首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 62 毫秒
1.
A wide range of trace elements contained in solution and suspension in surface waters in Amur River basin, which are subject to different anthropogenic load, has been considered. They have been found to vary widely because of their natural conditions, the impact of anthropogenic factors near cities (Khabarovsk, Komsomol’sk-on-Amur), and transboundary transport from the territory of China. Dissolved Mo, Br, and I are proposed as tracers of such transport.  相似文献   

2.
A method for quantitatively assessing sinkhole susceptibility (spatial probability) and hazard (spatio‐temporal probability) has been developed and independently tested in a 50 km2 sector of the Ebro Valley evaporite karst. Three genetic types of sinkholes have been mapped in the floodplain and a terrace surface: 947 small cover‐collapse sinkholes (type 1, terrace), large collapse sinkholes (type 2, floodplain) and large subsidence depressions (type 3, floodplain). The type 1 sinkhole inventory includes two temporal populations: 447 sinkholes formed before 24 November 2005, and 500 between that date and 2 November 2006. Sinkhole susceptibility models have been elaborated analysing the statistical relationships between the sinkholes of the 2005 inventory and a set of potential conditioning factors. The independent evaluation (validation) of the susceptibility models by means of several strategies (random, sequentially excluded, and temporal) has allowed us to select the most significant variables for each sinkhole type and assess quantitatively the quality of models; which are reasonable for the three sinkhole types. Validation has also provided information on the contribution of specific variables and the effect of changing their accuracy to the prediction capability of models. Susceptibility models for type 3 sinkholes have been validated satisfactorily with the 2006 sinkhole inventory (temporal validation). The best susceptibility model has been transformed into a hazard map considering the frequency of sinkholes that occurred in each susceptibility class between 2005 and 2006, as well as their average size. The susceptibility and hazard models obtained could be used as an objective basis for the application of mitigation measures, either of preventive or corrective nature. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

3.
Three types of sinkhole have been mapped in a 50 km2 stretch of the Ebro River valley downstream of Zaragoza: large collapse sinkholes, large shallow subsidence depressions and small cover-collapse sinkholes. The sinkholes relate to the karstification of evaporitic bedrock that wedges out abruptly downstream, giving way to a shale substratum. Twenty-three collapse sinkholes, up to 50 m in diameter by 6 m deep, and commonly hosting saline ponds, have been identified in the floodplain. They have been attributed to the upward stoping of dissolutional cavities formed within the evaporitic bedrock by rising groundwater flows. Twenty-four large shallow subsidence depressions were mapped in the floodplain. These may reach 850 m in length and were formed by structurally controlled interstratal karstification of soluble beds (halite or glauberite? and gypsum) by rising groundwater flow and the progressive settlement of the overlying bedrock and overburden sediments. A total of 447 small cover-collapse, or dropout, sinkholes have been recognized in a perched alluvial level along the southern margin of the valley. These sinkholes result from the upward propagation of voids through the alluvial mantle caused by the downward migration of detrital sediments into dissolutional voids. The majority of these sinkholes, commonly 1·5–2 m in diameter, are induced by human activities. Over the karstic bedrock, there is a significant increase in sinkhole density downstream. This is interpreted as being a result of the evaporitic bedrock wedging out and the convergence of the groundwater flow lines in the karstic aquifer. The collapse sinkholes in this area, locally with a probability of occurrence higher than 140 sinkholes/km2/year, cause substantial damage to the linear infrastructures, buildings and agriculture, and they might eventually cause the loss of human lives. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

4.
Appreciable observational data were used to reveal zonal features of the formation of the chemical composition of waters in small lakes on the territory of European Russia along a transect from tundra to the arid zone. Inter-zonal variability in the parameters of the chemical composition of waters is determined. Zonal differentiation according to hydrochemical parameters is substantiated. The main differentiating elements of the chemical composition of waters in different natural-climatic zones are distinguished. The contribution of the main natural and anthropogenic factors, determining the present-day processes of water formation is analyzed. Different degrees of the effect of non-zonal factors (including anthropogenic ones) on the formation of the chemical composition of lake waters in the humid and arid zones are demonstrated.  相似文献   

