地震强地面运动的特征描述

描述强地面运动特征的现行观点和发展趋势。过去十几年中,有赖于强地面运动观测数据的积累,得到一些改进的地面运动经验模型。然而,这些模型具有很大的不确定性,因为“震级-距离-土类型“”的参数化相对实际过于简单。其他一些对强地面运动有重要影响的参数,例如:近断层地区的破裂方向性、地壳波导效应、盆地响应等,没有在这些模型中得到反应。建立在地震学理论基础上,并包含了这些附加条件的地面运动数值模型已经得到开发,它们被记录到的地面运动验证是有效的,并且被用来评估过去地震的地面运动,以及对未来地震的地面运动进行预测。     

Trace metals in Choromytilus meridionalis

Concentrations of metals in mature females of the mussel Choromytilus meridionalis are approximately twice those in males and some other trace elements also differ according to sex. If this species is to be used as an indicator of trace-metal pollution, comparative data should relate to individuals of similar size and care must be taken to determine whether differences in trace-metal content are the result of seasonal variations or reflect abnormal metal uptake.     

Benchmarking the thermomechanical behaviour of clays — a progress report — the CEC interclay project

In 1989 a small-scale exercise conducted by the CEC as part of its research programme into the underground storage of radioactive waste highlighted the difficulty of making accurate predictions a priori, of the geomechanical behaviour of clay. Given source data about the Boom clay from the underground research facility at Mol, three organisations independently performed f.e. analyses of two somewhat hypothetical problems. While the results were very broadly in agreement, they were shown to be sensitive to both the type of constitutive model used and the way data was fitted to the model.

Subsequently, the CEC sponsored a more comprehensive benchmark exercise called INTERCLAY II. This involves eleven organisations from various member states of the EC in a project encompassing the three aspects of software development for predictive modelling: verification, validation on the laboratory scale and the treatment of in-situ tests. The paper briefly describes the exercise currently in progress and presents the main results achieved to date concentrating on validation aspects.     

Grain boundary diffusion of Si, Mg, and O in enstatite reaction rims: a SIMS study using isotopically doped reactants

Diffusion-controlled growth rates of polycrystalline enstatite reaction rims between forsterite and quartz were determined at 1,000 °C and 1 GPa in presence of traces of water. Iron-free, pure synthetic forsterite with normal oxygen and silicon isotopic compositions and quartz extremely enriched in ¹⁸O and ²⁹Si were used as reactants. The relative mobility of ¹⁸O and ²⁹Si in reactants and rims were determined by SIMS step scanning. The morphology of the rim shows that enstatite grows by a direct replacement of forsterite. Rim growth is modelled within a mass-conserving reference frame that implies advancement of reaction fronts from the initial forsterite-quartz interface in both directions. The isotopic compositions at the two reaction interfaces are controlled by the partial reactions Mg₂SiO₄=0.5 Mg₂Si₂O₆+MgO at the forsterite-enstatite, and MgO+SiO₂=0.5 Mg₂Si₂O₆ at the enstatite-quartz interface, implying that grain boundary diffusion of MgO is rate-controlling. Isotopic profiles show no silicon exchange across the propagating reaction interfaces. This propagation, controlled by MgO diffusion, is faster than the homogenisation of Si by self-diffusion behind the advancing fronts. From this, and using % MathType!MTEF!2!1!+- % feaaeaart1ev0aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiramaaDa % aaleaacaWGtbGaamyAaiaacYcacaWGfbGaamOBaaqaaiaadAfacaWG % VbGaamiBaaaaaaa!3DD2! D_Si,En^VolD_{Si,En}^{Vol} at dry conditions from the literature, results a % MathType!MTEF!2!1!+- % feaaeaart1ev0aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmirayaafa % Waa0baaSqaaiaadofacaWGPbGaaiilaiaadweacaWGUbaabaaaaOGa % eqiTdqgaaa!3CCD! D￠_Si,En dD'_{Si,En}^{} \delta value of 3᎒^-24 m³ s^-1 at 1,000 °C. The isotopic profiles for oxygen are more complex. They are interpreted as an interplay between the propagation of the interfaces, the homogenisation of the isotope concentrations by grain boundary self-diffusion of O within the rim, and the isotope exchange across the enstatite-quartz interface, which was open to ¹⁸O influx from quartz. Because of overlapping diffusion processes, boundary conditions are unstable and D´_Ox,En' cannot be quantified. Using measured rim growth rates, the grain boundary diffusivity D´_MgO' of MgO in iron-free enstatite is 8᎒^-22 m³ s^-1 at 1,000 °C and 1 GPa. Experiments with San Carlos olivine (fo₉₂) as reactant reveal lower rates by a factor of about 4. Our results show that isotope tracers in rim growth experiments allow identification of the actual interface reactions, recognition of the rate-controlling component and further calculation of D´' values for specific components.     

