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1.
Incidences of landsliding and gullying are prevalent in parts of southeastern Nigeria. It is proposed here that the apparent susceptibility of the geologic formations to landsliding and gullying may indeed derive substantially from the effects of palæo- and neotectonic features. Tertiary palæotectonics created regional cuestas, joints and faults that now determine the pace of gully erosion. Recent tectonics and seismic effects cause ground vibrations that initiate movement on the marginally stable slopes. It is observed that southeastern Nigeria has climatic and land-use characteristics which are very similar to those of southwestern Nigeria, as well as being underlain by similar Tertiary formations, yet gully erosion and landslides are much less common in the latter. This is ascribed to the differences in the palæotectonic setting. Recent case incidences of tectonics-related disasters are presented. 相似文献
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Nuray Tokgöz 《Environmental Earth Sciences》2010,59(7):1559-1567
The concept of sustainable development has gained wide acceptance in the fields of mining and environmental studies. Mining
is a temporary activity, but its impact on the environment persists long after mine closure. The aim of this research is to
investigate the effect of land-use change on the stability of the Agacli landslide, northern coastal part of the Istanbul
(Turkey), spanning periods of mining, reclamation, and afforestation. Geological and geophysical surveys were performed to
determine the effects of erosion on the landslide. To assess the possibility of water responsible for triggering a landslide–gully
complex, the dynamic elastic parameters of the field are calculated. Field observations indicate that surface erosion and
gully development have ceased in the afforested area; however, gullies in non-forested areas continue to increase in size
and depth. Uncontrolled surface water and water from stock watering ponds have trigger erosion and rapid sedimentation of
the landslide–gully complex, resulting in over-steepening and enhanced landslide activity on the flanks of the main slide. 相似文献
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Landslides - Check dams, which mitigate debris flow hazards, have been widely applied in mountainous areas. Usually, it is difficult to assess the effectiveness of these mitigation works. With the... 相似文献
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Carolina Lauro Stella M. Moreiras Sebastian Junquera Ivan Vergara Rafael Toural Johannes Wolf Ruben Tutzer 《Environmental Earth Sciences》2017,76(5):213
The Central-West region of Argentina was seriously affected by a series of convective summer storms on January–February of 2013 generating many debris flows and rockfall in the Central Andes mountain regions. In particular, the unreported 8th February event caused the sad death of a 10-year-old child being completely ignored by society and local authorities. Despite this, meteorological conditions associated with this event and further episodes were rarely measured and determined mainly due to scarce meteorological stations in Andean mountain areas. In this paper, meteorological data from CMORPH algorithm and measurements of surrounding gauges were analyzed for estimating the triggering precipitation value of this event. As well, the particular debris flow channeled into the main branch of the Amarilla gully in the Agua Negra valley was geomorphologically described. The amount of precipitation associated with this debris flow was 5.5 and 13.2 mm accumulated previous to the event. This violent debris flow was generated in a talus zone in a periglacial environment located just below a covered rock glacier. However, the influence of the permafrost thawing in this process is not feasible. The altitude of the 0 °C isotherm was lower during the previous days of the event, and no monitoring on permafrost is available for this area. The volume of removed mass was estimated in 5 × 104 m3, and the mean velocity was 35 km/h. Boulders of 4 m diameter were found in the source area, while the deposit is up to 75% sandy with clasts that hardly exceed 10 cm in the alluvial fan distal part. Herein the main objective is to advice about the probable catastrophic impact of similar events in the future. These findings could be useful for hazard remediation, mitigation, and prevention plans for the Agua Negra international pass under construction. 相似文献
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Astronomy Reports - Improvement of the prediction accuracy of the Earth’s rotation parameters (ERP) is one of the main problems of applied astrometry. In order to solve this problem, various... 相似文献
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Turchanina Oksana Satin Vladimir Derevyanko Aleksey 《中国地球化学学报》2006,25(B08):51-52
As is well known, a high content of sulphur in coals is an effect of the post-depositional history of coal seams and one of the most important criteria of its use as a fuel. Sulphur in coals can cause a serious environmental and technological problem during their utilization. This problem is very actual for the Donetsk Basin because 734 mined seams out of the total of 1009 （73%） are comprised of coals with sulphur content -2%. The chemical pre-treatment as a first stage in their processing is widely used in order to effectively obtain the thermal destruction products of coals （such as semi-coke, coke, adsorbents, etc.） and to simultaneously utilize coal wastes. Development in pre-treatment methods for high-sulphur, low-rank coals is especially desirable for reducing the sulphur contents of the solid products. The aim of the present work is to investigate the influence of coal pre-treatment on the yield and composition of thermal destruction products, and the sulphur distribution among different components of the coals of different genetic types by reductivity （low-reduced LRC and reduced RC coals）. The thermal behavior of the coals was studied by means of the Fisher method （heated to 520℃, at a rate of 7℃/min）. The composition of the semi-coking gas was investigated by means of a VTI gas analyzer. The coal samples were chemically treated directly before thermal destruction by the introduction of 1-% solutions of radical polymerization initiator AAD （acrylic acid dinitrile C8H12N4） and products of coal-tar distillation （absorber oil）. Coal pre-treatment increases the semi-coke yield and its coking ability, and changes the liquid/gaseous product ratio. 相似文献
