Natural Geological Conditions Research Articles

A study of the factors influencing the occurrence of landslides in the Wushan area

Due to the complex natural geological conditions, many slope-related geological hazards occur in the Three Gorges Reservoir area in China. This study focuses on the characteristics of landslide development and their underlying mechanisms in this area. A statistical analysis is conducted to determine the characteristics of landslide development in the Wushan area, including the landslide distribution as a function of the elevation, slope, landslide material composition, scale, lithology, boundary conditions, instability mechanism, stratigraphic age, attitude, and sliding direction. The mechanisms of slope instability and the effect on the occurrence of landslides are analyzed. This study provides important reference material for landslide research in the Three Gorges Reservoir area and similar stratigraphic areas.

Effects of golf course management on subsurface soil properties in Iowa

Abstract. Currently, in the USA and especially in the Midwest region, urban expansion is developing turfgrass landscapes surrounding commercial sites, homes, and recreational areas on soils that have been agriculturally managed for decades. Often, golf courses are at the forefront of conversations concerning anthropogenic environmental impacts as they account for some of the most intensively managed soils in the world. Iowa golf courses provide an ideal location to evaluate whether golf course management is affecting the quality of soils at depth. Our study evaluated how soil properties relating to soil health and resiliency varied with depth at golf courses across Iowa and interpreted relationships of these properties to current golf course management, previous land use, and inherent soil properties. Systematic variation in soil properties including sand content, NO3, and soil organic matter (SOM) were observed with depth at six Iowa golf courses among three landform regions. Variability in sand content was identified between the 20 and 50 cm depth classes at all courses, where sand content decreased by as much as 37 %. Highest concentrations of SOM and NO3 were found in the shallowest soils, whereas total C and P variability was not related to golf course management. Sand content and NO3 were found to be directly related to golf course management, particularly at shallow depths. The effects of golf course management dissipated with depth and deeper soil variations were primarily due to natural geologic conditions. The two abovementioned soil properties were very noticeably altered by golf course management and may directly impact crop productivity, soil health, and water quality, and while NO3 may be altered relatively quickly in soil through natural processes, particle size of the soil may not be altered without extensive mitigation. Iowa golf courses continue to be developed in areas of land use change from historically native prairies and more recently agriculture to urban landscapes. As soils are continually altered by human impacts, it is imperative that we monitor the changes, both physical and chemical, in order to establish management practices that maintain environmental sustainability and productivity.

Changes in river channel pattern as a result of the construction, operation and decommissioning of watermills – the case of the middle reach of the River Liswarta near Krzepice, Poland

Abstract Changes in river channel pattern in the middle reach of the River Liswarta and in the lower reaches of its tributaries near Krzepice were analysed, and were related to the construction, operation and decommissioning of watermills. For this purpose, old maps which covered the period from the beginning of the 18th century until the 20th century were used alongside written historical sources. Maps from the first half of the 19th century provided valuable source material. Traces of old mill water systems in the valley floor were analysed on the basis of a numerical terrain model and aerial photographs as well as on the basis of detailed geomorphological mapping. The research made it possible to determine the locations of former mills mentioned in written historical sources and also changes in the course of river channels related to mill construction. It was found that some reaches of the River Liswarta channel and the estuary reach of its tributary River Bieszcza were in fact old mill races. These mill races account for around 31% of the length of the river channel reaches analysed. Analysis of old maps indicated that in the 19th century, the River Liswarta near Krzepice had multiple channels. This development of the River Liswarta channel was not only the result of natural geological, geomorphological and climate conditions, but also the product of watermill construction, since some channels within this network were artificial canals, including mill races. As a result of the construction of mill races, river channel reaches ranging from 1 to 2.5 km in length were shifted. Of the mills studied, as many as 80% ceased to exist in different parts of the period covered by the research. Traces of some of them can still be found in the form of ruins of foundations or of a water system with the remains of hydraulic structures, while some have only left their mark on the river channel pattern.

