Recognition of environmentally caused variations in radon time series     

M. H. Shapiro  A. Rice  M. H. Mendenhall  J. D. Melvin  T. A. Tombrello 《Pure and Applied Geophysics》1984,122(2-4):309-326

Four techniques (pattern recognition, Fourier transformation, cross-correlation, and multiple linear regression) have been used to recognize nontectonic environmental factors affecting groundwater radon data collected by the Caltech automated geochemical network. Several factors, including air temperature, rainfall, water level, carbon dioxide concentration in the water, and barometric pressure, were found to correlate with radon level at some stations in the network. For example, approximately 60% of the variance in radon signal at one site studied (Pacoima) could be accounted for by nontectonic influences. However, it was not possible to correlate all the observed changes in radon concentration with nontectonic environmental variables. Some of the observed radon anomalies did appear to be related to either regional changes in tectonic strain or some individual earthquakes. A model is developed to account for spike-like increases in radon caused by carbon dioxide emission.  相似文献   

Acidity of twelve northern New England (U.S.A.) lakes in recent centuries     

Ronald B. Davis  Dennis S. Anderson  Stephen A. Norton  Mark C. Whiting 《Journal of Paleolimnology》1994,12(2):103-154

Studies of sediment cores from 12 acidic lakes in granitic, forested and uninhabited catchments in northern New England, U.S.A. produced diatom-inferred pH (IpH) 5.2 to 5.8 and alkalinity (Ialk) –12 to 31 µeq l^–1, with slowly declining values at some lakes, for one to four centuries prior to logging. Increases of IpH (0.05 to 0.60) and Ialk (5 to 40 µeq l^–1) correlate with logging in the catchments in the early-1800s to early-1900s. Recovery to pre-logging IpH and Ialk correlates with forest succession toward conifers, and is completed in the late-1800s to mid-1900s. Beginning at 1915–1920 (4 lakes), 1930–1950 (4 lakes) and 1965–1970 (4 lakes), IpH and Ialk start decreasing below pre-logging values due to atmospheric acidic deposition, leading to respective total decreases of 0.10 to 0.45 (X=0.25) and 5 to 25 µeq l^–1 (X=15). Inputs of anthropogenic Pb, Zn, V, polycyclic aromatic hydrocarbons, and soot from the atmosphere are first detectable in early- to late-1800s sediment, and Cu in late-1800s sediment, increase rapidly in the late-1800s to mid-1900s, and level off or decrease since the 1960s — partly due to emission controls. Decreasing Ca, Mn, and possibly Zn relative to other metals and normalized to organic content, and increasing flux of Fe to the lakes, indicate soil and water acidification after 1900.This is the fourteenth of a series of papers to be published by this journal which is a contribution of the Paleoecological Investigation of Recent Lake Acidification (PIRLA) project. Drs. D. F. Charles and D. R. Whitehead are guest editors for this series.  相似文献   

Seismogeological and hydrological criteria for the New European Macroseismic Scale (MSK-92)     

J. Vogt  R. M. W. Musson  M. Stucchi 《Natural Hazards》1994,10(1-2):1-6

In 1988, an ESC Working Group Macroseismic Scales started upgrading the MSK-81 Intensity Scale. This paper presents the background and decisions made with respect to the so-called seismogeological effects. Discussion has pointed out that they cannot be treated and used in the same way as the effects on humans, objects and buildings, for many reasons. Therefore, the WG adopted the solution of using such effects as a side tool for intensity assessment, providing a comprehensive table where the experimental relations between seismogeological effects and intensity degrees - assessed by means of other effects - are presented.  相似文献   

东北矿区资源开采诱发的工程地质灾害与环境损伤特征     

唐春安 《地球科学进展》2004,19(3):490-494

以东北老工业基地矿产资源型城市为基础，通过大量的实例和数据介绍了矿产资源开采诱发的工程灾害与环境损伤的内容和特点 ，并指出矿产资源开采诱发的工程灾害与环境损伤中的几个关键科学问题和所应当采用的分析研究方法。  相似文献   

祁连山区森林景观格局对水文生态效应的影响   总被引：14，自引：0，他引：14       下载免费PDF全文

杨国靖  肖笃宁  周立华 《水科学进展》2004,15(4):489-494

在地理信息系统ArcGIS环境下,结合1987-2001年的水文资料,用Spatial Analyst、Hydrologic Modeling等扩展模块,对祁连山中段北坡大野口河流域和海潮坝河流域的景观格局与水文特征进行比较分析,结果表明:大野口河流域的景观组分以低海拔的草地和乔木林占优势,草地所占面积最大,整个景观较为破碎;海潮坝河流域的景观组分以高海拔的裸地和灌丛占优势,裸地所占面积最大,景观破碎化程度相对较低。大野口河流域的蒸散发占降水量的61%,流域径流系数为0.39;而海潮坝河流域的蒸散发占降水量的41%,流域径流系数为0.59。研究表明,导致两流域生态水文效应相差较大的主要原因是两流域不同的景观格局。  相似文献   

