火成磷灰石矿床的产出模式、经济开发和世界资源

<正> 火成磷灰石矿床,在某些国家,特别在尚未发现或只有不利于商业开采的沉积磷矿的一些国家中日趋重要。世界上商品磷酸盐岩和精矿的总产量,在1978年约1.25亿吨,其中火成矿床的磷灰石产量超过1900万吨(表1),占世界总产量的15%以上。虽然其产量低于1977年(当时火成磷矿产量占世界产量的18%),但比过去十多年增加了1100万吨。这主要是由于苏联科拉半岛的希宾(Khibiny)矿山开采规模扩大所致。目前开采     

Linking historical smelter emissions across Humberside （UK） to enhanced soil metal concentrations using geostatistics and preserved environmental samples

Background： Analysis of human malignancies on Humberside （UK） in 1984 showed an increased risk close to the site of the local smelter. Geochemical survey data for Pb and Sn in soil collected soon after the smelter closed showed elevated concentrations relative to local background levels, and a strong spatial trend related to the prevailing wind direction. No historical emission data existed and evidence associating the smelter with the putative soil contamination plume was considered equivocal. In this work we test the hypotheses that： a） historical data can be used to estimate the excess quantities of Pb and Sn in the soil; b） tree bark ＆ attic dust can act as historical archives of particulate deposition; c） geochemical and mineralogical information assist in linking the source of the metal and the historical contamination plume.     

Is environmental antimony a potential health problem？

Antimony has long been recognized as a non-essential, potentially toxic element. It has recently been suggested, on the basis of measured elemental profiles in peat bogs, that natural levels of Sb in the environment have been overestimated by a factor of 10 and that anthropogenic Sb deposition from the atmosphere has closely followed that of Pb. The implication is that the health effects of environmental Sb may have been seriously underestimated. To examine these propositions, we have compared new data for Sb and Pb in dated cores from four Scottish ombrotrophic peat bogs, Carsegowan Moss, Flanders Moss, Red Moss of Balerno and Turclossie Moss, in southwest, west-central, east-central and northeast Scotland, respectively. Dried peat sections, 1 to 2 cm thick, were subjected to microwave-assisted digestion in nitric/hydrofluoric acid and subsequently analyzed for a range of elements （including Sb, Pb, and the conservative elements Sc, Ti） and Pb isotopic composition by ICP-OES and ICP-MS as appropriate. Three certified reference materials, including NIMT/UOE/FM/001 Peat, were used for quality control purposes. Radiometric dating of upper and lower sections of the cores was carried out using gamma spectrometry for ^21-Pb and accelerator mass spectrometry for ^14C, respectively Some 2000 years ago, in Roman times, both Sb and Pb were clearly elevated in Scottish peat but typically at concentrations below 0.1 mg/kg and 5 mg/kg, respectively, with an average anthropogenic Sb/Pb ratio of-0.01.     

第24章：监测执行《全面禁止核试验条约》的地震学方法

1996年9月，经过近40年期间遭遇许多次失败的协商谈判之后，对《全面禁止核试验条约》（CTBT）的文本最终达成了一致并在联合国开放供各国签署，随即由5个声称拥有核武器的国家（美、俄、中、英、法）进行了签署。在签字仪式上，克林顿总统称该条约为“最长久的追求、最艰苦的战斗、核武器控制的收获”。     

《地震活动图像动力学及地震触发》专辑介绍

由于地震对人类生活、基础设施和区域经济造成巨大损失，因此地震危险性的计算和评估十分重要。即使在1906年灾难性的旧金山大地震发生100年之后的今天，我们对地震破裂及其时空成核过程的认识仍然极其有限。原因之一是对于地下地震过程中重要状态变量（如地表下部压力及物性）的认识不足，这与天气预报等相关领域是不同的。对地下进行直接观测，仅在少数几个进行了昂贵的地壳深井钻探的地方才有可能。     

