The US Clean Water Act and habitat replacement: evaluation of mitigation sites in Orange County,California, USA

Both permit requirements and ecological assessments have been used to evaluate mitigation success. This analysis combines these two approaches to evaluate mitigation required under Section 404 of the United States Clean Water Act (CWA) and Section 10 of the Rivers and Harbors Act, which allow developers to provide compensatory mitigation for unavoidable impacts to wetlands. This study reviewed permit files and conducted field assessments of mitigation sites to evaluate the effectiveness of mitigation required by the US Army Corps of Engineers for all permits issued in Orange County, California from 1979 through 1993. The 535 permit actions approved during this period allowed 157 ha of impacts. Mitigation was required on 70 of these actions, with 152 ha of enhanced, restored, and created habitat required for 136 ha of impacts. In 15 permit actions, no mitigation project was constructed, but in only two cases was the originally permitted project built; the two cases resulted in an unmitigated loss of 1.6 ha. Of the remaining 55 sites, 55% were successful at meeting the permit conditions while 11% failed to do so. Based on a qualitative assessment of habitat quality, only 16% of the sites could be considered successful and 26% were considered failures. Thus, of the 126 ha of habitat lost due to the 55 projects, only 26 ha of mitigation was considered successful. The low success rate was not due to poor enforcement, although nearly half of the projects did not comply with all permit conditions. Mitigation success could best be improved by requiring mitigation plans to have performance standards based on habitat functions.     

Applying Ecological Risk Principles to Watershed Assessment and Management

Considerable progress in addressing point source (end of pipe) pollution problems has been made, but it is now recognized that further substantial environmental improvements depend on controlling nonpoint source pollution. A watershed approach is being used more frequently to address these problems because traditional regulatory approaches do not focus on nonpoint sources. The watershed approach is organized around the guiding principles of partnerships, geographic focus, and management based on sound science and data. This helps to focus efforts on the highest priority problems within hydrologically-defined geographic areas. Ecological risk assessment is a process to collect, organize, analyze, and present scientific information to improve decision making. The U.S. Environmental Protection Agency (EPA) sponsored three watershed assessments and found that integrating the watershed approach with ecological risk assessment increases the use of environmental monitoring and assessment data in decision making. This paper describes the basics of the watershed approach, the ecological risk assessment process, and how these two frameworks can be integrated. The three major principles of watershed ecological risk assessment found to be most useful for increasing the use of science in decision making are (1) using assessment endpoints and conceptual models, (2) holding regular interactions between scientists and managers, and (3) developing a focus for multiple stressor analysis. Examples are provided illustrating how these principles were implemented in these assessments.     

东川市土地退化（荒漠化）及其防治

分析了东川市土地退化现状：土地退化以水蚀为主,退化土地面积占总土地面积38．5％。土地退化类型主要有土壤退化、土地沙石化、土地石质化和侵蚀劣地。文章还探讨了东川市土地退化的原因,提出了土地退化防治对策。     

Assessment of Nonpoint Source Pollution from Inactive Mines Using a Watershed-Based Approach

/ A watershed-based approach for screening-level assessment of nonpoint source pollution from inactive and abandoned metal mines was developed and illustrated. The methodology was designed to use limited stream discharge and chemical data from synoptic surveys to derive key information required for targeting impaired waterbodies and critical source areas for detailed investigation and remediation. The approach was formulated based on the required attributes of an assessment methodology, information goals for targeting, attributes of data that are typical of basins with inactive mines, and data analysis methods that were useful for the case study. The methodology is presented as steps in a framework including evaluation of existing data/information and identification of data gaps; definition of assessment information goals for targeting and monitoring design; data collection, management, and analysis; and information reporting and use for targeting. Information generated includes the type and extent of and critical conditions for water-quality impairment, concentrations in and loadings to streams, differences between concentrations in and loadings to streams, and risks of exceeding target concentrations and loadings. Data from the Cement Creek Basin, located in the San Juan Mountains of southwestern Colorado, USA, were used to help develop and illustrate application of the methodology. The required information was derived for Cement Creek and used for preliminary targeting of locations for detailed investigation and remediation. Application of the approach to Cement Creek was successful in terms of cost-effective generation of information and use for targeting.KEY WORDS: Water quality assessment; Nonpoint source pollution; Inactive mines; Watershed     

