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河流泥沙与污染物相互作用数学模型 总被引:12,自引:4,他引:8
本文分析了水流-泥沙-污染物系统中主要物理化学过程对水体污染物的影响,以此为基础推导了描述吸附态、溶解态污染物迁移转化的基本方程。对于河床水体之间泥沙交换产生的环境变化,建立了泥沙冲淤对污染物影响的表达式,对于吸附解吸作用则采用以实验为基础的泥沙吸附动力学模式。根据三峡地区实测水沙、水质数据对模型进行了验证,研究结果表明,模型能够模拟泥沙冲淤过程中污染物的交换,并且可以反映泥沙吸附作用对水环境的动态影响,可以应用于河流及水库泥沙污染物相互作用的模拟和分析。 相似文献
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泥沙污染水质模型研究综述 总被引:1,自引:0,他引:1
对现有的泥沙污染水质模型进行分类,总结了国内外泥沙污染基本问题及泥沙污染水质模型研究的成果,指出模型发展方面应加强泥沙与污染物相互作用机理研究,进一步揭示污染物在水体、悬浮泥沙、底泥之间迁移转化的机理,模型的建立应综合考虑污染物的沉降再悬浮、以及吸附解吸、底泥释放等动态过程。 相似文献
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基于钱塘江河口闸口—澉浦段9个断面的溶解态、悬浮态、沉积态氮磷数据,研究不同介质中氮磷的含量及空间分布特征,探讨泥沙粒径对泥沙中氮磷含量的影响以及水体中溶解态和悬浮态氮磷的赋存比例。结果表明:各介质中的总氮含量沿程分布较均匀,悬浮态总氮含量大于沉积态总氮含量;溶解态总磷浓度自上游至下游总体呈增大趋势,悬浮态与沉积态总磷含量接近,沿程变化趋势不明显;水体中总氮以溶解态为主,而总磷则以悬浮态为主;氮磷含量与泥沙粒径的相关关系表明,泥沙粒径不是影响泥沙中氮磷含量的主要因素。成果可为揭示钱塘江河口氮磷在水、固两相间的迁移转化规律及污染控制提供科学依据。 相似文献
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重金属污染物动态吸附试验及数学模拟 总被引:3,自引:0,他引:3
本文采用泥沙动力学中Rouse等人用来研究泥沙浓度沿垂线分布的装置。对泥沙吸附重金属污染物进行了动态模拟。试验分有底泥和无底泥两种情况。研究中发现在Rouse装置的水力、泥沙条件下泥沙吸附重金属污染物达到平衡状态需要6小时以上,由极坐标下的重金属迁移转化数学模型方程,在本文具体试验条件下进行数值求解,计算结果和试验结果合良好,说明数学模型是正确合理的试验是可靠的。计算时依据室内静态试验结果,对动态 相似文献
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河流泥沙磷迁移过程的数学模型研究 总被引:4,自引:2,他引:2
水体中磷的迁移转化过程,对于河流生态环境有着至关重要的影响。传统的水质模型缺乏对磷迁移转化过程机理和规律的深入探讨与分析。本文建立河流中水动力-泥沙-磷迁移过程的分相模型,在水流运动与泥沙输移模拟的基础上,从基本的化学反应出发,研究磷在河流中的迁移过程。首先,考虑天然河流中磷的来源及其不同形态,基于泥沙颗粒表面电荷非均匀分布的认识,利用修正后的表面络合模型研究悬移质泥沙对磷的吸附;其次,分析有氧与无氧条件下泥沙颗粒中铁/铝(氢)氧化物的不同形态,以描述磷在活性底泥层中的赋存形式;然后,重点关注河床冲淤变形,分析磷在河床表面的沉积与再释放。最后,本文设计磷水槽试验,分析泥沙颗粒运动对磷迁移的影响,并对模型进行验证。结果表明,泥沙运动对磷迁移有显著影响,磷浓度沿程分布与含沙量间存在较好的线性关系,尤其是溶解相磷;本文建立的模型可以合理地反映磷随着泥沙颗粒的迁移过程。 相似文献
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根据冗各电站地下厂房开挖支护的施工顺序,以隐式杆单元模拟锚杆,以壳单元模拟混凝土喷层,采用三维非线性有限元技术,对洞室群的开挖支护动态过程进行了模拟计算。通过三维非线性有限元计算分析得到:洞室群动态开挖过程中围岩应力变形的分布规律,围岩塑性区的发展规律,锚杆受力变化情况。计算结果表明:整个开挖过程中,洞周围岩位移变化规律正常,量值较小,塑性区主要分布在洞室周边,围岩稳定性较好;但在洞室交叉口处围岩的变形较大,出现较大范围的塑性区,在此基础上提出了支护措施优化方案,并对优化方案的效果进行了评价。 相似文献
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The relocation of unionacean mussels is commonly used as a conservation and management tool in large rivers and streams. Relocation has been used to recolonize areas where mussel populations have been eliminated by prior pollution events, to remove mussels from construction zones and to re-establish populations of endangered species. More recently, relocation has been used to protect native freshwater mussels from colonization by the exotic zebra mussel Dreissena polymorpha. We conducted a literature review of mussel relocations and evaluated their relative success as a conservation and management strategy. We found that 43% of all relocations were conducted because of construction projects that were forced to comply with the Endangered Species Act 1973 and that only 16% were monitored for five or more consecutive years. Most (43%) relocation projects were conducted from July to September, presumably a period when reproductive stress is relatively low for most species and the metabolic rate is sufficient for reburrowing in the substrate. The mortality of relocated mussels was unreported in 27% of projects; reported mortality varied widely among projects and species and was difficult to assess. The mean mortality of relocated mussels was 49% based on an average recovery rate of 43%. There is little guidance on the methods for relocation or for monitoring the subsequent long-term status of relocated mussels. Based on this evaluation, research is needed to develop criteria for selecting a suitable relocation site and to establish appropriate methods and guidelines for conducting relocation projects. 相似文献
