滇川地下水异常时空转移特征研究

分析研究川滇及邻区地下水异常在中期— 短期— 临震孕震阶段认为, 异常时空转移是地震短临跟踪的一种有效方法。根据中期— 短期— 临震异常井孔数量少— 增多— 减少( 密集) 等变化, 判定地震孕育所处阶段。并用有无区域性异常时空转移等特征预测强震和非强震;用异常时空转移的方向大致估计可能的发震地区;用短临孕震阶段时空转移的明显程度预测发震时间。     

山西忻州奇村水汞观测干扰因素浅析

为进一步明确山西忻州奇村水汞观测过程中存在的干扰因素,分别对硫酸单一试剂、综合试剂、空气湿度、同一个水样多次观测等项进行了试验。试验表明,现用硫酸及其他试剂的汞污染均不明显,对水汞观测构不成于扰;观测室内空气高湿度对水汞观测有一定干扰,且湿度越大,干扰越强,高湿度导致测值大幅突跳;通常所测的水汞含量实为在鼓泡延续时间及空气流量固定不变特定情况下的相对含量,两者的改变会对测值的可比性产生人为干扰。     

用GPS 资料分析渭河盆地及邻近地区地壳运动特征

利用中国地壳运动观测网络工程1999 ~ 2002 年渭河盆地及邻近地区GPS 观测资料, 以及陕西省地震局2001 ~ 2002 年的GPS 观测资料, 研究了渭河盆地及邻近地区地壳运动速度场。结果表明, 渭河盆地及邻区的运动速率有明显的WE 向条带状变化特征, 鄂尔多斯块体南缘呈整体不连续性逆时针旋转运动, 相对鄂尔多斯块体内部的榆林测点, 平均速率约为5.7mm/ a;渭河盆地中部的彬县— 西安— 蓝田一线两侧存在一个左旋剪切带( 东侧) 和右旋剪切带, 左旋剪切带的北部区域与铜川— 泾阳— 临潼— 渭南小震频发区恰好对应;鄂尔多斯块体东南缘临汾盆地东侧, GPS 观测点资料表现出应力集中的迹象, 该区与临汾-韩城地震带也有较好的对应关系。     

丽江7.0级地震短临异常特征及震源硬化模型

重点讨论了丽江地震短临预报中识别继承性异常、继承性新异常及新异常的形态特征。同时讨论了判断丽江地震进入短临阶段的判据,如中期趋势异常的结束,巨变异常及异常同步转折等特征。最后,在讨论短临异常时空演化的基础上,结合震中区小震活动的异常平静,短临阶段定点前兆由外向震中迁移,异常外围幅度大、数量多等事实,作者提出了新的震源孕青模型——震源硬化模型。按此模型预测,震源区（余震展布区或地表宏观裂缝展布区）在中短期阶段应出现中小地震的异常平静,元或很少有定点前兆异常显示,但当强震孕育发展到破裂成核时——不可逆失稳阶段,某些地震震源区可能会出现明显的宏观破裂,即地表可见喷沙冒水或前震活动。     

水汞观测干扰分析

以试验方法改变日常水汞观测中涉及的化学试剂用量,来分析水汞观测的干扰因素,实验数据表明:硫酸试剂是影响水汞观测结果稳定性的主要因素之一,试剂量与观测结果(汞含量)成正相关关系;而高锰酸钾、氯化亚锡试剂对观测结果几乎没有影响.     

水汞观测资料对比分析

通过聊古一井井水中汞量的测定及对比观测试验,找到了影响数据内在质量的干扰因素,提出了浓硫酸、蒸馏水是干扰因素的主要来源,进行空白样的测定是排除干扰,提高观测资料内在质量的重要方法.     

山西忻州奇村水化站水汞观测干扰动态识别方法初探

通过对山西忻州奇村水化站水汞观测水样与空白样测值曲线所含信息的研究,论述了两者产生同步现象的原因及其动态特征,进而提出排除水汞干扰、识别水汞异常的方法。     

通渭温泉水汞映震能力的初步分析

介绍了通渭温泉观测点的基本情况，分析了水汞测量中的干扰因素，对水汞异常与地震的对应关系作了探讨。     

首都圈地壳垂直形变与未来强震活动

据首都圈地区精密水准复测资料,分析了近10年来地壳垂直形变状态与特征。结果表明,北京、天津和河北等平原地区,由于过量开采地下水导致了大空间、大量级的地面沉降,从而无法获得这些区域垂直向构造运动信息。在首都圈地区能够获得构造运动信息的区域主要位于该地区的东北端和西区,东北端为唐山—遵化—兴隆以东和以北的区域,西区指太行山以西的区域。东北端区域整体表现为下降,下降速率为2~ 4 mm/a,但“北升南降”的运动格局没有改变。西区为整体隆升,隆升速率最大近10 m m/a,运动的时空分布从具有“南快北慢”特征的总体上升逐步转变为“北升南降”的有升有降。2001年是西区上述运动性质发生变化的分界线,并由此导致了延怀盆地及其附近的区域出现了比较明显的四象限分布的形变图像。尽管从规模和量级上略小于大同地震前孕震体的变形,但两者的运动图像非常相似,所以该区域可能成为未来强震的孕震地区。     