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Yoko Shimamoto Yoshio Takahashi 《中国地球化学学报》2006,25(B08):114-114
Although inorganic species are predominant in natural systems, but there are many kinds of organoarsenic species such as methylated and phenylated arsenic compounds. Phenylarsonic acid （PA） is a degradation product of organoarsenics used for chemical warfare agents, which has been detected in well water at the disposal site of the agents in Japan. There are few reports studying behavior of PA in soil. In this study, PA was adsorbed onto ferrihydrite and its chemical forms were determined using high performance liquid chromatography connected to inductivity-coupled plasma mass spectrometry （HPLC-ICP-MS）. 100 mg/kg of PA was mixed with 0.03 g of 2-line ferrihydrite. For each suspension, pH was adjusted by HNO3 or NaOH. Each sample was incubated for more than 19 hours and the final pH was measured. After filtration, the chemical form of arsenic in the filtrate was measured using HPLC-ICP-MS. In addition, ferrihydrite separated by filtration was dissolved by 3 ml of 0.5 M HCI and the arsenic species in the solution was detected by HPLC-ICP-MS （column： Tosoh TSKgel SuperlC-AP, eluent： 0.01 M HNO3）. It was verified that PA is not degraded by heating in 0.5 M HCl solution. At pH 3.1, any arsenic compounds were not detected from the solution, because almost all arsenic species were adsorbed onto ferrihydrite at lower pH. At pH= 12, however, 7%-10% of inorganic arsenic was detected in the solution. In solid phase, there are some problems to determine the precise ratio of inorganic and organic species. When the solution includes Fe ion at 0.01 M level, the retention time of arsenic species drifted compared to those in standard solution, which makes it difficult to determine precisely the arsenic species adsorbed on ferrihydrite. Therefore, more study is needed to determine the ratio of inorganic and organic species in the system. 相似文献
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Zonal distribution of seepage hydrocarbon-induced altereb carbonates over oil/gas reservoirs is a common phenomenon observed in the field.The authors considered that the continuous production of CO2 within the “alteration chimney ”gives rise to a significant difference in physical and chemical properties between its interior and the surrounding country rocks.And it is this difference that has promoted the erosion and precipitation of carbonates,thus leading to the zonal distribution of seepage hydrocarbon-induced altered carbonates over oil/gas reservoirs.This may be a reasonable interpretation of the phenomenon described above. 相似文献
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Doklady Earth Sciences - The influence of variations in fo-, fa-, en-, fs-, di-, an-, and ab-components in a high-Mg basaltic melt on the topology of the spinellide liquidus was analyzed using the... 相似文献
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Vesignieite, Cu_3Ba(VO_4)_2(OH)_2, crystallizes in space group C_2 / m with a°=1.0270(2), b°=0.5911(1),c°=0.7711(2)nm and β=116.42(3)°. The intensity data were collected with the RIGAKU RASA-IISsingle-crystal four-circle diffractometer. The structure was determined by Patterson and Fourier methods andrefined by the least-square technique to a final R index of 0.051 for 614 independent diffraction points with|F? |>3σ|F?|. The crystal structure analysis shows that vesignieite has a layer structure parallel to (001). The powder diffraction lines were reindexed. 相似文献
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Abstract A new selected area electron diffraction (SAED) pattern was found from Fe‐illite. The lattice of the ED pattern can be described as a compound tessellation of (3,6)[79{3,6}], which is based on a large coincidence‐site lattice (CSL) with oriented crystal associations rotated by a non‐crystallographic angle 26°. This phenomenon corresponds to the plesiotwinning of Fe‐illite and has been never reported in the nature so far. 相似文献
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This paper deals with a simulated test of biogenic mineralization made with a blue-green alga species,Spirulina platensix. The data in the experiment were recorded by a computerized surveying system. The influ-ence of algae on the accumulation of phosphorus by changing their microenvironment to promote the forma-tion and deposition of phosphate was studied. The results show that the pH value of cultural liquor rose up to 10 and the redox potential (Eh) may dropby 100-200 mV during the algal logarithmic growth stage, and the cultrual liquor was changed into a mediumwith a weakly reducing condition. At the end of the logarithmic growth stage white deposits of Na_2Ca(CO_3)_2·5H_2O and Ca_2Mg (PO_4)_2·2H_2O were formed on the floor of cultural containers. The test presented a wduableevidence for the theory of biogenic mineralization. 相似文献
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Wang Ende Shenyang Institute of Gold Technology Shenyang Liaoningand Guan Guangyue Northeast U niversity of Technology Shenyang Liaoniny 《《地质学报》英文版》1994,68(1):31-42
The bacteria used in the experiment are Thiobacillus Ferrooxidans separated from acidic mine water in sulphide deposits. The chemoautotrophic bacteria can act directly on sulphides and accelerate the oxidation of sulphides. The experiment shows that the bacteria, as an important microbial factor of gold's supergenous enrichment within the oxidized zones of sulphide deposits, are helpful to dissolve gold and silver in ferric sulphate. In the bacterial oxidation process, the precipitation of goethite is concerned both with the lower activity of ferric ions and with the existence of carbonates in solution. Meanwhile, the acid-resisting and oxidizing ability of the bacteria will certainly lead up to a microbial way of treating the acidic mine water. 相似文献