• Volume 82,Issue 5,2008 Table of Contents
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    • Geochemical Mapping—Evolution of Its Aims, Ideas and Technology

      2008, 82(5):927-937.

      Abstract (1124) HTML (0) PDF 7.38 M (15) Comment (0) Favorites

      Abstract:The development of geochemical mapping progressed from local geochemical prospecting through regional geochemical exploration and regional geochemical mapping to national and global geochemical mapping. This paper discusses the evolution of aims, ideas and methodology of geochemical mapping in Western countries, Russia and China. The sophistication of geochemical mapping methodology will make great contributions to solving resources and environmental problems in the 21st century.

    • Surface Rupture and Co-seismic Displacement Produced by the Ms 8.0 Wenchuan Earthquake of May 12th, 2008, Sichuan, China: Eastwards Growth of the Qinghai-Tibet Plateau

      2008, 82(5):938-948.

      Abstract (1687) HTML (0) PDF 6.15 M (13) Comment (0) Favorites

      Abstract:An earthquake of Ms 8 struck Wenchuan County, western Sichuan, China, on May 12th, 2008 and resulted in long surface ruptures (>300 km). The first-hand observations about the surface ruptures produced by the earthquake in the worst-hit areas of Yingxiu, Beichuan and Qingchuan, ascertained that the causative structure of the earthquake was in the central fault zones of the Longmenshan tectonic belt. Average co-seismic vertical displacements along the individual fault of the Yingxiu-Beichuan rupture zone reach 2.5–4 m and the cumulative vertical displacements across the central and frontal Longmenshan fault belt is about 5–6 m. The surface rupture strength was reduced from north of Beichuan to Qingchuan County and shows 2–3 m dextral strike-slip component. The Wenchuan thrust-faulting earthquake is a manifestation of eastward growth of the Tibetan Plateau under the action of continuous convergence of the Indian and Eurasian continents.

    • Permafrost Characteristics of the Qinghai-Tibet Plateau and Methods of Roadbed Construction of Railway

      2008, 82(5):949-958.

      Abstract (1296) HTML (0) PDF 5.51 M (18) Comment (0) Favorites

      Abstract:Permafrost along the Qinghai-Tibet railway is featured by abundant ground ice and high ground temperature. Under the influence of climate warming and engineering activities, the permafrost is under degradation process. The main difficulty in railway roadbed construction is how to prevent thawing settlement caused by degradation of permafrost. Therefore the proactively cooling methods based on controlling solar radiation, heat conductivity and heat convection were adopted instead of the traditional passive methods, which is simply increasing thermal resistance. The cooling methods used in the Qinghai-Tibet railway construction include sunshine-shielding roadbeds, crushed rock based roadbeds, roadbeds with rock revetments, duct-ventilated roadbeds, thermosyphon installed roadbeds and land bridges. The field monitored data show that the cooling methods are effective in protecting the underlying permafrost, the permafrost table was uplifted under the embankments and therefore the roadbed stability was guaranteed.

    • Late Cenozoic Geology and Paleo-environment Change in the Eastern Edge of Qinghai-Xizang Plateau

      2008, 82(5):959-966.

      Abstract (1517) HTML (0) PDF 5.90 M (14) Comment (0) Favorites

      Abstract:There are late Cenozoic lacustrine deposits and loess and red clay and moraines in eastern edge of the Qinghai-Xizang Plateau. Various genetic sediments recorded rich information on late Cenozoic paleo-environment changes. Xigeda lacustrine formed during 4.2 Ma B.P.–2.6 Ma B.P. There were 9 periodic warm-cold alternations. Eolian deposition in western Sichuan began at 1.15 Ma B.P. The loess-soil sequences recorded successively 14 paleo-monsoon climate cycles. Laterite in Chengdu plain recorded 5 stages of paleoclimatic stages since 1.13 Ma B.P. There was an old glacial period of 4.3 Ma B.P. in eastern Qinghai-Xizang Plateau. During Quaternary, there are 5 extreme paleoclimatic events corresponding with 5 glaciations.