Spatial modeling of annual minimum and maximum temperatures in Iceland

Bayesian hierarchical modeling is applied to the analysis of annual minimum and maximum temperatures. In both cases the generalized extreme value distribution is selected as the marginal distribution at each site due to its flexibility and theoretical basis. This distribution has three unknown parameters, a location parameter, a scale parameter and a shape parameter. The location and scale parameters are assumed to vary across sites while the shape parameter is assumed to be the same for all sites. The location and the scale parameters are modeled as two independent Gaussian spatial processes which are governed by the Matérn correlation function. These spatial processes play a central role in spatial predictions at unobserved sites. The location parameter is also modeled with a common time effect which includes a linear trend and a linear site effect with altitude, distance to open sea, latitude and longitude as covariates. This model allows for spatial predictions for any set of unobserved sites, the scale of the grid can be as fine as possible as long as the covariates are observed at each of the unobserved sites. Data on the annual minimum and maximum temperatures in Iceland from 1961 to 2009?at 72 sites are analyzed and used to predict the 2nd percentile of the minimum temperature for the 12-month period from July 2011 to June 2012 and the 98th percentile of maximum temperature for the year 2011 for a large set of unobserved sites across Iceland at which the covariates are available. The spatial predictions reveal that the 2nd percentile of minimum temperature for 2011 to 2012 reaches ?35°C in the central part of Iceland and ranges from ?12 to ?22°C around the coast of Iceland with the lowest coastal temperatures in the Northern part and the Northeastern part. The 98th percentile of maximum temperature in 2011 ranges from 10 to 30°C where the warmest areas are found in the Eastern part, the North-Eastern part and the Southern part of the country. The estimated increase in minimum and maximum temperatures over the years 1961 to 2009 is 0.71 and 0.47°C per decade, respectively, while the average annual temperature increased 0.24°C per decade over the same period.     

61～50kaBP亚洲季风百年尺度气候振荡的黔西南石笋记录

12个U/Th年龄测试结果显示,黔西南普安县雾露洞长度分别为667mm和830mm的两支石笋覆盖了61～50kaBP时段。据两支石笋999个δ18O数据建立了平均分辨率达15年的亚洲夏季风强度变化序列。雾露洞δ18O记录揭示了4个振幅达1.7‰的千年尺度季风增强事件,对应于格陵兰冰心DO17—DO14事件。在总体特征上,该记录峰谷振荡特征及振幅与贵州董歌洞、南京葫芦洞记录一致,进一步证实亚洲季风区大气降水同位素组成变化在大范围空间内具有一致性。在百年尺度上,亚洲季风区石笋δ18O清晰记录了MIS3早期6个DO亚旋回事件,而且在更短时间尺度上具有类似高纬气温振荡特征。这种低纬季风系统与北高纬气候变化的耦合关系表明,大气环流快速重组和传输可能是连接高低纬DO旋回及亚旋回气候变化的主要纽带。     

Thickness of the mixed bottom layer in the Northern Atlantic

The thickness of the mixed bottom boundary layer (BBL) has been analyzed based on the CTD data at transoceanic sections in abyssal waters of the Northern Atlantic. The measurements were carried out at two transoceanic sections approximately along 48° N (ASV-99) and 5° N (AI-2000) in 1999 and 2000. These data, and the WOCE data obtained at four zonal sections (AR7E and AR12 along 57° N, AR01 along 24.5° S, and A06 along 7.5° N), were used for the calculation of the statistical characteristics of the BBL??s thickness H _B . The probability distribution function F(H _B ) was close to lognormal. The mean value ??H _B ?? at different latitudes was in the range from 30 to 60 m. The averaged BBL thickness = 46.1 m. The BBL??s thickness was about 1% of the ocean??s depth D; the ratio H _B /D was the minimum (0.8%) near the equator and increased up to 1.6% in the polar latitudes.     

