Scoping the effective marine environmental assessment of dredging and ocean disposal of coastal sediments in Korea   总被引：1，自引：0，他引：1  

Dae-In Lee  Ki-Hyuk Eom  Gui-Young Kim  Gun-Wook Baeck 《Marine Policy》2010

The application of scoping is reviewed to improve the efficiency and rationality of the marine environmental impact assessment system applied to the dredging of coastal sediments and the oceanic disposal of dredged material in Korea. Both the impact levels and those items requiring assessment vary in response to differing goals of the coastal activities involved and also to changes in the characteristics of different marine environments. As a consequence, different assessment fields need to be emphasized for evaluation of the impact that both dredging and dumping might have on the sites involved. The status of current assessment procedures is examined and its problems are diagnosed. Following a survey of interested parties and a review of case studies of the oceanic disposal of dredged sediment in other countries, checklists of core assessment items are proposed as part of a revamped review process, along with improvements to the assessment system.  相似文献   

中印度洋洋盆GC11岩心富稀土深海沉积的元素地球化学特征   总被引：1，自引：1，他引：0  

张霄宇  黄牧  石学法  黄大松 《海洋学报》2019,41(12):51-61

对中印度洋洋盆的沉积GC11岩心开展了主量元素、微量元素和稀土元素分析研究,根据主微量元素相关性特征、稀土元素富集程度以及澳大利亚后太古代平均页岩归一化模式特征,初步探讨了GC11岩心的沉积地球化学特征,以及影响稀土元素富集的可能因素。研究表明,GC11岩心稀土元素总量在400.64×10?6～742.74×10?6,平均值为658.41×10?6,略低于邻近海域的GC02岩心,与沃顿海盆DSDP213岩心中含沸石型深海粘土层位中的稀土元素含量相当。δCe负异常明显,(La/Yb)_N为0.42,显示重稀土相对富集的特点。稀土元素与P₂O₅呈显著正相关性,CaO/P₂O₅的平均值为2.3,表明生物钙磷灰石可能是稀土元素的主要载体矿物,而铁锰水合物可能对富集稀土元素有一定的促进作用,但影响不大;GC11岩心中δCe负异常程度远低于GC02岩心,略低于DSDP213岩心,中稀土富集特征与GC02和DSDP213岩心基本一致。不同程度陆源物质的混入可能是导致以上不同岩心中稀土元素富集程度和分馏特征的主要原因。  相似文献   

Kelvin's article on the magnetic centre and Schmidt's one on the optimal eccentric dipole,revisited     

《Comptes Rendus Geoscience》2015,347(2):64-65

Thomson's formulas (1872) that give the position of the magnetic centre of a magnet and the first results on the global geomagnetic field were sufficient to show that the source of this field had a disymmetry in the equatorial plane. To confirm this with Schmidt's (1934) explicit formulas giving the position of the optimal eccentric dipole, numerical calculus was necessary. To obtain their relatively simple formulas, Thomson and Schmidt used lengthy algebra that was avoidable.  相似文献   

Spatial variations in damage zone width along strike-slip faults: An example from active faults in southwest Japan     

《Journal of Structural Geology》2013

Field investigations reveal spatial variations in fault zone width along strike-slip active faults of the Arima–Takatsuki Tectonic Line (ATTL) and the Rokko–Awaji Fault Zone (RAFZ) of southwest Japan, which together form a left-stepping geometric pattern. The fault zones are composed of damage zones dominated by fractured host rocks, non-foliated and foliated cataclasites, and a fault core zone that consists of cataclastic rocks including fault gouge and fault breccia. The fault damage zones of the ATTL are characterized by subsidiary faults and fractures that are asymmetrically developed on each side of the main fault. The width of the damage zone varies along faults developed within granitic rocks of the ATTL and RAFZ, from ∼50 to ∼1000 m. In contrast, the width of the damage zone within rhyolitic tuff on the northwestern side of the ATTL varies from ∼30 to ∼100 m. The fault core zone is generally concentrated in a narrow zone of ∼0.5–∼5 m in width, consisting mainly of pulverized cataclastic rocks that lack the primary cohesion of the host rocks, including a narrow zone of fault gouge (<0.5 m) and fault-breccia zones either side of the fault. The present results indicate that spatial variations in the width of damage zone and the asymmetric distribution of damage zones across the studied strike-slip faults are mainly caused by local concentrations in compressive stress within an overstep area between left-stepping strike-slip faults of the ATTL and RAFZ. The findings demonstrate that fault zone structures and the spatial distribution in the width of damage zone are strongly affected by the geometric patterns of strike-slip faults.  相似文献   