    • Distribution of Palygorskite in the Lingtai Profile of Chinese Loess Plateau: Its Paleoclimatic Implications

      2008, 82(5):967-974.

      Abstract (1178) HTML (0) PDF 5.89 M (12) Comment (0) Favorites

      Abstract:Palygorskite is a typical indicator mineral of the arid and strong evaporation environment. Distribution of palygorskite in loess-red clay sequences may act as an important indicator for reconstruction of the paleoenvironment and paleoclimate. In this paper, field emission scanning electron microscope and high-resolution transmission electron microscope observations on the red clay-loess-paleosol of the Renjiapo profile at Lingtai, Gansu Province indicate that palygorskite occurs widely in red clay sequences formed before 3.6 Ma, but no occurrence has been found in eolian sediments since 3.2 Ma. Micromorphological features and microstructure of palygorskite show that it is an autogenic mineral formed during pedogenesis, and transformed from illite-montmorillonite under the pore water action. In the Lingtai profile, the disappearance horizon of palygorskite is consistent with those of increasing magnetic susceptibility, dust flux and depositional rate. The distribution of palygorskite in the profile indicates that the interval of around 3.6 Ma was an important transformation period of the East Asian paleomonsoon, when changes took place in the East Asia paleoclimate pattern, i.e. a high-frequency strong fluctuation alternative evolution of the environment. Therefore, palygorskite is a key indicator mineral of the East Asian paleomonsoon evolution of that time.

    • δ13C-δ18O Covariance: An Effective Indicator of Hydrological Closure for Lakes?

      2008, 82(5):975-981.

      Abstract (1530) HTML (0) PDF 4.55 M (13) Comment (0) Favorites

      Abstract:The correlation between the δ13C and δ18O in primary carbonates is affected by several factors such as hydrological balance, total CO2 concentrations, climatic condition and lake productivity. The influence of these factors on the δ13C-δ18O correlation may be different on different time scales. In this paper, two different-type lakes in southwestern China, Lake Erhai and Lake Chenghai, are selected to investigate the influence of climatic pattern on the δ13C-δ18O correlation and to evaluate the reliability of the δ13C-δ18O covariance as an indicator of hydrological closure. The results show that there exists good correlation between the δ13C and δ18O in Lake Erhai (overflowing open lake) and in Lake Chenghai (closed lake). This suggests that the δ13C-δ18O covariance may be not an effective indicator of hydrological closure for lakes, especially on short time scales. On the one hand, a hydrologically open lake may display covariant δ13C and δ18O as a result of climatic influence. The particular alternate warm-dry and cold-wet climatic pattern in southwestern China may be the principal cause of the δ13C-δ18O covariance in Lake Erhai and Lake Chenghai. On the other hand, a hydrologically closed lake unnecessarily displays covariant trends between δ13C and δ18O because of the buffering effect of high CO2 concentration on the δ13C shift in hyper-alkaline lakes. We should be prudent when we use the covariance between δ13C and δ18O to judge the hydrological closure of lake.

    • Weathering-pedogenesis of Carbonate Rocks and Its Environmental Effects in Subtropical Region

      2008, 82(5):982-993.

