Dose estimates for exposure to radioactivity in gas mantles

In this paper dose estimates are given for internal and external exposure that result, due to radioactive thorium, from the use of the incandescent mantles for gas lanterns.The collective, effective dose equivalent for all users of gas mantles is estimated to be about 100 Sv per annum in the Netherlands. For the population involved (ca. 700,000 persons) this is roughly equivalent to 5% to 10% of the collective dose equivalent associated with exposure to radiation from natural sources. The major contribution to dose estimates comes from inhalation of radium during burning of the mantles. A pessimistic approach results in individual dose estimates for inhalation of up to 0.2 mSv.     

About the assumption of linearity in soil-to-plant transfer factors for uranium and thorium isotopes and 226Ra

The linearity assumption for soil and plant concentrations of radionuclides is usually a good approximation for use in food-chain models. To verify this assumption, different samples of plant and substrate were collected from a granitic zone located near a disused uranium mine in order to cover a large range of concentrations. In all of the samples, the activity concentration of 226Ra and of different isotopes of uranium (238U and 234U) and thorium (232Th, 230Th and 228Th) were determined. The results indicate that the linearity assumption can be considered valid when the range of concentrations taken into account is large (approx. two orders of magnitude). Otherwise, there is a clear deviation from linearity. Also, the influence of different stable elements on the soil-plant transfer factors was studied by using multivariate regression methods. The uptake of uranium, thorium and radium was found to be mainly associated with the concentration of iron in the plant and the phosphorus and alkaline earths in the substrate.     

Analysis of the level of comprehension of chemical hazard labels: a case for Zambia

We have surveyed the impact of chemical hazard label elements on four target sectors, i.e. the agricultural, industrial, transport and the consumer (the general public) sectors, in order to assess the type of reactions the respondents perceive to a given chemical label element such as symbol, hazard phrase, color, and hazard signal word. The survey revealed that the level of education, gender and/or age did not influence the respondents' perception of the extent of hazard but rather familiarity or frequency of use of the chemicals and acquaintance with chemical label elements was significant in the assessment of the extent of perceived hazard posed by a given chemical. Symbols such as the St Andrews Cross--though common--is virtually not understood by more than 80% of the respondents in all the sectors. We noted that respondents appreciate symbols they can relate to, which are flame-like, ghost-like and exert immediate impacts to respondents. Color codes have found use in the agriculture sector because of their ease to be recalled especially by the majority of illiterate farm workers. The survey revealed that red in agricultural circles is well associated with high toxicity while other colors such as yellow and blue can not clearly be associated with hazard. The word "toxic" is not used in the industry and transport sectors where the most hazard signal word is "danger". The Globally Harmonized System (GHS) classification adopted "danger" and "warning" for use as signal words. The survey revealed that effective chemical hazard symbols must not be too abstract to the client but should contain features that are known or easily comprehended.     

Daily intakes of 238U, 234U, 232Th, 230Th, 228Th and 226Ra in the adult population of central Poland.

Activity concentration of the uranium and thorium series radionuclides was determined in foodstuffs and drinking water in central Poland. Annual and daily intake for the adult population was estimated from the concentrations determined and average annual consumption of food and water. The daily intakes (in mBq) were 22.1 (238U), 26.5 (234U), 2.38 (232Th), 4.06 (230Th), 11.2 (228Th) and 42.2 (226Ra). The intake of uranium isotopes occurred mainly with water; the main intake of thorium isotopes was with animal products, vegetables, cereals and potatoes, whereas 226Ra entered mainly with animal products, cereals and vegetables. From the intake and dose coefficients, the annual effective doses for the ingested radionuclides were calculated. The annual effective dose was 5.95 microSv, of which 72.4% originated from 226Ra.     