5.
Stenina  A. S.  Khokhlova  L. G.  Patova  E. N.  Lytkina  Zh. A. 《Water Resources》2004,31(5):545-552
Chemical characteristics of the surface water and algae in lakes in the Seduiyakha River basin are presented. Specific features of components of limnetic ecosystems under the influence of anthropogenic factors in the territory of an oil–gas condensate field are shown. Ambiguous response of algal communities to changes in the aquatic environment is revealed.  相似文献   

6.
This paper explores the suitability and advantages of combining the trenching technique with geophysical surveys [ground penetrating radar (GPR) and electrical resistivity tomography (ERT)] for sinkhole characterization in a mantled karst area. The approach is applied to two active sinkholes concealed by anthropogenic deposits and formed by contrasting subsidence mechanisms; collapse and sagging. The ERT section acquired across the collapse sinkhole images the clayey fill of the depression as an obvious low resistivity area, showing the approximate location of the sinkhole edges. Spatially dense GPR surveys provide information on the position of the boundaries of the concealed subsidence structures and their three‐dimensional (3D) internal geometry, revealing the dominant subsidence mechanism. We illustrate the impact of several factors on the quality of the GPR data such as sinkhole size, nominal frequency of the antennas, antenna shielding, and the presence of backfilled excavations and above‐surface objects. Trenches provided detailed information on the subsurface structure of the sinkhole, subsidence magnitude, partitioning of the strain, and the position of the sinkhole edges, especially when they are deep enough and excavated across the central sector and perpendicular to the boundaries. The stratigraphic and structural relationships observed in the trench were then used to infer the spatial evolution of the sinkholes (e.g. enlargement), their kinematic behavior (episodic versus progressive), and to differentiate discrete subsidence events and their associated magnitude. Numerical dates were used to estimate average subsidence rates and the recurrence of subsidence events. Such integrated data sets may be used as an objective basis to forecast the future behavior of potentially damaging sinkholes and to assess the associated hazard and risk. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

7.
Regularities in the distribution of some Al compounds in surface water in different southern taiga ecosystems have been studied. The main source of Al in surface water in both ecosystems has been shown to include the top organogenic and mineral horizons of soils within the 40–50-cm loam deposits, underlain by moraine loam. Al concentration in surface water is 1–2 orders of magnitude greater than that in a spring’s water. The amount of Al carried out from ecosystems with predominant occurrence of peat-podzol-gley soils is greater that from ecosystems with dominating podzol soils. In creeks in ecosystems with peat-podzol-gley soils, Al occurs both as a component of organoaluminum compounds and as monomeric aquahydroxocomplexes. In creeks that drain a territory with dominating podzol soils, almost all Al occurs in complexes with organic matter. Al concentration has been shown to have seasonal dynamics, and the concentration of toxic compounds in surface water has been predicted to increase because of anthropogenic acidification.  相似文献   

8.
The percolation of water in the ground is responsible for measurable electric potentials called self‐potentials. These potentials are influenced by the distribution of the electrical conductivity of the ground. Because sinkholes are associated both with self‐potential and electrical conductivity anomalies, a joint inversion of EM‐34 conductivity and self‐potential data is proposed as a way of delineating the location of these features. Self‐potential and EM conductivity data were obtained at a test site in Normandy (France) where sinkholes and crypto‐sinkholes are present over a karstic area in a chalk substratum overlain by clay‐with‐flint and loess covers. The presence of sinkholes and crypto‐sinkholes is associated with negative self‐potential anomalies with respect to a reference electrode located outside the area where the sinkholes are clustered. The sinkholes also have a conductivity signature identified by the EM‐34 conductivity data. We used the simulated‐annealing method, which is a global optimization technique, to invert jointly EM‐34 conductivity and self‐potential data. Self‐potential and electrical conductivity provide clear complementary information to determine the interface between the loess and clay‐with‐flint formations. The sinkholes and crypto‐sinkholes are marked by depressions in this interface, focusing the groundwater flow towards the aquifer contained in the chalk substratum.  相似文献   

