Comparison of the element composition in several plant species and their substrate from a 1500000-km2 area in Northern Europe.

Leaves of 9 different plant species (terrestrial moss represented by: Hylocomium splendens and Pleurozium schreberi; and 7 species of vascular plants: blueberry, Vaccinium myrtillus; cowberry, Vaccinium titis-idaea; crowberry, Empetrum nigrum; birch, Betula pubescens; willow, Salix spp.; pine, Pinus sylvestris and spruce, Picea abies) have been collected from up to 9 catchments (size 14-50 km2) spread over a 1500000 km2 area in Northern Europe. Soil samples were taken of the O-horizon and of the C-horizon at each plant sample site. All samples were analysed for 38 elements (Ag, Al, As, B, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, S, Sb, Sc, Se, Si, Sn, Sr, Th, Tl, U, V, Y, Zn and Zr) by ICP-MS, ICP-AES or CV-AAS (for Hg-analysis) techniques. The concentrations of some elements vary significantly between different plants (e.g. Cd, V, Co, Pb, Ba and Y). Other elements show surprisingly similar levels in all plants (e.g. Rb, S, Cu, K, Ca, P and Mg). Each group of plants (moss, shrubs, deciduous and conifers) shows a common behaviour for some elements. Each plant accumulates or excludes some selected elements. Compared to the C-horizon, a number of elements (S, K, B, Ca, P and Mn) are clearly enriched in plants. Elements showing very low plant/C-horizon ratios (e.g. Zr, Th, U, Y, Fe, Li and Al) can be used as an indicator of minerogenic dust. The plant/O-horizon and O-horizon/C-horizon ratios show that some elements are accumulated in the O-horizon (e.g. Pb, Bi, As, Ag, Sb). Airborne organic material attached to the leaves can thus, result in high values of these elements without any pollution source.     

Biogeochemical cycles for the chemical elements in Nymphaea odorata ait. and the aphid Rhopalosiphum nymphaeae (L.) living in Linsley Pond

A hydrogeochemical study to determine the abundance of the chemical elements in the water of Linsley Pond, North Branford, Conn., U.S.A., was initiated in 1965. As the investigation progressed, it became clear that the aquatic macrophytes, associated sediments, and the soils and rocks of the basin had to be examined chemically in order to elucidate the biogeochemical cycle of the elements in the water. This aspect of the study concerns the elemental chemical composition of Nymphaea odorata Ait. and the aphid Rhopalosiphum nymphaeae (L.) feeding on its leaves. Thirty-five elements were detected in the water but fifty-four were found in this water-lily and its aphid. Those not encountered in lake water concentrated twenty-fold were Cs, Sc, Y, La, Ce, Pr, Nd, Sm, Gd, Dy, Er, Yb, Ge, Zr, Hf, Th, As, Nb and Se. The water-lily, the aphid, the lake sediment and the soils and rocks of the basin all contained detectable quantities of the rare earths, though beyond Sm only those of even atomic number were encountered. The aphids contained more Na, Li, Cs, Ba, Zn, Al, Ga, Si, Ge, Pb, Ti, Hf, P, Bi, S, Se, Cr, Mo, I, Fe, Co, Ni, Mn, Y, La, Ce, Pr and Sm than the leaves upon which they feed. The water-lily leaves contain more Ag, Ca, Mg, Cd, Hg, B, Sn, Zr, Th, Cl, Br, Nd and Sc than the aphids. The amount of Be, Gd, Dy, Er, Yb, K, Rb, Cu, Sr, As, V and F is essentially the same in the insects as in the leaves which support them. Pertinent comparative data from other sources are also presented.     

Comparative studies of trace elements in air particulate in northern Nigeria

Atmospheric measurements were made throughout 1976 at a rural site in the nigerian savanna. Concentrations of trace and major elements in air were an order of magnitude higher in the dry season, when air is of Saharan origin, than in the rainy season when maritime tropical air dominates. The annual average concentrations of elements originating from soil dust, Al, Ce, Mg, Sc and Ti were more than an order of magnitude higher compared with southern England, whereas levels of heavy metals were generally lower. The enrichment factors (ratio of elements to Sc in the air relative to ratios of the same elements in average soil) found in northern Nigeria for As, Br, Cl, Pb, Sb and Zn were two orders of magnitude below those in rural England: this is attributed to less industrial development at equatorial relative to northerly latitudes. Enrichment factors in Nigeria are also compared with data from south Africa and urban regions in England.     