Uranium and thorium in weathering and pedogenetic profiles developed on granitic rocks from NW Spain

Uranium and thorium were analyzed in seven weathering and pedogenetic soil profiles developed on granitic rocks from NW Spain. Concentrations were measured by X-ray fluorescence spectrometry (XRF) and the U- and Th-bearing minerals were studied by scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). Both elements were determined in rock, bulk soil and in different grain-size fractions (sand: 2000-50 microm, silt: 50-2 microm, and clay: <2 microm). U concentrations in the rock varied between 5.3 and 27.7 mg kg(-1) and Th concentrations from 5.5 to 50.7 mg kg(-1). The most alkalic rocks can be considered as U-rich granites. Bulk soil U and Th concentrations are similar to those of the rocks (4.8-29.2 and 7.4-56.7 mg kg(-1), respectively), but in the grain-size fractions both elements show the lowest concentrations in the sand and the highest in the clay. In the latter, concentrations are always higher than those of the rocks, particularly in the C horizons with enrichments up to 4 times for U and 5 times for Th. The concentration profiles and the ratios to the parent rock suggest that U and Th are leached from the surface soil and accumulate in the deeper horizons. Mass balance calculations, using Ti as a reference immobile element, also support U and Th leaching in the solum and supergene enrichment in bottom horizons. Leaching seems to be more intense on horizons with gravel content higher than 20%. The leaching of U and Th in the topmost horizons and the accumulation in the bottom soil horizons can be considered as a natural attenuation of the impact of these radiogenic elements in the environment. But their enrichment in the potentially airborne fraction poses some risk of redistribution in the ecosystems.     

Assimilation of thorium isotopes into terrestrial vegetation

Vegetation and root zone soil from 17 locations within and near the boundaries of a former thorium processing plant were collected and analyzed for 232Th, 228Th and 230Th in order to evaluate the degree of movement of these radionuclides from soil to root tissue, as well as the extent of their translocation into above-ground plant compartments. Concentration ratio (CR) values ranged as follows: 232Th: 0.0003-0.3218 (shoots), 0.0065-0.9057 (roots); 228Th: 0.0038-0.3300 (shoots), 0.0183-0.7335 (roots); 230Th: 0.0007-0.4560 (shoots), 0.0076-1.252 (roots). Root/shoot ratios were 1.03-85.6 (232Th), 1.54-45.8 (228Th) and 1.36-54.5 (230Th). In nearly all instances, the CR values for 228Th exceeded those for 232Th, with the average 228Th/232Th CR ratios being 3.36 and 1.68 for shoots and roots, respectively. No discernable difference was observed between 230Th and 232Th concentration patterns. The increased 228Th/232Th CR ratio observed is presumably due to the intake of 228Ra into the plant structure, leading to subsequent production of 228Th, through decay, within the plant. It is estimated that approximately 80% of the resident 228Th in above-ground vegetation originates through this mechanism.     

The effect of EDTA on the groundwater transport of thorium through sand

The effect of the anthropogenic complexing agent EDTA on thorium transport in groundwater has been studied using sand-packed columns and flow rates in the range of 20-100 m y⁻¹. The concentrations injected into the columns were in the range of 0.4-4 mM for Th and 4-40 mM for EDTA, and with EDTA:Th ratios in the range 1:1 to 10:1. The results show that EDTA can significantly increase Th transport, but two very different behaviours are observed at Th concentrations of 0.4 and 4 mM. At the lower concentration, Th breakthrough is retarded with respect to a conservative tracer, with a peak width that is consistent with a single K_d value, followed by a longer tail, and the behaviour is very sensitive to the flow rate. However at 4 mM Th, the breakthrough peak appears near to that of the tracer, and the width of the peak is consistent with a distribution of K_d values and/or a larger dispersivity than the tracer. Speciation and transport modelling have been used to interpret the data, and a model was developed that could explain the 0.4 mM behaviour. This suggests that ternary surface complexes are important in these systems, with at least two different species involved, although the complexity of Th speciation in these systems leads to significant uncertainty in the values of the equilibrium and kinetic parameters. For the 4 mM systems, the rapid transport observed could not be explained by a simple chemical model; instead it is likely that EDTA plays an important role in stabilising and transporting thorium colloids and clusters.     