9.
This article provides an assessment of river runoff of organic matter into seas from the territory of the Commonwealth of Independent States, its anthropogenic component and tendencies in their changes over certain periods from 1936 to 2000. The distribution within a year, modules, runoff ratio of organic matter and major ions are discussed.  相似文献   

10.
The paper presents the results of analysis of present-day scientific data on the dynamics of global hydroclimatic processes (with the establishment of long-term variations in the global water exchange processes) and the features of water abundance in territories under the effect of various natural and anthropogenic factors. Possible transformations of the hydrogeological situation under global climate changes are considered. The basic principles of the concept regarding the assessment of the effect of global hydroclimatic changes on the population health are presented. Medical-environmental data on the consequences of water-triggered environmental crises, taken as analogous natural models, are analyzed. The processes and regularities in the development of human pathology under the conditions of higher and lower water abundance in a territory are identified. The succession, time stages, and phases of the development of infection, parasitic, noninfectious pathologies are determined. Cause-and-effect relationships were established between the observed pathology and the effect of a complex of changing natural, anthropogenic, and social-environmental factors. Methodological approaches to the assessment of medical-environmental consequences of distinct changes in the water abundance in the territories are described. The possible use of subsurface water sources as a reserve of domestic water supply under emergencies are considered.  相似文献   

11.
Since the 1990s a large number of sinkholes have appeared in the Dead Sea (DS) coastal area. Sinkhole development was triggered by the lowering of the DS level. In the literature the relationship between the sinkholes and the DS level is explained by intrusion of relatively fresh water into the aquifer thereby dramatically accelerating the salt dissolution with creation of subsurface caverns, which in turn cause sinkholes. The main goal of our project was detection and localization of relatively fresh groundwater. During our study we used the transient electromagnetic method (TEM) to measure the electrical resistivity of the subsurface. As a test site we selected Nahal Hever South which is typical for the DS coast. Our results show that resistivity of the shallow subsurface reflects its vertical and lateral structure, e.g., its main hydrogeological elements explain the inter-relations between geology, hydrogeology, and sinkholes. The TEM method has allowed detailed differentiation of layers (clay, salt, etc.) in the subsurface based on their bulk resistivity. The 10 m-thick salt layer composed of idiomorphic crystals of halite deposited during the earlier Holocene period was extrapolated from borehole HS-2 through the study area. It was found that in Nahal Hever the typical value of the bulk resistivity of clay saturated with the DS brine varies between 0.2 and 0.3 Ωm, whereas saturated gravel and sandy sediments are characterized by resistivity between 0.4 and 0.6 Ωm. The high water salinity of the aquifer (enveloping the salt layer) expressed in terms of resistivity is also an important characterization of the sinkhole development mechanism. The electrical resistivity of the aquifer in the vicinity of the salt unit and its western border did not exceed 1 Ωm (in most cases aquifer resistivity was 0.2-0.6 Ωm) proving that, in accordance with existing criteria, the pores of the alluvial sediments are filled with highly mineralized DS brine. However, we suggest that the criterion of the aquifer resistivity responsible for the salt dissolution should be decreased from 1 Ωm to 0.6 Ωm corresponding to the chloride concentration of approximately 100 g/l (the chloride saturation condition reaches 224 g/l in the northern DS basin and 280 g/l in the southern one).Based on TEM results we can reliably conclude that in 2005, when most of sinkholes had appeared at the surface, salt was located within a very low resistivity environment inside sediments saturated with DS brine. Intrusion of relatively fresh groundwater into the aquifer through the 600 × 600 m2area affected by sinkholes has not been observed.  相似文献   

