江口水库诱发地震的有限元分析

本文利用有限元方法计算了武隆江口水库蓄水后可能引起的水库诱发地震。在水库底部有断裂通过时,对江口水库在不同的假设宽度情况下进行了分析,给出了水库底部各处的最大剪应力。结果表明,水库底部岩石发生破坏的可能性很大,极可能引起水库的诱发地震,其最大震级为5级左右。     

Phosphorus Distribution in Bottom Deposits of the Mozhaisk Reservoir

The spatial distribution and accumulation of different forms of phosphorus in bottom deposits of the Mozhaisk Reservoir are discussed with account taken of the granulometric composition and organic matter content of the soil and the hydrodynamic conditions in the reservoir. The total amount of P in the 10-cm layer of bottom deposits is calculated and the rate of P accumulation is assessed by the balance method. Data on the concentrations of P fractions in silts in the reservoir channel trough in the 1970s and currently are presented; they indicate to a considerable increase in the non-apatite fraction of P.     

Structural Variations of Bottom Sediments in the Rybinsk Reservoir

Long-standing variations in the structure of bottom sediments within typical habitats of the aquatic life are characterized using the Volzhskii Pool of the Rybinsk Reservoir as an example. The role of hydrodynamic processes of the littoral zone in the formation of the ground complex of shallow water areas of the pool is discussed. The trends in variation in the quality of bottom substrate in fish habitats are analyzed. The peculiarities of long-standing variations in the distribution of types of bottom sediments in the entire reservoir are shown.     

Manganese concentration in the silts of the Mozhaisk Reservoir

The causes of the high Mn concentration in the solid phase and pore solution of bottom sediments in the Mozhaisk Reservoir are discussed. Regularities are identified in variations the concentrations of Mn forms in reservoir deposits from its upper part to the dam.     

Impact of natural (waves and currents) and anthropogenic (trawl) resuspension on the export of particulate matter to the open ocean: Application to the Gulf of Lion (NW Mediterranean)

Modern sediment deposits on continental margins form a vast reservoir of particulate matter that is regularly affected by resuspension processes. Resuspension by bottom trawling on shelves with strong fishing activity can modify the scale of natural disturbance by waves and currents. Recent field data show that the impact of bottom trawls on fine sediment resuspension per unit surface is comparable with that of the largest storms.     

Distribution of Heavy Metals in Lake Seliger Bottom Deposits

The distribution of some microelements in the surface and stratified layers of bottom sediments in Lake Seliger is studied. Data on the bottom deposit pollution by heavy metals is used to determine the anthropogenic load on the lake ecosystem. Cd, Zn, and Pb are shown to rapidly accumulate in thick (>1 m) bottom deposits that have formed during the period of lake existence. The concentrations of Cd and Zn are shown to correlate with the organic matter in thick bottom deposits.     

深厚库底回填料上面板堆石坝动力反应分析

深厚库底回填料是影响面板堆石坝动力响应的重要因素之一。为深入研究深厚库底回填料对面板堆石坝动力响应的影响,基于某拟建抽水蓄能电站,采用三维动力有限元分析系统研究其上库面板坝的地震反应,主要包括坝体加速度、面板动力响应、接缝变位情况以及库底防渗土工膜的动应变等。计算结果表明:由于库底回填料的存在,坝体加速度放大效应被明显削弱;面板周边以受拉为主,中部大部分区域受压;垂直缝呈现出周边张开、中间闭合的趋势;土工膜的顺河向和坝轴向的动拉应变皆小于屈服应变,最大应变出现在库底材料分界处,为提高坝体渗透安全性,建议对主堆石区与连接板相接处的回填料进行适当范围换填的处理措施。研究成果可以为类似工程提供参考。     

Plant Pigments in the Ivankovo Reservoir Silts as Indicators of Destruction Processes

The trophic state of the Ivankovo Reservoir is evaluated based on the characteristics of phytoplankton development and silt accumulation. Data on the space and time distribution of plant pigments in silt deposits are examined. Correlation between plant pigments and the main characteristics of silts are established. The ratio of chlorophyll content of the normal annual layer of sediment accumulation to the annual primary production of phytoplankton is calculated. The bedding of gray clayey silts onto gray sandy silts is shown to correlate with an increase in pigment concentrations in the top sediment horizons.     

Mercury Input and Distribution in the Ecosystem Elements of the Sheksna Reservoir

Hg input into the ecosystem elements of the Sheksna Reservoir is studied. The accumulation and distribution of Hg in water, bottom sediment, fish, and snow falling onto the reservoir surfaces are considered. The distribution of Hg in water, bottom sediment, and snow is found to be specially nonuniform. The main sources of Hg are shown to be atmospheric precipitation and surface runoff from the watershed. The regularities of Hg accumulation in fish in different parts of the reservoir are studied.     

Mineral water formation in the eastern part of the Cheboksary deposit

The results of multidisciplinary uranium-isotopic and microelement hydrochemical studies were used to establish that mineral waters in the eastern part of the Cheboksary reservoir have formed from mixing of strata waters of Tatarskie deposits with a deep water, entering through fractured-weakened zones of deep faults of the Gor’kii-Kil’mezskaya lineament zone.     

Oil Products in Bottom Sediments of Freshwater Bodies

The specific features of freshwater bodies are shown to facilitate the accumulation of oil products in bottom deposits. The oil product components are found to be represented by hydrocarbons and tars. The latter component can account for more than 50% of their total. The extent of bottom deposits pollution by oil products is assessed for a number of freshwater bodies in Russia.     