套管水泥环组合抗挤强度模型及其弹性分析

建立了套管水泥环组合抗挤强度模型，导出了管外水泥环对套管屈服抗挤强度的影响系数，提出了套管水泥环组合抗挤强度弹性概念；计算分析了管外水泥环的存在对套管屈服抗挤强度的影响程度，并对套管水泥环组合抗挤强度对套管水泥环参数变化的敏感性，即套管水泥环组合抗挤强度弹性进行了计算分析。     

建构视角下的色彩“饰面”

色彩伴随建筑出现并且是建筑设计的重要组成部分,却常被认为是属于绘画装饰领域的词汇．但从建构视角来看,色彩却可以被理解为“饰面”,进而成为“再现”建筑设计过程的重要途径。随着对建构理论的深入研究,出现了对建构基本概念的不同理解,色彩对于“再现”的意义和方式也有了新的阐释。该文主要从建构理论发展的角度重新认识和理解色彩“饰面”。     

河北下营坊杂岩体地球化学特征、成因及构造环境指示意义

下营坊杂岩体相对亏损镁、铁、钙等组分,具富钾、准铝质—弱过铝质特征,可归类为富钾弱过铝质钙碱性系列的岩石。杂岩体中闪长玢岩和花岗斑岩地球化学特征对比,表明它们为同源岩浆连续演化的产物。闪长玢岩和花岗斑岩都是由壳幔混源的富钾钙碱性岩浆演化而来。闪长玢岩中Ba、K较为富集,Nb、Ta、Th、U均现较明显亏损,其岩浆源应为麻粒岩相下地壳与上地幔热物质的混合,具体过程可能是由于上地幔热软流圈上涌引起麻粒岩相下地壳的部分熔融,并且源区残留相为富Nb、Ta、Ti的金红石。其形成于一个正处于构造体制重大转折的大地构造背景下。     

Factors affecting forms of finding Th(IV) in aqueous solutions

We have investigated forms of finding Th(IV) in aqueous solutions based on experimental data and calculated with the use of stability constants. It has been shown that Th(IV) in the concentration range 1 × 10^?5–1 × 10^?3 M in solutions with pH ≤ 4 exists in the form of monomer hydroxocationic forms. At pH ≥ thorium is found in the form of thermodynamically unstable hydrolysis products being formed and associated in colloids of hardly soluble hydroxides—Th(OH)₄. Charged positively such particles, provided the presence of mineral weighed masses, and are sorbed on the negatively charged surface of the mineral irrespective of its nature, by the precipitation mechanism.     

罐区可燃气体探测器覆盖率评估及布置优化

液化烃属于甲A类火灾危险液体,一旦发生泄漏,遇点火源会产生严重后果.为了有效预防液化烃储罐气体泄漏,以某石化液化烃罐区为例,采用FLACS软件模拟液化烃泄漏及可燃蒸气气云溢散分布,通过分析蒸气云扩散规律对现有可燃气体探测器布置方案进行评估,并提出优化方案.结果表明,原有布置方案下可燃气体探测器覆盖率为46.88％,优化...     

盐岩地下储气库泄漏的喷射火事故后果定量分析

 为提高盐岩储气库营运的安全性,建立燃气从注采井套管破裂时的稳态泄漏率模型,提出将热辐射模型与伤害概率方程相结合的方法,对盐岩地下储库气体泄漏后可能发生的喷射火的热辐射后果进行研究,并与事故调查数据进行对比验证。研究结果表明,提出的喷射火热辐射危险距离的计算值与已发生的天然气输送管道喷射火事故现场观察的燃烧面积基本一致,计算值与实际观察值的误差都在20%以内。采用该方法对影响盐岩储气库喷射火事故后果的主要因素进行分析,得出喷射火的伤害半径随着注采井管径和运营压力(埋深)的增大而增大。提出的方法可为盐岩地下储库气体泄漏后的喷射火热辐射后果定量评价提供参考。     

"9·15"利川天然气井喷事故处置对策

对利川市天然气井喷事故基本情况、井喷物质理化性质及主要危害做了简要介绍 ,着重从工艺流程及原理的角度分析了处置方案 ,并对每一环节存在的危险性及采取的相应消防对策进行了分析     

