A method to determine U activity in environmental soil samples by using 63.3-keV-photopeak-gamma HPGe spectrometer

The paper presents a method of measuring ²³⁸U activity in environmental soil samples by a low background HPGe spectrometer at the 63.3 keV gamma photopeak. The low ²³⁸U activity requires a large size soil sample with a mass of about 100 g. The geometrical and self-absorption effects as well as the density dependence of soil samples were then investigated. A procedure of analyzing environmental soil samples was established with a relative error of about 10%. Two soil samples of known activity were tested and 106 surface soil samples collected from the Southern part of Vietnam were analyzed, and then these results were compared by instrumental neutron activation analytical method.     

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.     

Differences of natural radioactivity and radon emanation fraction among constituent minerals of rock or soil

We examined differences in the radioactive characteristics among the main minerals forming granite materials. Using a non-toxic high-density agent, minerals were separated from rock (granite–gneiss) and soil (weathered granite) samples. The natural radioactivity (²³⁸U and ²²⁶Ra) and radon emanation fraction of the minerals were then studied by gamma-ray spectrometry. The radon emanation fractions (27–43%) of the minerals from the soil were much higher than those (0.6–4.6%) of the rock minerals. Additionally, the emanation fractions differed greatly among the minerals separated from both the bulk rock and soil. These results were discussed in terms of the differences of surface area and radium distribution in the mineral grains. It was noticeable that a higher emanation fraction than expected for quartz was commonly observed in the rock and soil samples. We then estimated the contribution of each constituent mineral to the total radon exhalation from the bulk samples. The result depended not only on the radon emanation fraction, but also on the ²²⁶Ra activity and the mineral content. Furthermore, using the obtained data, we also discussed the effect of grain size on radon emanation and why this has been reported to vary markedly in previous studies.     

珍宝岛地区“三班倒”吸血昆虫的研究 Ⅵ.珍宝岛地区伊蚊越冬卵的分布和主要蚊种孳生地调查

1982年和1983年的4月底至5月初,在珍宝岛地区冻土层尚未完全解冻的草甸、林缘还积有余雪残冰之时,我们从五类生境中取土样108份,共孵出幼虫641条.其中刺扰伊蚊(Aedes vexans)占69.9%,刺痛伊蚊(Ae excrucians)占22.5%,而丛林伊蚊(Ae cataphylla)和普通伊蚊(Ae communis)只占很少比例.刺扰伊蚊卵分布于该区各类生境,但以林缘坑为最多,孵出幼虫数为孵出刺扰伊蚊幼虫总数的86.6%.上述几种伊蚊卵在表层土壤越冬,至初春雪融时开始孵化.1983年在蚊虫孳生地调查中,采获蚊幼虫17种,其中刺扰伊蚊、东方库蚊(Culex orientalis)和中华按蚊(Anopheles sin-ensis)数量较多,持续时间较长,而刺扰伊蚊孳生数量占三种蚊幼虫和蛹总数的84.9%.刺扰伊蚊在各类生境中均有孳生,但以林缘坑为最多,占各类生境采获幼虫和蛹总数的88.7%.东方库蚊和中华按蚊除岛上外其它生境均有采获.东方库蚊在林缘坑中孳生较多,占其采获幼虫总数的70%以上.中华按蚊幼虫在营区周围水坑中孳生较多,占其采获幼虫总数的53.7%.     

Classification of soil samples according to geographic origin using gamma-ray spectrometry and pattern recognition methods.

Multivariate data analysis methods were used to recognize and classify soils of unknown geographic origin. A total of 103 soil samples were differentiated into classes, according to regions in Serbia and Montenegro from which they were collected. Their radionuclide (226Ra, 238U, 235U, 40K, 134Cs, 137Cs, 232Th and 7Be) activities detected by gamma-ray spectrometry were then used as the inputs in different pattern recognition methods. For the classification of soil samples using eight selected radionuclides, the prediction ability of linear discriminant analysis (LDA), k-nearest neighbours (kNN), soft independent modelling of class analogy (SIMCA) and artificial neural network (ANN) were 82.8%, 88.6%, 60.0% and 92.1%, respectively.     

