常压混酸溶矿一电感耦合等离子体发射光谱法测定铌钽

混酸溶解矿石样品,在酒石酸介质中,用电感耦合等离子体发生光谱法(ICP-AES)测定溶液中的铌钽。该方法ρ(Nb₂O₅)和ρ(Ta₂O₅)在0～20 μg/mL时,铌钽原子发射光谱强度与浓度呈良好的直线关系,Nb、Ta标准曲线相关系数尺分别为0.999 9和0.999 7。检出限分别为0.023 μg/mL和0.072 μg/mL。本方法测定标准样品,测定值与认定值相符。对实际样品分析,Nh、Ta的相对标准偏差(n=6)分别为0.42％～2.3％和1.8％～3.3％,加标回收率均为97％～103％,适合地质找矿、选冶等领域的样品测试。     

Chemo‐mechanics of cemented granular solids subjected to precipitation and dissolution of mineral species

This paper studies the chemo‐mechanics of cemented granular solids in the context of continuum thermodynamics for fluid‐saturated porous media. For this purpose, an existing constitutive model formulated in the frame of the Breakage Mechanics theory is augmented to cope with reactive processes. Chemical state variables accounting for the reactions between the solid constituents and the solutes in the pore fluid are introduced to enrich the interactions among the microstructural units simulated by the model (i.e., grains and cement bonds). Two different reactive processes are studied (i.e., grain dissolution and cement precipitation), using the chemical variables to describe the progression of the reactions and track changes in the size of grains and bonds. Finally, a homogenization strategy is used to derive the energy potentials of the solid mixture, adopting probability density functions that depend on both mechanical and chemical indices. It is shown that the connection between the statistics of the micro‐scale attributes and the continuum properties of the solid enables the mathematical capture of numerous mechanical effects of lithification and chemical deterioration, such as changes in stiffness, expansion/contraction of the elastic domain, and development of inelastic strains during reaction. In particular, the model offers an interpretation of the plastic strains generated by aggressive environments, which are here interpreted as an outcome of chemically driven debonding and comminution. As a result, the model explains widely observed macroscopic signatures of geomaterial degradation by reconciling the energetics of the deformation/reaction processes with the evolving geometry of the microstructural attributes. Copyright © 2015 John Wiley & Sons, Ltd.     

Influence of humic acid on bioavailability of heavy metals in sediments

The mimetic ocean environment and chemical method were used to research the bioavailability effect of humic acid on five heavy metals in sediment, including Cd, Cu, Zn, Pb and Ni. The sediment was separated into four containers with artificial seawater, and each of them had different concentrations of humic acid. The values of concentrations covered the whole range found in natural sediment （0.1%-10%）. According to the 48 hours LC50 of clam and distribution coefficient, metals were added in artificial seawater, and their speciation was determined at first and then after two days＇ incubation. It was found the bioavailability of heavy metals was reduced in the presence of humic acid. The obvious negative effect on Zn was observed, but the influence on Cd was not remarkable. In addition, the contents of Pb and Ni increased obviously in organic phase, and they are correlative with the concentrations of humic acid.     

地质灾害监测技术现状与发展趋势

文章对地质灾害监测方法、监测仪器进行了系统归类。详细介绍了崩滑体变形监测、物理场与化学场监测、地下水监测和滑坡等诱发因素监测方法、特点。对地质灾害监测方法的应用现状进行了总结；文章还介绍了BOTDR新技术的起源与发展、基本原理和应用于地质灾害监测的几个关键问题；对地质灾害监测方法的发展趋势进行了预测；最后文章提出了进行地质灾害监测技术优化集成的基础和优化原则。     

攀枝花地区基性-碱性岩系Th、Ta、Hf地球化学特征

攀枝花地区的基性—碱性岩系,是一套与钒钛磁铁矿、稀土矿、铍、钪、镓等多种矿产有关的含矿岩浆岩系。该岩系的Th、Ta、Hf地球化学特征极为相似,其Th/Hf比值在0.3～1.0之间,Ta/Hf比值更为接近,在0.2～0.5之间。在Th/Hf-Ta/Hf双对数图上,该岩系的源区特征和演化特征非常明显。此结果与峨嵋山地区的玄武岩和会东地区的基性岩系对比,Th、Ta、Hf特征都十分相近,因此该区原来被认为是两个地质时期(华力西期与印支期)的岩系,实际上是同一地质时期(华力西晚期)同源但不同阶段的产物,均是与峨嵋地幔柱关系密切的峨嵋玄武岩浆演化的结果。     

The high‐K calc‐alkaline Alagoinhas pluton: anisotropy of magnetic susceptibility,geochemistry, emplacement setting,and implications for the evolution of Borborema Province,NE Brazil