Sensing underground coal gasification by ground penetrating radar

The paper describes the results of research on the applicability of the ground penetrating radar (GPR) method for remote sensing and monitoring of the underground coal gasification (UCG) processes. The gasification of coal in a bed entails various technological problems and poses risks to the environment. Therefore, in parallel with research on coal gasification technologies, it is necessary to develop techniques for remote sensing of the process environment. One such technique may be the radar method, which allows imaging of regions of mass loss (voids, fissures) in coal during and after carrying out a gasification process in the bed. The paper describes two research experiments. The first one was carried out on a large-scale model constructed on the surface. It simulated a coal seam in natural geological conditions. A second experiment was performed in a shallow coal deposit maintained in a disused mine and kept accessible for research purposes. Tests performed in the laboratory and in situ conditions showed that the method provides valuable data for assessing and monitoring gasification surfaces in the UCG processes. The advantage of the GPR method is its high resolution and the possibility of determining the spatial shape of various zones and forms created in the coal by the gasification process.

FACTORS AND GEOLOGICAL AND ECONOMIC INDICATORS THAT MEASURE GAS AND SHALE DEPOSITS VALUE

Introduction. The article investigates the natural geological, technical, technological, economic and environmental conditions of the economic activity concerning the exploration and mining of natural gas from shale formations. Purpose. The article aims to is the identify, characterize and classify the factors that determine the value of natural gas fields which are connected with the shale rocks. Particular attention is given to the characterization of parameters that allow to carry out a quantitative assessment of the impact of these factors on the formation of spendings and the efficiency of shale gas extraction processes. The method (methodology). The methodological basis of the study is a set of scientific methods. Among them we can single out method of theoretical generalization, method of details, method of grouping, method of comparison, method of graphics, systems and factor methods. Results. It has been worked out the classification of the factors and parameters that determine the value and effectiveness of the exploration and development of deposits of natural gas which are connected with shale formations. The identified factors and indicators for determination their quantitative measurement are divided into four groups: natural and geological group, physical and chemical group, technical and technological group, economic and environmental group. In each group some specific factors and indicators and methodological approaches for their quantitative characterization and evaluation are identified and described.

Groundwater geochemical evolution under the influence of polymetallic deposit in Czarnów (Western Sudetes, SW Poland)

Water environment in the vicinity of Czarnow (Rudawy Janowickie Mts., Western Sudetes) is characterized by an occurrence of rich variety of trace elements affecting its quality directly. Based on the analyses of chemical composition of waters supported by geochemical modeling using PHREEQC code the significant influence of either natural geological conditions or former and contemporary mining activity has been confirmed. The results of inverse modeling suggest the contribution of carbon dioxide dissolution, pyrite oxidation, carbonates and plagioclases dissolution and ionic exchange between Ca2+ and Na+ as major chemical processes influencing water chemistry evolution. The anomalous concentration of arsenic in several locations as a result of probable desorption from iron oxide–hydroxides under the elevated pH conditions can be observed. The evaluation of changes in waters chemical composition during the past three decades indicates the tendency of their self-purification.

Nitrate fate and transport through current and former depressional wetlands in an agricultural landscape, Choptank Watershed, Maryland, United States

Understanding local groundwater hydrology and geochemistry is critical for evaluating the effectiveness of wetlands at mitigating agricultural impacts on surface waters. The effectiveness of depressional wetlands at mitigating nitrate (NO₃) transport from fertilized row crops, through groundwater, to local streams was examined in the watershed of the upper Choptank River, a tributary of Chesapeake Bay on the Atlantic Coastal Plain. Hydrologic, geochemical, and water quality data were collected from January of 2008 through December of 2009 from surface waters and networks of piezometers installed in and around current or former depressional wetlands of three major types along a gradient of anthropogenic alteration: (1) natural wetlands with native vegetation (i.e., forested); (2) prior-converted croplands, which are former wetlands located in cultivated fields; and (3) hydrologically restored wetlands, including one wetland restoration and one shallow water management area. These data were collected to estimate the orientation of groundwater flow paths and likely interactions of groundwater containing NO₃ from agricultural sources with reducing conditions associated with wetlands of different types. Natural wetlands were found to have longer periods of soil saturation and reducing conditions conducive to denitrification compared to the other wetland types studied. Because natural wetlands are typically located in groundwater recharge areas along watershed divides, nitrogen (N) from nearby agriculture was not intercepted. However, these wetlands likely improve water quality in adjacent streams via dilution. Soil and geochemical conditions conducive to denitrification were also present in restored wetlands and prior-converted croplands, and substantial losses of agricultural NO₃ were observed in groundwater flowing through these wetland sediments. However, delivery of NO₃ from agricultural areas through groundwater to these wetlands resulting in opportunities for denitrification were limited, particularly where reducing conditions did not extend throughout the entire thickness of the surficial aquifer allowing NO₃ to pass conservatively beneath a wetland along deeper groundwater flow paths. The complexity of N fate and transport associated with depressional wetlands complicates the understanding of their importance to water quality in adjacent streams. Although depressional wetlands often contribute low NO₃ water to local streams, their effectiveness as landscape sinks, for N from adjacent agriculture varies with natural conditions, such as the thickness of the aquifer and the extent of reducing conditions. Measurement of such natural geologic, hydrologic, and geochemical conditions are therefore fundamental to understanding N mitigation in individual wetlands.