Implementation of a high-order combined compact difference scheme in problems of thermally driven convection and dynamo in rotating spherical shells     

Futoshi Takahashi 《地球物理与天体物理流体动力学》2013,107(3):231-249

We present an improved solution method for modeling thermally driven convection and dynamo in a rotating spherical shell. In this method, we introduce a high-order three-point combined compact difference scheme (CCDS) on non-uniform grid points in radius, while spherical harmonic expansion is conventionally performed in the angular direction. The governing equations in the spectral form are time-stepped together with the implicit CCDS up to the second derivative. To improve stability of the scheme, a boundary closure scheme is developed on non-uniform mesh. Numerical comparison with a published benchmark solution at moderate Ekman and Rayleigh numbers demonstrates that accuracy and convergence of the CCDS is fairly good and superior to the existing finite difference scheme using more stencil. With this scheme, we could more accurately solve problems of convection and also dynamo action in planetary core with less grid points.  相似文献   

CO2-induced dissolution of low permeability carbonates. Part II: Numerical modeling of experiments     

《Advances in water resources》2013

We used the 3D continuum-scale reactive transport models to simulate eight core flood experiments for two different carbonate rocks. In these experiments the core samples were reacted with brines equilibrated with pCO₂ = 3, 2, 1, 0.5 MPa (Smith et al., 2013 [27]). The carbonate rocks were from specific Marly dolostone and Vuggy limestone flow units at the IEAGHG Weyburn-Midale CO₂ Monitoring and Storage Project in south-eastern Saskatchewan, Canada. Initial model porosity, permeability, mineral, and surface area distributions were constructed from micro tomography and microscopy characterization data. We constrained model reaction kinetics and porosity–permeability equations with the experimental data. The experimental data included time-dependent solution chemistry and differential pressure measured across the core, and the initial and final pore space and mineral distribution. Calibration of the model with the experimental data allowed investigation of effects of carbonate reactivity, flow velocity, effective permeability, and time on the development and consequences of stable and unstable dissolution fronts.The continuum scale model captured the evolution of distinct dissolution fronts that developed as a consequence of carbonate mineral dissolution and pore scale transport properties. The results show that initial heterogeneity and porosity contrast control the development of the dissolution fronts in these highly reactive systems. This finding is consistent with linear stability analysis and the known positive feedback between mineral dissolution and fluid flow in carbonate formations. Differences in the carbonate kinetic drivers resulting from the range of pCO₂ used in the experiments and the different proportions of more reactive calcite and less reactive dolomite contributed to the development of new pore space, but not to the type of dissolution fronts observed for the two different rock types. The development of the dissolution front was much more dependent on the physical heterogeneity of the carbonate rock. The observed stable dissolution fronts with small but visible dissolution fingers were a consequence of the clustering of a small percentage of larger pores in an otherwise homogeneous Marly dolostone. The observed wormholes in the heterogeneous Vuggy limestone initiated and developed in areas of greater porosity and permeability contrast, following pre-existing preferential flow paths.Model calibration of core flood experiments is one way to specifically constrain parameter input used for specific sites for larger scale simulations. Calibration of the governing rate equations and constants for Vuggy limestones showed that dissolution rate constants reasonably agree with published values. However the calcite dissolution rate constants fitted to the Marly dolostone experiments are much lower than those suggested by literature. The differences in fitted calcite rate constants between the two rock types reflect uncertainty associated with measured reactive surface area and appropriately scaling heterogeneous distribution of less abundant reactive minerals. Calibration of the power-law based porosity–permeability equations was sensitive to the overall heterogeneity of the cores. Stable dissolution fronts of the more homogeneous Marly dolostone could be fit with the exponent n = 3 consistent with the traditional Kozeny–Carman equation developed for porous sandstones. More impermeable and heterogeneous cores required larger n values (n = 6–8).  相似文献   