The Alagoinhas pluton is a member of the widespread high‐K calc‐alkaline association of northeastern Brazil. Some authors suggest that this region represents an amalgamation of distinct tectonic terranes assembled during the Brasiliano (Pan‐African) orogeny. Our work compares geochemical data (major, trace and REE) of the Alagoinhas with other plutons of same petrotectonic association (Caruaru‐Arcoverde batholith). These plutons apparently intrude several distinct tectonic terranes, separated by a major E‐W dextral transcurrent system, the East Pernambuco shear zone (EPSZ). Anisotropy of magnetic susceptibility and structural data for the Alagoinhas pluton are used to compare tectonic regimes across the EPSZ. The results indicate that the Caruaru‐Arcoverde batholith and the Alagoinhas pluton evolved from similar sources and were subjected to the same tectonic regime during emplacement, placing severe restrictions on use of the EPSZ as a suture zone between distinct tectonic terranes.     

Variation and pattern in the responses of mammal faunas to Late Pleistocene climatic change in southeastern South Australia

We examined mammal occurrence and variability through the Late Pleistocene vertebrate fossil deposit of Grant Hall in Victoria Fossil Cave, Naracoorte, South Australia. To determine long‐term patterns of change, we compared the composition and relative abundance trends of the assemblage with a nearby Middle Pleistocene deposit in Cathedral Cave. Total species richness did not change through the Grant Hall sequence, dated from 93 ± 8 to 70 ± 5 ka. However, species relative abundances varied between ecologically divergent species, and in some cases between species that demonstrate similar environmental preferences. For some species this variation is comparable to that recorded in Cathedral Cave. Of those showing similar trends between the two deposits, the forest inhabitant, Pseudomys fumeus, recorded an 8.6% decline through Grant Hall, coincident with a 9.7% increase in the dry heath/mallee dweller Pseudomys apodemoides. These patterns indicate that climatic transition from relatively warm, moist to cooler, drier conditions impacted some species in similar ways through climatic cycles of the past. However, the majority of the fauna demonstrated complex responses that are individual and variable through time. Statistical tests of species trends from the Grant Hall assemblage caution that large fossil samples are required to validate patterns observed. Copyright © 2012 John Wiley & Sons, Ltd.     

Flooding of the continental shelves as a contributor to deglacial CH4 rise

The transition from the last glacial and beginning of Bølling–Allerød and Pre‐Boreal periods in particular is marked by rapid increases in atmospheric methane (CH₄) concentrations. The CH₄ concentrations reached during these intervals, ～650–750 ppb, is twice that at the last glacial maximum and is not exceeded until the onset of industrialization at the end of the Holocene. Periods of rapid sea‐level rise as the Last Glacial Maximum ice sheets retreated and associated with ‘melt‐water pulses’ appear to coincide with the onset of elevated concentrations of CH₄, suggestive of a potential causative link. Here we identify and outline a mechanism involving the flooding of the continental shelves that were exposed and vegetated during the glacial sea‐level low stand and that can help account for some of these observations. Specifically, we hypothesize that waterlogging (and later, flooding) of large tracts of forest and savanna in the Tropics and Subtropics during the deglacial transition and early Holocene would have resulted in rapid anaerobic decomposition of standing biomass and emission of methane to the atmosphere. This novel mechanism, akin to the consequences of filling new hydroelectric reservoirs, provides a mechanistic explanation for the apparent synchronicity between rate of sea‐level rise and occurrence of elevated concentrations of ice core CH₄. However, shelf flooding and the creation of transient wetlands are unlikely to explain more than ～60 ppb of the increase in atmospheric CH₄ during the deglacial transition, requiring additional mechanisms to explain the bulk of the glacial to interglacial increase. Similarly, this mechanism has the potential also to play some role in the rapid changes in atmospheric methane associated with the Dansgaard–Oeschger cycles. Copyright © 2012 John Wiley & Sons, Ltd.     

Nonseismic phenomena in the generation and augmentation of tsunamis

While earthquakes generate about 90% of all tsunamis, volcanic activity, landslides, explosions, and other nonseismic phenomena can also result in tsunamis. There have been 53 000 reported deaths as a result of tsunamis generated by landslides and volcanoes. No death tolls are available for many events, but reports indicate that villages, islands, and even entire civilizations have disappeared. Some of the highest tsunami wave heights ever observed were produced by landslides. In the National Geophysical Data Center world-wide tsunami database, there are nearly 200 tsunami events in which nonseismic phenomena played a major role. In this paper, we briefly discuss a variety of nonseismic phenomena that can result in tsunamis. We discuss the magnitude of the disasters that have resulted from such events, and we discuss the potential for reducing such disasters by education and warning systems.