      Abstract (1340) HTML (0) PDF 7.99 M (18) Comment (0) Favorites

      Abstract:We investigated the weathering-pedogenesis of carbonate rocks and its environmental effects in subtropical regions of China. The investigation demonstrated that the weathering-pedogenesis of carbonate rocks is the process of a joint action of corrosion and illuviation and metasomatism in subtropical region. It is characterized by multi-stage, multi-path and multi-style. With the persisting development of weathering-pedogenesis of carbonate rocks, metasomatic pedogenesis progressively became the main process of the weathering-pedogenesis and the dominant style of formation of minerals. And it proceeds through the whole process of evolution of the weathering-pedogenesis of carbonate rocks. The stage evolution of weathering-pedogenesis of carbonate rocks and the fractionation evolution of newly produced minerals are characterized by obvious vertically zoning structures and the rules of gradation of elements geochemical characteristics in the carbonate rocks weathering profiles. The geochemical process of weathering-pedogenesis of carbonate rocks can be divided into three geochemical evolution stages, i.e., the Ca, Mg-depletion and Si, Al-enrichment stage; the Fe, Mn enrichment stage and the Si-depletion and Al-enrichment stage in the subtropical regions. Consistent with the three geochemical evolution stages, the sequence of formation and evolution of minerals can be divided into the clay mineral stage; the Fe, Mn oxide and the gibbsite stage. The influence of weathering-pedogenesis of carbonate rocks on the chemical forms of heavy elements is mainly affected via newly produced components and minerals in the process of weathering-pedogenesis, e.g., iron oxide minerals and organic matters. The important mechanism for the mobilization, transport and pollution of F and As is affected the selective adsorption and desorption of F and As on the surface of iron oxide minerals in the subtropical karst zones, i.e., the selective adsorption and desorption on mineral surfaces of newly produced minerals in the process of weathering-pedogenesis control the geochemical behavior of elements on the Earth’s surface and environmental quality in subtropical regions.

    • Calcite Dissolution in Deionized Water from 50°C to 250°C at 10 MPa: Rate Equation and Reaction Order

      2008, 82(5):994-1001.

      Abstract (1266) HTML (0) PDF 4.55 M (15) Comment (0) Favorites

      Abstract:Carbonate minerals and water (or geofluids) reactions are important for modeling of geochemical processes and have received considerable attention over the past decades. The calcite dissolution rates from 50°C to 250°C at 10 MPa in deionized water with a flow rate varying from 0.2 to 5 mL/min were experimentally measured in a continuous flow column pressure vessel reactor. The dissolution began near the equilibrium with c/ceq > 0.3 and finally reached the equilibrium at 100°C-250°C, so the corresponding solubility was also determined as 1.87, 2.02, 2.02 and 1.88′10-4·mol/L at 100°C, 150°C, 200°C and 250°C respectively, which was first increasing and then switching to decreasing with temperature and the maximum value might occur between 150°C and 200°C. The experimental dissolution rate not only increased with temperature, but also had a rapid increase between 150°C and 200°C at a constant flow rate of 4 mL/min. The measured dissolution rates can be described using rate equations of R = k(1-c/ceq)n or R = kc-n. In these equations the reaction order n changed with temperature, which indicates that n was a variable rather than a constant, and the activation energy was 13.4 kJ/mol calculated with R = k(1-c/ceq)n or 18.0 kJ/mol with R = kc-n, which is a little lower than the surface controlled values. The varied reaction order and lower activation energy indicates that calcite dissolution in this study is a complex interplay of diffusion controlled and surface controlled processes.

    • Heavy Metal Distributions and Source Tracing in the Lacustrine Sediments of Dongdao Island, South China Sea

      2008, 82(5):1002-1014.

      Abstract (1019) HTML (0) PDF 8.75 M (13) Comment (0) Favorites

      Abstract:The levels and depth distributions of As, Cd, Cu, Zn, Pb, Hg, Fe and Mn in two sediment cores DY2 and DY4 collected from the “Cattle Pond” of Dongdao Island, South China Sea, were determined and analyzed with the main objective to identify the sources of these elements and evaluate the corresponding sedimentological and geochemical processes. Lithological characters and sedimentary parameters such as LOI950°C, CaO, LOI550°C and TOC indicate that the depth of 96 cm and 87 cm are the critical points for DY2 and DY4 cores, respectively. As, Cd, Cu, Zn, Hg and P are remarkably enriched in the ornithogenic sediments above the critical depth points; their concentration-versus-depth profiles are similar to those of TOC and LOI550°C; the ratios of As, Cd, Cu, Zn, Hg over Ca are significantly correlated with P/Ca. Statistical and comparative analyses of these elements’ levels in the ornithogenic sediments of DY2 and DY4 strongly suggest that seabird droppings are the main source of these elements. Additionally, for the upper sediment layers of DY2 and DY4 cores, Fe oxide sorption mechanism, like organic matter, may also play an important role in the abundances of heavy metals. Heavy metal Pb has geochemical characteristics distinctly different from those of As, Cd, Cu, Zn, Hg and P, and its isotope composition indicates an origin of anthropogenic emissions from the surrounding countries. These geochemical characteristics in the orinithogenic sediments of Xisha Islands are compared with the studies in the remote Antarctic and Arctic regions.