新疆昌吉市天然退化打草场改良效果观察

松土补播显著增加天山北坡中山带退化打草场的草层高度、盖度,松土补播优质牧草当年至第3年比对照区依次增加24．64％、123．7％、76_3％;88．9％、111．1％、111．1％。松土补播可以有效提高牧草产量及优良牧草比例,松土补播优质牧草当年至第3年比对照区依次提高173．5％、90．6％、157．2％;57％、73．2％、75％。在松土补播的基础上进行根部施肥可显著增加草层高度、盖度、干草产量,试验当年至第3年比对照区草层高度平均提高57．4％、94．7％、7938％;盖度依次提高72．73％、70％、72．73％;干草产量依次提高49．93％、56．33％、52．3％。在松土补播的基础上进行叶面施肥对草层高度、盖度的影响显著,当年至第3年分别提高43．5％、189．4％、55．2％;88．9％、111．1％、111．1％。对牧草总产量的影响不显著。对于退化打草场适时刈割对牧草营养的影响不显著。     

新疆巴音布鲁克高寒草地土壤几种公害物生态安全的研究

在随机采样和精确检测的基础上,参照国家土壤环境质量标准,对新疆巴音布鲁克高寒草地亚高山草原土中,六六六、敌敌畏、铅和砷的生态安全予以了评估,结果表明：土壤中六六六、敌敌畏、铅和砷的生态安全率均达100％。亚高山草原土居于生态安全状态。     

Tracing recent outdoor geolocation by analyzing microbiota from shoe soles and shoeprints even after indoor walking

The microbial communities on shoe soles and shoeprints could carry microbial information about where someone walked. This is possible evidence to link a suspect in a crime case to a geographic location. A previous study had shown that the microbiota found on shoe soles depend on the microbiota of the soil on which people walk. However, there is a turnover of microbial communities on shoe soles during walking. The impact of microbial community turnover on tracing recent geolocation from shoe soles has not been adequately studied. In addition, it is still unclear whether the microbiota of shoeprints can be used to determine recent geolocation. In this preliminary study, we investigated whether the microbial characteristics of shoe soles and shoeprints can be used to trace geolocation and whether this information can be destroyed by walking on indoor floors. In this study, participants were asked to walk outdoors on exposed soil, then walk indoors on a hard wood floor. High-throughput sequencing of the 16S rRNA gene was performed to characterize the microbial communities of shoe soles, shoeprints, indoor dust, and outdoor soil. Samples of shoe soles and shoeprints were collected at steps 5, 20, and 50 while walking indoors. The PCoA result showed that the samples were clustered by geographic origin. The shoeprint showed a more rapid turnover of microbial community than the shoe sole during indoor walking. The result of FEAST showed that the microbial communities of shoe sole and shoeprint were mainly (shoe sole, 86.21∼92.34 %; shoeprint, 61.66∼90.41 %) from the soil of the outdoor ground where the individual recently walked, and a small portion (shoe sole, 0.68∼3.33 %; shoeprint, 1.43∼27.14 %) from the indoor dust. Based on the matching of microbial communities between geolocation and shoe sole or shoeprint, we were able to infer the recent geolocation of the individual with relatively high accuracy using the random forest prediction model (shoe sole: 100.00 %, shoeprint: 93.33∼100.00 %). Overall, we are able to accurately infer the geolocation of an individual’s most recent outdoor walk based on the microbiota of shoe sole and shoeprint, even though these microbiotas show a turnover when walking indoor floor. The pilot study was expected to provide a potential method for tracing recent geolocation of suspects.     

Estimating soil erosion losses in Korea with fallout cesium-137

The contents of fallout ¹³⁷Cs in soil profiles were used to estimate erosion losses from steeply sloping croplands in Korea. Seven undisturbed sites with no apparent erosion or deposition, and 15 cropland sites were examined to a depth of 30 cm. The cropland sites had been cultivated for periods ranging from 5 to more than 80 y (median 10 y), and their slopes ranged from 5 to 26% (median 13%). All except one of the cropland sites contained less ¹³⁷Cs than undisturbed sites in the same area. Three cropland sites contained essentially no ¹³⁷Cs, indicating erosion of the entire cultivated layer of soil in from 6 to 10 years. Other cropland sites, particularly those with sandy texture, showed little loss of ¹³⁷Cs over longer periods of cultivation. Cesium-137 measurements may be useful in identifying site characteristics that reduce the vulnerability of sloping soils to erosion damage.     

