Radon-222 exhalation from open ground on and around a uranium mine in the wet-dry tropics

Radon-222 exhalation from the ground surface depends upon a number of variables such as the 226Ra activity concentration and its distribution in soil grains; soil grain size; soil porosity, temperature and moisture; atmospheric pressure, rainfall and temperature. In this study, 222Rn exhalation flux density measurements within and around the Ranger uranium mine in northern Australia were performed to investigate the effect of these variables within a tropical region. Measurements were taken at the waste rock dumps, ore stockpiles, mine pits, and at sites where effluent water with elevated 226Ra concentration has been spray irrigated over land, as well as at sites outside the mine. The sites selected represented a variety of geomorphic regions ranging from uranium-bearing rocks to ambient soils. Generally, wet season rains reduced 222Rn exhalation but at a few sites the onset of rains caused a step rise in exhalation flux densities. The results show that parameters such as 226Ra activity concentration, soil grain size and soil porosity have a marked effect on 222Rn flux densities. For similar geomorphic sites, 226Ra activity concentration is a dominant factor, but soil grain size and porosity also influence 222Rn exhalation. Surfaces with vegetation showed higher exhalation flux densities than their barren counterparts, perhaps because the associated root structure increases soil porosity and moisture retention. Repeated measurements over one year at eight sites enabled an analysis of precipitation and soil moisture effects on 222Rn exhalation. Soil moisture depth profiles varied both between seasons and at different times during the wet season, indicating that factors such as duration, intensity and time between precipitation events can influence 222Rn flux densities considerably.     

Assessment of the uncertainties in the Radiological Protection Institute of Ireland (RPII) radon measurements service

The RPII radon (Rn) laboratory holds accreditation for the International Standard ISO/IEC 17025. A requirement of this standard is an estimate of the uncertainty of measurement. This work shows two approaches to estimate the uncertainty. The bottom-up approach involved identifying the components that were found to contribute to the uncertainty. Estimates were made for each of these components, which were combined to give a combined uncertainty of 13.5% at a Rn concentration of approximately 2500Bqm(-3) at the 68% confidence level. By applying a coverage factor of k=2, the expanded uncertainty is +/-27% at the 95% confidence level. The top-down approach used information previously gathered from intercomparison exercises to estimate the uncertainty. This investigation found an expanded uncertainty of +/-22% at approximately 95% confidence level. This is good agreement for such independent estimates.     

Occupational dosimetric assessment (inhalation pathway) from the application of phosphogypsum in agriculture in South West Spain

Phosphogypsum (PG) has been traditionally applied as Ca-amendment in saline marsh soils in SW Spain, where available PG has 710 ± 40 Bq kg⁻¹ of ²²⁶Ra. This work assesses the potential radiological risk for farmers through ²²²Rn exhalation from PG-amended soils and by inhalation of PG-dust during its application. A three-year field experiment was conducted in a commercial farm involving two treatments: control and 25 t PG ha⁻¹ with three replicates (each 0.5 ha plots). The ²²²Rn exhalation rate was positively correlated with potential evapotranspiration, which explained 67% of the variability. Statistically significant differences between the control and PG treatments were not found for ²²²Rn exhalation rates, and mean values were within the lowest quartile of the typical range for ²²²Rn exhalation from soils. Airborne dust samples were collected during the application of PG and sugar-beet sludge amendments. The highest PG-attributable ²²⁶Ra concentration in the dust samples was 3.3 × 10² μBq m⁻³, implying negligible dose increment for exposed workers.     

Using radon-222 as indicator for the evaluation of the efficiency of groundwater remediation by in situ air sparging

A common approach for remediation of groundwater contamination with volatile organic compounds (VOCs) is contaminant stripping by means of in situ air sparging (IAS). For VOC stripping, pressurized air is injected into the contaminated groundwater volume, followed by the extraction of the contaminant-loaded exhaust gas from the vadose soil zone and its immediate on-site treatment. Progress assessment of such remediation measure necessitates information (i) on the spatial range of the IAS influence and (ii) on temporal variations of the IAS efficiency. In the present study it was shown that the naturally occurring noble gas radon can be used as suitable environmental tracer for achieving the related spatial and temporal information. Due to the distinct water/air partitioning behaviour of radon and due to its straightforward on-site detectability, the radon distribution pattern in the groundwater can be used as appropriate measure for assessing the progression of an IAS measure as a function of space and time. The presented paper discusses both the theoretical background of the approach and the results of an IAS treatment accomplished at a VOC contaminated site lasting six months, during which radon was applied as efficiency indicator.     