    • Removal of Arsenic(V) from Aqueous Solutions by Lanthanum-loaded Zeolite

      2008, 82(5):1015-1019.

      Abstract (1152) HTML (0) PDF 3.11 M (2) Comment (0) Favorites

      Abstract:A new adsorption process for the removal of As(V) ion from aqueous solutions is studied in this paper using lanthanum-loaded zeolite. The removal efficiency of different adsorbents, activated alumina and activated carbon are obtained in the study for comparison. The results show that lanthanum-loaded zeolite is an effective adsorbent for the removal of As(V) from aqueous solutions. Then, the pH effect and regeneration of modified zeolite on the As(V) removing efficiency are also assessed. It functions with a wide range of pH (2-8). After adsorption, zeolite adsorbed with As(V) ions can be regenerated successfully with 1 M NaOH. Based on the data obtained, an adsorption mechanism and the possible complex structure are tentatively presented. Compare to other adsorbents, easy availability of this adsorbent, excellent adsorption capacity, wide optimum pH range, and regeneration are expected to be utilized in practical operations.

    • The Role of Fracture Structure in Leachate Pollution at Landfills: A Case Study of a Landfill in Chongqing City

      2008, 82(5):1020-1026.

      Abstract (1145) HTML (0) PDF 4.35 M (15) Comment (0) Favorites

      Abstract:This paper studies a landfill where there are three faults running through. As serious pollution has occurred to the geological environment, the landfill is to be closed up and renovated. The paper aims to explore the role of fracture structure in leachate pollution at the landfill. The research was carried out in several stages. First, mathematical models of the pre-renovation landfill with three faults running through and the landfill after renovation were established. And then, the boundary conditions and parameters of the two mathematical models were determined. The groundwater level of the landfills was simulated in order to modify the two mathematical models. As a result, a feasible mathematical model was achieved. Based on this model, a comparison was made of the COD concentration variations in the inside leachate and outside leachate between the two landfills. Accordingly, the impacts of the fracture structure on the pollution of leachate at the landfills could be identified. The study results show that while faults contribute to the migration of leachate, they also serve as a confluence of leachate, thus further deteriorating the environment. The COD concentrations of the inside leachate and the outside leachate of the pre-renovation landfill are respectively 800 mg/L and 220 mg/L higher than those of the post-renovation landfill. Therefore, measures must be taken to handle the leachate seepage in areas where there are faults as well as the neighboring areas so as to get the environmental pollution under control.

    • Study on Assessment of Mine Environments

      2008, 82(5):1027-1034.

      Abstract (1090) HTML (0) PDF 6.14 M (14) Comment (0) Favorites

      Abstract:Mine environmental evaluation is the key to mine environmental study. On the basis of the characteristics of the mine environmental problems, they are classified into (1) three wastes problem, (2) ground distortion, (3) contradiction among mine drainage, water supply, ecological environment, (4) desertification, and (5) soil erosion. The evaluation is the basis of mine environmental problem classification and investigation, mine environmental rehabilitation, and the information system constructed can be used for subsequent research of evaluation techniques. A synthetic assessment of the 5 kinds of mine environmental problems can be divided into single-factor or multi-factor synthetic assessments; while by the viewpoint of time, the mine environmental assessment can be classified as the historical assessment, the current status assessment and the forecasting assessment.

    • Environmental Investigation and Evaluation of Land Subsidence in the Datong Coalfield Based on InSAR Technology

      2008, 82(5):1035-1044.

