Classification and Gradation of Cultivated Land Quality in Bishan County of Chongqing, China   总被引：4，自引：0，他引：4  

SHAO Jing＇an GE Xiaofeng WEI Chaofu XIE Deti 《中国地理科学(英文版)》2007,17(1):82-91

The conflicts among food security, economic development and ecological protection are the “sticking point” of undeveloped southwestern mountainous areas of China. The objectives of this study are to identify appropriate inte- grated indicators influencing the classification and gradation of cultivated land quality in the southwestern mountainous area of China based on semi-structure interview, and to promote the monitoring of cultivated land quality in this region. Taking Bishan County of Chongqing as a study case, the integrated indicators involve the productivity, protection, ac- ceptability, and stability of cultivated land. The integrated indicators accord with the characteristics of land resources and human preference in southwestern mountainous area of China. In different agricultural zones, we emphasize different indicators, such as emphasizing productivity, stabilization and acceptability in low hilly and plain agricultural integrative zone (LHP-AIZ), protection, productivity and stability in low mountain and hill agro-forestry ecological zone (LMH-AEZ), and acceptability in plain outskirts integrative agricultural zone (PO-IAZ), respectively. The pronounced difference of classification and gradation of cultivated land, regardless of inter-region or intra-region, is observed, with the reducible rank from PO-IAZ, LHP-AIZ to LMH-AEZ. Research results accord with the characteristics of assets management and intensive utilization of cultivated land resources in the southwestern mountainous area of China. Semi-structure interview adequately presents the principal agent of farmers in agricultural land use and rural land market. This method is very effective and feasible to obtain data of the quality of cultivated land in the southwestern mountainous area of China.  相似文献   

Early biodégradation of ligneous organic materials and its relation to ore deposition in the tréves zn-pb ore body (gard, france)     

J.R. Disnar  B. Gauthier  A. Chabin  J. Trichet 《Organic Geochemistry》1986,10(4-6)

Previous petrographical and geochemical studies on the organic content of mineralized and non-mineralized carbonate series in the Trèves Zn-Pb stratiform deposit led to the conclusion that ore deposition occurred during the diagenetic history of the sediments, in a mixed fresh/hydrothermal system (Gauthier and Disnar, 1984; Gauthier et al., 1985a). These circulations of fluids are probably responsible for the dolomitization of the original limestones and for the deposition of the ore through microbial activity (Gauthier, 1984; Gauthier el al., 1985b).The occurrence of this activity is supported by the formation of two kinds of organic components which are attributable to this uncommon bio-alteration process: alphatic-rich bitumen-like products and aromatic polyethers. The chemical composition of these two types of compounds suggests that they were produced from ligneous debris by (sulfate-reducing?) bacteria.Other indications of the occurrence of a biological activity have been found in the nature and relative abundance of microbial amino compounds. However, these constituents are thought to have been introduced only recently into the sediments whereas other evidence supports the idea that ore deposition occurred before diagenesis.  相似文献   

基于数字图像处理技术的砂土颗粒级配分析研究     

吕超  唐朝生  李胜杰  谢约翰  刘博  徐其良  王东伟 《高校地质学报》1997,25(3):431

砂土颗粒级配是影响砂土工程性质的重要参数之一，传统的颗分试验方法由于试验原理不同而具有不同的适用范 围。为更加方便、准确地获取砂土颗粒级配，提出了一种基于数字图像处理技术来获取SEM照片中的砂颗粒粒径参数及级 配特征的新方法。将准备好的砂土样品打磨成薄片放在扫描电镜下拍照，然后利用Photoshop软件对照片进行拼接，并采用 自主研发的SMAS数字图像分析系统对拼接好的照片进行定量分析处理，获取样品的微观结构参数，将获得的“土颗粒等 效直径”和“土颗粒面积”分别等效为实际土颗粒粒径和土颗粒质量，进而换算得到砂土的颗粒级配曲线；然后将通过数 字图像技术获得的砂土颗粒级配曲线与通过传统筛分法和激光粒度分析法得到的颗粒级配曲线进行对比，验证了提出的数 字图像处理方法的有效性和可靠性，同时分析了两种方法之间存在的差异及其原因，并对数字图像处理方法和传统颗分方 法各自的优缺点进行了讨论。  相似文献   

In situ anaerobic degradation of petroleum alkanes in marine sediments: preliminary results     

Delphine Massias  Vincent Grossi  Jean-Claude Bertrand 《Comptes Rendus Geoscience》2003,335(5):435-439

The degradation of acyclic petroleum hydrocarbons was studied during a 24-month experiment in Mediterranean coastal sediments (Gulf of Fos). Sediment cores entirely contaminated with oil (Arabian Light Crude Oil) were incubated in situ. The use of conservative tracers of sediment's particles reworking (luminophores) allowed the distinction of the reworked layer from the anoxic deeper sediments. Using the 17α,21βC₃₀ hopane (C₃₀H) as an inert internal reference, we could demonstrate that, after 24 months of experiment, acyclic petroleum hydrocarbons can be degraded under natural anaerobic conditions. The reactivity of individual alkanes appeared to depend on their chemical structure. To cite this article: D. Massias et al., C. R. Geoscience 335 (2003).To cite this article: D. Massias et al., C. R. Geoscience 335 (2003).  相似文献   