Modelling the long-term consequences of a hypothetical dispersal of radioactivity in an urban area including remediation alternatives

The Urban Remediation Working Group of the International Atomic Energy Agency's EMRAS (Environmental Modelling for Radiation Safety) program was organized to address issues of remediation assessment modelling for urban areas contaminated with dispersed radionuclides. The present paper describes the second of two modelling exercises. This exercise was based on a hypothetical dispersal of radioactivity in an urban area from a radiological dispersal device, with reference surface contamination at selected sites used as the primary input information. Modelling endpoints for the exercise included radionuclide concentrations and external dose rates at specified locations, contributions to the dose rates from individual surfaces, and annual and cumulative external doses to specified reference individuals. Model predictions were performed for a “no action” situation (with no remedial measures) and for selected countermeasures. The exercise provided an opportunity for comparison of three modelling approaches, as well as a comparison of the predicted effectiveness of various countermeasures in terms of their short-term and long-term effects on predicted doses to humans.     

Mapping of the geogenic radon potential in France to improve radon risk management: methodology and first application to region Bourgogne

In order to improve regulatory tools for radon risk management in France, a harmonised methodology to derive a single map of the geogenic radon potential has been developed. This approach consists of determining the capacity of the geological units to produce radon and to facilitate its transfer to the atmosphere, based on the interpretation of existing geological data. This approach is firstly based on a classification of the geological units according to their uranium (U) content, to create a radon source potential map. This initial map is then improved by taking into account the main additional parameters, such as fault lines, which control the preferential pathways of radon through the ground and which can increase the radon levels in soils. The implementation of this methodology to the whole French territory is currently in progress. We present here the results obtained in one region (Bourgogne, Massif Central) which displays significant variations of the geogenic radon potential. The map obtained leads to a more precise zoning than the scale of the existing map of radon priority areas currently based solely on administrative boundaries.     

Assessment of polychlorinated dibenzo-p-dioxins and dibenzofurans in sludges according to the European environmental policy

The amount of sewage sludge generated in Europe is expected to surpass the 10 million tons/year in 2006 as a result of the waste water treatment process according to the Water Policy in European Union. Sewage sludge is what is left behind after water is cleaned in waste treatment plants and is characterized for this high content in nitrogen and phosphorous that could be of great importance in agriculture as fertilizer or soil conditioner. On the other hand, pollutants like metals and organic contaminants are usually removed from water and are accumulated in the sewage sludge, reaching the food chain if their concentrations are not below the safe limits established by the European legislation. The latter issue is of great concern nowadays and in this sense, different works alert against the use of the sewage sludge in agriculture arguing that serious illnesses, even resulting in death as well as adverse environmental impacts are associated to the application of sewage sludge. This work is a continuation of a former comprehensive survey on of priority organic pollutant in sludges for agricultural purposes carried out by our group in Catalonia and this time is focused on the polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F), one of the most toxic group of organic compounds listed in the Work Document on Sludge which is the reference tool in this field in Europe and is also included in the Stockholm Convention. Eighty eight samples were collected from the end of 2003 to April 2006 and the concentrations detected were lower than the 100 ng/kg I-TEQ limit recommended by the European legislation (EC, 2000). Thus, sewage sludges generated in Catalonia do not represent a threat to human health if they are used as fertilizers in agriculture.     

Effect of increased ambient temperature on the growth rate of young pine forests in the impact zone of a petroleum gas flare

The effect of increased ambient temperature on the vertical, radial, and volume increments of Scots pine (Pinus sylvestris L.) trees has been studied in the zone of thermal impact from a burning petroleum gas flare. Regular age-dependent changes in the pattern of increment dependence on the distance from the flare and ambient temperature have been revealed. The mechanisms of these changes are explained. It is concluded that an increase in ambient temperature by 1.0–1.5° C has a favorable effect on the dynamics of Scots pine growth.     

