (FNPP) accident were measured. Additionally, specific activity in contaminated surface soils sampled from the same area was measured. (1) All cattle teeth examined were contaminated with 90 Sr. The specific activity, however, varied depending on the developmental stage of the teeth during the FNPP accident; teeth that had started development before the accident exhibited comparatively lower values, while teeth developed mainly after the accident showed higher values. (2) Values of 90 Sr-specific activity in teeth formed after the FNPP accident were higher than those of the bulk soil but similar to those in the exchangeable fraction (water and CH 3 COONH 4 soluble fractions) of the soil. The findings suggest that 90 Sr was incorporated into the teeth during the process of development, and that 90 Sr in the soluble and/or leachable fractions of the soil might migrate into teeth and contribute to the amount of 90 Sr in the teeth. Thus, the concentration of 90 Sr in teeth formed after the FNPP accident might reflect the extent of 90 Sr pollution in the environment. [ABSTRACT FROM AUTHOR]

After the Fukushima Dai-ichi Nuclear Power Plant accident on March 2011, continuous monitoring of the detailed vertical distribution of radiocesium in soil is required to evaluate the fate of radiocesium and establish strategies for remediation and management of the contaminated land. It is especially important to investigate paddy soil because little knowledge has been accumulated for paddy soil and wetland rice is a major staple in Japan. Therefore, we monitored the vertical distribution of 137 Cs in abandoned paddy soil in a planned evacuation zone from June 2011 to March 2016. The decontamination works (i.e., 5 cm of surface soil removal and re-covering with uncontaminated soil) were conducted by the government in 2015. As a result of monitoring, the 137 Cs gradually migrated downward with time and the 137 Cs concentration in the 0–10 cm soil was almost homogenous in October 2014, although it was non-cultivated. The liner relationship was obtained between the median depth, which is the thickness of a soil layer containing half of the total 137 Cs inventory, and the time after the accident, indicating the migration rate was constant (1.3 cm y −1 ) before the decontamination works. After the decontamination works, the 137 Cs concentration in the uppermost surface layer was reduced by 90%, however the total 137 Cs inventory was reduced by only 50–70%. It was shown that the efficiency of 137 Cs removal by the decontamination works decrease linearly over time in fields like the studied paddy, in which the homogenization of 137 Cs concentration occurred. Conversely, the downward migration of 137 Cs to subsurface layers deeper than 10 cm (i.e., plowpan layer) with low permeability rarely occurred. It is expected that these unique trends in distribution and migration of 137 Cs would be found in abandoned paddy soils with properties similar to the studied soil, sandy loam but poorly drained because of the low permeable plowpan layer, although further validation is necessary. [ABSTRACT FROM AUTHOR]

The vertical distribution of radio-caesium ( 137 Cs and 134 Cs) in undisturbed soil profiles of grassland and forest soils, derived from the Fukushima-Daiichi Nuclear Power Plant (FDNPP) accident that occurred on 11 March 2011, was studied. Surface soil and depth profile soil samples were collected from six locations within the 20 km zone of FDNPP, during November 2012 and June 2013. The activity ratio for 137 Cs and 134 Cs was found to be almost constant about 1 within the soil profiles as well as in the surface soil, indicative of FDNPP accident origin. From soil depth profile distribution of Cs activity, it is observed that Cs is strongly bound to soil materials, which slows Cs migration. > 90% of the activity was found to be retained within the upper 5 cm layer. Retardation of Cs movement has been quantified by measuring sorption of Cs in soil in terms of distribution coefficient (K d ) using the laboratory batch method. Faster migration has been observed in case of forest land soil compared to grassland soil. The empirical migration velocity of Cs radio isotope was estimated from the depth profile Cs concentration and found to vary from 1.1 to 1.7 and 0.85 to 3.5 cm y − 1 in grassland and forest soil, respectively. The residential half life for Cs isotopes was found to be 1.03–7.75 y and 1.18–4.67 y for grassland and forest land respectively using a compartmental model. In addition to the empirical analysis of the profiles, analytical models were fitted to the data which may help elucidate the physical nature of the transport of trace elements. [ABSTRACT FROM AUTHOR]

