铂矿标准物质的核分析方法研究

针对铂矿标样基体中高铜、高镍、高硫等特点．对常规的镍锍试金预处理中子活化分析流程作了适当改进，包括铂矿样品的灼烧、调节试金配方、改变酸溶条件和仪器测试条件。流程中铂族元素的回收率均在86％以上。用南非的铂矿标准物质SARM7和我国的铜镍硫化物铂族元素标准物质975作了对照分析,结果与标准值相符。表明改进后的流程适用于同类含铂铜镍矿样品中铂族元素的测试。     

Air Pollution Studies in Central Russia (Tver and Yaroslavl Regions) Using the Moss Biomonitoring Technique and Neutron Activation Analysis

Data of 34 elements, including heavy metals, halogens, rare earth elements, U, and Th in 139 moss samples, collected in Central Russia in 2000–2002 in the Tver and Yaroslavl regions and in the northern part of the Moscow region, are presented. Factor analysis with VARIMAX rotation was applied to identify possible sources of the elements determined in the mosses. The seven resulting factors represent crust, vegetation and anthropogenic components. Some of the factors were interpreted as being associated with ferrous smelters (Fe, Zn, Sb, Ta); combination of non-ferrous smelters and other industries (Mn, Co, Mo, Cr, Ni, W); an oil-refining plant, and oil combustion at the thermal power plant (V, Ni). The geographical distribution patterns of the factor scores are also presented. Dependency equations of elemental content in mosses versus distance from the source were derived.     

Influence of waves and horseshoe crab spawning on beach morphology and sediment grain-size characteristics on a sandy estuarine beach

The effects of wave action and horseshoe crab spawning on the topography and grain-size characteristics on the foreshore of an estuarine sand beach in Delaware Bay, New Jersey, USA were evaluated using data collected over six consecutive high tides. Data were gathered inside and outside a 25 m long exclosure constructed to create a control area free of disturbance by crabs. The density of crabs in the swash zone outside the exclosure was 8·1 organisms m⁻². The maximum depth of sediment activation on the upper foreshore where spawning occurred was 0·103 m during periods characterized by low significant wave heights: < 0·08 m. This depth is greater than the depth of activation by waves alone during moderate significant wave heights of 0·16–0·18 m but less than the maximum depth (0·127 m) recorded when spawning occurred during periods of moderate wave heights. Spawning, combined with moderate wave heights, creates a concave upper foreshore that is similar to the type of profile change that occurs during storms, thus lowering the wave-energy threshold for morphological response. Spawning during low wave heights increases the mean grain size and sorting of surface sediments caused by the addition of gravel to the swash. Sedimentological differences are most pronounced on the upper foreshore, and data from this location may be most useful when using grain-size characteristics to interpret the effect of spawning in the sedimentary record. Depths of sediment reworking by horseshoe crabs can be greater than those by subsequent storm waves, so evidence of spawning can be preserved on non-eroding beaches. Greater depth of activation by horseshoe crab spawning than by waves alone, even during moderate-energy conditions, reveals the importance of crab burrowing in releasing eggs to the water column and making them available for shore birds.     

Determination of Ti, K, Sm and Gd Values in Geological Survey of Japan Reference Materials by Prompt Gamma Neutron Activation Analysis

Prompt gamma neutron activation analysis was applied to the determination of the titanium, potassium, samarium and gadolinium contents of nine Geological Survey of Japan (GSJ) reference materials (JB-1, 1a, 2, 3; JA-1, 2, 3; JR-1, 2). Firstly, the values in JB-1 were determined by the standard addition method: pressed powder disks of JB-1 were used for neutron irradiation and gamma-ray measurements, after known quantities of standard reagents had been added. Secondly, the contents of eight other reference materials were determined by comparison methods using JB-1 as the comparative standard. The precision of analyses were obtained by replicate determinations on these samples. The relative standard deviation was generally less than 5%. For most samples, analysed values agreed well (< 5%) with the recommended values.     

MIPAS-Transall Observations of the Variability of CLONO2 during the Arctic Winter of 1994/95