12.
The study area refers to the class of highly complex geotechnical conditions. Hazardous geological processes (HGP) are active here, including high seismicity up to 7 points MSK-64, karst, suffosion, subsidence and collapses of land surface, underflooding and flooding, erosion, ecological processes, etc. Large industrial plants with hazardous production and complex infrastructure are in operation here. One such plant is the First Berezniki Potassium Production Mine (BPPM-1), which have been operated since 1954. Its mine field extends below the industrial zone and the residential quarters of the town. An accident took place here in 2006, resulting in the inundation of the entire mined-out space with a volume of more than 80 million m3 and the formation of huge collapses of land surface in 2007, 2010, 2011, and 2015. The geological structure of a mine in the Verkhnekamskoe deposit of potassium salts is used as an example to discuss the effect of two leading groups of geological factors on the formation of karst sinkholes. Analysis is given to the hydrodynamic conditions and geomechanical structure of the above-salt rock stratum, whose synergy determines the diversity of models of possible development of deformations and collapses of land surface. The article gives the possible development schemes of land surface collapses above the mined-out space. The objective of the study is to assess and forecast the development of hazardous geological processes in the territory of Berezniki T. based on the geotechnical interpretation of the available materials of geological works, engineering surveys, and integral monitoring observations.  相似文献   

13.
Port Blair is the capital city of Andaman & Nicobar Islands, the union territory of India. More than 50% of the population of these islands lives around Port Blair Bay. Therefore the anthropogenic effects in the bay water were studied for monitoring purpose from seven stations. Physico-chemical parameters of seawater were analyzed in samples collected once in every 3 months for 2 years from seven sampling stations located in Port Blair Bay, South Andaman Island to evaluate the spatial and tidal variation. Cluster analysis and factor analysis were applied to the experimental data in an attempt to understand the sources of variation of physico-chemical parameters. In cluster analysis, the stations Junglighat Bay and Phoenix Bay having high anthropogenic influence formed a separate group. The factors obtained from factor analysis indicated that the parameters responsible for physico-chemical variations are mainly related to land run-off, sewage outfall and tidal flow.  相似文献   

14.
Yan Meng  Li  Zhuojun  Jia  Long 《Water Resources》2020,47(4):530-536
Water Resources - In China’s Pearl River Delta, numerous sinkholes caused by excessive groundwater pumping from a karst aquifer have opened. These sinkholes can cause wells and springs to dry...  相似文献   

15.
A comparative study of the dynamics of Heterotrophic bacteriocenoses was carried out in three springs in the territory of Krylatskie Kholmy reserve in Moscow. The effect of abiotic (including anthropogenic) factors was assessed. Overall, the abundance of heterotrophic bacteria in springs in Krylatskie Kholmy reserve is at the level common for spring water. However, despite the relative closeness of springs, the microbiological characteristics of the “Svyatoi istochnik” spring radically differed from those in the other two springs. In particular, the number of bacteria by inoculation in this spring was always lower. This suggests the higher quality of water in the “Svyatoi istochnik” spring in terms of microbiological characteristics, which is likely due to a lesser anthropogenic effect.  相似文献   

16.
Differential Interferometric Synthetic Aperture Radar (DInSAR) has been applied to detect and measure ground deformation in a stretch of the Ebro River valley (Spain) excavated in salt‐bearing evaporites. The capability of the Small Baseline Subset (SBAS) DInSAR technique to detect ground displacement is analyzed comparing the DInSAR results with the available geomorphological information. The deformation map derived from 27 European Remote Sensing (ERS) satellite images covering more than five years provides sub‐centimeter displacement measurements in zones coinciding with known active sinkholes and landslides. Moreover the map provides the first account of mining subsidence in the area. The measured deformation rates reach 1·68 cm/y for the sinkholes, 0·80 cm/y for the landslides and 1·45 cm/y for the area affected by mining subsidence. The SBAS DInSAR technique provided deformation measurements in a small proportion (5–10%) of the known active sinkholes and landslides. This limitation is mainly due to the lack of coherence in agricultural areas, the spatial resolution of the deformation map (pixel size of 90 m), and the parallelism between the ERS satellite line of sight and the linear escarpment on which most of the landslides occur. Despite this, the interferometric technique provides valuable data that complement traditional geomorphological studies including the quantification of the deformation phenomena, the identification of mining subsidence otherwise only recognizable by geodetic methods, and the detection of creep deformation which might correspond to premonitory indicators of catastrophic sinkholes and landslides capable of causing the loss of lives. Detailed DInSAR studies combined with field data would be required to improve the analysis of each deformation area. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