In this study, gross alpha and beta radioactivity in food crops and surface soil collected from Ho Chi Minh City, Vietnam were measured. Based on the annual effective dose from ingestion of food crops, the degree of risk to human health was estimated. We found out that the obtained values of the dose do not exceed the WHO recommended level (290 µSv year). The estimated soil-to-plant transfer factors for gross alpha (TF) and beta (TF) for food crops were also presented. It was found that TF varied in the range from 0.009 ± 0.005 to 0.99 ± 0.06, TF varied in the range from 2.26 ± 0.10 to 10.87 ± 0.53 and the maximum values of transfer factors were found in the root of ipomoea batatas. [ABSTRACT FROM AUTHOR]

An increase of health problems has been reported in the city of Triunfo, Paraíba, NE Brazil. This pattern has been attributed to environmental radiation since there are uranium deposits in the neighboring municipalities. The present study aimed to carry a radiometric survey in Triunfo to determine effective dose from external outdoor radiation exposure. The results were obtained through 'in situ' measurements using a gamma spectrometry system. The results ranged from 0.06 to 0.38 mSv/y, mean of 0.20 mSv/y. Due to the low value of the effective dose rate, we concluded that the area is characterized by low background radiation. Therefore, natural radioactivity is probably not directly influencing the increase in cancer incidence in the region. However, there is a need for complementary studies in this area to evaluate the dose from potential exposure to ingested and inhaled natural radionuclides from natural radioactivity in soil, rocks, vegetation and water. [ABSTRACT FROM AUTHOR]

Knowing the concentration of 226Rn in soil and of 222Rn in soil gas is important for the analysis of indoor radon data and the prediction of radon-prone areas. Except for soil Rn in Ardenne, the data concerning these two radionuclides in Belgian soils are very scarce. In the context of Master theses and international courses, students made 92 measurements of 226Rn in soil samples, 105 of 222Rn in soil gas, and 74 of soil permeability, a significant addition to the existing similar data. The data are analysed in relation with soil texture, geological units and indoor radon risk. There is no clear correlation between radium in soil and indoor radon risk, the most important factor of risk being soil permeability. [ABSTRACT FROM AUTHOR]

Radioactive contamination in the Tokyo metropolitan area in the immediate aftermath of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident was analyzed via surface soil sampled during a two-month period after the accident. 131I, 134Cs, and 137Cs were detected in these soil samples. The activity and inventory of radioactive material in the eastern part of Tokyo tended to be high. The 134Cs/137Cs activity ratio in soil was 0.978 ± 0.053. The 131I/137Cs ratio fluctuated widely, and was 19.7 ± 9.0 (weighted average 18.71 ± 0.13, n = 14) in the Tokyo metropolitan area. The radioactive plume with high 131I activity spread into the Tokyo metropolitan area and was higher than the weighted average of 6.07 ± 0.04 (n = 26) in other areas. The radiocesium activity and inventory surveyed in soil from a garden in Chiyoda Ward in the center of Tokyo, fell approximately 85% in the four months after the accident, and subsequently tended to rise slightly while fluctuating widely. It is possible that migration and redistribution of radiocesium occurred. The behavior of radiocesium in Tokyo was analyzed via monitoring of radiocesium in sludge incineration ash. The radiocesium activity in the incineration ash was high at wastewater treatment centers that had catchment areas in eastern Tokyo and low at those with catchment areas in western Tokyo. Similar to the case of the garden soil, even in incineration ash, the radiocesium activity dropped rapidly immediately after the accident. The radiocesium activity in the incineration ash fell steadily from the tenth month after the accident until December 2016, and its half-life was about 500 days. According to frequency analysis, in central Tokyo, the cycles of fluctuation of radiocesium activity in incineration ash and rainfall conformed, clearly showing that radiocesium deposited in urban areas was resuspended and transported by rainfall run-off. [ABSTRACT FROM AUTHOR]