Speciation of aluminium in forest soil extracts by size exclusion chromatography with UV and ICP-AES detection and cation exchange fast protein liquid chromatography with ETAAS detection

Aluminium speciation was studied in forest soil extracts by size exclusion chromatography (SE) with UV and inductively coupled plasma-atomic emission spectrometric (ICP-AES) detection and cation exchange fast protein liquid chromatography (FPLC) with ETAAS detection. Size exclusion chromatography was performed on a Superdex HR75 10/30 column. Isocratic clution with 0.15 mol dm(-3) NaCl in TRIS-HCl buffer (pH = 5.5) was applied over 100 min at a flow rate of 0.35 cm(3) min(-1). The chromatographic run was followed at 278 nm and separated Al species also determined 'off line' in 0.875 cm3 fractions by ICP-AES. The analytical procedure enabled speciation of high molecular weight Al complexes. Cation exchange FPLC was performed on a Mono S HR 5/5 column. Aqueous 8 mol dm(-3) NH4NO3 linear gradient elution was applied over 10 min at a flow rate of 1 cm3 min(-1). Separated Al species were collected in 0.5 cm3 fractions and Al determined 'off line' by ETAAS. The analytical procedure enabled speciation of some positively charged monomeric Al species. Negatively charged species were eluted with the solvent front. The combination of the two analytical techniques was successfully employed in speciation of Al in forest soil extracts. Water was used as an extracting solution. It was found experimentally that 80-95% of Al in aqueous extracts of forest soils exists in monomeric Al forms. Water soluble Al (30-40%) is bound to high molecular weight complexes with humic substances. The remaining monomeric Al in the low molecular weight fraction exists as AIF2+, Al-oxalate and Al-citrate species.     

表面改性对光固化3D打印Al2O3陶瓷性能的影响

陶瓷粉体表面改性是一种改善陶瓷浆料流变性能的有效方法,已应用于光固化3D打印用Al2O3陶瓷浆料的制备,然而目前鲜有关于表面改性对光固化3D打印Al2O3陶瓷烧结体性能影响的研究报道.本文采用油酸对Al2O3陶瓷粉体进行表面改性处理,利用光固化3D打印技术制备Al2O3陶瓷,研究表面改性对Al2O3陶瓷浆料流变性能、固...     

多元素分析在岩性及含矿性判别的应用——以塞尔维亚佩吉铜金矿床为例

塞尔维亚佩吉铜金矿床位于世界著名的特提斯欧亚成矿带西端的Timok岩浆杂岩带南部.该矿床由上部高硫型铜金矿化和下部斑岩型铜金矿化组成,矿化主要赋存在下部安山岩中.文章通过分析岩石多元素地球化学特征,并结合地质编录,认为下部安山岩并非单一岩性,而是由三种不同的岩性组合而成.其中LA-2系列安山岩是主要的赋矿围岩,具有高V...     

Use of synthetic zeolites for arsenate removal from pollutant water

Arsenic is known to be a hazardous contaminant in drinking water that causes arsenical dermatitis and skin cancer. In the present work, the potential use of a variety of synthetic zeolites for removal of arsenic from water below the current and proposed EPA MCL has been examined at room temperature. Experiments have been conducted to examine the extent of arsenic removal as a function of pH. The effect of initial arsenic concentration and liquid to solid ratio in the batch reactions has also been studied. Zeolite NH4+/Y (NY6) showed significant arsenate removal capacity over a wide initial pH range of 2-12. Zeolite NY6 achieved this performance by buffering the initial pH to within a range of 3.5 < pH < 7 where uptake of arsenate onto aluminol surface groups is at a maximum. The high aluminum content of NY6 (i.e. low Si/Al ratio) was an important factor governing the improved performance of this zeolite relative to other tested zeolites with higher Si/Al ratio. The pH buffering capacity of NY6 could lead to savings in cost and process time for industrial effluent treatment due to avoidance of a pH pre-conditioning step prior to arsenate removal.     

