Effect of iron type on kinetics and carbon isotopic enrichment of chlorinated ethylenes during abiotic reduction on Fe(0)

Four samples of two commercially available iron brands used as substrate for iron permeable reactive barriers (PRBs) were tested for suitability for remediation of perchloroethylene (PCE), trichloroethylene (TCE), cis-dichloroethylene (cDCE) and vinyl chloride (VC). Kinetic studies indicate that rates of reaction are enhanced for cDCE and VC on Connelly iron (2.8 x 10(-4) to 6.9 x 10(-4) L/m2/hr and 2.0 x 10(-4) to 9.0 x 10(-4) L/m2/hr, for cDCE and VC, respectively) vs. Peerless iron (3.1 x 10(-5) to 4.6 x 10(-5) L/m2/hr and 2.4 x 10(-5) to 4.1 x 10(-5) L/m2/hr, for cDCE and VC, respectively). Carbon isotopic analyses of the residual chlorinated ethylene (CE) during degradation indicate significant fractionation occurs during reductive dechlorination, with, for example, up to 70% enrichment in carbon isotopic values observed when VC is more than 99% degraded. Comparison of fractionation factors (epsilon) indicates significant differences in carbon isotopic fractionation for different iron types and for different CEs. For the lower CEs (cDCE and VC) in particular, both slower reaction rates and larger fractionation are observed for degradation on Peerless vs. Connelly iron. This is the first study to establish a correlation between the rate of abiotic degradation on Fe(0) and the extent of isotopic fractionation, and the first to confirm consistent differences in these two parameters as a function of iron type. The possibility that these differences in kinetics and carbon isotopic fractionation for cDCE and VC are related to differences in branching ratios between competing hydrogenolysis and beta-elimination reactions during reductive dechlorination on the iron surfaces is discussed.     

Impacts of the Jessica oil spill on intertidal and shallow subtidal plants and animals

Densities of fishes, invertebrates and plants at rocky intertidal and shallow subtidal sites were censused 1-2 days prior to the Jessica oil spill and compared with information obtained for the same sites one month after the spill, both for sites impacted by oil and unaffected reference sites. While the availability of pre-spill data made this analysis one of the most powerful to date for testing impacts of oil on shoreline environments, no clear changes attributable to oiling could be identified. Discharged oil appeared to cause very little impact in the intertidal and shallow subtidal zones, with such impacts lying within the range of natural spatial and temporal variation at sites investigated. Factors considered to minimize impact in Galápagos included paucity of fully sheltered shores in spill path, moderate wave action, warm temperature, high levels of sunlight, and mixing of bunker oil with diesel.     

基于WebGIS的一种配电管理系统的设计与实现

以GeoSurf 4.0作为WebGIS开发平台,采用模块化动态构建的思想,建设了一个既包含WebGIS功能又包含电力应用的配电管理WebGIS平台,不仅实现了地理图、站内图、结线图的显示、浏览和查询,与SCADA实时信息的集成,还定义了电力应用模板组件,便于配电管理业务封装成独立的功能模块,通过配置信息动态加入系统中,利于系统升级和扩充.     

空间信息多级网格的划分方法及编码研究

介绍国内外网格研究成果,提出一种新的网格划分方法和针对不同研究领域的各种扩展方法,并详细阐述了网格的编码策略及存储方式,最后给出了网格编码与地面坐标之间的相互转换方法。     

面向GIS的空间数据标准性检查研究

分析了数据源头在进行数据采集、整理时标准性控制、检查方面的不足,给出了一套面向GIS的检查空间数据标准性的解决方案。     

我国地球空间数据框架的设计思想与技术路线

根据当前我国基础地理信息系统的发展态势,较为详尽地讨论了１∶１万至１∶５万基础地理信息系统的设计思路,提出了地球空间数据框架（ＤＧＤＦ）的概念,即基于数字正射影像和ＤＥＭ及与若干层矢量框架数据（如大地控制、交通图、水系、境界、行政边界、注记等）的整体集成的栅格－矢量一体化空间数据库,目的在于尽快建立起有活力的和可更新的国家和省级基础地理信息系统。还详尽讨论了建立基础地理信息系统的主要技术路线和数据采集与数据处理的工艺流程。     

地理信息系统基础软件吉奥之星NT版的总体设计思…

介绍了新一代面向对象的ＧＩＳ基础折系统吉奥之星ＮＴ版的总体设计思想，系统结构，功能特点和有关关键技术。     

基于矢量的WebGIS用户响应时间问题的若干研究

在ＷｅｂＧＩＳ中,为了减少用户响应时间,需要对服务器端、数据传输、客户端的数据组织和操作进行各种处理,对响应的数据压缩、动态调度、缓存等技术手段作了分析和总结。     

面向网络的海量影像空间数据在线分发技术

阐述了基于J2EE的海量空间数据在线分发系统原理和关键技术，给出了海量影像空间数据在线浏览发布的实例。     

基于JSP/JavaBean的Web GIS实现技术

研究了如何利用JSP／JavaBean技术更好地实现WebGIS系统，提出了基于JSP／JavaBean的WebGIS实现模型，并以应用实例加以说明。