Research on the SGD in the Yang River Downstream Region Based on Visual MODFLOW

In this paper, the scope of study area and boundary conditions are determined by anglicizing the natural geographical and geological hydrogeological conditions of the study area. Building the groundwater system conceptual model and numerical model with the Visual MODFLOW software, and then, identifying and validating the numerical model with the dynamic observation dates from 2001 to 2010. At last, simulating and analyzing the conveying capacity of SGD to Jiaozhou Bay with the model after identifying and validating. The results show that：1）Atmospheric precipitation influences on SGD greatly, the conveying capacity is 28.38×106m3/a in rainy year（2007）, but only 0.24×106m3/a in dry year；2）The river leakage recharge influence the SGD；3）The Aquifer Medium、types of aquifer and lithology all influence the SGD；4）The changes of sea level and briny physical properties influence the SGD.

Arsenate Retention by Epipsammic Biofilms Developed on Streambed Sediments: Influence of Phosphate

Natural geological conditions together with the impact of human activities could produce environmental problems due to high As concentrations. The aim of this study was to assess the role of epipsammic biofilm-sediment systems onto As (V) sorption and to evaluate the effect of the presence of equimolar P concentrations on As retention. A natural biofilm was grown on sediment samples in the laboratory, using river water as nutrient supplier. Sorption experiments with initial As concentrations 0, 5, 25, 50, 100, 250, and 500 μg L−1 were performed. The average percentage of As sorbed was 78.9 ± 3.5 and 96.9 ± 6.6% for the sediment and biofilm-sediment systems, respectively. Phosphate decreased by 25% the As sorption capactity in the sediment devoid of biofilm, whereas no significant effect was observed in the systems with biofilm. Freundlich, Sips, and Toth models were the best to describe experimental data. The maximum As sorption capacity of the sediment and biofilm-sediment systems was, respectively, 6.6 and 6.8 μg g−1 and 4.5 and 7.8 μg g−1 in the presence of P. In conclusion, epipsammic biofilms play an important role in the environmental quality of river systems, increasing As retention by the system, especially in environments where both As and P occur simultaneously.

Degradability of n-alkanes during ex situ natural bioremediation of soil contaminated by heavy residual fuel oil (mazut)

It is well known that during biodegradation of oil in natural geological conditions, or oil pollutants in the environment, a degradation of hydrocarbons occurs according to the well defined sequence. For example, the major changes during the degradation process of n-alkanes occur in the second, slight and third, moderate level (on the biodegradation scale from 1 to 10). According to previous research, in the fourth, heavy level, when intensive changes of phenanthrene and its methyl isomers begin, n-alkanes have already been completely removed. In this paper, the ex situ natural bioremediation (unstimulated bioremediation, without addition of biomass, nutrient substances and biosurfactant) of soil contaminated with heavy residual fuel oil (mazut) was conducted during the period of 6 months. Low abundance of n-alkanes in the fraction of total saturated hydrocarbons in the initial sample (identification was possible only after concentration by urea adduction technique) showed that the investigated oil pollutant was at the boundary between the third and the fourth biodegradation level. During the experiment, an intense degradation of phenanthrene and its methyl-, dimethyl-and trimethyl-isomers was not followed by the removal of the remaining n-alkanes. The abundance of n-alkanes remained at the initial low level, even at end of the experiment when the pollutant reached one of the highest biodegradation levels. These results showed that the unstimulated biodegradation of some hydrocarbons, despite of their high biodegradability, do not proceed completely to the end, even at final degradation stages. In the condition of the reduced availability of some hydrocarbons, microorganisms tend to opt for less biodegradable but more accessible hydrocarbons.

