Investigating soil thermodynamic parameters of the active layer on the northern Qinghai-Tibetan Plateau   总被引：3，自引：1，他引：2  

Ren Li  Lin Zhao  Tonghua Wu  Yongjian Ding  Yao Xiao  Yongliang Jiao  Yanhui Qin  Yufei Xin  Erji Du  Guangyue Liu 《Environmental Earth Sciences》2014,71(2):709-722

The soil thermodynamic parameters, including thermal conductivity, diffusivity and volumetric capacity within the active layer on the northern Tibetan Plateau, were calculated using the measured data of soil temperature gradient, heat flux, and moisture at four stations from October 2003 to September 2004. The results showed that the soil thermodynamic parameters exhibited clear seasonal fluctuation. The thermal conductivity and diffusivity in summer and autumn at Beiluhe, Kexinling, and Tongtianhe were larger than those in winter. The volumetric thermal capacity causes an opposite change; it was larger in autumn and winter than in summer. In spring, the soil thermal conductivity at the Kekexili station was larger than that in summer. Generally, fine-grained soils and lower saturation degrees in the topsoil might be a reason for the lower soil thermal conductivity in winter. For a given soil, soil moisture was the main factor influencing the thermodynamic parameters. The unfrozen water content that existed in frozen soils greatly affected the soil thermal conductivity, whose contribution rate was estimated to be 55 %. The thermodynamic parameters of frozen soils could be expressed as a function of soil temperature, volumetric ice content and soil salinity, while for the unfrozen ground the soil moisture content is the dominant factor for those thermal parameters. As for the soil thermal diffusivity, there exists a critical value of soil moisture content. When the soil moisture content becomes less than a critical value, the soil thermal diffusivity increases as the soil moisture content rises.  相似文献   

Exploring the effects of data quality,data worth,and redundancy of CO2 gas pressure and saturation data on reservoir characterization through PEST inversion     

Zhufeng Fang  Zhangshuan Hou  Guang Lin  Dave Engel  Yilin Fang  Paul Eslinger 《Environmental Earth Sciences》2014,71(7):3025-3037

This study examined the impacts of reservoir properties on carbon dioxide (CO₂) migration after subsurface injection and evaluated the possibility of characterizing reservoir properties using CO₂ monitoring data such as spatial–temporal distributions of gas pressure, which can be reasonably monitored in practice. The injection reservoir was assumed to be located 1,400–1,500 m below the ground surface such that CO₂ remained in the supercritical state. The reservoir was assumed to contain layers with alternating conductive and resistive properties, which is analogous to actual geological formations such as the Mount Simon Sandstone unit. The CO₂ injection simulation used a cylindrical grid setting in which the injection well was situated at the center of the domain, which extended out 8,000 m from the injection well. The CO₂ migration was simulated using the latest version of the simulator, subsurface transport over multiple phases (the water–salt–CO₂–energy module), developed by Pacific Northwest National Laboratory. A nonlinear parameter estimation and optimization modeling software package, Parameter ESTimation (PEST), is adopted for automated reservoir parameter estimation. The effects of data quality, data worth, and data redundancy were explored regarding the detectability of reservoir parameters using gas pressure monitoring data, by comparing PEST inversion results using data with different levels of noises, various numbers of monitoring wells and locations, and different data collection spacing and temporal sampling intervals. This study yielded insight into the use of CO₂ monitoring data for reservoir characterization and how to design the monitoring system to optimize data worth and reduce data redundancy. The feasibility of using CO₂ saturation data for improving reservoir characterization was also discussed.  相似文献   

Scale matching of multiscale digital elevation model (DEM) data and the Weather Research and Forecasting (WRF) model: a case study of meteorological simulation in Hong Kong     

Chunxiao Zhang  Hui Lin  Min Chen  Liang Yang 《Arabian Journal of Geosciences》2014,7(6):2215-2223

It is becoming easier to combine geographical data and dynamic models to provide information for problem solving and geographical cognition. However, the scale dependencies of the data, model, and process can confuse the results. This study extends traditional scale research in static geographical patterns to dynamic processes and focuses on the combined scale effect of multiscale geographical data and dynamic models. The capacity for topographical expression under the combined scale effect was investigated by taking multiscale topographical data and meteorological processes in Hong Kong as a case study. A meteorological simulation of the combined scale effect was evaluated against data from Hong Kong Observatory stations. The experiments showed that (1) a digital elevation model (DEM) using 3 arc sec data with a 1 km resolution Weather Research and Forecasting (WRF) model gives better topographical expression and meteorological reproduction in Hong Kong; (2) a fine-scale model is sensitive to the resolution of the DEM data, whereas a coarse-scale model is less sensitive to it; (3) better topographical expression alone does not improve weather process simulation; and (4) uncertainty arising from a scale mismatch between the DEM data and the dynamic model may account for 38 % of the variance in certain meteorological variables (e.g., temperature). This case study gives a clear explanation of the significance and implementation of scale matching for multiscale geographical data and dynamic models.  相似文献   