Environmental aspects and health risks of leather tanning industry: a study in the Hazaribag area

The tannery industry in Hazaribag, which is one of the most polluted areas in Dhaka City, produces a huge quantity of wastes every day. Without treatment, these are discharged into the Buriganga River and pollute the surrounding environment. This article examines the impacts of tannery wastes on workers’ health and the environment in that particular area. As part of the methodology, a semi-structured interview was conducted in order to obtain quantitative data and 112 respondents were interviewed using purposive sampling. The findings of the study indicate that tannery wastes affect the environment severely, causing ecological imbalance and the spreading of different kinds of fatal and contagious disease among the tannery workers and other individuals. Moreover, the current waste management system of the Hazaribag tannery industries is very suspect due to outdated technology, defective drainage systems, lack of financial input, and the exploitative attitude of their owners. The findings also indicate that tannery workers are unaware of the effects of tannery waste as they choose not to wear personal protective equipment in the workplace. This empirical study helps policy makers implement appropriate measures to raise awareness, among both owners and workers, that can influence changes in the public’s attitude and reduce environmental pollution to a great extent. Although considerable research has been undertaken focusing on tannery waste impact assessment, less attention has been paid to the issue of workers’ health. Therefore, both governments and policy makers can benefit from the findings of this study.     

山东省经济发展与环境保护关系的计量分析

经济增长与环境污染之间的关系常用环境库兹涅茨曲线（EKC）来描述。典型的EKC一般量倒U形。本文选取1988-2002年的山东省环境与经济数据．建立单位GDP污染排放量横型和人均GDP污染排放量模型,对山东省经济发展与环境保护之间的关系进行了计量与分析。通过单位GDP污染负荷模型分析发现。单位GDP的污染负荷量下降态势。这说明山东省产业结构调整已产生明显成效。通过人均GDP污染排放量模型发现．山东省的EKC不完全符合典型的库兹涅茨曲线特征。呈显着的三次曲线特点。其中,工业废水曲线为“U＋倒U”形．两个转折点的理论计算值分别为3416元和9975元。废气与固废曲线近似于倒U形EKC的左半部分．尚来到达转折点。由此可见．环境质量的改善并非随着收入水平的提高而自动发生。除了收入因素。影响山东省EKC的因素还有国家或地区的环境政策、工业化进程等。     

On the influence of faulting on small-scale soil-gas radon variability: a case study in the Iberian Uranium Province

In order to evaluate the influence of faulting on the variability of geogenic radon at detailed scale (1:2000), data on gamma ray fluxes, U and Th concentrations in rocks, radon in soil-gas and radon in groundwater were collected in three target areas on the Oliveira do Hospital region (Central Portugal). This region stands on the Iberian Uranium Province, and is dominantly composed of Hercynian granites and metasedimentary rocks of pre-Ordovician age, crosscut by faults with dominant strike N35°E, N55°E and N75°E. Radiometric anomalies are frequent, associated with faults of the referred systems and metasedimentary enclaves; the analytical data confirms that these anomalies are produced by local high uranium contents in rocks and fault-filling materials (n = 34, range 13-724 ppm), while other radiogenic elements are relatively constant (e.g. Th 4-30 ppm). Radon concentration in soil can be extremely high, up to 12,850 kBq m⁻³ (n = 215), with a large proportion of results above 100 kBq m⁻³. Unsurprisingly, groundwater also shows high radon concentrations, with observed values in the range 150-4850 Bq.L⁻¹ (n = 17). From the results it is concluded that metasedimentary enclaves, as well as faults, can accumulate uranium from circulating fluids, and as a consequence, strongly locally enhance geogenic radon potential. Due to this fact, for the purpose of land use planning in such uranium-enriched regions, very detailed geological mapping is needed to precisely recognize radon high risk areas. A correlation between radon concentration in soil or in groundwater and gamma ray fluxes was established pointing to the possible use of these fluxes as a first step in assessing geogenic radon potential, at least to geological setting similar to the study area.     

Variation of short-lived beta radionuclide (radon progeny) concentrations and the mixing processes in the atmospheric boundary layer

Radon is emitted to the atmosphere with quasi constant emission rates depending on the radium concentration in the earth's crust and soil physical properties. In this way, the ²²²Rn and ²²⁰Rn concentration in air reflects significantly the thickness of the atmospheric boundary layer (ABL). The aerosol-associated, beta-emitting progeny nuclides of ²²²Rn were measured daily in the framework of the atmospheric radioactivity monitoring program of NIMH at Sofia. The ²¹⁴Pb concentration was estimated from the measured short-lived beta activity of 24-h filter samples, changed daily at 6:00 GMT. The impact of some meteorological factors such as wind direction, wind velocity, humidity, and temperature on short-lived beta radionuclides is estimated, and the results show no simple statistical relationship. A seasonal pattern was observed with winter minima and late summer-early autumn maxima. High variability in daily morning concentrations and mean monthly values was observed. There were well pronounced differences between years. The height of the convective ABL was estimated from daily radio-soundings at 12:00 GMT for the period 2001-2006 and from seven soundings per day during the experimental campaign in Sofia in October 2003. In general, concentrations of short-lived ²²²Rn progeny nuclides decreased with increased convective ABL height.     