Nitrogen Balance in the Lower Fraser River Basin of British Columbia

/ A study was conducted to determine the extent of nitrogenpollution in agricultural lands in the Lower Fraser River basin of BritishColumbia, Canada. The specific objectives were to determine the distributionof leachable nitrogenand estimate the nitrogen concentration in groundwaterrecharges. Nitrogen and water mass balances were conducted on the entirebasin and on each of the four districts comprising it over the period1971-1991 in intervals of five years. The results indicated that the averagenitrogen concentration in the groundwater recharge for the entire basin rosefrom nondetectable in 1971 to 6 mg/liter in 1991. Estimates for theindividual districts ranged from 4 to 14 mg/liter in Central Fraser and fromnondetectable to 7 mg/liter in Fraser-Cheam and 3 mg/liter in both GreaterVancouver and Dewdney-Alouette. So far, excessive levels of nitrogen areconfined to Central Fraser. Although they have remained within the acceptablerange, nitrogen concentrations in the other three districts have definitelyincreased over the 20-year study period. Sensitivity analyses indicated thatanimal manure and fertilizer had the largest contribution in groundwaterrecharge. Decreasing the rate of manure application to agricultural lands issuggested as the most practical way of reducing nitrogen pollution in CentralFraser.KEY WORDS: Nitrogen balance; Water balance; Sensitivity analysis     

再论高压水射流清洗技术应用的专业化、规模化与社会化

高压水射流技术在清洗领域的应用，因其具有一系列优势，越来越为社会所认同和欢迎。以何种模式运行才能使其发展的更快、更好，是在该领域的工作者所普遍关注的问题。在理论与实践相结合的基础上，再次讨论并提出高压水射流清洗技术应用的专业化、规模化与社会化，以期在更大的范围引起同行的参与，共同寻求发展我国高压水射流清洗技术应用的最佳战略、策略和实施的方式。实践证明，高压水射流清洗技术应用的专业化、规模化与社会化是可以实现的。坚持为国民经济建设服务，使其专业化、规模化与社会化并逐步充实、完善，定能使之有更大的发展     

我国水污染现状及防治对策

我国是一个水资料严重匮乏和水污染十分严重的国家，加强水污染管理和控制刻不容缓。为此，本文结合发达国家立法现状，从组织，民众意识、水污染排放标准，监测方法等方面论述加强水污染控制的管理。     

加强水土保持 防止生态恶化

本文论述了水土水流失对生态环境的影响和对农业生产的危害，阐明增强环境意识，加强水土保持时防止生态恶化，是我国振兴农业的重要性与紧迫性的任务。     

新型滤料──短纤维性能研究

短纤维作为一种滤料应用于水过滤器中，具有密度小，孔隙率大，比表面积大的优点，它在过滤进程中，滤速高，阻力小，过滤周期长，能使悬浮物脱除率达到９６％以上，是一种应用前景很好的滤料。在本文中对短纤维滤料的过滤性能作了系统地研究。     

优选法及正交试验在选择废水处理最佳条件中的应用

从试验考核指标出发，运用“水质指数（ＷＱＩ）”，分析影响废水处理效果的诸因素，选取ｐＨ值和处理剂加入量为可控因素，利用优选法找出钻井废水处理的最佳条件；选取两个因素水平进行正交试验，选用Ｌ４（２３）正交表，合理安排试验，确定最优因素水平组合。总之，应用优选法及正文试验于钻井废水处理工作中，获得了处理的最佳条件，对钻井生产中废水处理统一操作，降低消耗，保证废水处理达标率起着很重要的作用。