地下水汞观测中干扰因素的实验研究

本文通过对水中汞量测定过程中，可能出现的干扰因素进行了有关试验和讨论，提出了使用的浓硫酸试剂是干扰因素的主要来源，进行水样的空白测定的消除综合干扰，提高观测质量的重要措施。     

复杂地区油气地球物理勘探技术集成

随着我国油气勘探程度的不断提高,勘探难度不断加大.全国油气资源战略选区调查与评价项目历经六年,通过对深水海域、西部复杂山地、西藏高原、南方碳酸盐岩、火山岩覆盖区等几类典型地球物理勘探久攻不克的复杂地区开展地震、重磁电、综合地球物理勘探联合攻关,以及天然地震层析成像攻关实验,取得了长足进步,直接带动获得了一批有价值的油气...     

Bioassessment Techniques for Monitoring of Eutrophication and Nutrient Limitation in Coastal Ecosystems

Bioassesment by the use of the macroalga, Ulva lactuca L., was carried out in the Limfjord, Denmark, to assess the significance of nitrogen and phosphorus as limiting factors for primary production during 1985, 1993, 1994 and 1995 and for the detection of changes in eutrophication levels.

Minimum and critical tissue concentrations for nitrogen and phosphorus in macroalgae were identified. The concentrations of nitrogen were generally below the critical concentration level in June–October in 1985, 1993, and 1995 but in 1994 nitrogen was only limiting for primary production in short periods. Only in early spring in 1985 and 1993 were the tissue concentrations of phosphorus below the critical concentration level, whereas in 1994 up to 3–4 months showed phosphorus limited growth, indicating that significant changes in limitation patterns can occur between different years.

It was concluded that the use of biomonitoring techniques is well suited as a bioassessment method for direct detection and for providing a time-integrated measure of nutrient availability in coastal waters, and thus for assessing ecosystem health with regard to eutrophication. It is recommended that biomonitors and the concept of critical tissue concentrations should be used in environmental management and incorporated in future monitoring programmes.     

Emergency planning and mitigation at Vesuvius: A new evidence-based approach

Disasters from explosive volcanic eruptions are infrequent and experience in emergency planning and mitigation for such events remains limited. The need for urgently developing more robust methods for risk assessment and decision making in volcanic crises has become increasingly apparent as world populations continue to expand in areas of active explosive volcanism. Nowhere is this more challenging than at Vesuvius, Italy, with hundreds of thousands of people living on the flanks of one of the most dangerous volcanoes in the world. We describe how a new paradigm, evidence-based volcanology, has been applied in EXPLORIS to contribute to crisis planning and management for when the volcano enters its next state of unrest, as well as in long-term land-use planning. The analytical approach we adopted enumerates and quantifies all the processes and effects of the eruptive hazards of the volcano known to influence risk, a scientific challenge that combines field data on the vulnerability of the built environment and humans in past volcanic disasters with theoretical research on the state of the volcano, and including evidence from the field on previous eruptions as well as numerical simulation modelling of eruptive processes. Formal probabilistic reasoning under uncertainty and a decision analysis approach have provided the basis for the development of an event tree for a future range of eruption types with probability paths and hypothetical casualty outcomes for risk assessment. The most likely future eruption scenarios for emergency planning were derived from the event tree and elaborated upon from the geological and historical record. Modelling the impacts in these scenarios and quantifying the consequences for the circumvesuvian area provide realistic assessments for disaster planning and for showing the potential risk–benefit of mitigation measures, the main one being timely evacuation, but include for consideration protecting buildings against dilute, low dynamic pressure surges, and temporary roof supports in the most vulnerable buildings, as well as hardening infrastructure and lifelines. This innovative work suggests that risk-based methods could have an important role in crisis management at cities on volcanoes and small volcanic islands.     

长江流域近50年降水变化及其对干流洪水的影响

根据我国长江流域气象观测站近42年的资料,分析了整个流域年和季节平均面雨量、暴雨日数和暴雨量的变化特征,以及降水对流域径流和洪水的影响.长江流域年和夏季平均面雨量存在明显的年际和年代变化特征,也表现出比较显著的趋势变化特点.大部分测站年平均面雨量呈增加趋势,夏季和冬季平均面雨量的增加趋势尤其明显;秋季平均面雨量呈显著下降趋势.同时,年和夏季暴雨日数和暴雨量也在较大范围内呈显著增加趋势.长江流域的降水对干流平均流量具有重要影响.1973年、1983年和1998年的洪水主要是由明显高于平均的流域面雨量引起的;长江下游平均流量变化趋势也同流域年平均面雨量、夏季平均面雨量变化趋势基本一致,特别是70年代末以来,下游平均流量和流域面雨量的上升趋势更加明显,并同时在1998年达到最高值.长江流域大的丰水年一般对应El Nino年或El Nino次年,表明E1 Nino对长江较大洪水可能具有一定影响.     

