GROUND WATER NITRATE REDUCTION IN GIANT CANE AND FOREST RIPARIAN BUFFER ZONES1

ABSTRACT: Ground water contamination by excess nitrate leaching in row‐crop fields is an important issue in intensive agricultural areas of the United States and abroad. Giant cane and forest riparian buffer zones were monitored to determine each cover type's ability to reduce ground water nitrate concentrations. Ground water was sampled at varying distances from the field edge to determine an effective width for maximum nitrate attenuation. Ground water samples were analyzed for nitrate concentrations as well as chloride concentrations, which were used as a conservative ion to assess dilution or concentration effects within the riparian zone. Significant nitrate reductions occurred in both the cane and the forest riparian buffer zones within the first 3.3 m, a relatively narrow width. In this first 3.3 m, the cane and forest buffer reduced ground water nitrate levels by 90 percent and 61 percent, respectively. Approximately 40 percent of the observed 99 percent nitrate reduction over the 10 m cane buffer could be attributed to dilution by upwelling ground water. Neither ground water dilution nor concentration was observed in the forest buffer. The ground water nitrate attenuation capabilities of the cane and forest riparian zones were not statistically different. During the spring, both plant assimilation and denitrification were probably important nitrate loss mechanisms, while in the summer nitrate was more likely lost via denitrification since the water table dropped below the rooting zone.     

State Park Directors' Perceptions of Mountain Biking

/ This study intended to explore the perceptions of mountain bikingmanagement through a mail survey of state park directors in all 50 states.With a 100% response rate, it was found that 47 states permit mountainbiking in their state parks, however, few state parks have formalized plansto manage this outdoor activity. The management policies that do exist arenot followed on a statewide basis but vary within each state and at eachstate park. Many states have worked cooperatively with local mountain bikingclubs to develop and maintain mountain bike trails, promote rider education,and provide volunteer patrols on trails. The issue of user conflict surfacedwith almost three-fourths of the managers responding that conflict existedbetween mountain bikers and other trail users. This preliminary study shouldprompt further research with on-site managers focusing on the use ofmanagement plans for mountain biking, cooperation between managers and usergroups, and user conflict. It is recommended that an Internet-basedinformation clearinghouse or discussion group be made available to landmanagers by a national bicycling organization.KEY WORDS: Mountain biking; State parks; State park directors;Recreation resource management     

我国燃煤电厂脱硫技术应用现状及展望

介绍了我国二氧化硫排放及污染现状，分别从燃烧前、燃烧中、燃烧后三个阶段，阐述了我国脱硫煤生产、低硫污染燃烧技术及燃煤烟气脱硫的污染控制技术现状和发展方向，提出我国控制燃煤硫污染的对策及建议。     

电力工业发展与环境保护

从我国电力工业发展历程、面临的主要环境问题、污染控制等方面全面简述我国电力工业环境保护取得的发展与成就；展望“十一五”电力发展目标及电力环保指标；分析了为实现环境目标需要实施的污染控制措施。     

高层建筑物附近架空高压输电线路的走廊问题

采用镜像法实例计算了高层建筑物附近架空高压输电线路的工频电场和无线电干扰场强，并从电磁环评的角度对输电线路走廊的选择提出了一些建议。     

超滤膜处理火电厂废水的工业性试验研究

结合现场中试探讨了超滤作为反渗透预处理工艺的可行性，确定了超滤工艺处理某火电厂废水的基本参数，研究了超滤膜的恢复及效果，并且提出了系统设计的相关建议，对工业系统设计具有指导意义。     

火电厂石灰石湿法烟气脱硫废水处理方法

阐述了石灰石湿法烟气脱硫（FGD）废水的水质特征，介绍了国内外普遍应用的化学沉淀去除脱硫废水中重金属、悬浮物等物质的工艺特点及其不足，并着重介绍了最新发展的流化床法、沉淀一微滤法等FCD废水处理新型工艺。     

四川彭州铜尾矿库植被特征分析与植物群落演替初探

本文分析了四川彭州铜矿尾矿库的植被特征、群落特征与演替。在该尾矿库上自然定居的高等植物共91种，隶属38科79属，以菊科（Compositae）和禾本科（Gramineae）植物为主。形成6种相对稳定的群落类型；在2003年弃耕后形成的地段分布有史蒿＋小飞蓬群落（Artemisia argyi＋Conyza conadensis Comm．）、艾蒿＋打破碗花花群落（Artemisia argyi＋Anemone hupehensis Comm．）、艾蒿群落（Artemisia argyi Comm．）和白车轴苹群落（Trifolium repens Comm．）；在经过30～40年自然演替的地段分布有芭茅＋羊耳菊群落（Miscanthus sinensis＋Inula cappa Comm．）和羊耳菊＋千里光＋密蒙花群落（Inula cappa＋Senecio scandens＋Buddleja officinalis Comm．）；在近十年内新形成的地段现主要覆盖地衣和葫芦藓（Funaria hygrometrica）。通过对群落结构和不同地段植被特征的对比，对本铜尾矿库的演替现状和规律进行了分析，井讨论了人为影响对演替进程的影响，提出了人工恢复措施的建议。     

重庆地区吴茱萸属药用植物资源的调查研究

经调查鉴定，重庆地区吴茱萸属药用植物有9种（含种下等级），首次发现吴茱萸红花品系。重点介绍了它们的生境分布、药材商品与生产经营现状等，并编制了分种检索表，为科研、教学、生产经营及开发利用提供了科学依据。     

普通车床工件工具飞出伤人事故树分析

针对普通车床常见、多发的工件、工具飞出伤人事故,采用事故树分析事故原因,并提出安全对策措施.