Compared Analysis of Embankment Thermal Stabilities in High Temperature Permafrost Regions with and without Climatic Warming

The heat stabilities of embankment on the high temperature permafrost regions in the eastern Tibetan Plateau without climate warming and with air temperature rising speed of 0.04°C/a were modeled, and the heights of embankment were discussed and figured out, comparatively and respectively for asphalt-paved, concrete and gravel road surface, according to the natural geographic and geologic conditions in the high temperature permafrost regions in the district. The different confined conditions about embankment critical heights with climate warming and without climate warming were discussed in the paper. Finally, the result had been obtained by numerical calculation: in the high temperature area, for the two types of laying of cement concrete and gravel surface road, the two critical heights of the thermal stable conditions were (road operation for 30 years), respectively, do not consider climate change as 2.5 m and 2.0 m, consideration of climate change were 3.5 m and 3.0 m.

Analysis for the Uncertainty and Changeability of Groundwater Causticity

During wet season and dry season, the groundwater quality analysis results of one engineering site in Nanning indicated that the causticity of groundwater mainly included acid causticity (pH value), calcareous causticity (corrosive CO2) and leaching causticity (HCO3-). Though the twice analysis results of water causticity are both moderately corrosion, the types of decomposed corrosion are different. It indicated the uncertainty and changeability of decomposed corrosion. In actual projects, some special ingredients in groundwater, the site natural environment and hydrologic geologic conditions should be considered together to define the groundwater’s causticity. Moreover, the change of site hydrologic geologic conditions caused by the construction should be considered, because this change can also influence the groundwater’s causticity. In addition, the groundwater’s causticity will influence the selection of cement types and the type of cement will influence the type of foundation, then all these will influence the construction cost finally. So, the change of groundwater’s causticity caused by the site hydrologic geologic conditions should be considered at engineering design time.

Direct current (DC) resistivity measurements in long-term groundwater monitoring programmes

Effective leak detection systems are most often needed to enable early warnings of groundwater contamination from landfill areas. In order to monitor the groundwater chemical changes over time direct current (DC) resistivity measurements have been used, since variation in groundwater ion concentration give changes of the electrical potential field. A simple, low-cost system for long-term monitoring has been developed and used for 4 years at an existing operational landfill in central Sweden. The paper describes the construction and operation of the geoelectrical monitoring system based on a fixed electrode Wenner array, situated in a glaciated terrain. The simplicity of the system enables non-experts in geophysics to run the system and evaluate the results. The lateral resistivity variations (up to 10,000% from the mean lateral value) clearly reflect strongly different natural geological conditions, whereas the variations over time (15% from the mean value at each specific point) reflect mainly the seasonal soil humidity and groundwater level variations. Leachates from the landfill have a low resistivity (about 1 ohmm) and the moderate seasonal variations in electrical resistivity favour the possibilities for identification of leakage from the landfill. Evaluation of resistivity data comprises modified double mass calculations versus data from reference measurement sites, which enables detection of contamination although it influences the resistivity less than the natural seasonal variations.

Farm Well Water Quality in Alberta

Abstract On-farm groundwater supplies in Alberta were evaluated for chemical (routine chemistry, trace metals), herbicides and microbiological (total and fecal coliforms) parameters to determine the suitability of domestic drinking water usage based on the Guidelines for Canadian Drinking Water Quality (GCDWQ). The sampling program was conducted between May and October of 1995 and 1996. Thirty-two percent of the 816 farm water wells surveyed (depth range 2 to 284 m) exceeded the GCDWQ for maximum acceptable concentration (MAC) or interim maximum acceptable concentration (IMAC) of at least one parameter. In addition, the water from 92% of the sites exceeded the GCDWQ for at least one of the aesthetic objectives (AO). The chemicals were ranked from most to least frequently exceeding the GCDWQ MAC, in the following order: F >> NO3 −N + NO2−N > As > Se > Pb > B > U > Cr (13, 6, 3, 3, 2, 0.9, 0.4 and 0.2% of all samples, respectively). The parameters ranked from most to least frequently, exceeding the AO, in the following order: TDS > Na > Fe > Mn > pH > SO4 > Cl > Al > Zn > Cu (85, 64, 36, 34, 23, 19, 6, 2, 1 and 0.1 % of the samples, respectively). The majority of the higher concentrations of most inorganic parameters are due to natural geological conditions defined by source aquifer mineralogy. The effects of primary agriculture are likely limited to the 3% herbicide detections and to some nitrate and microbiological contaminations observed; this water should not be used for human consumption without some form of site-specific treatment. Some rural residents may be “mistreating” their water, and a general lack of water testing among rural residents was noted.