首都减灾圈的思考与建议

首都减灾圈,系首都减轻自然灾害预测防治圈。1991年12月20—21日在北京召开了《首都圈自然灾害及其减灾对策研讨会》。本文根据这次会议所提供的材料,在从整体上实现减灾的思想指导下,就首都减灾圈的“成灾背景”、“首都减灾圈的组成”、“首都减灾圈的灾害预测与防治状况”、“首都减灾圈的灾害关联性分析”、“首都减灾圈的减灾实效预估”和“首都减灾圈的减灾对策与实施”等六个带有共同性的问题,进行了讨论。供制定首都圈减灾方案时参考。     

MÉTHODE D'ÉTUDE DES NAPPES LIBRES DANS LES AQUIFÈRES ANISOTROPES

Abstract

The necessary and sufficient conditions for non-zero phase shift and non-zero attenuation in linear flood routing can be derived from the continuity equation alone and are found to depend on the existence of an imaginary part in the expression for frequency or in the expression for wave number. It is shown that in linear flood routing the phase lag between flow rate and area of flow is directly related to the attenuation per unit wave length. The effects of using various forms of the momentum equation, in addition to the continuity equation, are exemplified by deriving analytical expressions in terms of the frequency, both for attenuation per unit channel length and for phase shift, for the kinematic wave, the general diffusion analogy, and the complete St. Venant equation.     

关于砂土液化判别的若干意见

简要回顾了我国抗震规范中液化判别方法的发展历史,并对我国若干规范中的液化初步判别的条文进行了比较,提出了修改意见;对我国有代表性的几种液化判别方法及基于Seed简化方法修正的美国NCEER法进行了评述和综合对比,指出了我国现行若干规范中有关液化判别规定方面的错误;此外,还将GB50011－2001《建筑抗震设计规范》液化判别公式转变为类似于NCEER法的表达式,拓宽了该规范方法的应用范围。最后,结合某长江大桥工程的地基液化判别工作,探讨了深层土液化判别的可能性,结果表明,本文建议的方法是可行的。     

Non-stationary future return levels for extreme rainfall over Extremadura (southwestern Iberian Peninsula)

Based on a previous study for temperature, a new method for the calculation of non-stationary return levels for extreme rainfall is described and applied to Extremadura, a region of southwestern Spain, using the peaks-over-threshold approach. Both all-days and rainy-days-only datasets were considered and the 20-year return levels expected in 2020 were estimated taking different trends into account: first, for all days, considering a time-dependent threshold and the trend in the scale parameter of the generalized Pareto distribution; and second, for rainy days only, considering how the mean, variance, and number of rainy days evolve. Generally, the changes in mean, variance and number of rainy days can explain the observed trends in extremes, and their extrapolation gives more robust estimations. The results point to a decrease of future return levels in 2020 for spring and winter, but an increase for autumn.     

Concentrations and transport of trace metals in the St. Lawrence River

Samples of raw water were collected in the St. Lawrence River during six sampling trips from August 1990 to April 1992. Water samples were analyzed for both dissolved and particulate phases for five trace metals. Partition coefficients (Kd) and metal fluxes were calculated in order to determine metal transport. A mass balance equation was used for the determination of the major metal sources to the St. Lawrence River and an estimation of metal loadings to the estuary was made. Average dissolved metal concentrations were found to be Cd 10 ng/L, Co 74 ng/L, Cu 64 ng/L, Fe 69 µg/L and Mn 700 ng/L. Particulate concentrations were (in µg/g) 1.68 for Cd, 31 for Co, 73 for Cu, 25 mg/g for Fe and 1.69 mg/g for Mn. Co, Fe and Mn were transported essentially in the particulate phase while Cd and Cu were predominantly found in the dissolved phase at 56% and 48% of the total metal concentration respectively. Log Kd values varied from 5.1 (for Cu) to 6.8 (for Mn). In the dissolved phase the major sources were found to be the Great Lakes and the Ottawa River whereas in the particulate phase Québec tributaries appear to be the most important. Industrial inputs are quite important in both the dissolved and the particulate phases for Cd, whereas other sources are very variable, especially for the dissolved phase.     

A Review of the Concepts and Application of Rehabilitation Following Heavy Mineral Dune Mining

Dune mining has had an enormous impact in some coastal regions. This paper reviews: the concepts of rehabilitation, restoration and revegetation as applied to dune mining for heavy minerals, the basic principles of dune rehabilitation, some case studies of rehabilitation and its success, the methods for measuring the success of rehabilitation, the process of producing a dune rehabilitation plan, and makes recommendations for pilot studies and guidelines for the implementation of the rehabilitation plan. Studies in Australia and South Africa in particular, provide successful models to draw upon in formulating the criteria and principles discussed in this paper.