在某些热水矿物中稀土元素的分配结晶的控制证据

稀土元素丰度在硬石膏(CaSo_4)、重晶石(BaSo_4)、菱铁矿(FeCo_3)和方铅矿(Pbs)中用中子活化分析测定了。一种简单的结晶化学模式定性的描述了在硬石膏、重晶石和菱铁矿中稀土元素代替的相对亲合力。当地壳的丰度正常化时(近似热液稀土元素模式),三个热水矿物个别的和集体的对数稀土元素丰度是一种惊人地线形函数。(大阳离子离子半径——稀土元素的离子半径)。然而,重要的例外是Eu,相对于稀土元素的邻近原子序数和三价离子的半径,Eu在重晶石中异常富集而在菱铁矿中缺失。原则上,共生热水矿物的成对稀土元素分析,结合适当的实验资料,能得到稀土元素含量和原始热液的温度。 稀土元素仅有微弱的亲铜倾向,反映在方铅矿上有很低的丰度——La 0.6P Pb,Sm 0.06P Pb;其余的稀土元素含量低于侦查极限。     

EXPERT SYSTEM FOR THE CHARACTERIZATION OF LABORATORY SAMPLE INPUT SIGNALS:AUTOCORR

An expert system is presented for automated time series analysis of laboratory sample input signals.Thesystem,AUTOCORR,builds a model of the time series by identifying the processes that are present.These are an uncorrelated random process and,underlying this,possibly one or more of the following:a first-order autoregressive process,a trend and a periodic process.AUTOCORR has a knowledge baseof 44 rules and 41 facts for this purpose.The employed shell,INFER,allows the use of algorithmicprocedures.Elaborate tests with simulated signals show that AUTOCORR has a very low false positivescore and is successful in describing time series for laboratory simulation models.     

Constraining the Late Mesozoic and Early Tertiary Tectonic Evolution of Southern Mexico: Structure and Deformation History of the Tierra Caliente Region

We analyze the structure and assess the deformation history of the Tierra Caliente Metamorphic Complex (TCMC) of southern Mexico, where Laramide accretion of exotic terranes is in debate. The TCMC consists of a south-plunging antiform fault that is bounded on both its eastern and western flanks. Tierra Caliente Metamorphic Complex rocks show at least two phases of compressional deformation. The first and most prominent records a mean tectonic transport direction of 068 degrees. This phase is responsible for east-verging asymmetrical folding and thrusting of both metamorphic and superjacent sedimentary rocks. The second phase has an average transport direction of 232 degrees and is restricted to the western portion of the TCMC. A third phase is responsible for normal faulting. Lack of discernible deformation before Late Cretaceous time indicates that the main deformation phase is coincident with Laramide orogenesis elsewhere in the North American Cordillera. The stratigraphy, structure, and deformational history of the TCMC do not require accretion of exotic terranes. We explain the Mesozoic tectonostratigraphic evolution of the TCMC in terms of deposition and deformation of Mesozoic volcanic and sedimentary strata over the attenuated continental crust of the North American plate.     

Statistical Properties of SGR 1806-20 Bursts

We present statistics of SGR 1806-20 bursts, combining 290 events detected with the Rossi X-Ray Timing Explorer/Proportional Counter Array, 111 events detected with the Burst and Transient Source Experiment, and 134 events detected with the International Cometary Explorer. We find that the fluence distribution of bursts observed with each instrument are well described by power laws with indices 1.43, 1.76, and 1.67, respectively. The distribution of time intervals between successive bursts from SGR 1806-20 is described by a lognormal function with a peak at 103 s. There is no correlation between the burst intensity and either the waiting times until the next burst or the time elapsed since the previous burst. In all these statistical properties, SGR 1806-20 bursts resemble a self-organized critical system, similar to earthquakes and solar flares. Our results thus support the hypothesis that the energy source for soft gamma repeater bursts is crustquakes due to the evolving, strong magnetic field of the neutron star, rather than any accretion or nuclear power.     

Hard X-Ray Emission from the Galaxy Cluster A2256

After the positive detection by BeppoSAX of hard X-ray radiation up to approximately 80 keV in the Coma Cluster spectrum, we present evidence for nonthermal emission from A2256 in excess of thermal emission at a 4.6 sigma confidence level. In addition to this power-law component, a second nonthermal component already detected by ASCA could be present in the X-ray spectrum of the cluster, which is not surprising given the complex radio morphology of the cluster central region. The spectral index of the hard tail detected by the Phoswich Detection System on board BeppoSAX is marginally consistent with that expected for the inverse Compton model. A value of approximately 0.05 μG is derived for the intracluster magnetic field of the extended radio emission in the northern regions of the cluster, while a higher value of approximately 0.5 μG could be present in the central radio halo, which is likely related to the hard tail detected by ASCA.