西南某水利枢纽废旧煤洞的工程效应研究     

汪家林  王运生  黄润秋  邓良胜 《地球科学进展》2004,(Z1)

通过对西南某水利枢纽工程坝区煤系地层的系统研究,揭示了在坝区左右岸煤洞的展布特征,结合工程,分析了煤洞的存在及其变形的工程效应。最后,对煤洞的变形提出了针对性的处理建议。  相似文献   

青藏高原腹地现代植物δ~(13)C空间分异反映的环境信息     

王谋  李勇  张玉修  李亚林  黄润秋 《地球科学进展》2004,(Z1)

对研究区植被碳同位素组成进行分析,该区高山嵩草样δ~(13)C值在-25.63‰～-27.95‰之间,平均值-26.63‰;高寒草原区混合样δ~(13)C值于-26.29‰～-27.73‰之间,平均-27.04‰。高山嵩草样总体呈现由南东往北西方向正偏趋势,与高原夏季风运移方向一致(r=0.44603,n=29,p<0.05);研究区北部高寒草原区混合植物样则更明显的指示了研究区由南向北干旱化的趋势(r=0.8112,n=5,p<0.1)。现代植物碳同位素组成是特定环境影响的结果,在研究区内的变化趋势,则被认为是主要受降水环境影响的结果。成规律展布的区域降水条件与地理位置耦合,建立高原腹地地表植物碳同位素组成与其地理位置的相关。同时通过对该区碳同位素组成的研究反映控制植被生长发育的环境信息。  相似文献   

湖相沉积物中重金属环境污染研究进展   总被引：6，自引：1，他引：6  

王静雅  李泽琴  程温莹  罗丽 《地球科学进展》2004,(Z1)

综述了湖相沉积物重金属环境污染研究进展。介绍了该领域研究的主要研究内容、主要研究方法和湖相沉积物重金属污染的评价方法。并指出了该领域研究中比较薄弱的环节以及将来的发展方向,以期推动该领域的进一步研究。  相似文献   

Characterization of forward-directivity ground motions in the near-fault region   总被引：22，自引：0，他引：22  

Jonathan D. Bray  Adrian Rodriguez-Marek 《Soil Dynamics and Earthquake Engineering》2004,24(11):815-828

Ground motions close to a ruptured fault resulting from forward-directivity are significantly different than other ground motions. These pulse-type motions can place severe demands on structures in the near-fault region. To aid in the characterization of these special type of ground motions, a simplified parameterization is proposed based on a representative amplitude, pulse period, and number of significant pulses in the velocity–time history. Empirical relationships were developed for estimating the peak ground velocity (PGV) and period of the velocity pulse (T_v) of available forward-directivity motions. PGV in the near-fault region varies significantly with magnitude and distance. Additionally, the PGV for soil sites are systematically larger than those at rocks sites. T_v is a function of moment magnitude and site conditions with most of the energy being concentrated within a narrow-period band centered on the pulse period. Hence, lower magnitude events, which produce lower pulse periods, might produce more damaging ground motions for the stiff structures more common in urban areas.  相似文献   

A uniform approach to seismic site effect analysis in Bucharest, Romania     

W. Wirth  F. Wenzel  V. Yu. Sokolov  K. -P. Bonjer 《Soil Dynamics and Earthquake Engineering》2003,23(8):737-758

As a uniform approach to the assessment of ground motion variation within the Romanian capital Bucharest we analyze and compare strong motion records from analog recorders, weak motion data from a modern digital accelerometer network, and intensity observations of previous strong earthquakes. These different data sets allow to clearly characterize geographical trends in the distribution of ground shaking in the city for future earthquakes. Below 2 Hz the variability is small. Between 2 and 5 Hz, however, variations by a factor of 3–4 have to be expected. As the key source for the seismic hazard—the intermediate depth Vrancea earthquakes—remain at hypocentral distances in excess of 150 km from the city the ground motion variation must be predominantly attributed to site effects. This geometry of Vrancea sources to the site of Bucharest is ideal for the application of source-site separation techniques. However, despite this fact site effect amplification functions display a very large amount of aleatory uncertainty. In other words the standard source-site parameterization is too simple and we do not yet fully understand the cause and size of site effects.  相似文献