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Samples were taken year-round at eleven sites along the altitudinal profile (2900-1400 m a.s.l.) of the Gunnison River, a 329 km tributary of the Colorado River, to document the distribution of the Plecoptera and to evaluate responses to hypolimnial-release dams in the headwaters and middle reaches. Twenty-two species were present, with the greatest species richness occurring in an unregulated segment upstream of the middle reach dams; average nymphal biomass over the study period (175 organisms, 395 mg dry mass m?2) was also greatest in this segment. Only four species (58 organisms, 48 mg m?2) were present in the tailwaters of the headwater dam and values were greatly reduced (nine species; 35 organisms, 180 mg m?2) below the middle reach dams. The stonefly community recovered ca. 80 km downstream from the last dam (15 species; 244 organisms, 250 mg m?2), apparently in response to natural resetting of environmental conditions corresponding to those above the middle reach dams. At the most downstream site (11) only four species (four organisms, 16 mg m?2) were present. The observed distributional pattern is a classic serial discontinuity in response to hypolimnial stream regulation in a temperate latitude river. 相似文献
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In the lower River Murray, Australia, populations of gastropods have declined markedly over the past 40 years. Of the native fauna of about 18 species, only the ancylid Ferrissia petterdi remains common (but in patches), and another five species feature in sporadic local resurgences. Until recently the viviparid Notopala was thought to be extinct. The introduced physid Physa acuta is widespread, but in low numbers. The decline probably is associated with flow regulation, high turbidity and the introduction of common carp. Snail populations have persisted, however, in irrigation pipelines fed from the river, where they periodically cause blockages. This paper reports the discovery of the only known populaion of Notopala hanleyi in a pipeline where the inner wall accumulates microbial and other organic matter, providing high quality food for snails. In the Murray before regulation most of the periphytic biomass was probably microbial, as fluctuating water levels would have maintained littoral communities in a highly productive, early state of succession his postulated that, by stabilizing seasonal water levels, regulation has promoted the production of filamentous green algae, an inferior food source, and so displaced snail populations from the open aquatic environment. 相似文献
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V. K. Konovalov O. V. Yashkin V. V. Ermakov 《Power Technology and Engineering (formerly Hydrotechnical Construction)》2008,42(2):105-109
A system for removal and pneumatic transport of fly ash is examined, in which air pulses act on batches (pistons) of ash formed
in a duct. Studies are made of the effect of several physical parameters on the force required to displace a piston of ash
and these serve as a basis for choosing a system for removal and pneumatic transport of ash simultaneously from several hoppers
of an electric precipitator. This makes it possible to separate the ash particles according to size without introducing additional
components. Formulas are given for calculating the structural and dynamic parameters of this system and measurements of indirect
dynamic parameters are used to calculate the input-output characteristics of the system. In order to optimize the system,
configurations for summing several ducts into a single transport duct for pneumatic ash transport are proposed. Some variants
of dry ash utilization and the advantages of producing of size-separated particles are considered.
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Translated from élektricheskie Stantsii, No. 2, pp. 26–30 (2008). 相似文献
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Peter B. Bayley 《河流研究与利用》1991,6(2):75-86
The ‘flood pulse advantage’ is the amount by which fish yield per unit mean water area is increased by a natural, predictable flood pulse. Evidence for this increase is presented from tropical and temperate fisheries. It is argued that increasing multispecies fish yield by restoring the natural hydrological regime is consistent with increasing production of other trophic levels and with restoration from ecological and aesthetic viewpoints. When applied to a river-floodplain system, this restoration would provide a large, self-sustaining potential for recreation, commercial exploitation, and flood control. An interim ‘natural flood pulse’ restoration approach is proposed for systems modified for navigation. This approach approximates the natural hydrological regime in a river reach and is intended as a first step in the long process of restoring the watershed. 相似文献