The deposition of trace elements and major nutrients in dust and rainwater in northern Nigeria

The deposition of trace and major elements from the atmosphere was measured throughout 1976 at a rural site in the Nigerian savanna. Separate measurements were made of the deposition in rainwater and dry deposition, and of the dry deposition velocity that is related to particle size.The total (wet and dry) deposition of many elements showed marked seasonal dependence, increasing by an order of magnitude when, in April, the northerly winds from the Sahara desert are replaced by a tropical maritime air stream which remains predominant until October. The concentration in rainwater and deposition of elements associated with soil dust in Nigeria exceeded those in the U.K., e.g. for Al, Fe and Sc. However, the reverse was true for potentially toxic pollutants (As, Pb, Se, V). These differences were emphasised by a comparison of enrichment factors (ratio of element to Sc in total deposition relative to ratios of the same elements in average soil).In most cases the element/Sc ratios in total deposition and in locally grown sorghum grain were very similar though the ratios for some elements were higher in total deposition than in local and “average” soil. The input of elements from the atmosphere exceeded their removal in the grain.     

Determination of chloride diffusivity through partially saturated Portland cement concrete by a simplified procedure

A recently proposed methodology for measuring the diffusion coefficient of chloride ions through concrete partially saturated with water, has been applied to five high-early-strength Portland cement mortars. The method is based on putting solid NaCl in contact with the concrete surface during the diffusion test. The results obtained indicate a strong dependence of the diffusion coefficient on the water saturation degree. The ionic diffusivities through these mortars are higher than those obtained with the same approach for five pozzolanic cement mortars of similar compositions. It has been also shown that the proposed test methodology and a different one based on the interaction of HCl(g) with the tested concrete surface, can yield comparable results. The D values obtained are of similar magnitude, and the same type of dependence on the water saturation degree is found through both methods, when applied to similar Portland cement concrete mixes with cement content of about 350 kg/m³ and water/cement ratios between 0.5 and 0.6.     

Geographic patterns of elemental deposition in the Aegean region of Turkey indicated by the lichen, Xanthoria parietina (L.) Th. Fr

Lichen samples from different parts of the world have been known to accumulate elements to a greater degree than higher plants, if they are exposed to these elements from the atmosphere or from water and sediments. It has been hypothesized that lichens can be used to monitor air pollution around point and area emission sources. Local variation (variation in substrate, age and morphology of lichen samples) of element concentrations would not be large enough to affect the concentration patterns in large areas. We tested this hypothesis in the Aegean region of Turkey, which is very urbanized and industrialized. No such study has been conducted before in this part of the country. A total of 234 samples of the lichen Xanthoria parietina were collected from a 51,800-km2 area. Samples were washed and analyzed by INAA and ICP-AES for 35 elements. The range of the concentrations for most of the elements on a local scale was an order of magnitude lower than for the element concentrations on a regional scale. The mean local coefficient of variance (CV) was found to be 15, providing that the local variation did not affect the concentration of elements in the sampling region. According to cluster analysis, 8 (As, Hg, Pb, Sb, Fe, Mn, Na and K) elements are indicative of important local pollution locations and their zone of impact in the region. By mapping the concentrations of eight indicative elements in lichen Xanthoria parietina of the Aegean region, it was possible to relate deposition to the existence of known sources of pollution in certain areas. Location of pollution sources such as iron-steel plants, and coal burning in the cities, industrial activity and two important coal-fired power plants generally corresponded with locations of highest element accumulations in the lichens.     

浙江省燕山期花岗岩化学元素丰度及特征

本研究从浙江省87个燕山期花岗岩体中系统采集了189件样品,采用等离子体光谱法等11种分析方法,获得了Ag、As、Au、B、Ba、Be、Bi、Br、Cd、Cl、Co、Cr、Cs、Cu、F、Ga、Ge、Hf、Hg、I、In、Li、Mn、Mo、N、Nb、Ni、P、Pb、Rb、S、Sb、Sc、Se、Sn、Sr、Ta、Te、Th、Ti、Tl、U、V、W、Zn、Zr、La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、Y、SiO₂、Al₂O₃、TFe₂O₃、MgO、CaO、K₂O、Na₂O共68项主量、微量、稀土元素值以及TC、pH的实测数据,计算了扬子板块东缘与华南造山带燕山期花岗岩的化学元素丰度。岩石地球化学特征显示,这些花岗岩为高硅、富碱、弱过铝质的高钾钙碱性花岗岩,具有较强的Eu负异常,富集Rb、Th、U、K,亏损Sr、Ba、P、Ti、Nb、Ta等元素的特征,其普遍富铝和低MgO含量的岩石化学特征,指示它们的岩浆源区以壳源为主。     