Natural radionuclides and stable elements were measured in weaver ants, leaves and soils collected from three sites in tropical northern Australia. Radionuclide concentration ratios for ants relative to soil were derived from the measurements and used to refine the current environmental radiological assessment for remediation of Ranger uranium mine. Use of site-specific concentration ratios for weaver ants gave a more conservative estimate of environmental exposure to the arthropod wildlife group than use of default concentration ratios in the ERICA Tool. This was primarily because the 226 Ra concentration ratio for weaver ants was more than 7 times greater than for generic arthropods. [ABSTRACT FROM AUTHOR]

A survey of artificial ( 137 Cs, 238 Pu, 239+240 Pu, 241 Am) and natural ( 226 Ra, 232 Th, 40 K, 210 Pb) radioactive isotopes in proglacial soils of an Arctic glacier have revealed high spatial variability of activity concentrations and inventories of the airborne radionuclides. Soil column 137 Cs inventories range from below the detection limit to nearly 120 kBq m −2 , this value significantly exceeding direct atmospheric deposition. This variability may result from the mixing of materials characterised by different contents of airborne radionuclides. The highest activity concentrations observed in the proglacial soils may result from the deposition of cryoconites, which have been shown to accumulate airborne radionuclides on the surface of glaciers. The role of cryoconites in radionuclide accumulation is supported by the concordant enrichment of the naturally occurring airborne 210 Pb in proglacial soil cores showing elevated levels of artificial radionuclides. The lithogenic radionuclides show less variability than the airborne radionuclides because their activity concentrations are controlled only by the mixing of material derived from the weathering of different parent rocks. Soil properties vary little within and between the profiles and there is no unequivocal relationship between them and the radionuclide contents. The inventories reflect the pathways and time variable inputs of soil material to particular sites of the proglacial zone. Lack of the airborne radionuclides reflects no deposition of material exposed to the atmosphere after the 1950s or its removal by erosion. Inventories above the direct atmospheric deposition indicate secondary deposition of radionuclide-bearing material. Very high inventories indicate sites where transport pathways of cryoconite material terminated. [ABSTRACT FROM AUTHOR]

The problem of mathematical simulation of the vertical migration of radionuclides in a catalytic porous medium under nonisothermal conditions is considered. A numerical solution of the corresponding one-dimensional nonlinear boundary-value problem is obtained by the finite difference method. Numerical experiments are carried out and their analysis is made. [ABSTRACT FROM AUTHOR]

Measurements of ambient gamma radiation dose and radioactivity of soil and rocks samples have been carried out in 103 sites located in the region of Marrah mountain (western Sudan) using survey meters and gamma spectrometry techniques, respectively. The ambient dose varied from 0.05 to 0.25 µSv/h with mean value of 0.18 ± 0.05 (SD) µSv/h. At high altitudes (> 1500 m), relatively high values were observed (0.18-0.22 µSv/h). The levels of U, Th and K in soil-rocks were in the ranges 12-80, 12-66 and 120-937 Bq/kg with mean ± SD of (41 ± 6.9), (24 ± 12) and (540 ± 99) Bq/kg, respectively, equivalent to total gamma absorbed dose of 23-142 (66 ± 20) nGy/h. The ambient dose data were presented in cartography format, and correlation to geological maps was attempted. Surface map of the absorbed dose created using geostatistical kriging tools showed the spatial distribution of dose. Analyses showed that trends of high values were located in and around areas characterized by local flow and basaltic flow lithology, while the low values were observed at locations of basement rocks (granitic) in general. That was attributed to the differences in environmental conditions in various altitude and weathering processes. The highest readings (0.25 µSv/h and 142 nGy/h) were found in Deriba Complex Pumice air-fall deposits (younger explosive phase). Health risk was assessed by calculating annual effective dose for the inhabitants resulted in values range between 0.14 and 1.4 mSv/y (mean ± SD of 0.40 ± 0.12 mSv/y). The observed values of dose rates are comparable with some countries but higher than the worldwide average for outdoor annual affective dose of 0.07 mSv/y. [ABSTRACT FROM AUTHOR]