LMWOA (low molecular weight organic acid) exudation by salt marsh plants: Natural variation and response to Cu contamination

This work aimed to evaluate, in vitro, the capability of roots of two salt marsh plants to release low molecular weight organic acids (LMWOAs) and to ascertain whether Cu contamination would stimulate or not organic acids exudation. The sea rush Juncus maritimus and the sea-club rush Scirpus maritimus, both from the lower Douro river estuary (NW Portugal), were used. Plants were collected seasonally, four times a year in 2004, during low tide. After sampling, plant roots were washed for removal of adherent particles and immersed for 2 h in a solution that matched salinity (3) and pH (7.5) of the pore water from the same location to obtain plant exudates. In one of the seasons, similar experiments were carried out but spiking the solution with different amounts of Cu in order to embrace the range between 0 and 1600 nM. In the final solutions as well as in sediment pore water LMWOAs were determined by high performance liquid chromatography. Plants were able to release, in a short period of time, relatively high amounts of LMWOAs (oxalate, citrate, malate, malonate, and succinate). In the sediment pore water oxalate, succinate and acetate were also detected. Therefore, plant roots probably contributed to the presence of some of these organic compounds in pore water. Exudation differed between the plant species and also showed some seasonally variation, particularly for S. maritimus. The release of oxalate by J. maritimus increased with Cu increase in the media. However, exudation of the other LMWOAs did not seem to be stimulated by Cu contamination in the media. This fact is compatible with the existence of alternative internal mechanisms for Cu detoxification, as denoted by the fact that in media contaminated with Cu both plant species accumulated relatively high amounts (29–83%) of the initially dissolved Cu. This study expands our knowledge on the contribution of globally dominant salt marsh plants to the release of LMWOAs into the environment.     

Deposition of trace substances via cloud interception on a coniferous forest at Kleiner Feldberg

A resistance model to calculate the deposition of cloud droplets on a coniferous forest and some improved parameterizations of the indispensable input parameters are described. The deposition model is adapted to the coniferous forest at the Kleiner Feldberg site and verified by the data of a drip water monitoring station below the forest canopy. The measurements of liqud water content, wind speed and trace substance compounds in cloud water of the Ground-based Cloud Experiment (GCE) at Kleiner Feldberg in 1990 are used to calculate the cloud water deposition fluxes and the deposition of trace substances via cloud water interception. The calculated deposition of trace substances via cloud water interceptions is three to six times higher than via rain during the experiment. On a long term data basis the yearly amount of cloud water deposition is 180 mm year^–1 at Kleiner Feldberg site (840 m a.s.l.) while the precipitation amount is 1030 mm year^–1. Due to higher trace substance concentrations in cloud water compared to rain the ionic deposition via cloud water interception and via precipitation were assessed to be of comparable magnitude.     

Lysosomal membrane stability and metallothioneins in digestive gland of Mussels (Mytilus galloprovincialis Lam.) as biomarkers in a field study

The lysosomal membrane destabilization and the metallothionein content in the digestive gland cells of mussels (Mytilus galloprovincialis Lam.), collected along the east coast of the North Adriatic (Istrian and Kvarnerine coast, Croatia), were examined over a period of four years (1996–1999). The lysosomal membrane stability, as a biomarker of general stress, showed that the membrane labilization period in mussels from polluted, urban- and industrial-related areas was significantly decreased (p<0.05) when compared to mussels from control, clean sea water sites. In the harbour of Rijeka, the most contaminated site, the lysosomal membrane stability was reduced by more than 70% compared to the control. This method also proved to be a useful biomarker for detection of additional stress caused by short-term hypoxia that occurred once during this study inside the polluted and periodically quite eutrophic Pula Harbour. The concentration of metallothioneins in the mussel digestive gland, as a specific biomarker of exposure to heavy metals, did not reveal significant differences (p<0.05) between sites covered by this study.