基于三维力学模型的大范围自然边坡稳定性概率评价方法

 为了对大范围自然边坡的滑坡危险度进行评价,利用GIS技术作为平台,把传统的三维极限平衡力学模型耦合到概率统计分析框架中,提出一个基于边坡单元的定量评价的新方法。在把大面积的研究区域划分为边坡单元后,采用一个基于GIS的三维力学模型计算每个边坡单元三维安全系数的分布。假定此分布遵从对数正态分布,再采用一个可靠性指标计算该分布中小于某临界值的概率,并以此来定量评价该边坡单元的整体滑坡危险度。此方法同时也可以求得各边坡单元的最危险滑动面的位置和规模。开发一个专业GIS系统来完成所有的计算分析步骤,本系统能够快速、高效地完成大量的三维建模与安全系数计算,综合了三维力学模型与概率统计方法的优点,实现了对地形地质条件复杂多变的大范围自然边坡的稳定性定量评价。通过对日本一国道边坡应用对本方法的有效性进行了验证。     

Comparative study of the Cd. Cu and Pb determination by AAS and by ICP-AES in river water : Application to a mediterranean river (Congost river, Catalonia, Spain)

The accuracy, precision, detection limit and rapidity in the determination of Cd, Cu and Pb in river water by AAS determination, previous extraction with APDC-MIBK system, is compared with direct determination method ICP-AES. Both methods show a similar detection limit and an analogous accuracy by the addition standard method. With a calibration curve only ICP-AES presents good accuracy, this technique is advantageous in long term precision and requires minimum sample preparation. The sample stability at different temperature conservation is studied. Finally both methods are applied to the determination of Cd, Cu and Pb in Congost river water.     

岩石Ⅱ型和Ⅰ-Ⅱ混合型断裂研究

For the mode I rock fracture toughness measurement, three standard methods have beenrecommended by the ISRM, but there has not been a standard method for the determination of mode II and mixedmode I-II rock fracture toughness. However mode II and mixed mode I-II fracturing of rock structures is morecommonly observed than mode I in various geological and structural engineering settings. So it is of greatimportant to thoroughly research these rock fracture problems and establish a standard method for determining themode II or mixed mode I-II fracture toughness for rock materials. Based on the progress made for mode I rock fracture research, the cracked chevron notched Brazilian disk(CCNBD) specimen was also introduced for mode II and mixed mode I-II rock fracture toughness measurement.When the crack is orientated at an angle with respect to the diametrical loading, the crack of the CCNBD specimenis exposed to the mode II or mixed mode I-II stress distribution conditions. The solutions for stress intensityfactors in the vicinity of the crack tip have been evaluated by the stepwise superimposition technique. In order tomake sure that the theoretical analysis is correct, numerical calculation method has been employed to calibrate thetheoretical results. It has been proved that the theoretical results yielded by the dislocation method are correct andreliable. According to the characteristic that the propagation of the crack in the CCNBD specimen is in its own planeand application of the energy superposition principle, the stress intensity factor of the mixed mode I-II has beendefined in dimensionless terms as Y≠mix = [(Y1*)2 + (Y*11)2]1/2. It was found that the curve of Y*mix was concave. Thereexists a lowest point which corresponds to the maximum external load and indicates the crack has reached itscritical state. Since the values of Y*mix, Y*1 and Y*II are only dependent on the specimen geometry(α0, α1, αB and θ), the critical values of Y*mix, Y1* and Y*II can be to known as long as the CCNBD specimen isprepared ready. It is only necessary to record the maximum load during the fracture tests. The fracture locus is very useful to know whether the crack in a rock structure has reached its criticalcondition. According to the amount of practical fracture testing data obtained, the rock fracturing locus was foundto be(K1/KIC)3/2+(Ku/kuc)3/2 =1 and the S-critical criterion was found to be more suitable for rock mixed mode I-IIfracturing assessment.     

