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排序方式: 共有506条查询结果,搜索用时 569 毫秒
1.
长江下游船舶溢油应急处理措施框架   总被引:2,自引:0,他引:2  
介绍长江下游船舶溢油污染的现状,论述溢油污染对沿岸生态和环境的影响以及溢油防治研究的重要性。以长江南京段为例,分析影响江中及岸边事故溢油迁移转化规律的因素,提出船舶事故溢油应急处理措施的三个重要部分,即溢油模拟及污染区预测、溢油清除回收和溢油风险评价。针对三个部分提出了具体的研究内容,为国内各大中型江河不同河段的船舶溢油的研究提供参考。  相似文献   
2.
铬渣的无害化处理和综合利用   总被引:13,自引:2,他引:11  
铬渣产量大、毒性剧烈,是严重污染生态环境和危害人类健康的危险废物.本文介绍了铬渣各种无害化处理方法的解毒机理、工艺过程和应用实践,阐述了对铬渣进行综合利用的途径,并就铬渣的防治措施提出了建议.  相似文献   
3.
An approach is presented to satisfy the demand for simple criteria, guidelines and models for the preliminary sizing of horizontal subsurface flow (SF) constructed wetland systems. This approach eliminates time-consuming calculations and iterations by providing graphical solutions for wetland system sizing. Therefore, it can be used for the preliminary assessment of new or performance evaluation of existing subsurface flow constructed wetland systems. The validity of this methodology is checked with data from existing systems and is found to be quite satisfactory. This methodology is combined with simple equations predicting the maximum wetland capacity in summer, so as to assist designers in sizing installations in tourist areas with increased summer populations. Furthermore, based on this methodology, a sensitivity analysis is performed of the area requirements for wastewaters of various strengths and various design conditions and performance criteria. The results provide a useful overview to engineers and further simplify the design methodology of new subsurface flow constructed wetland systems.  相似文献   
4.
Many dams in the USA have outlived their intended purpose and an increasing number are being considered for removal. Yet, quantitative studies of the potential physical, biological and ecological responses are needed to assess dam removal decisions. In this paper, the responses of migratory walleye (Sander vitreus) to increased spawning habitat availability as a result of dam removal was studied by comparing scenarios with and without a high‐head dam in the Sandusky River (Ohio), a major tributary to Lake Erie. A conceptual, ecological model was proposed to define the relationship between hydrodynamics and walleye spawning, egg hatching, larval drift and survival. A mathematical, ecological model of the early life‐history stages was then developed and coupled with time series of depth and velocity predictions over the spawning grounds from a 1‐D hydrodynamic model. Model simulations were run for 1984–1993 for both the with‐ and without‐dam scenarios to assess the potential benefit of dam removal. The simulation results demonstrated that velocity, depth and water temperature are major factors influencing adult walleye spawning success. Without the dam, 10 times the amount of spawning habitat would be available for walleye to spawn. This increase in spawning habitat area resulted in up to five times the total egg deposition and seven times the larval output to the nursing grounds, based on the assumption that 5% of the walleye population of Lake Erie migrated up the Sandusky River to spawn. We concluded that the spawning habitat in the current condition (with the dam) is limiting and additional spawning habitat upstream could significantly increase the number of larval walleye drifting to Lake Erie. The model sensitivity analysis showed that the number of walleye migrating up the river in spring is the dominant factor for larval recruitment to the lake. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
5.
张林成 《人民长江》2001,32(12):9-11
安徽省境内765km的长江干堤,由于均是在原来旧堤的基础上经逐年加高培厚的,修筑时均未按设计要求施工,致使堤身密实度不够,新老堤土之间结合不牢,在汛期高水位时易产生渗漏。20世纪70年代以来,安徽省高度重视对长江干堤渗漏隐患的处理,经过长期的实践,逐渐摸索出一套行之有效的除险加固方法,如锥探灌浆、灭杀白蚁、冲抓套吉、垂直铺塑防渗、粘土铺盖及压渗盖重等处理措施。使长江干堤的渗漏隐患得以基本消除,其具体作法可供类似工程借鉴。  相似文献   
6.
纯氧曝气的研究进展   总被引:9,自引:0,他引:9  
介绍了纯氧曝气的生化机理、应用领域、供氧方式、污泥性能等以及它与普通空气曝气相比在技术、经济方面显示出的优越性。随着纯氧曝气的发展和国家新标准增加了脱氮除磷方面的排放要求,使得纯氧曝气在城市污水处理老厂的改造和新厂的建设中具有很好的前昔。  相似文献   
7.