Reservoir characteristics and main controlling factors of oil sand in Houba area,northwestern Sichuan Basin,China   总被引：1，自引：0，他引：1  

Xuefei Yang  Xingzhi Wang  Shaonan Zhang  Hao Tang  Deming Zeng  Lin Xie 《Arabian Journal of Geosciences》2014,7(6):2119-2128

Houba oil sand in frontier Longmenshan Mountain is one of the most typically important unconventional resources. The basic reservoir characteristics of oil sand and the main factors affecting reservoir quality were examined in this article based on porosity, permeability, and mercury porosimetry measurements; thin section analyses; SEM observation; and X-ray diffraction analysis. This study shows that the oil-bearing sandstone reservoir is mainly medium?coarse-grained sublitharenite and litharenite. The main pore type is intergranular pores, including residual primary intergranular pores, dissolved intergranular pores, and dissolved intragranular pores; fractures are common in this study area. The quality of sandstone reservoir is of high porosity and high permeability with a high oil saturation of 89.84 %. It is indicated that the main controlling factors of the reservoir in the study area include deposition, diagenesis, and tectonism. Deposition laid a foundation to porosity evolution, and channel sand is the most favorable depositional facies for the reservoir. Diagenetic alterations are the keys to reservoir evolution; dissolution and chlorite coatings cementation play an effective role in the generation and preservation of pores. Compaction, carbonate cementation, and quartz overgrowth cause many damages to the reservoir porosity. Fractures caused by structural breakages can improve the reservoir permeability and they also can provide fluid migration pathways to the late corrosion, which formed a lot of corroded fissures as reservoir and percolation spaces.  相似文献   

Zircon U-Pb ages and geochemistry of the monzonitic granite in Rongguo area in Middle Gangdise Belt     

HU Lin  XU Gang  LIU Daming 《中国地质调查》2014,7(4):67-75

In order to determine the geochronology, petrogenesis and tectonic background of the monzonitic granite in Rongguo area, the authors conducted the research on petrology, LA-ICP-MS zircon U-Pb geochronology and geochemistry. The results show that the zircons from the monzonitic granite are of magmatic genesis, and the zircon ²⁰⁶Pb/²³⁸U dating is (69±1) Ma, belonging to the Late Cretaceous. Al₂O₃, Na₂O, K₂O contents and K₂O/Na₂O ratio are 13.83%~14.41%, 3.68%~3.94%, 4.28%~4.35% and 1.08~1.18 respectively. The average aluminum saturation index (A/CNK) is 1.02, belonging to the weak peraluminous series. The rocks are enriched in LILE (Rb,U,K), strongly depleted in HFSE (Nb, Ta, Ti, etc.). Combined with the study of regional tectonics, the authors insisted that magma activity had not stopped from 80 to 69 Ma. The rock mass is the magmatic product of the subduction of the Neo-Tethys Ocean, forming in the orogenic environment during the whole orogenic movement period.  相似文献   

Decoupling of the East Asian summer monsoon and Indian summer monsoon between 20 and 17 ka   总被引：2，自引：0，他引：2  

Xiuyang Jiang  Yaoqi He  Chuan-Chou Shen  Shi-Yu Lee  Bang Yang  Ke Lin  Zhizhong Li 《Quaternary Research》2014

Marine Oxygen Isotope Stage (MIS) 2, with its profound environmental and climatic changes from before the last glacial maximum (LGM) to the last deglaciation, is an ideal period for understanding the evolution of the East Asian summer monsoon (EASM) and Indian summer monsoon (ISM), two Asian monsoon sub-systems. With 875 stable oxygen isotope ratios and 43 ²³⁰Th dates from stalagmites in Sanxing Cave, southwestern China, we construct and interpret a new, replicated, Asian summer monsoon (ASM) record covering 30.9–9.7 ka with decadal resolution. δ¹⁸O records from this site and other reported Chinese caves display similar long-term orbitally dominated trends and synchronous millennial-scale strong and weak monsoonal events associated with climate changes in high northern latitudes. Interestingly, Sanxing δ¹⁸O and Arabian Sea records show a weakening ISM from 22 to 17 ka, while the Hulu and Qingtian records from East and Central China express a 3-ka intensifying EASM from 20 to 17 ka. This decoupling between EASM and ISM may be due to different sensitivities of the two ASM sub-systems in response to internal feedback mechanisms associated with the complex geographical or land-ocean configurations.  相似文献   

Spatial distribution of soil erosion and suspended sediment transport rate for Chou-Shui river basin     