In the winter of 1994/95 the German Transall research aircraft performed 5 campaigns in the European Arctic with 22 flights altogether. An extensive dataset of HNO3, ClONO2 and O3 column amounts was obtained by MIPAS-FT (Michelson Interferometer for Passive Atmospheric Sounding - Flugzeug Transall) onboard the aircraft. In this paper we present the variability of the ClONO2 reservoir gas in the course of the winter. We include groundbased FTIR measurements of HF, HCl and ClONO2 to discuss the airborne observations with regard to the partitioning of inorganic chlorine.From mid-December until the end of January, MIPAS measured a stable ClONO2 collar with constantly low column amounts inside the polar vortex and maxima at the edge. This observation reflected widespread conversion of ClONO2 to reactive chlorine inside the vortex for at least six weeks. In good accordance, the ground stations measured low in-vortex HCl and ClONO2 column amounts and conversion of HCl into ClONO2 in the region of the ClONO2 maxima. In the first week of February the ClONO2 amounts started to increase in the edge region as well as inside the vortex. Between March 21 and 27, just one week after the last cold period, MIPAS observed exclusively high ClONO2 column amounts inside the vortex, indicating fast deactivation of active chlorine. In the same period the ground stations measured an excess of ClONO2 over HCl. Further, the high ClONO2 implies that the polar vortex was renoxified in March. Lower ClONO2 values, observed inside the vortex on the flights of April 5 and 8, and an increased HCl/ClONO2 ratio, measured from ground, marked the starting redistribution within the chlorine reservoir species to the photochemically more stable HCl.In February, March and April, MIPAS observed mixing of ClONO2-rich air masses with midlatitude air at the vortex edge. A very clear event happened on March 27. On this flight a distinct ClONO2 minimum was measured at the vortex edge, which was closely correlated with a filament of midlatitude air observed by OLEX (Ozone Lidar EXperiment) onboard the Transall.     

中国大陆东部晚中生代构造活化及其演化过程

与中生代中期造山型构造活化不同．晚中生代期间,中国大陆东部的构造活化表现为规模宏大的断陷盆地系、变质核杂岩、花岗岩浆侵位、火山岩喷发以及沿大型走滑断层的转换伸展为特征的大陆裂陷作用。根据岩浆活动、盆地的充填记录,构造格架和盆地的沉降史分析,可以将裂陷作用划分为两个大的阶段,即由兴安岭群火山喷发为代表的第一阶段和以巴彦花群含煤、油碎屑岩系为代表的断陷盆地形成阶段。盆地沉降史回剥研究表明,裂陷作用第二阶段断陷盆地的发育受控于次一级的幕式构造作用过程。此外．对晚中生代裂陷作用的动力学背景的探讨需要阐明岩石圈的深部过程和构造应力场的反转这个两个重要的问题。     

云南个旧矿区富锡、铜矿体成矿学浅析

论述了构造岩浆活化与富锡、铜矿体形成的地质条件。作者将个旧矿区富锡、铜矿体分为两大类：①岩浆改造富化型;②岩浆迭加富化型。从控矿地质条件和矿物包裹体成分、同位素组成论述了两类矿体多因复成特征。分析了构造岩浆活化与富锡、铜成矿的关系。     

Elemental composition of particulate material sampled from the Arctic haze aerosol

Thirty-six aerosol filter samples collected in tropospheric Arctic haze layers, in the stratosphere, and in the marine boundary layer during the 1983 Arctic Gas and Aerosol Sampling Program were analyzed for trace elements using instrumental neutron activation analysis. Average crustal dust concentrations were 540 ng/m³ and 330 ng/m³ for samples collected in Arctic haze over the North American and Norwegian Arctic, respectively. An average marine salt concentration of 120 ng/m³ was obtained for haze samples collected above the marine boundary layer on both sides of the Arctic.Meteorological and wind trajectory information were used to identify specific haze transport pathways, which brought relatively unmixed aerosol from the central Soviet Union into the AGASP sampling areas. Results from individual filters collected within these transport zones are discussed, with emphasis on certain trace metal ratos which have been proposed by other researchers as discriminators of aerosols from different source regions. Our aircraft-collected data are compared with previously-collected ground-based measurements, and show reasonably good agreement for most tracer elements and ratios. Specifically, we have determined the As/Sb ratio tracer, named by other researchers as the most effective elemental discriminator of aerosol from the central Soviet Union, to be approximately 5–6. This relatively high tracer value is consistent with previous ground-based findings. A significantly lower V/Sb ratio was observed throughout this study, possibly indicating a change in the source signature.     

Geometrical relationships between unconformities and subsequent folding: the Arro fold system (southern Pyrenees)Relations entre discordances et plissement dans le système de plis et chevauchements d'Arro (bassin de Graus-Tremp,Pyrénées)

The Arro system is an oblique fold system involving the Eocene sediments of the Graus-Tremp basin. It consists of westward-verging folds, trending NNW–SSE, some of them related with thrusts, in piggyback sequence. Seismic profiles allow to infer the geometry of structures at depth: folds and thrusts are ‘decolled’ over an unconformity between turbiditic and platform sediments. Re-activation of bedding surfaces by folding in the underlying units resulted in folding and thrusting in the upper series. To cite this article: A.M. Casas et al., C. R. Geoscience 334 (2002) 765–772.