Assessment of indoor radiation level in the environs of the uranium deposit area of West Khasi Hills District,Meghalaya, India

An estimation of the indoor background radiation dose distribution was carried out in dwellings of eleven villages located within and around the uranium mineralization area of Kylleng-Pyndensohiong, Mawthabah in West Khasi Hills District of Meghalaya, India. The ambient indoor gamma radiation level was monitored using Thermo Luminescence Dosimeters (TLDs) while the indoor radon and thoron concentration was measured using twin-cup dosimeters employing Solid State Nuclear Track Detectors (SSNTDs). Results obtained from the study reveals that the local inhabitants of villages located close to the mining site receive higher doses than those inhabitants of villages located at a much farther distance from the mining site. The average total annual effective dose was found to be varying from 1.2 mSv y⁻¹ in the village of Langpa to 3.4 mSv y⁻¹ in the village of Nongbah Jynrin. The data obtained will serve as a reference in documenting changes to environmental radioactivity if mining is to be carried out in the future.     

Effect of emissions from petroleum gas flares on the reproductive state of pine stands in the northern taiga subzone

Characteristics of the adaptive response of the female generative system of Scotch pine to air pollution caused by petroleum gas burning in flares during oil production in Western Siberia have been studied. The relationship between the individual and endogenous variations of the quantitative parameters of pine cone morphology has been analyzed in different zones of deterioration.     

草原生态补奖政策对农牧民牲畜养殖规模的影响——基于生计分化的调节效应分析

实现对牲畜养殖规模的有效管控是草原生态补奖政策成败的关键。在农牧民生计分化日益加深的背景下,探讨草原生态补奖政策与生计分化对农牧民牲畜养殖规模的影响,对于完善草原生态补奖政策,实现草原生态保护与农牧民生计转换的有机结合具有重要的现实意义。本文阐释了草原生态补奖政策影响农牧民牲畜养殖规模的机理,并引入生计分化变量,基于实地调研获取的317份农牧交错区农牧民微观数据,运用最小二乘回归和分位数回归实证分析了草原生态补奖政策对农牧民牲畜养殖规模的影响以及生计分化在草原生态补奖政策影响农牧民牲畜养殖规模中的调节效应。研究结果表明:①补奖金额与牲畜养殖规模之间存在稳健的“倒U型”关系,表明补奖政策在短期内对牲畜数量的增加具有积极的促进作用,但随着补奖金额的增加,促进作用将逐渐减弱,最终趋于抑制。②根据非农牧收入占比和生计对牧业生产依赖程度的差异可将农牧民分为牧业为主型、农业为主型、均衡型、高兼型和深兼型五种类型农牧民。③农牧民生计分化对牲畜养殖规模的扩大具有抑制作用,且在草原生态补奖政策与牲畜养殖规模二者关系中具有调节作用。即在“倒U型”曲线的左侧,生计分化能够弱化草原生态补奖政策对牲畜养殖规模扩大的促进作用;在“倒U型”曲线的右侧,生计分化能够促使补奖金额对牲畜养殖规模的负向影响趋于放缓,有助于避免因补奖金额的增加引致牲畜养殖数量的锐减。根据以上结论,建议政府应进一步提高补奖标准以增强补奖弥补损失的有效性,重视发挥农牧民生计分化在牲畜养殖规模调控中的作用。     

Measurements of indoor radon concentrations in the Santiago de Compostela area

Galician soils are among those with the highest (222)Rn exhalation rates in Spain. A year-round study of the indoor (222)Rn concentration in buildings in the Santiago de Compostela area (Galicia, Northwest of Spain) was performed. The study is based on systematic samplings with active charcoal canisters, following a modified EPA 520/5-87-005 protocol. These measurements were complemented by others obtained using etched track dosimeters. Each data set follows a log-normal distribution, with a geometric mean of (253+/-3)Bqm(-3) for charcoal canisters and (285+/-2.5)Bqm(-3) for etched track detectors. After correcting for the different measuring conditions, the mean value of both methods differed by only 2%. A careful analysis of the seasonal dependence of our measurements did not reveal any significant seasonal variations in the (222)Rn concentration. Parallel to these measurements, different meteorological parameters were recorded, which revealed a direct correlation between the indoor radon concentration and the outdoor temperature derivative with respect to time.     