      Abstract (1389) HTML (0) PDF 7.13 M (20) Comment (0) Favorites

      Abstract:Heavy mining of Jurassic and Carboniferous horizontal coal seams in the Datong coalfield has seriously affected the local geological environment, which is mainly manifested by such geohazards as soil avalanches, landslides, mudflows, surface subsidence, surface cracks, surface solid waste accumulation and surface deformation. More seriously, coal mining causes groundwater to leak. Overpumping of groundwater has resulted in substantial land subsidence of the urban area in Datong City. Based on the previous geo-environmental investigation in the work area, the authors used radar remote sensing techniques such as InSAR (synthetic aperture radar interferometry) and D-InSAR (differential synthetic aperture radar interferometry), supplemented by the optical remote sensing method, for geo-environmental investigation to ascertain the geo-environmental background of the Datong Jurassic and Carboniferous-Permian coalfield and evaluate the effects of the geohazards, thus providing a basis for the geo-environmental protection, geohazard control and prevention, land improvement and optimization of the human environment. In this study 8 cog-nominal ERS-1/2 SAR data frames during 1992 to 2003 were used, but the following processing was made: (1) the multi-temporal SAR magnitude images were used to interpret the geological structure, vegetation, micro-geomorphology and drainage system; (2) the multi-temporal InSAR coherent images were used to make a classification of surface features and evaluate the coherence change due to coal mining; and (3) the multi-temporal cog-nominal SAR images were used to complete D-InSAR processing to remove the information of differential deformation areas (sites). In the end, a ten-year time series of differential interferograms were obtained using the multi-temporal cog-nominal SAR images. In the tests, 84 deformed areas (sites) were obtained, belonging to those in 1993–1996, 1996–1997, 1997–1998, 1998–2001, 1998–2002 and 2001–2003 respectively. Of the 84 areas, 44 are mining subsidence ones, 23 urban subsidence ones and 17 landslide subsidence ones. They cover a total area of 1824.4 km2, equivalent to the area of the whole Datong coalfield. Then an accurate evaluation was made on the geo-environment of the Datong coalfield. The tests show that InSAR is now the only feasible technical means for making one all-weather, real-time measurement of a coal mining land subsidence area covering up to 10,000 km2 to subcentimeter resolution. This study is a successful application of InSAR in the investigation and evaluation of land subsidence, especially in coal mining areas.

    • Selection and Basic Properties of the Buffer Material for High-Level Radioactive Waste Repository in China

      2008, 82(5):1050-1055.

      Abstract (1138) HTML (0) PDF 4.55 M (1) Comment (0) Favorites

      Abstract:Radioactive wastes arising from a wide range of human activities are in many different physical and chemical forms, contaminated with varying radioactivity. Their common features are the potential hazard associated with their radioactivity and the need to manage them in such a way as to protect the human environment. The geological disposal is regarded as the most reasonable and effective way to safely disposing high-level radioactive wastes in the world. The conceptual model of geological disposal in China is based on a multi-barrier system that combines an isolating geological environment with an engineered barrier system. The buffer is one of the main engineered barriers for HLW repository. It is expected to maintain its low water permeability, self-sealing property, radio nuclides adsorption and retardation properties, thermal conductivity, chemical buffering property, canister supporting property, and stress buffering property over a long period of time. Bentonite is selected as the main content of buffer material that can satisfy the above requirements. The Gaomiaozi deposit is selected as the candidate supplier for China’s buffer material of high level radioactive waste repository. This paper presents the geological features of the GMZ deposit and basic properties of the GMZ Na-bentonite. It is a super-large deposit with a high content of montmorillonite (about 75%), and GMZ-1, which is Na-bentonite produced from GMZ deposit is selected as the reference material for China’s buffer material study.

    • Preparation and Structural Investigation of CuCl2 Graphite Intercalation Compounds

      2008, 82(5):1056-1060.