Determination of natural and anthropogenic radionuclides in soil--results of an European Union comparison

A comparison was organised by the Institute for Reference Materials and Measurements (IRMM) among 73 environmental radioactivity monitoring laboratories for the determination of 15 radionuclides in soil. The reference material IAEA-375 soil was reprocessed to provide the comparison material and reference values traceable to SI units and SIR were established at IRMM. The analytical procedures used by participants laboratories are discussed and performances evaluted using relative deviations and E(n) numbers. This paper focuses on the results for (40)K, (90)Sr, (137)Cs, (226)Ra, (234)U, (235)U and (238)U. Worst performance was found for (90)Sr and (235)U, where 65% and 78% of the results, respectively, deviate more than 20% from the reference values. The use of the E(n) criterion revealed that the uncertainty estimation of many participants is poor.     

土壤物理性质对土壤氡浓度及地表氡析出率的影响

目的探讨土壤性质对土壤氡浓度及地表氡析出率的影响。方法在北京、贵阳、呼和浩特的31个测量点进行土壤氡浓度及析出率的现场实测。采集土壤样品，在实验室进行土壤镭含量、含水量、孔隙度和粒径分布等物理性质测量。用线性拟合方法分析了实测土壤氡、析出率数据之间的相关性，以及它们与土壤镭含量的关系。结果地表氡析出率与土壤氡浓度和土壤镭含量有正相关关系；土壤含水饱和度过高或过低均会使析出率和土壤氡浓度降低；贵阳地区土壤镭含量较高，但其粉砂黏土壤的特性使土壤氡浓度很难准确采样，导致结果偏低。结论地表氡析出率和土壤氡浓度虽然与土壤镭含量有正相关关系，但在实际环境中易受含水量等多因素影响，而且土壤氡浓度的准确测量受土壤特性限制较大。     

Using Cesium-137 technique to study the characteristics of different aspect of soil erosion in the Wind-water Erosion Crisscross Region on Loess Plateau of China.

The most serious soil erosion on Loess Plateau exists in the Wind-water Erosion Crisscross Region. In the past 20 years, the types and intensity of soil erosion and its temporal and spatial distribution were studied, but studies on the difference of soil erosion between slope aspects and slope positions in this area have no report. However, it is very important to analyze and evaluate quantitatively the characteristics of different aspects and positions of soil loss for the prevention and treatment of soil erosion in this area. The spatial pattern of net soil loss on 4 downslope transects in four aspects (east, west, south and north) on a typical Mao (round loess mound) in Liudaogou catchment in Wind-water Erosion Crisscross Region was measured in 2000 using the resident cesium-137 deficit technique. The purposes of this investigation were undertaken to determine whether or not 137Cs measurement would give a useful indication of the extent of soil loss and their characteristics from cultivated hillsides in different slope aspect and slope position in the study area. The results showed that the difference of soil erosion in different aspect was significant and the erosion rate was in this order: north > east > south > west. Compared with other areas, the difference of erosion rate between north hillside and south hillside was on the contrary, and the possible explanations could be the effect of wind erosion. Also, the percentage of wind erosion was estimated to be at least larger than 18% of total soil loss by comparing the difference of erosion amount in south hillside and north hillside. The erosion rates on different slope positions in all aspects were also different, the highest net soil loss occurred in the lower slope position, and the upper and middle slope positions were slight. The general trend of net soil loss on sloping surface was to increase in fluctuation with increasing downslope distance.     