Mining activities can increase the mobility of metals by accelerating the dissolution and leaching of minerals from the rocks and tailing piles to the environment and, consequently, their availability for plants and subsequent transfer to the food chain. The weathering of minerals and the disposal of coal waste in tailing piles can accelerate the generation of acid mine drainage (AMD), which is responsible for the higher dissolution of metals in mining areas. In this context, the behavior of U, Th and K in soils and sediment, and the transfer factor (TF) of 238 U, 234 U and 210 Po for soybean, wheat, pine and eucalyptus cultivated around a coal mine in southern Brazil was evaluated. Alpha and gamma spectrometry were used for the measurements of the activity concentration of the radioelements. 210 Po was the radionuclide that is most accumulated in the plants, especially in the leaves. When comparing the plant species, pine showed the highest TF values for 234 U (0.311 ± 0.420) for leaves, while eucalyptus showed the highest TF for 238 U (0.344 ± 0.414) for leaves. In general, TF were higher for the leaves of soybean and wheat when compared to the grains, and grains of wheat showed higher TF for 210 Po and 238 U than grains of soybean. Deviations from the natural U isotopic ratio were recorded at all investigated areas, indicating possible industrial and mining sources of U for the vegetables. A safety assessment of transport routes and accumulation of radionuclides in soils with a potential for cultivation is important, mainly in tropical areas contaminated with solid waste and effluents from mines and industry. [ABSTRACT FROM AUTHOR]

The occurrence of radiocesium in food has raised sharp health concerns after nuclear accidents. Despite being present at low concentrations in contaminated soils (below μ m), cesium (Cs+) can be taken up by crops and transported to their edible parts. This plant capacity to take up Cs+ from low concentrations has notably affected the production of rice ( Oryza sativa L.) in Japan after the nuclear accident at Fukushima in 2011. Several strategies have been put into practice to reduce Cs+ content in this crop species such as contaminated soil removal or adaptation of agricultural practices, including dedicated fertilizer management, with limited impact or pernicious side-effects. Conversely, the development of biotechnological approaches aimed at reducing Cs+ accumulation in rice remain challenging. Here, we show that inactivation of the Cs+-permeable K+ transporter Os HAK1 with the CRISPR-Cas system dramatically reduced Cs+ uptake by rice plants. Cs+ uptake in rice roots and in transformed yeast cells that expressed Os HAK1 displayed very similar kinetics parameters. In rice, Cs+ uptake is dependent on two functional properties of Os HAK1: (i) a poor capacity of this system to discriminate between Cs+ and K+; and (ii) a high capacity to transport Cs+ from very low external concentrations that is likely to involve an active transport mechanism. In an experiment with a Fukushima soil highly contaminated with 137Cs+, plants lacking Os HAK1 function displayed strikingly reduced levels of 137Cs+ in roots and shoots. These results open stimulating perspectives to smartly produce safe food in regions contaminated by nuclear accidents. [ABSTRACT FROM AUTHOR]

The effects of fire events on contaminant radionuclides within soils of the Belarusian Exclusion Zone were investigated. A number of cores were taken from locations known to have been subject to fire events in the past as well as a series of cores from nearby unburnt locations. Both burnt and unburnt cores were analyzed for contaminant radionuclides as well as a range of relevant soil parameters. The distribution of 137 Cs between various fractions (reversibly bound, irreversibly bound and insoluble) was analyzed. Results indicate no evidence of enhancement or enrichment of radionuclides within the soil column although this does not negate the possibility that such effects were evident at some point in the past, the fire events at two of the sites having occurred almost ten years earlier. Evidence was present of a persistent effect on how 137 Cs was distributed between different fractions of the soil, primarily in relation to the proportions associated with oxides of Fe and Mn and organic matter. The results of the study appear to indicate that the long-term effects of a forest fire on contaminant 137 Cs within the soil column are expressed through changes in the physico-chemical forms of the nuclide to a larger extent than simple redistribution of the contaminant within the soil column. [ABSTRACT FROM AUTHOR]

