RELATIONSHIPS BETWEEN FLOOD FREQUENCIES AND RIPARIAN PLANT COMMUNITIES IN THE UPPER KLAMATH BASIN,OREGON1

ABSTRACT: This study was conducted in the Klamath Basin of southwestern Oregon to evaluate the dependency of riparian plant communities upon infrequent flooding. Plant communities were sampled with 1 m² quadrats along established cross‐sections. Data collected for purposes of hydraulic modeling included channel and floodplain elevations (i.e., cross‐sectional profiles) and water surface elevations associated with specific discharges. The elevational distribution of hydrophytic plant communities relative to modeled return periods provided the basis for establishing relationships between these variables for nine sites. Results indicate that, on average, a peak flow frequency of 4.6 years (range of 3.1 to 7.6 years) was needed to sustain riparian plant communities at seven of nine sites. At two sites, results indicated return periods of more than 25 years were needed; these results possibly were influenced by local geomorphic conditions (a narrow steep channel in one case and an incised channel in the other). Overall, these results tend to confirm a strong dependency of riparian plant communities on overbank flows.     

IMPACTS OF URBAN LANDUSE ON MACROINVERTEBRATE COMMUNITIES IN SOUTHEASTERN WISCONSIN STREAMS1

ABSTRACT: Macroinvertebrates were used to assess the impact of urbanization on stream quality across a gradient of watershed imperviousness in 43 southeastern Wisconsin streams. The percentage of watershed connected imperviousness was chosen as the urbanization indicator to examine impact of urban land uses on macroinvertebrate communities. Most urban land uses were negatively correlated with the Shannon diversity index, percent of pollution intolerant Ephemeroptera, Plecoptera, and Trichoptera individuals, and generic richness. Nonurban land uses were positively correlated with these same metrics. The Hilsenhoff biotic index indicated that stream quality declined with increased urbanization. Functional feeding group metrics varied across a gradient of urbanization, suggesting changes in stream quality. Proportions of collectors and gatherers increased, while proportions of filterers, scrapers, and shredders decreased with increased watershed imperviousness. This study demonstrated that urbanization severely degraded stream macroinvertebrate communities, hence stream quality. Good stream quality existed where imperviousness was less than 8 percent, but less favorable assessments were inevitable where imperviousness exceeded 12 to 20 percent. Levels of imperviousness between 8 and 12 percent represented a threshold where minor increases in urbanization were associated with sharp declines in stream quality.     

基于模拟的腐蚀管道可靠性分析

腐蚀失效是压力管道失效的主要模式之一。通常采用腐蚀管道剩余强度估算的方法 ,评价腐蚀管道的安全性。腐蚀管道的剩余寿命则采用可靠性理论计算得到。以各种局部腐蚀缺陷的评定方法来建立模拟模型 ,直接采用蒙特卡罗模拟可以计算得到不同时间下的管道的失效概率 ,同时根据目标可靠度来确定腐蚀管道的剩余寿命。含多个腐蚀缺陷的管道的失效概率需要考虑缺陷间的相关性。采用模拟方法可以计算失效概率的秩相关 ,避免采用独立假设来计算管道的失效概率     

水上个体救生具性能测试方法的比较研究

对比研究了国际标准化组织 (ISO) ,国际海事组织 (IMO) ,英国标准 (BS) ,美国军事标准 (MIL) ,日本工业标准 (JIS) ,中华人民共和国标准 (GB) ,中华人民共和国交通部标准 (JT)等各类标准中关于水上个体救生具的整体救生性能、主体材料和部件性能、属具性能的测试方法 ,在此基础上 ,笔者提出了我国水上个体救生具在性能检测方面的研发方向。     

藻类生物技术在水环境保护中的应用前景探讨

简要综述了藻类生物技术在水污染生态毒理学和污水生物净化方面的研究成果及应用实例,同时对其研究前景进行了探讨。应用藻类生物检测技术对重金属、农药、有机污染物、有毒有害废弃物等的毒性评价结果证明,一些二价重金属阳离子对藻类的毒性顺序大致为Hg~(2+),Cd~(2+),Cu~(2+),Ni~(2+)和 Zn~(2+);酚类、酯类和芳烃类有机污染物对藻类生长的抑制作用十分显著;农药对藻类的毒害作用主要通过破坏藻类生物膜的结构和功能而抑制藻类的光合作用、呼吸作用和固氮作用。有关藻类污水处理的研究资料显示,阳光的强弱,污水在系统内的停留时间,藻类生物量的多寡是确保藻类污水处理效果的关键。     

水解酸化-CASS工艺处理水产加工废水

采用水解酸化-CASS工艺处理水产加工废水,实践表明工艺合理、技术先进、设备投资小、运行费用低,污水处理后达到<污水综合排放标准>(GB 8978-96)中的一级排放标准.     