The detection of residual gasoline for forensic soil investigation in arson

The cause of an arson fire is difficult to investigate. Detection of gasoline residue can provide important information to link evidence with an arson scene. Soil can be taken as physical evidence from an arson scene and also used to indicate the presence of gasoline residue. Since each soil has different characterisation details, this study was undertaken to present an effective method for soil sampling. Gasoline permeability in soil is affected by soil type. This study investigates the permeation of gasoline into four different soil types and determines the optimum soil depth for gasoline detection. The effect of burning duration and the time between extinguishing the fire and taking the sample were also investigated. The studied soils were collected from various soil series in Thai Northern region. The results indicate that soil structure, burning duration and sampling period are important factors that have a significant effect on residual gasoline detection in each of the soil series studied. The key finding of this study was that the optimum depth for all studied soil series was 5 cm below the surface. These findings have implications for crime scene investigators carrying out soil evidence investigation at an arson scene.     

Retrospection of recent 30-year changes in the process of soil wind erosion in the Luanhe River Source Area of North China using Cesium-137

The Luanhe River Source Area belongs to typical semi-arid, agro-pastoral ecotone of North China. It is very important for the prevention and treatment of soil erosion in North China to analyze and evaluate quantitatively the recent 30-year changes in the process of soil wind erosion in this area. Based on long field observations, soil samples from different depths in a representative wind-deposited soil profile in the Luanhe River Source Area were collected. Then the ¹³⁷Cs activity of soil samples from different depths in the soil profile was determined using a GEM series HPGe (high-purity germanium) coaxial detector system (ADCAM-100), and their soil properties, such as the soil particle fraction and so on, were analyzed. According to the detected ¹³⁷Cs activity of different depths, a continuous time sequence of the wind-deposited soil profile in the study area was established. Furthermore, through assumption on a soil relative wind erosion intensity index (SWEI), recent 30-year changes in the process of soil wind erosion in the Luanhe River Source Area were retrospected . The analysis results revealed that weaker soil wind erosion occurred in the study area from the 1970s to the early 1980s and from the late 1980s to the mid to late 1990s. Conversely, intense periods of soil wind erosion occurred in the mid-1980s and from the late 1990s to 2002.     

Determination of multi-element profiles of soil using energy dispersive X-ray fluorescence (EDXRF).

The source profile for soil in Hong Kong is important both for determination of the main air pollutant source in Hong Kong and for assessment of the impact of Asian dust storms on Hong Kong. Soil associated with different rock types have been sampled, and the concentrations of 19 chemical elements, Na, Al, Si, Ti, V, Cr, Mn, Fe, Co, K, Ca, Ni, Cu, Zn, Pb, Rb, Sr, Y and Zr, have been determined using energy dispersive X-ray fluorescence. A profile for the average soil for Hong Kong has been determined by taking average values for the different soil categories. The values for the Hong Kong soil are commensurate with values for rural soil derived by other workers, except that Hong Kong soil has much lower Fe and Ca concentrations. The abundance of Al, Ca and Fe in the average Hong Kong soil are 9.23%, 0.11% and 0.85%. We conclude that Ca provides a good marker element for identifying dust episodes in Hong Kong while Al does not.     

Influence of soil storage and exposure period on DNA recovery from teeth

A study was performed to determine the influence of garden soil on the deoxyribonucleic acid (DNA) recovery from teeth depending on the duration of storage. In the first series 24 teeth supplied by dentists were exposed to garden soil storage for a maximum of 18 weeks. Selected samples were excavated for DNA extraction at time intervals of 6,12 and 18 weeks. For the second series 20 teeth were stored for one year in garden soil. Following phenol/chloroform extraction with decalcification (first series) and without decalcification prior to extraction (second series) DNA was quantified, amplified using the polymerase chain reaction (PCR) for the tandem repeat loci D1S80, tyrosine hydroxylase, intron 1 (TH01) and Von Willebrand factor, intron A (VWA) (first series), human alpha fibrinogen (FGA) (second series) and sequenced in the hypervariable regions 1 and 2 (HV1, HV2) of the mitochondrial DNA (second series). The DNA concentration of the extracts after the first 6 weeks in soil was reduced by more than 90%. Amplification and direct sequencing of HV1 and HV2 of the mitochondrial genome was the most successful DNA technique. Received: 5 June 1998 / Received in revised form: 11 July 1998     

Use of 137Cs measurements to estimate changes in soil erosion rates associated with changes in soil management practices on cultivated land.