In the field conditions, the long-term (2013–2015) small-plots experiment was carried out for evaluation of radiological efficiency of application of ameliorants as the countermeasures for reduction of the 137 Cs uptake to herbage at the Peat-boggy (Histosols) soils of Ukrainian Polissya. At the late stage after the Chernobyl accident, the average radiological efficiencies of application of sand (175–200 ton ha −1 ) and ferrocyn (0.2 ton ha −1 ) as the ameliorants were rather low ranging from 0.8 to 1.6. Application of 4 ton ha-1 of chalk and 5 ton ha-1 of peat ash decreased 1.7–1.9 times the 137 Cs activity concentrations in plans. The highest radiological efficiencies, 4.4 ± 2.0 and 7 ± 2, were reached at applications of chalk-ferrocyn ameliorant (4 + 0.2 ton ha −1 ) and ferrocyn-bentonite absorbent HZH-90 (30 ton ha −1 ), respectively. [ABSTRACT FROM AUTHOR]

The activities of natural radionuclides in the environment can be used to assess radiological effects. Monitoring the radiation level in soils is important for public health. It also has important geochemical implications as most of the sediment eroded from river basins is from soil. Therefore, we carried out a soil sampling campaign along a subtropical river basin in southeastern China (Jiulong River). Surface and depth profile soils were collected, and the natural radionuclide activities were measured. The activities of the natural radionuclides 238U, 232Th, and 40K in the surface soils varied from 31.6 to 132.1 Bq kg-dry-1, 37.8 to 174.0 Bq kg-dry-1, and 52.3 to 596.2 Bq kg-dry-1, with average values of 56.7 ± 30.3 Bq kg-dry-1, 86.7 ± 41.3 Bq kg-dry-1, and 352.8 ± 190.6 Bq kg-dry-1, respectively. The absorbed gamma dose in air and the annual effective dose equivalent (AEDE) in surface soils along the river basin were both higher than the world average. In the depth profiles, excess 210Pb (210Pbex) decreased with depth and significant correlation between 210Pbex and TOC was observed, suggesting that they are affected by similar processes (leaching and sorption). [ABSTRACT FROM AUTHOR]

The development of two radioactivity-in-soil reference materials is described – one for peat and one for soil with high sand content. Each bulk material was processed, subdivided and measured before being sent to participants in an NPL Environmental Radioactivity Proficiency Test Exercise. Activity concentrations of radionuclides in each material were determined by ‘consensus’ evaluations of participants’ results using two weighted mean methods. The project demonstrated the use of such exercises in delivering reference materials to the user community. [ABSTRACT FROM AUTHOR]

Studies have been carried out to investigate the baseline radioactivity level (gross alpha, gross beta and 226Ra) of soil, rocks and groundwater in the Fuling block, Chongqing, the largest shale gas exploitation area of China. The results show that there is a general activity concentration trend of gross alpha, gross beta and 226Ra: shale > soil > limestone due to the high content of uranium, thorium and potassium in shale and low content in limestone. The average activities of shallow groundwater from a limestone aquifer are 0.14, 0.13 and <0.008 Bq/L for gross alpha, gross beta and 226Ra, respectively. The radioactivity concentrations of gross alpha, gross beta and 226Ra (4.37, 1.40 and 0.395 Bq/L, respectively) of the formation water were far lower than those of formation water in the Marcellus shale in the USA (with ranges of 86-678, 23-77 and 16-500 Bq/L, respectively). One polluted shallow groundwater source and its associated stream sediments had been polluted due to leakage of drilling fluid with relatively high radioactivity levels and high concentration of main ions. Overall, this study provides an important baseline radioactivity level to assess the impact of shale gas exploitation on a shallow environment. [ABSTRACT FROM AUTHOR]