Chin-Ping Lin  Ching-Nuo Chen  Yu-Min Wang  Chih-Heng Tsai  Chang-Tai Tsai 《Journal of Earth System Science》2014,123(7):1517-1539

In this study, a Physiographic Soil Erosion–Deposition Model (PSED) is applied for better management of a watershed. The PSED model can effectively evaluate the key parameters of watershed management: surface runoff discharge, suspended sediment transport rate, quantity of soil erosion, and spatial distribution of soil erosion and deposition. A basin usually contains multiple watersheds. These watersheds may have complex topography and heterogeneous physiographic properties. The PSED model, containing a physiographic rainfall-runoff model and a basin scale erosion–deposition model, can simulate the physical mechanism of the entire erosion process based on a detailed calculation of bed-load transportation, surface soil entrainment, and the deposition mechanism. With the assistance of Geographic Information Systems (GIS), the PSED model can handle and analyze extremely large hydrologic and physiographic datasets and simulate the physical erosion process without the need for simplification. We verified the PSED model using three typhoon events and 40 rainfall events. The application of PSED to Chou-Shui River basin shows that the PSED model can accurately estimate discharge hydrographs, suspended sediment transport rates, and sediment yield. Additionally, we obtained reasonable quantities of soil erosion as well as the spatial distribution of soil erosion and deposition. The results show that the PSED model is capable of calculating spatially distributed soil erosion and suspended sediment transport rates for a basin with multiple watersheds even if these watersheds have complex topography and heterogeneous physiographic properties.  相似文献   

Effect of nano-hematite morphology on photocatalytic activity     

Y. H. Chen  C. C. Lin 《Physics and Chemistry of Minerals》2014,41(10):727-736

Nano-hematites, i.e., hematites with nanoparticle-, nanorod-, and nanotube-like morphologies, were synthesized via the hydrothermal method by controlling the reaction time, temperature, and reactant concentration. The nano-hematites of different crystal shapes all exhibited band gaps within the visible-light region (1.56–2.1 eV). Further, they showed weak ferromagnetic behavior, and their coercive magnetic field was larger than that of the bulk hematite. Moreover, all the nano-hematites also exhibited high photocatalytic activities during the degradation of methylene blue under visible-light irradiation. The experimental data fitted the Langmuir–Hinshelwood kinetics model very well. The nanorods had the highest photocatalytic rate constant per unit surface area, possibly owing to a higher aspect ratios; this lowers the electron–hole recombination rate. These results suggest that the crystal morphology of hematites has a significant effect on their physical and photocatalytic properties. Therefore, controlling the morphology of the materials is essential for obtaining well-tailored photocatalysts.  相似文献   

桐柏山L构造岩的构造特征与形成环境探讨          下载免费PDF全文

刘欢  宋传中  林寿发  李加好  黄鹏  王微  韩建军  杨帆 《地质科学》2014,(2):542-555

桐柏山太白顶、殷店和天河口一带,发育有大量的L构造岩,拉伸线理极其发育,面理较弱,线理产状向南东东倾伏,倾伏角为1°～20°。桐柏山L构造岩具有以下主要特征：在三维空间上,L构造岩强烈发育杆状构造,这种“杆”状构造是由大量沿X轴方向定向排列连在一起的椭球体矿物构成的,其变形机制主要为石英的颗粒边界迁移和长石的位错蠕变,形成的平均压力为0.59GPa,平均温度为550 ℃～600 ℃,形成于中-高温-中压环境,变质相为高绿片岩相到低角闪岩相,形成深度大致在15～20 km,属于中地壳的产物。L构造岩在桐柏山的发现可能反映了桐柏山造山带中桐柏杂岩岩块相对两侧榴辉岩岩片具有近东西向挤出构造的特征。  相似文献   

Evacuees’ information sources and reentry decision making in the aftermath of Hurricane Ike     

Chih-Chun Lin  Laura K. Siebeneck  Michael K. Lindell  Carla S. Prater  Hao-Che Wu  Shih-Kai Huang 《Natural Hazards》2014,70(1):865-882

In the aftermath of a hurricane, local emergency managers need to communicate reentry plans to households that might be scattered over multiple counties or states. To better understand evacuees’ households’ reliance on different information sources at the time they decided to return home, this study collected data on reentry after Hurricane Ike. The results from a survey of 340 evacuating households indicated that there was low compliance with official reentry plans and that none of the information sources produced greater compliance with official reentry plans. Nonetheless, there were significant changes in the utilization of different sources of emergency information over the course of an evacuation but local news media remained the most common sources throughout the event. There also were significant differences in the relative importance of different sources of reentry information, with people relying most on information from peers. In summary, local authorities need to identify more effective ways to communicate with evacuees that have relocated to distant communities and to motivate them to comply with official reentry plans.  相似文献