主题公园生命周期的演化

旅游地生命周期理论向我们描绘了旅游地在发展过程中有规律性的阶段变化,但对于任何一个旅游地来说,其发展演化都有着自己独特的特点.根据旅游地生命周期理论,并结合国际、国内主题公园的实际发展情况,对其演化情况作了具体分析研究,认为主题公园的发展存在双周期模型,并就该模型的各发展阶段提出了一定的发展策略.     

An accelerated laboratory study evaluating the disintegration rates of plastic films in simulated aquatic environments

Six plastic films were exposed to accelerated sunlight while in simulated aquatic environments to determine the effects of chemical composition and environment on the disintegration rates. An environment of UV light/no water was used as a control to determine if the microorganisms in the aquatic systems enhanced the breakdown of the plastic films. The disintegration rate of the plastics was determined by monitoring changes in selected physical properties. The plastics included two conventional plastics commonly used in packaging (LDPE and polystyrene) and four plastics enhanced to have more rapid breakdown in the environment (2% ECO, 10% ECO, PE with ketone graft, and PE with starch). The two ECO copolymers had a significantly faster loss of physical properties than the other plastics evaluated in this study. Degradation was influenced by environmental conditions. Those plastics that showed a change in physical properties had a greater change faster in the UV light/no water than in the environments where water was present. Plastics on the surface of the water showed a more rapid loss of properties than those samples partially or completely submerged. This can be attributed to decreased light intensity and the lack of heat buildup.     

ASSESSING POTENTIAL SOURCES OF ASBESTOS FIBERS IN WATER SUPPLIES OF S. E. QUEBEC1

ABSTRACT: A comparative study of the concentration of asbestos fibers in drinking water supplies of southeastern Quebec was undertaken to assess the relative contributions of fibers by asbestos-bearing railway ballast and naturally occurring asbestos deposits. Water samples were taken from areas where one or the other potential sources or neither potential source was present. In addition, rainwater samples were taken to assess the importance of atmospheric contributions. The sampling design accounted for potential variations in fiber counts due to the season, location and analytical procedures. Fiber concentrations were estimated from counts made on a JEOL 100CX scanning transmission electron microscope and statistically compared among areas. These levels were then compared with levels found in other areas of Canada and the United States. The results indicate that the rail ballast could be contributing statistically (albeit marginally) significant quantities of fibers to water supplies during the summer but not in the spring. Estimated concentrations in water supplies ranged between 1.7 × 10⁶fibers/liter and 147.8 × 10⁶fibers/liter. Fiber levels in samples taken during the spring were significantly higher and more variable than those taken during the summer. The presence of fibers in rainwater samples at concentrations of 1.9 × 10⁶fibers/liter, 18.3 × 10⁶fibers/liter and 23.7 × 10⁶fibers/liter suggests that atmospheric transport may play an important role in contributing fibers to regional systems. Fiber levels found in these systems are not unique when compared to levels observed elsewhere in North America.     

ASSESSMENT OF RESTORED RWERINE HABITAT USING RCHARC1

ABSTRACT: The Riverine Community Habitat Assessment and Restoration Concept (RCHARC) was developed to integrate habitat enhancement into the stream restoration process. RCHARC assumes that aquatic habitat quality is closely related to hydraulic diversity based upon a “comparison standard” reach approach to stream restoration. A Beta test was performed by applying the RCHARC process to Rapid Creek in Rapid City, South Dakota. Standard and restored stream reaches were selected and data were collected. A comparison of field data and velocity-depth distributions indicated that the restored stream closely replicated the standard reach. The RCHARC methodology has the potential to assess habitat quality for planned comparison reaches and indicate the level of success resulting from restoration.