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31.
河流水生态环境质量评价方法研究与应用进展 总被引:7,自引:6,他引:1
河流生态质量的监测和评价是从河流生态系统健康状况的角度对河流质量进行的评价。河流生态健康的评价已经向多要素多指标综合、多种评价方法(预测模型法、生物完整性指数、多要素综合评价)、流域尺度方向发展。该文重点介绍了国外评价体系产生的背景和研究基础,分析了广泛应用的几类评价方法的特点、在不同国家和流域的应用情况以及各方法的应用前景,分析了国内开展河流生态质量评价研究的发展过程、阶段性研究进展和应用案例,并根据目前研究基础评述了我国评价体系现存问题及应用前景,为河流生态质量评价体系的建立及发展方向提供建议和参考。 相似文献
32.
从数据比对、硬件维护两个方面探讨岛津TNP-4110在线仪的日常维护问题。通过分析各种干扰因素来查找造成数据比对差异的原因并提出相应解决措施。在仪器日常维护上设立不同周期保养计划、共享设备维护经验,结合实践制定了合适的检修流程图。 相似文献
33.
34.
大气环境综合观测研究站(简称大气超级站)是开展大气环境污染综合立体观测、进行大气重污染过程污染特征动态表征、深入分析大气污染成因的重要平台。了解中国当前不同地区大气超级站的建设和应用现状、存在的问题及发展需求,有利于科学指导和规范中国大气超级站的设计、建设、运维和应用,提高其在大气重污染过程应急管控和空气质量改善中的技术支撑能力。研究通过对国内60余个大气超级站进行问卷调研,综述了中国目前大气超级站的现状,并基于统计分析结果,对中国大气超级站发展提出建议。 相似文献
35.
大气背景监测站多位于高山且相对清洁地区,在运行维护方面和城市点位有很大不同,低量程仪器和其他自动监测仪器在运行维护上也有所不同。国家大气背景监测福建武夷山站是国内14个大气背景监测站之一,该站于2011年3月4日运行,文章总结该站运行以来的维护经验,从运行条件、日常维护、简单故障判断、数据处理等几个方面详细叙述,给出维护经验和注意事项,以期为其他类似背景站的运行维护提供参考。 相似文献
36.
ABSTRACT: The probability distributions of annual peak flows used in flood risk analysis quantify the risk that a design flood will be exceeded. But the parameters of these distributions are themselves to a degree uncertain and this uncertainty increases the risk that the flood protection provided will in fact prove to be inadequate. The increase in flood risk due to parameter uncertainty is small when a fairly long record of data is available and the annual flood peaks are serially independent, which is the standard assumption in flood frequency analysis. But standard tests for serial independence are insensitive to the type of grouping of high and low values in a time series, which is measured by the Hurst coefficient. This grouping increases the parameter uncertainty considerably. A study of 49 annual peak flow series for Canadian rivers shows that many have a high Hurst coefficient. The corresponding increase in flood risk due to parameter uncertainty is shown to be substantial even for rivers with a long record, and therefore should not be neglected. The paper presents a method of rationally combining parameter uncertainty due to serial correlation, and the stochastic variability of peak flows in a single risk assessment. In addition, a relatively simple time series model that is capable of reproducing the observed serial correlation of flood peaks is presented. 相似文献
37.
The Neebing-McIntyre floodway in Thunder Bay, Ontario, Canada, has been constructed with a relatively straight and uniform trapezoidal channel, compared with the prechannelized sinuous reaches of the Neebing and the McIntyre rivers. The flow regime of the floodway also contrasts significantly with the prechannelized regime, because of the combination of discharges from these rivers into a new channel and the regulation of flows by a diversion structure. The maximum channel capacity of the floodway is about 284 m3 s–1 (175-year regional flood), compared with about 40 m3 s–1 and 60 m3 s–1, respectively, for the Neebing and the McIntyre. According to regime theories, the construction of a straight and trapezoidal channel has upset the equilibrium of the stream system and therefore should lead to some accelerated erosion and sedimentation processes in the new channel immediately after construction. Erosion potential is particularly high during higher discharge events, when flow velocities are expected to be greater than the prechannelized velocities of the Neebing and the McIntyre. The overall sediment yield of the watershed is low (71t km–2 yr–1), compared with other documented watersheds of North America, but the rates of deposition in the floodway are relatively high, mainly due to the backwater effect of Lake Superior. Unless maintained by constant channel work, the floodway will tend to fill up with sediment, until a postconstructional equilibrium is reestablished. 相似文献
38.
为确保炼油厂设备安全而稳定地运行,各生产装置都要定期进行停工检修,在此期间排放的污染物对环境将产生一定的影响。停工检修中的环保工作包括实施环保措施;加强环境管理;并且将2000m~3隔油池由一间式变为两间式,提高污水处理率和达标率。 相似文献
39.
为了解听力防护用品使用过程中的问题,提高我国噪声暴露工人听力防护用品的使用率和有效率,选择噪声危害较大的某飞机维修公司的员工,进行听力防护用品使用情况的问卷调查。结果显示:该公司为员工提供耳塞和耳罩两种听力防护用品;员工的听力保护意识、使用情况较好,使用率达95%,但对听力防护用品相关知识的了解不够全面;能够在工作中一直坚持使用的工人较少,仅占11%,影响工人工作时间使用听力防护用品时间长短的因素主要是其舒适性。调查分析提示:在未来听力防护用品的生产过程中,需要进一步加强和改善舒适性的技术;政府、企业和个人3方面共同参与,降低职业性噪声暴露对工人听力的损伤。 相似文献
40.
Motoko Y. Lee Richard D. Warren 《Journal of the American Water Resources Association》1981,17(6):948-955
ABSTRACT: The effectiveness of water conservation policies on reduction of water consumption was evaluated by use of a multiple regression predictive model. Data were obtained from eight Iowa communities, with regard to water consumption and water conservation policies adopted during the drought of 1977. The proposed model, which takes precipitation, temperature, month effects, and uniqueness of communities into account, is considered superior to the use of simple percent changes in evaluating the significance of reduction in water consumption due to conservation efforts. Among the variety of policies reviewed, mandatory policies with per capita restrictions were found to be most effective. However, voluntary conservation policies also resulted in significant reduction in some communities located in close proximity to other communities with severer water shortages. High credibility of local governments as to water shortage information was singled out as the most important factor in successful conservation by water resource policymakers of these communities. Use of the proposed predictive model for water consumption was demonstrated. Recommendations regarding future water conservation were made. 相似文献