虹桥商务区核心区域地质灾害隐患预防监测与分析     

张东杰  秦振伟 《城市地质》2016,(2):78-83

上海地区深基坑工程、轨道交通等重大工程集聚地,大型商业CBD、城市功能中心等是地质灾害易发区。地质灾害应急管理工作考量区域建设活动和人工活动的强度和密度,选择开发程度高、项目类型多、地下空间开发力度大、人工活动频繁的区域,作为典型区域进行地质灾害隐患预防监测,对于研究典型区域内地质灾害隐患发展趋势,掌握区域地质灾害隐患长期发展规律,完善区域地质灾害隐患预防措施十分必要。本文以2012—2014年虹桥商务区核心区域的监测数据为基础,以地表沉降数据为主进行研究,发现大量地下工程同时施工,对区域地质环境影响明显,导致的地面沉降危害逐渐显现,危害程度逐渐增大。  相似文献   

南黄海NT2孔沉积物物源研究   总被引：2，自引：0，他引：2  

蓝先洪  张志珣  李日辉  丁东 《沉积学报》2010,28(6):1182-1189

用等离子体质谱法(ICP—MS)对苏北岸外南黄海陆架区NT2孔72个沉积物样品的稀土元素(REE)进行了分析,研究了中更新世中、晚期以来苏北岸外南黄海陆架区沉积物物源的变化。相关分析揭示NT2孔粒度和化学风化对REE组成影响较小。判别函数和稀土元素配分模式表明南黄海NT2孔沉积物物源主要为长江源和黄河源。 REE判别图解揭示NT2孔上部0~5.50 m和5.50~19.30 m沉积物以长江源为主,中部19.30~27.00 m沉积物以黄河源为主,27.00~54.60 m沉积物以长江源为主,下部54.60~70.31 m沉积物以黄河源为主。研究表明黄河在中更新世中晚期已开始对南黄海陆架沉积作用有明显影响,而长江从晚更新世早期到现代对南黄海陆架起着主要作用。  相似文献   

WMO信息系统中气象元数据的设计与实现   总被引：1，自引：1，他引：0       下载免费PDF全文

祝婷  李湘 《应用气象学报》2012,23(2):238-244

随着越来越多基于网络、自动化的信息共享系统的广泛使用,元数据已成为不同学科间共享信息的关键。近年来气象数据的应用领域不断扩展,气象数据面临着海量信息流通共享的迫切需要,由此气象元数据应运而生。该文介绍的气象元数据是在满足WMO (世界气象组织) 信息系统提出的包括提供在线元数据、数据目录服务和提高元数据定义、收集、归档和交换的标准化水平在内的总体需求的背景下,依据WMO核心元数据标准设计并由自开发程序自动生成的。北京GISC系统是WMO信息系统中承担区域间及全球资料交换的主干通信中心之一,至2012年1月,北京GISC系统制作并提供系统内全部数据对应的气象元数据,共计约12万条。  相似文献   

A3M联测技术在岩芯分析中的研究及应用          下载免费PDF全文

沈联蒂 《地球物理学报》1997,40(2):247-256

总结国内外岩芯分析技术，综合应用现代控制论、信息论、系统工程论的基本原理，提出A3M理论性认识和联测技术的新概念，研制出一套具有多学科、多目的（任务）、多项目（参数）的岩芯综合分析技术，即岩性、物性、岩石电性、声波等联测的技术．完成了一套与联测技术流程相配套的实用软件包，这套技术提供了系统的、有代表性的、可对比的岩芯分析资料，可直接用于油田现场与实验室岩芯分析生产、科研和管理及油田的开发中，有利于认识非均质储层岩石地质、物理特征以及各种信息之间的内在规律．  相似文献