针对流域突发性重金属污染,不同浊度下的泥沙对重金属有一定的去除效果。以浊度为指示指标,通过试验研究了常温(25 ℃)和低温(5 ℃)条件下浊度50~650 NTU(Nephelometric Turbidity Unit)范围内泥沙对重金属镉、铅、砷吸附去除的影响。试验结果表明:泥沙对重金属镉、铅、砷的去除效果为铅>镉>砷,其中铅的去除率达到99%。浊度与能处理达标的最高重金属浓度呈线性关系,常温下浊度与能处理达标的最高镉、铅、砷浓度关系曲线的相关系数分别为0.996、0.998、0.999,低温下其相关系数分别为0.999、0.996、0.998。常温较低温更利于泥沙对重金属镉、铅、砷的去除,能去除更高浓度的重金属,达到生活饮用水卫生标准。  相似文献   
8.
Stream habitat restoration is an important tool for fisheries management in impaired lotic systems. Although small‐scale benefits of stream habitat restoration are commonly investigated, it is difficult to demonstrate population effects. The Pahsimeroi River Chinook salmon Oncorhynchus tshawytscha population was previously restricted to the lower portion of the river by multiple irrigation structures. To address fish passage issues, a combination of restoration projects was initiated including barrier removals, instream flow enhancements and installation of fish screens on diversions. The largest barrier was removed in 2009, more than doubling the amount of accessible linear habitat. We hypothesized restoration efforts would expand the distribution of spawning salmon in the Pahsimeroi River watershed, leading to a broader distribution of juveniles. We also hypothesized a broader juvenile distribution would have population effects by reducing the prevalence of density‐dependent growth and survival. Redds were documented in newly accessible habitat immediately following barrier removal and accounted for a median of 42% of all redds in the Pahsimeroi River watershed during 2009–2015. Snorkel surveys also documented juvenile rearing in newly accessible habitat. Juvenile productivity increased from a median of 64 smolts/female spawner for brood years 2002–2008 to 99 smolts/female spawner for brood years 2009–2014. Overall, results suggested increased habitat accessibility in the Pahsimeroi River broadened the distribution of spawning adult and rearing juvenile salmon and reduced the effects of density‐dependent survival. Large‐scale stream restoration efforts can have a population effect. Despite the large‐scale effort and response, habitat restoration alone is likely not sufficient to restore this population.  相似文献   
9.
Conservation planning aims to optimize outcomes for select species or ecosystems by directing resources toward high‐return sites. The possibility that local benefits might be increased by directing resources beyond the focal area is rarely considered. We present a case study of restoring river connectivity for migratory fish of the Great Lakes Basin by removing dams and road crossings within municipal jurisdictions versus their broader watersheds. We found that greater river connectivity could often be achieved by considering both intra‐jurisdictional and extra‐jurisdictional barriers. Focusing on jurisdictional barriers alone generally forfeited <20% (median = 0%) of habitat gains for those who value solely habitat gains within the jurisdiction, but >75% (median = 100%) for planners who value larger‐scale habitat gains. Similarly, cost savings tended to be between ?50% and +50%, but in some cases were very negative. Our study underscores the local‐scale benefits of broadening restoration investments, especially for decision makers of the Great Lakes Basin and contributes to a discussion of appropriate and efficient scales of conservation planning. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   
10.
畜禽养殖废水有机物水质水量变化大,有机物、氨氮与磷的浓度较高,直接排放会严重危害环境。通过构建厌氧-好氧序批式反应器(SBR)处理预酸化畜禽养殖废水,分析了不同进水负荷条件下反应器对污染物的去除性能和微生物群落结构的变化规律。结果表明:SBR反应器对高负荷进水中TN、PO3-4—P和COD的平均去除率可分别达到64.5%、97.5%和94.5%。反应器出现NH+4—N和NO2—N亚硝酸同时积累的短程硝化现象,这可能与高进水负荷对氨氧化菌和亚硝酸盐氧化菌的活性和种群的影响有关。与乙酸盐相比,以丙酸盐作碳源时污泥的强化生物除磷活性更高。随着进水负荷的增大,聚糖菌(GAOs)的相对丰度明显升高。四联球状菌(Tetrasphaera)为反应器中始终占优势的聚磷菌(PAOs),对反应器除磷性能有重要贡献。在高有机负荷条件下,SBR内PAOs与GAOs之间不存在明显的底物竞争关系,系统脱氮除磷性能未受影响。  相似文献   
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