Migration of colloids in discretely fractured porous media: effect of colloidal matrix diffusion

Numerical simulations of colloid transport in discretely fractured porous media were performed to investigate the importance of matrix diffusion of colloids as well as the filtration and remobilization of colloidal particles in both the fractures and porous matrix. To achieve this objective a finite element numerical code entitled COLDIFF was developed. The processes that COLDIFF takes into account include advective-dispersive transport of colloids, filtration and remobilization of colloidal particles in both fractures and porous matrix, and diffusive interactions of colloids between the fractures and porous matrix. Three sets of simulations were conducted to examine the importance of parameters and processes controlling colloid migration. First, a sensitivity analysis was performed using a porous block containing a single fracture to determine the relative importance of various phenomenological coefficients on colloid transport. The primary result of the analysis showed that the porosity of the matrix and the process of colloid filtration in fractures play important roles in controlling colloid migration. Second, simulations were performed to replicate and examine the results of a laboratory column study using a fractured shale saprolite. Results of this analysis showed that the filtration of colloidal particles in the porous matrix can greatly affect the tailing of colloid concentrations after the colloid source was removed. Finally, field-scale simulations were performed to examine the effect of matrix porosity, fracture filtration and fracture remobilization on long-term colloid concentration and migration distance. The field scale simulations indicated that matrix diffusion and fracture filtration can significantly reduce colloid migration distance. Results of all three analyses indicated that in environments where porosity is relatively high and colloidal particles are small enough to diffuse out of fractures, the characteristics of the porous matrix that affect colloid transport become more important than those of the fracture network. Because the properties of the fracture network tend to have greater uncertainty due to difficulties in their measurement relative to those of the porous matrix, prediction uncertainties associated with colloid transport in discretely fractured porous media may be reduced.     

城市污水排江工程模型试验的研究

对城市污水排江问题进行了模拟试验,通过对水力模型不同试验工况中改变喷嘴个数、射流速度、射流角度和上升管间距条件下的试验结果分析,结合武汉市污水排江工程问题,确定了黄浦路、平湖门尾水排放中的近区多喷口形式的最佳工程参数,实践证明效果良好。     

论环境监测综合信息系统的建设规划

根据对各级环保机械综合信息技术应用的调研,提出环境监测综合信息系统设计原则及技术路线。     

计算机企业环境管理信息系统研究

本文介绍了计算机辅助企业环境管理信息系统软件的设计思路、设计方法、技术特点及应用情况,该软件将企业环境管理事后的、末端的资料变为生产全过程控制的信息,实现了企业污染预报和企业环境的动态管理。有效地预防污染事故的发生,使企业环境管理迈上科学化、规范化、标准化的新台阶。     

南水北调中线工程输水干线水质监测管理信息系统研究

介绍了由数据采集与传输子系统、数据库子系统、水质预警预报子系统、数据输出子系统和人机交互界面组成的南水北调中线工程输水干线的水质监测管理信息系统,根据该系统的实际需求,阐述了开发该系统应该具备的关键技术。     

GIS辅助矿区环境质量评价系统设计与实现

以提高环境质量评价的空间信息处理能力和检索查询功能为目的,提出应用 GIS ARCVIEW软件和空间信息管理和分析技术对矿区环境质量因子进行分析,建立环境质量评价系统的方法,在矿区实践应用,使环境质量评价更具合理性和可操作性,评价结果形象、直观,为矿区环境管理和决策提供了有利依据。     

Characteristics and driving factors of marsh changes in Zhalong wetland of China

Zhalong National Nature Reserve in the northeast of China is a large wetland and a habitat of hundreds species of fauna and flora. The rare red-crowned crane is one kind of endangered birds in it. Recently, Zhalong wetland is shrinking and it encounters many problems including occasional fires, bad water quality, human activities, etc. In order to find out a proper way to protect and restore the wetland, this study, using a geographic information system, the global positioning system and remote sensing techniques, analyses the spatial characteristics of the changes in marsh landscape pattern and examines the driving factors for these changes. Data sources include 8 Landsat Thematic Mapper satellite images of Zhalong area in the period of 1986–2002 and the investigation information on site. Based on the analysis of changes of marsh area and annual precipitation during the 16 years, it is found that there is a close correlation between annual precipitation and marsh area. It means that climate is one of driving factors of marsh pattern changes. To understand influences of other kinds of land uses on marsh spatial distribution in Zhalong wetland, this paper analyses the relationship between marsh and different kinds of land uses, such as water surface, residential area, farmland, salina land and grass land, respectively. According to the patch analysis theory, a fragmental index and a fractal dimension of the marsh are calculated with perimeter-area method. The results indicate that the marsh pattern is affected by human activities significantly. In addition, the location alteration of marsh centroid point over the 16 years is studied. The movement trace of marsh centroid point is concerned with different hydrological situation in different areas of the wetland. In summary the characteristics of the marsh landscape pattern evolution during the 16 years are affected by multiple driving factors. The main driving factors are climate, human activities, distribution of other kinds of land uses and hydrological situation in different areas.     

Information technologies and the sharing of disaster knowledge: the critical role of professional culture

A comparative survey of a diverse sample of 96 US and Italian emergency management agencies shows that the diffusion of new information technologies (IT) has transformed disaster communications. Although these technologies permit access to and the dissemination of massive amounts of disaster information with unprecedented speed and efficiency, barriers rooted in the various professional cultures still hinder the sharing of disaster knowledge. To be effective the available IT must be attuned to the unique settings and professional cultures of the local emergency management communities. Findings show that available technology, context, professional culture and interaction are key factors that affect the knowledge transfer process. Cultural filters appear to influence emergency managers' perceptions of their own professional roles, their vision of the applicability of technology to social issues, and their perspective on the transferability of disaster knowledge. Four cultural approaches to the application of IT to disaster communications are defined: technocentric; geographic,; anthropocentric; and ecocentric.     

战略环境评价系统及工作程序

介绍了战略环境评价系统组成的五个要素 ,即评价者、评价对象、评价目的、评价标准和评价方法 ,分析了其相互关系及各要素与战略环境评价系统的关系 ,并提出了战略环境评价工作程序。     

松嫩盆地资源环境信息系统空间数据库的设计与开发

文章介绍了松嫩盆地资源环境信息系统空间数据库的设计思路,总体目标、构成及功能以及系统建立的关键技术。该系统的建立,使得对松嫩盆地资源开发管理和相关信息的查询、检索更方便,同时对松嫩盆地资源合理开发利用和管理决策提供了科学依据。