Rare earth elements and select actinoids in the Canadian House Dust Study

Nationally representative baseline data are presented for rare earth elements (REE), thorium (Th) and uranium (U) in house dust sampled from 1025 urban homes, in units of concentrations (μg g^?1), loadings (μg m^?2), and loading rates (ng m^?2 d^?1). Spearman rank correlations indicate that, in addition to outdoor sources, consumer products and building materials can influence indoor dust concentrations of REE, Th, and U. Correlations (P<.01) with numbers of occupants, dogs, and cats suggest soil track‐in. Correlations (P<.01) with hardwood floors suggest release of REE additives used in pigments and coatings during daily wear and tear. Concentrations of light REE are elevated in smokers’ homes compared to non‐smokers’ homes (P<.001), suggesting that a key source is “mischmetal,” the REE alloy used in cigarette‐lighter flints. Indoor sources include geological impurities in raw materials used in consumer products, such as U and Th impurities in bentonite clay used in cat litter, and REE impurities in phosphates used for a variety of applications including dog food and building materials. Median gastric bioaccessibility (pH 1.5) of most REE in dust ranges from about 20% to 29%. Household vacuum samples correlate with fresh dust samples from the same homes (P<.001 for all investigated elements).     

浅谈建筑艺术的“美”和“丑”

美与丑总是相比较而存在的。文章分析了建筑艺术“美”与“丑”的表现形式及相互转换关系，提出科学、客观的认识建筑艺术“美”和“丑”的相对性，使美与丑都为创造人类的美好生活及塑造优美的建筑服务。     

A review of mining-induced seismicity in China

Active seismicity and rockbursting have been an emerging problem in Chinese mines. The distribution and characteristics of mining-induced seismicity in China, and its monitoring, mitigation, and research, are reviewed in this paper. Mining at depth and the activity of current tectonic stress field are the two major factors leading to rockburst hazards. Three critical depths, i.e., critical initiation depth, roof upper-bound depth, and floor lower-bound depth, have been identified based on hypocenter data of seismic events in coalmines. A strong correlation between rockbursts and gas outbursts in coalmines has also been established, and it is recommended to use this correlation for rockburst and gas outburst hazard assessment and warning interchangeably. We find that the key problems of rockburst hazard mitigation in China are the lack of mine seismicity-monitoring networks in most mines, and the need for improvement of the accuracy of the monitoring systems for mines that have been equipped with such systems. Because the demand for minerals resources is extremely high and the mining activities are progressing deeper and deeper, an increasing trend of mining-induced seismicity hazards in China may be anticipated for the near future. Mining-induced seismicities are hazards, but at the same time they have been found useful for studying geophysical problems in deep ground, particularly in the field of earthquake prediction. With the enforcement of relevant laws for the mining industry and the continuous effort to study rockburst problems using rock mechanics and geophysics principles and methods, it is believed that new approaches for rockburst hazard control and mitigation can be developed.     

青海五龙沟金矿幔枝构造成矿与深部矿源

文章论述了五龙沟金矿田的区域幔枝构造特征、矿区幔枝构造特征、矿床幔枝构造特征及其成矿过程,进一步通过硫、铅、氢、氧、碳同位素特征及流体包裹体特征的分析,认为矿田位于可可西里-巴颜喀拉地幔亚热柱东昆仑幔枝构造区,受五龙沟变质核杂岩构造的控制,变质核杂岩是幔枝构造活动晚期阶段在地表的表现形式,岩浆侵入以及南北向应力作用形成变质核杂岩构造及其北西向的韧脆性断裂系统。矿质来源为深部幔源,深切地幔的超岩石圈韧性断裂沟通了深部及地表,金银多金属矿源随岩浆沿北西向韧性断裂侵入而向地表运移,在构造扩容段成矿。超岩石圈韧性断裂其深部表现为韧性剪切变形,浅部表现为脆性断裂,金银多金属矿含矿热液在韧性剪切带与脆性断裂的构造转换部位成矿,受北西向的韧脆性断裂控制,主成矿时代为幔枝构造产物变质核杂岩构造活动的印支期,其余阶段为次要成矿阶段,不具备主导地位。     