Intensification of agricultural production in south-central Chile since the 1970s has caused problems of increased soil erosion and associated soil degradation. These problems have prompted a shift from conventional tillage to no-till management practices. Faced with the need to establish the impact of this shift in soil management on rates of soil loss, the use of caesium-137 (137Cs) measurements has been explored. A novel procedure for using measurements of the 137Cs depth distribution to estimate rates of soil loss at a sampling point under the original conventional tillage and after the shift to no-till management has been developed. This procedure has been successfully applied to a study site at Buenos Aires farm near Carahue in the 9th region of Chile. The results obtained indicate that the shift from conventional tillage to no-till management has caused net rates of soil loss to decrease to about 40% of those existing under conventional tillage. This assessment of the impact of introducing no-till management at the study site must, however, be seen as provisional, since only a limited number of sampling points were used. A simplified procedure aimed at documenting the reduction in erosion rates at additional sampling points, based solely on measurements of the 137Cs inventory of bulk cores and the 137Cs activity in the upper part of the soil has been developed and successfully tested at the study site. Previous application of 137Cs measurements to estimate erosion rates has been limited to estimation of medium-term erosion rates during the period extending from the beginning of fallout receipt to the time of sampling. The procedures described in this paper, which permits estimation of the change in erosion rates associated with a shift in land management practices, must be seen as representing a novel application of 137Cs measurements in soil erosion investigations.     

Postmortem microbial communities in burial soil layers of skeletonized humans

Microorganisms are major ecological participants in the successional decomposition of vertebrates. The relative abundance, or the scarcity, of certain microbial taxa in gravesoil has the potential to determine the ecological status of skeletons. However, there are substantial knowledge gaps that warrant consideration in the context of the surrounding terrestrial ecosystem. In the current study, we hypothesized that i.) soil microbial diversity is disparate in the latter stage of decomposition (skeletonization) compared to the earlier stages (fresh, bloat, active and advanced decay), and ii.) the three layers of gravesoil (top, middle, and bottom) encompass similar microbial taxa and are analogous with control soil. To test these hypotheses, microbial communities in layers of burial soil of skeletonized bodies (treated) and from control soil, obtained from burial plots with no bodies (untreated), were compared using sequencing data of the 16S rRNA gene. The results demonstrated that Acidobacteria was confirmed as the most abundant microbial genus in all treated and untreated soil layers. Furthermore, Proteobacteria demonstrated a relatively low abundance in skeletonized gravesoil which is dissimilar from previous findings that assessed soil from earlier stages of human decomposition. Also, these results determined that soil microbial signatures were analogous in all three soil layers under the effects of similar abiotic and biotic factors, and they were similar to the communities in untreated soil. Therefore, the current study produced empirical data that give conclusive evidence of soil microbial successional changes, particularly for Proteobacteria, for potential use in forensic microbiology research.     

Nuclear spectroscopy for in situ soil elemental analysis: Monte Carlo simulations

We developed a model to simulate a novel inelastic neutron scattering (INS) system for in situ non-destructive analysis of soil using standard Monte Carlo Neutron Photon (MCNP5a) transport code. The volumes from which 90%, 95%, and 99% of the total signal are detected were estimated to be 0.23 m3, 0.37 m3, and 0.79 m3, respectively. Similarly, we assessed the instrument's sampling footprint and depths. In addition we discuss the impact of the carbon's depth distribution on sampled depth.     

Neutron computerized tomography in compacted soil

This work applies the computerized tomography technique using thermal neutron beams for inspection of compacted soil specimens. Several specimens were analysed whose bulk densities vary from 1.61 up to 1.93 g·cm⁻³ and the water content from 7.8 up to 14.8%. The images reconstructed with thermal neutrons are compared with the reconstruction obtained with gamma rays of 316 keV, to demonstrate the sensitivity of the neutron technique. By analysing the reconstructed images it is possible to detect the different water content levels and to identify the soil composition. The macroscopic total cross-section values and the compactation curves obtained using the tomographic images agree with the expected data.