Evaluation of Microphytobenthos Productivity in Lake Pleshcheevo Based on Plant Pigment Stock

Results of spectrophotometric determination of plant pigments (chlorophylls, phaeo-pigments, and carotenoids) in the upper 3-cm layer of the littoral and sublittoral lake bottom sediments are presented for the depths corresponding to water transparency of 0.2, 0.5; 1, 2, and 3. Pigment characteristics are analyzed for the conditions, theoretically ensuring the possibility of photosynthesis and development of microphytobenthos. The presence of live algae in the bottom sediments is confirmed by directly counting the cells capable of positive photokinesis. The specific character of pigments' horizontal distribution is determined by a circum-bathymetric structure of the lake sediment complex and by illumination conditions. Potentially active, “pure” chlorophyll prevails in the euphotic area in the zone of light saturation, whereas phaeo-pigments prevail in the area of limited illumination. Regression equations describing relations between pigments concentration and depth have been obtained. The ratio between chlorophyll concentration in microphytobenthos and that of phytoplankton in the lake is estimated.     

Hydrochemical regime of the Ukrainian part of Danube nearshore area

Data of studies of 2004–2010 have been used to describe the formation of the hydrochemical regime of Danube nearshore area. The role of this zone as a “marginal filter” on the path of Danube water transformation in the northwestern part of the Black Sea is confirmed. The role of bottom deposits as a source of secondary eutrophication of the system is demonstrated.     

Heavy Metals in the Ivan'kovo Reservoir Bottom Sediments

Spatial and temporal variability of heavy metals concentrations in the Ivan'kovo Reservoir bottom sediments was studied. It was found that for the period of 1983–1998, their content largely decreased in many sections of the reservoir, with the exception of individual deep-water channel stretches and certain bays. The character of vertical distribution of microelements in the bottom sediments is shown to be related to the level of contamination and character and rate of water exchange in the reservoir.     

Effects of reservoir bottom absorption and dam-water-foundation rock interaction on frequency response functions for concrete gravity dams

The linear response of an idealized concrete gravity dam monolith to harmonic horizontal or vertical ground motion is presented for a range of the important system parameters that characterize the properties of the dam, foundation rock, impounded water and reservoir bottom materials. Based on these frequency response functions, the effects of alluvium and sediments at the reservoir bottom on the response of the dam, including its interaction with the impounded water and foundation rock, are investigated. It is shown that the partial absorption of hydrodynamic pressure waves by the reservoir bottom materials has an important effect on the dynamic response of concrete gravity dams.     

电阻率成像技术在水库库底溶洞探测中的应用

利用电阻率层析成像技术,对辉县市常村镇尖圪头水库溶洞进行了探测。水库库底内的破碎、裂缝以及溶洞等隐患部位有清晰的反映。水库库底的隐患探测具有重要价值和意义,是水库安全的保障,而且关系到局部地区安全的大事。     

Concentrations of Heavy Metals in the Upper Volga Bottom Deposits

The distribution of heavy metals in the Volga bottom deposits is studied. According to the degree of pollution with heavy metals, three stretches are singled out within the river reach under consideration. A drastic increase in Cu and Cd concentrations in bottom deposits is established. A close statistical correlation between Cu and Pb accumulation and the organic matter content of bottom deposits is revealed.     

Mechanism of development of inversion folding in the subsalt

The numerical modeling of the Archimedean upwelling of a salt bed predicts that, with mature diapirs (from the finger stage and later), an about 2-km-thick zone of inversion (mirror) folding, where the suprasalt diapirs correspond to the subsalt synclines while the suprasalt inter-diapir sags correspond to the anticlines in the subsalt, should be expected immediately below the bottom of the salt deposits. These deformations decay with depth. The development of the inversion folding is exceptionally due to the flow caused by the rising of the unstable layer.     

Effect of reservoir bottom on earthquake response of concrete dams

The absorption of hydrodynamic pressure waves at the reservoir bottom has dominant effects on the structural response of the dam when subjected to ground motion. In the present study, a model is proposed for the absorption effects of the reservoir bottom in the earthquake analysis of dams. The model utilizes the wave reflection coefficient approach and is based on the solution of the wave equation in a sediment layer of viscoelastic material with a constant thickness overlying an elastic, semi-infinite foundation. Numerical studies were conducted to evaluate the effect of the sediment layer thickness and material properties as well as the effect of reflection of waves from the underlying rock. It is shown that the current approach of assuming the wave reflection coefficient at the reservoir bottom based on the characteristics of the sediment material and excluding the effect of the reflected waves from the underlying rock, may significantly underestimate the seismic response of the dam.     

Use of Structural Characteristics of Bacterio- and Zoobenthos for Assessing the Quality of Bottom Deposits: Case Study of Water Bodies in the Upper Volga Basin

Analysis is given of the modern approaches and methods used to assess the quality of bottom deposits based on the conditions of bacterio- and zoobenthos communities. The structural characteristics of bacterio- and zoobenthos communities of small rivers in the Upper Volga basin are studied. The type of substrate is shown to have appreciable effect on the quantitative characteristics of both the communities. The analysis of these data is used to create a generalized classification of the quality of bottom deposits and assess the extent of their pollution in the examined water bodies.