      Abstract (1245) HTML (0) PDF 2.33 M (12) Comment (0) Favorites

      Abstract:Superfine graphite powder was prepared by ball-milling exfoliated graphite containing anhydrous CuCl2 in planetary ball milling systems. Nano-scale CuCl2 graphite intercalation compounds were synthesized by heating a mixture of anhydrous CuCl2 and graphite nanosheets. Scanning electron microscopy, energy-dispersive X-ray spectroscopy and high-resolution transmission electron microscopy were performed to characterize the microstructures of stage-1 nano-scale CuCl2 graphite intercalation compounds. The structure and components of the domain wall and core in the nano-scale CuCl2 graphite intercalation compounds are described. The results show that the content of CuCl2 in the mixture plays a crucial role in the size of the nano-scale CuCl2 graphite intercalation compound.

    • Groundwater Systems and Resources in the Ordos Basin, China

      2008, 82(5):1061-1069.

      Abstract (1902) HTML (0) PDF 5.61 M (11) Comment (0) Favorites

      Abstract:The Ordos Basin is a large-scale sedimentary basin in northwestern China. The hydrostratigraphic units from bottom to top are pre-Cambrian metamorphic rocks, Lower Paleozoic carbonate rocks, Upper Paleozoic to Mesozoic clastic rocks and Cenozoic deposits. The total thickness is up to 6000 m. Three groundwater systems are present in the Ordos Basin, based on the geological settings, i.e. the karst groundwater system, the Cretaceous clastic groundwater system and the Quaternary groundwater system. This paper describes systematically the groundwater flow patterns of each system and overall assessment of groundwater resources.

    • Numerical Modelling of Dissolving and Driving Exploitation of Potash Salt in the Qarhan Playa ? A Coupled Model of Reactive Solute Transport and Chemical Equilibrium in a Multi-component Underground Brine System

      2008, 82(5):1070-1082.

      Abstract (1110) HTML (0) PDF 7.69 M (14) Comment (0) Favorites

      Abstract:Firstly, the macroscopic chemical equilibrium state of a series of chemical reactions between intercrystal brine and its media salt layer (salt deposit) in Qarhan Salt Lake was studied by using the Pitzer theory. The concept of macroscopic solubility product and its relation with accumulated ore dissolving ratio were presented, which are used in the numerical model of dissolving and driving exploitation of potassium salt in Qarhan Salt Lake. And secondly, with a model forming idea of transport model for reacting solutes in the multi-component fresh groundwater system in porous media being a reference, a two-dimensional transport model coupled with a series of chemical reactions in a multi-component brine porous system (salt deposits) was developed by using the Pitzer theory. Meanwhile, the model was applied to model potassium/magnesium transport in Qarhan Salt Lake in order to study the transfer law of solid and liquid phases in the dissolving and driving process and to design the optimal injection/abstraction strategy for dissolving and capturing maximum Potassium/Magnesium in the mining of salt deposits in Qarhan Salt Lake.

    • Three Practical Methods for Analyzing Slope Stability

      2008, 82(5):1083-1088.

      Abstract (1188) HTML (0) PDF 3.79 M (26) Comment (0) Favorites

      Abstract:Since the environmental capacity and the arable as well as the inhabitant lands have actually reached a full balance, the slopes are becoming the more and more important options for various engineering constructions. Because of the geological complexity of the slope, the design and the decision-making of a slope-based engineering is still not practical to rely solely on the theoretical analysis and numerical calculation, but mainly on the experience of the experts. Therefore, it has important practical significance to turn some successful experience into mathematic equations. Based upon the abundant typical slope engineering construction cases in Yunnan, Southwestern China, 3 methods for analyzing the slope stability have been developed in this paper. First of all, the corresponded analogous mathematic equation for analyzing slope stability has been established through case studies. Then, artificial neural network and multivariate regression analysis have also been set up when 7 main influencing factors are adopted.

Chief Editor:HOU Zengqian

Governing Body:China Association for Science and Technology

Organizer:Geological Society of China

start publication :1922

ISSN:ISSN 1000-9515

CN:CN 11-2001/P

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