东北地区开发规模扩张的资源环境响应演变及影响因素

提出"区域开发规模扩张的资源环境响应"的概念,并构建了区域开发规模扩张的资源环境响应指数、响应度模型及评价指标体系,通过定量分析1995-2008年东北地区开发规模扩张的资源环境响应变化及影响因素,得出以下结论:1995年以来东北地区开发规模不断扩大,而资源环境水平总体呈现出"先升后降"的波动变化态势。资源环境对东北地区开发规模扩张具有由"正响应"向"负响应"转变的特征,与此相对应,区域开发规模扩张对资源环境的影响程度也呈现出由"弱促进"向"强胁迫"变化的态势,这说明近年来在东北地区开发规模加速扩展的同时,其对区域资源环境造成的压力也日益增大。1995-2008年由经济快速增长导致的资源环境压力增长是引致东北地区开发规模扩张对资源环境影响由"正向促进"向"负向胁迫"转化的重要内部因素,而区域投资的不断增长以及工业的快速发展是东北地区开发规模扩张对资源环境影响由"弱促进"向"强胁迫"变化的主要因素。     

基于集约评价的城市开发区规模计量研究——以南京市省级以上开发区为例

随着开发区集约利用评价工作的全面开展,合理界定其用地规模成为研究的重点。本文以南京市为例,首先运用多目标决策法评价开发区集约利用等级,然后采用逐步回归法选取与集约利用相关度较大的因素作为预测依据,进而计量其合理的规模。研究结果表明:其一,A、B和C开发区集约等级为II级,可以适当扩大开发区规模;D、E、F和G开发区集约等级为III级,应该维持开发区规模;而H和I开发区集约等级为IV级,应适当缩小开发区规模。其二,当B开发区、A开发区和其他开发区地均工业总产值增长率分别达到23.10%、18.18%和15%时,可以充分发挥土地利用潜力。其三,即使实现土地集约利用,B开发区仍需扩充6.08 km2。最后,本文提出通过科学设定地均工业总产值增长率来提升开发区集约利用水平的政策建议。     

中国城市用地增长极限规模测算

快速城市化出现的城市建设用地扩张问题,受到人们广泛关注,借鉴发达国家经验,我国需要测算一个极限区间值进行自上而下的总量控制,以促进最严格耕地保护制度和节约用地制度的落实.但是如何测算这个极限规模一直没有得到很好解决.本文提出了一个常规方法组合和关键指标相结合的技术思路来尝试解决这个问题.研究首先对城市用地扩展规模的影响因子进行了分析,讨论了城市人口数量和GDP分别与建成区面积相关性,确定了城市人口数量对建成区面积影响更大;在此基础上,采用逻辑斯蒂模型,依据我国1950-2010年经济数据,对城市化水平进行预测;用自回归分布滞后模型,依据1951-2010年全国人口数据对未来人口规模进行预测,并分为三个方案对结果进行了讨论;最后按照城市用地分类与规划建设用地标准,以节约集约用地为原则,将人均城市用地规模取值控制在65.0-115.0 m2,计算城市用地扩展极限规模.结果表明,到2045年,中国的城市化预测水平为79.99％,在中国人口增长控制较好的情况下,人口规模将达到14.97亿人,城市用地扩展规模为77 857.38-137 747.70 km1;若中国人口达到有关研究的预测峰值16亿人,中国城市化水平稳定在80％,城市用地扩展极限规模将会是83 200.00-147 200.00 km2.综合以上分析,未来我国的城市建设用地总量应在7.8万km2到14.7万km2之间.     

我国区域土壤侵蚀与环境研究述评

区域土壤侵蚀与环境研究，是在比较大的中间尺度和较长的时间尺度上，对土壤侵蚀发生发展过程、土壤侵蚀因子、土壤侵蚀定量评价方法，以及土壤侵蚀治理对环境的影响进行研究的科学与技术体系。该领域的研究，即能直接为国家水土保持宏观决策提供支持，又能揭示土壤侵蚀的宏观规律，并于全球变化研究相联系。我国在该领域的研究主要概括四个方面，包括：①区域土壤侵蚀因子研究，是为认识土壤侵蚀环境特征和进行土壤侵蚀定量评价的基础，②区域土壤侵蚀评价研究，包括调查制图、定性评价和定量评价等，是该研究服务于水土保持实践的基本途径；③水土保持的环境效应研究，是从另外一个视角对土壤侵蚀环境与水土流失及其治理关系的认识。是确切评估水土保持效益，保证水土保持工作健康持续稳定发展的基础。今后应尽快开发区域水土流失定量评价模型，并在区域尺度上对环境效应的方式、范围、程度和发展趋势做出综合计价和分析预测。