内插地价监测点进行土地级别调整的研究   总被引：2，自引：1，他引：2  

雷蓉  章牧  郭永梅 《武汉大学学报(信息科学版)》2004,29(10):937-939

针对城镇基准地价更新中土地级别范围调整问题,提出了内插地价监测点调整土地级别技术在建立地价动态监测体系的基础上,运用合适的空间内插模型,通过插值计算得到城镇内每个点的地价,然后根据一定的地价幅度生成等值线图,进而由地价等值线图结合原有土地级别进行土地级别范围的确定和调整。  相似文献   

海域分等与海域使用基准价评估研究——以广东省沿海地市为例     

王平  谢健 《热带海洋学报》2008,27(1):65-69

海域使用基准价是海域使用金征收标准科学制定的基础.以广东省各地级市海域作为研究对象,以实例方式详细阐述了海域分等的工作程序、技术方法,在借鉴土地评估的基本理论和方法的基础上,从海域的实际情况出发,探讨了海域使用基准价的组成、计算思路和方法,初步建立了不同海域类型的海域使用基准价评估方法体系,这对完善海域分等定级与海域基准价评估理论、科学制定海域使用金征收标准具有重要意义.  相似文献   

抗震设计中结构的性能等级与设计性能安全指数   总被引：1，自引：0，他引：1  

李应斌  刘伯权  史庆轩 《地震工程与工程振动》2004,24(6):73-78

通常根据结构的破坏程度可以将结构的破坏划分为：基本完好、轻微破坏、中等破坏、严重破坏、倒塌等5个阶段。根据这5个阶段,本文将结构在地震过程中的性能极限状态划分为：功能连续极限状态、破坏控制极限状态、控制损失极限状态和防止倒塌极限状态,并以此作为划分结构性能等级的标准。定义结构失效概率的自然对数的负值为设计性能安全指数,通过计算结构失效概率对各构件可靠指标的一阶偏导数的方法,求出结构的设计性能安全等级。这种方法可以考虑建筑结构构件、建筑非结构构件以及其它非结构构件的性能,而且同时可以考虑结构系统总体效应的影响,因而能够比较全面地反映结构的抗震性能等级。  相似文献   

EQUATIONS FOR GRAIN SIZE DISTRIBUTION CURVE     

PrabhataK.SWAMEE NimishaSWAMEE 《国际泥沙研究》2004,19(1):66-74

The grain size distribution of particulate material is of particular interest in the field of sediment transport. The size distribution is described by various equations, however no equation is flexible enough to satisfy the grain size distribution data faithfully. Presented herein are the equations for unimodal and multimodal grain size distribution curves. A graphical method has been given to evaluate the parameters involved in these equations. The size distribution equation can be used to estimate many properties of sediment sample like number of sediment particles, surface area of the particles and hydraulic conductivity. It is hoped that the equations will find many applications in studying sedimentation processes.  相似文献   

农产品质量安全导向的耕地质量评价及在城市开发边界划定中的应用——以南通市为例   总被引：1，自引：1，他引：0  

陈诚 《地理研究》2016,35(12):2273-2282

快速城镇化过程中,耕地面临日益严重的质量和数量安全问题,改进耕地质量评价方法并探索其在城市开发边界划定中的应用研究,对于耕地和农产品质量安全保护、“多规合一”的实施具有重要意义。通过融合农用地自然质量分等和多目标地球化学调查成果,重构耕地质量评价指标体系与集成方法,结合耕地质量与规划城镇用地的耦合分析,探索可占用耕地与城市开发边界识别路径,并以南通为例进行验证。研究表明：沿江地区土壤重金属含量较高,沿海地区土壤肥力较差,西部和北部地区土壤肥沃,耕地质量较好。沿江地区规划城镇用地和耕地质量空间匹配较好,可占耕地和开发边界范围较大,北部地区相反。耕地质量评价—耕地与规划城镇用地耦合—可占用耕地选择与边界框定的方法,可以为城市开发边界划定提供指引,但城市用地需求和耕地可占用规模确定是有待深入研究的问题。  相似文献   

不同级配粗颗粒材料动力特性试验研究     

傅华  赵大海  韩华强  凌华 《岩土力学》2016,37(8):2279-2284

级配是粗颗粒材料最基本特征,根据大量试验结果和长期积累的试验经验,总结出了试验级配缩制的具体原则,并基于粗颗粒材料中小于等于5 mm粒径含量变化,分析了级配优劣对其充填关系的影响,级配越优,粗颗粒材料的充填关系越好,粗颗粒材料能达到较大的干密度,反之则越差,粗颗粒材料也难以获得较大的干密度。级配的优劣对堆石料动力特性的影响在低围压状态下并不明显,随着围压的升高,级配优的堆石料动力特性指标明显变优;砂砾料由于颗粒浑圆度较好,级配的优劣对其动力特性的影响逐渐减弱。针对上述级配对粗颗粒材料动力特性的影响规律,对于高土石坝来说有必要采用级配优的粗颗粒材料作为坝体的填筑料,通过其在高应力条件下力学性能的优势来控制坝体整体变形和提高其抗震性能。  相似文献