17.
A universal procedure is proposed for integral assessment of water management activity in a region based on geoinformation technology. The stages of study are described including the natural–economic zoning of the territory, ranking by the rate of total anthropogenic load on water objects and river basins, and the zoning of the territory to optimize the purpose-oriented use of water resources. A GIS of water use in Baikal basin, based on materials of federal statistical observation is presented. A system of measures is proposed for optimizing water use in zones of purpose-oriented water resources management.  相似文献   

18.
Soil magnetometry was used for detailed mapping of immission load over the territory of the Giant Mountains National Park. This project is a continuation of our previous study, which suggested that low-field magnetic susceptibility of topsoils in this region is controlled by atmospherically deposited anthropogenic ferromagnetic particles. In the present study, we have compiled a map of topsoil magnetic susceptibility on the basis of measurements on more than 460 sites. Elevated values of magnetic susceptibility can be attributed to local sources of pollution, located within and at the margins of the Park. We have identified a group of heavy metals of anthropogenic origin, present in the topsoils, and found a positive correlation between the concentration of Pb and magnetic susceptibility. Our results prove that magnetic mapping is a sensitive, fast and robust method, which can be advantageously applied to regions with relatively low degree of pollution, such as the Giant Mountains National Park.  相似文献   

19.
Ground fissures, especially if they open due to a sudden collapse of the surface, is a serious risk for populated areas. Their common occurrence in unconsolidated sediments of the Main Ethiopian Rift was found to be mostly a result of piping. The fissures start by piping in linear sub-horizontal underground voids, which often propagate upwards resulting in ceiling collapse and formation of deep and long ground fissures with vertical walls. In the southern and central Main Ethiopian Rift the fissures pose a serious risk to infrastructure and settlements. The ground fissures are often linear (up to several kilometres long and often tens of metres deep) and accompanied by sinkholes (along the length). A detailed field mapping of the geological (rock composition, orientation and character of lithological boundaries, primary fabrics and brittle structures) and geomorphological features (especially a length, width and depth of fissures, sinkholes and gullies) followed by in situ seismic anisotropy measurements and a laboratory determination of the geomechanical properties of volcanoclastic deposits was carried out to investigate the ground fissures' origin. The conditions and factors leading to the formation of the ground fissures have been linked to: (a) the presence of regional normal faults and the associated extensional joints and (b) the alternation of lithological units with contrasting hydraulic permeability. The latter corresponds to a sequence of less permeable hard rocks (e.g., rhyolitic ignimbrites) overlain by heterogeneous, soft and permeable, unconsolidated volcaniclastic deposits with a low amount of clay (less than 10%). The ground fissures' occurrence has shown affiliation to areas which have a significantly high seismic anisotropy (more than 20% at the study sites), which can be used as a proxy to map out high risk areas prone to piping and ground fissure formation.  相似文献   

20.
Oxygen and hydrogen isotopes were used in this study to detect a hydraulic connection between a sinkhole lake and a karst spring. In karst areas, surface water that flows to a lake can drain through sinkholes in the lakebed to the underlying aquifer, and then flows in karst conduits and through aquifer matrix. At the study site located in northwest Florida, USA, Lake Miccosukee immediately drains into two sinkholes. Results from a dye tracing experiment indicate that lake water discharges at Natural Bridge Spring, a first-magnitude spring 32 km downgradient from the lake. By collecting weekly water samples from the lake, the spring, and a groundwater well 10 m away from the lake during the dry period between October 2019 and January 2020, it was found that, when rainfall effects on isotopic signature in spring water are removed, increased isotope ratios of spring water can be explained by mixing of heavy-isotope-enriched lake water into groundwater, indicating hydraulic connection between the lake and the spring. Such a detection of hydraulic connection at the scale of tens of kilometers and for a first-magnitude spring has not been previously reported in the literature. Based on the isotope ratio data, it was estimated that, during the study period, about 8.5% the spring discharge was the lake water that drained into the lake sinkholes.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号