Space decomposition based parallelization solutions for the combinedfiniteediscrete element method in 2D

The combined finiteediscrete element method （FDEM） belongs to a family of methods of computationalmechanics of discontinua. The method is suitable for problems of discontinua, where particles aredeformable and can fracture or fragment. The applications of FDEM have spread over a number of disciplinesincluding rock mechanics, where problems like mining, mineral processing or rock blasting canbe solved by employing FDEM. In this work, a novel approach for the parallelization of two-dimensional（2D） FDEM aiming at clusters and desktop computers is developed. Dynamic domain decompositionbased parallelization solvers covering all aspects of FDEM have been developed. These have beenimplemented into the open source Y2D software package and have been tested on a PC cluster. Theoverall performance and scalability of the parallel code have been studied using numerical examples. Theresults obtained confirm the suitability of the parallel implementation for solving large scale problems.
2014 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.     

浅谈无人机在消防灭火救援实战研究

我国的消防事业面临着日益复杂的救援环境,传统的监测救护手段已经不能高质量的完成救护工作,无人机的发展和完善为消防提供了新的解决方案和途径.上海总队在灭火救援过程中应用无人机航拍技术对火场画面进行实时传输,这种方法在"12.13"上海嘉里粮油火灾现场得到了很好的应用,各个层级通过无人机的视频传输看到了火灾现场的实时图像.本文对滴水湖中队是否可在到达火场前就对火场的相关信息进行采集,进行了无人机侦察的实地测试.     

The elemental composition and sources of house dust and street dust

The elemental compositions of house dust, street dust and soil have been determined for 26 elements on material collected in Christchurch, New Zealand. The elements Hf, Th, Sc, Sm, Ce, La, Mn, Na, K, V, Al and Fe may be considered to be soil-based and contribute about 45–50% to house dust and 87% to street dust. The elements which are enriched (>3 times) in the dusts relative to the levels found in local soils, are Br, Cu, Cl, Pb, Zn, Cr, Ca, Co, As and Sb in house dust, and Zn, Cr, Cu and Pb in street dust.     

在交变荷载作用下钢筋砼连续梁、框架的安定分析

本文论述了安定定理的基本概念。对三根钢筋砼连续梁和三榀钢筋砼门架进行交变荷载试验表明,试验结果与理论安定分析是一致的,从而初步证明了安定定理同样适用于钢筋砼结构。 理论分析和试验都表明,交变荷载比同样大小的简单加载情形更为不利。考虑交变荷载作用,按安定极限状态进行设计,可获得确切的可靠度和一定的经济效果。     

新疆西天山阿拉套山南缘阿克沙克组变质碎屑岩地球化学特征及其对物源区和构造环境的制约

新疆阿拉套山南缘出露的下石炭统阿克沙克组沉积地层,是西天山石炭纪构造演化的重要物质记录.阿克沙克组第一段以碎屑岩发育为特点,在泥质粉砂岩中含少量珊瑚、腕足及苔藓虫化石;阿克沙克组第二段受后期晚石炭世花岗岩侵吞,呈残留状出露,以碎屑岩角岩化和含板岩为特征.阿克沙克组变质碎屑岩岩原岩为泥质岩,高SiO2含量(63.91％～...     

含中心裂纹薄壁型钢的又一组应力强度因子解

首先根据无限大中心裂纹板在Ⅰ型荷载作用下应力分布的全场解析解,构建薄壁杆件在均匀拉伸时沿裂纹所在截面的正应力的分布模型;然后利用平衡条件确定无量纲应力强度因子Y(ξ)获得含中心裂纹拉伸薄壁型钢的又一组无量纲应力强度因子Y(ξ)的近似解析解。与现有的数值结果比较表明,该方法不仅简单实用,而且结果可靠。文中给出的几种常见薄壁杆件含Ⅰ型中心裂纹时的无量纲应力强度因子的近似简单解析表达式,既适用于焊接组合薄壁杆件,也适用于冷弯薄壁杆件。