A study of different mathematical models for evaluation of hydrocarbon generation from source rock kerogen thermal degradation

The pyrolysis kinetics of source rock kerogen with hydrocarbon formation is studied by using modified Rock-Eval apparatus with constant heating rates. Different mathematical models such as the overall first order reaction model, the maximum reaction rate model, the parallel reaction model and the series reaction model are used for simulating the experimental data respectively. Apparent activation energy and the pre-exponential factor are obtained. Based on these parameters and the geothermal gradient and deposition rate, the hydrocarbon generation of source rock kerogen at different burial depths under natural geological conditions is calculated by using different kinetic models. Source rock from the Dongpu Depression is used as the experimental sample. The calculated results of different models are compared with the real situations. It is shown that the maximum reaction rate model and the series reaction model are better.

Existence and uniqueness properties for the one-dimensional magnetotellurics inversion problem

The one-dimensional magnetotelluric (MT) inversion problem is well known to be ill posed and nonlinear. This paper seeks an understanding of the mappings underlying the nonlinear relationships. These properties are used to study the validity of some exploration aspects of the problem that are essential for the practical use of MT as an exploration tool. This study has two major segments—results in response space and results in geologic space. In response space, the existence of optimal admittance curves has been proven. In the case of continuous data, uniqueness has been established. For discrete data, a relationship between alternative optimal solutions has been derived. In geologic space, the results are extremely significant to MT’s applicability to exploration. A class of conductivity functions Y, which contains all possible natural geological conditions, has been used as a framework for the study. Over this class Y, the one-dimensional magnetotellurics problem has been proven to be uniquely invertible from the admittance curves. This precludes the possibility of two different geologic models yielding the same complete data. As a result, the path is now clear to generate a description of a unimodal statistical distribution of feasible inversions to the real-world exploration problem with finitely sampled noisy data.

Development of hydromechanization and hydraulic construction from the First Five-Year Plan to the present

1. The effect that can be attained as a result of application of the hydraulicking method of building dams is quite significant; in selecting the design of a dam, we cannot be restricted to traditional dam designs and universally adopted schemes for their construction. In each specific case, a careful search should be made of both the design of the dam and the technology of its construction as applies to the natural-geologic conditions. 2. Hydromechanization cannot be treated as a seasonal work method; the length of the season should be substantiated from the design in each specific case. 3. An increase in the level of mechanization of strictly hydraulicking operations should be classed as one of the priority problems facing technologists and designers working in the field of hydromechanization. 4. Organizational and technical measures providing for a sharp acceleration in the implementation of solutions that have already been tested for the improvement of equipment for hydromechanization should be developed and put in practice.

The effect of strontium on the aragonite-calcite ratios of Pleistocene corals [Florida

ABSTRACT The Pleistocene coral reefs which form the upper Florida Keys are in a state of alteration from aragonite to calcite. A quantitative relationship between the strontium content of the corals and their aragonite-calcite ratios was found. Strontium and calcium determination were made with a Zeiss flame photometer. Aragonite-calcite ratios were determined qualitatively with Meigen stains and quantitatively using X-ray techniques. Where the stains showed that aragonite was high relative to calcite, the strontium content was correspondingly high. Where the stains indicated that calcite was dominant, the strontium content was low. X-ray analyses confirmed these results. In several cases it was noted that within a single sample there were distinct areas which were aragonite and others which w re calcite. These sections were separated and analyzed. In all such cases the aragonite portion of a sample contained about twice as much strontium as did the calcite portion of the same sample. It is suggested that strontium content is a factor which inhibits the alteration of aragonite to calcite under natural geologic conditions, and only when much of the strontium is removed may the alteration take place.