The ecology of "fecal indicator" bacteria commonly found in pulp and paper mill water systems

Coliform bacteria have long been used to indicate fecal contamination of water and thus a health hazard. In this study, the in-mill water and external effluent treatment systems of seven typical Canadian pulp and paper mills were all shown to support the growth of numerous coliforms, especially Klebsiella Spp., Escherichia coli. Enterobacter spp., and Citrobacter spp. In all mills and most sampled locations, klebsiellas were the predominant coliforms. Although all but one of the mills had no sewage input and most disinfected their feed (input) water, all contained the most typical fecal indicator bacterium, E. coli. Many of the mill coliforms were classified as fecal coliforms by standard "MPN" and metabolic tests, but this was shown to be due to their thermotolerance, not their origin. Mill coliforms were shown not to be just simple transients from feedwater or furnish (wood), but to be continuously growing, especially in some of the primary clarifiers. Isolated mill coliforms grew very well on a sterilized raw combined mill effluent. The fecal streptococci (enterococci), alternative indicators of fecal health hazards, were common in all mills in the absence of sewage. Ten strains of E. coli isolated from four mills were all shown to be non-toxigenic strains of harmless serotypes. No salmonellas were found. Therefore, the use of total coliform, fecal coliform, enterococci, or E. coli counts as indicators of fecal contamination, and thus of health hazard in pulp and paper mill effluents or biosolids (sludges) known to be free of fecal input is invalid.     

Fire Hazard Assessment: Roadblock or Opportunity?

If a civil engineer designs a bridge, the basic requirement is that the bridge be safe. The designer must guarantee that the bridge will resist the traffic across it and weather conditions it will be exposed to. On the other hand, a fire protection engineer designing the interior of a building is not explicitly required to vouch for the building's fire safety. Though the authority having jurisdiction states that the interior finish materials, for example, must meet some requirements in terms of various fire properties, the authority leaves implicit a critical assumption: the expectation that using these materials will ensure fire safety—in other words, it will ensure that nobody would die should a fire break out in the building. This procedure for designing fire safe buildings has been in place for so long, it gives a significant level of comfort to all involved, and it implies minimum risk: the manufacturer knows exactly what is required and the authority having jurisdiction does not feel responsible for making any additional commitments of either time or money to make changes.Unfortunately, this practice has come to harm us over the years: new materials, products, or systems are being developed continually, some of which offer improvements, while others require compromises. Retaining the existing system can hurt the authority having jurisdiction in two ways: first, it may prevent the use of new designs, with overall better fire performance; and second, it may allow new designs to be assessed with inappropriate tools, so that they appear to be better than they are (examples of this type are too many to enumerate).Alternative designs may be approved today through a fire hazard assessment that may lead to a request for a code variance, called an equivalency. Regulations or specifications, including those by the authority having jurisdiction, may also require a fire hazard assessment to ensure fire safety in so-called fire performance-based code. Two other practical reasons why such fire hazard assessments might be undertaken are, first, if a manufacturer wants to develop an improved product and compare its fire performance with that of existing ones, and second, if a lawyer involved in product liability fire litigation requires a more technical basis to justify the use (or condemn the potential misuse) of a product involved in a fire incident where something went unfortunately wrong.There is understandable reluctance to follow the fire hazard assessment route because it may rock the boat. Manufacturers fear they may need to retest their materials or products, or that they may end up with increased product liability and, ultimately, lose market share. In addition, such assessments may call on the authorities having jurisdiction to develop technical reasons to accept or reject a design. However, proper fire hazard assessment should back up proven designs that have been shown, through long-term use, to be safe. Proper assessment should also ensure that adequate safety is maintained and business continues as usual. Finally, fire hazard assessment offers opportunities for entrepreneurship, innovation, and ingenuity, characteristics that drive our markets.