气、液两相流水平管道中溶解氧变化规律的实验研究

水泵在常规输送水时,进水口处产生负压,进行自动抽吸空气,气、水通过水泵叶轮混合后,在水平管道中流动.气、液两相流在不同气水比时,水平管道中沿程压力损失也有变化.文中应用试验研究的方法,测得水平管道中的水头损失与溶解氧量的变化;由关系图可知其相关规律性;并应用数学分析软件Origin6.1对实验数据进行了拟和,得出了两者之间关系的曲线方程公式.研究工作和所得数据,对于研究低压水平管道输送气、液两相流时,氧气溶解的变化规律有一定的借鉴作用.由于气、液两相流时对水泵的动力需求比纯液体流小,可改变水泵驱动电机的供电参数,达到了节能曝气的目的;进而可减少污水处理曝气池中的曝气量.     

除氧器乏汽的回收再利用

介绍了国电吉林热电厂对热力式除氧火力发电机组的高压除氧器乏汽进行全部回收,创造了可观的经济、环境和社会效益,在当前国际国内能源供应形势紧张、大力提倡节能环保的情况下,具有积极意义.     

ZFP-1380型曝气转盘充氧性能的测试和分析

介绍了ZFP-1380型曝气转盘的参数和性能，并对其在氧化沟污水处理工艺中的主要指标——充氧能力和动力效率的主要影响因素作了测试和分析。该转盘适宜的浸没深度为480～510mm、转速为52～56r/min，在此运转条件下，单片转盘的充氧能力为1.78～1.98kg/h，动力效率为3.18～3.43kg/(kW     

Should We Protect the Strong or the Weak? Risk,Resilience, and the Selection of Marine Protected Areas

Abstract: It is thought that recovery of marine habitats from uncontrollable disturbance may be faster in marine reserves than in unprotected habitats. But which marine habitats should be protected, those areas at greatest risk or those at least risk? We first defined this problem mathematically for 2 alternate conservation objectives. We then analytically solved this problem for both objectives and determined under which conditions each of the different protection strategies was optimal. If the conservation objective was to maximize the chance of having at least 1 healthy site, then the best strategy was protection of the site at lowest risk. On the other hand, if the goal was to maximize the expected number of healthy sites, the optimal strategy was more complex. If protected sites were likely to spend a significant amount of time in a degraded state, then it was best to protect low‐risk sites. Alternatively, if most areas were generally healthy then, counterintuitively, it was best to protect sites at higher risk. We applied these strategies to a situation of cyclone disturbance of coral reefs on Australia's Great Barrier Reef. With regard to the risk of cyclone disturbance, the optimal reef to protect differed dramatically, depending on the expected speed of reef recovery of both protected and unprotected reefs. An adequate consideration of risk is fundamental to all conservation actions and can indicate surprising routes to conservation success.     

Decline in Relative Abundance of Bottlenose Dolphins Exposed to Long-Term Disturbance

Abstract:  Studies evaluating effects of human activity on wildlife typically emphasize short-term behavioral responses from which it is difficult to infer biological significance or formulate plans to mitigate harmful impacts. Based on decades of detailed behavioral records, we evaluated long-term impacts of vessel activity on bottlenose dolphins ( Tursiops sp.) in Shark Bay, Australia. We compared dolphin abundance within adjacent 36-km² tourism and control sites, over three consecutive 4.5-year periods wherein research activity was relatively constant but tourism levels increased from zero, to one, to two dolphin-watching operators. A nonlinear logistic model demonstrated that there was no difference in dolphin abundance between periods with no tourism and periods in which one operator offered tours. As the number of tour operators increased to two, there was a significant average decline in dolphin abundance (14.9%; 95% CI =−20.8 to −8.23), approximating a decline of one per seven individuals. Concurrently, within the control site, the average increase in dolphin abundance was not significant (8.5%; 95% CI =−4.0 to +16.7). Given the substantially greater presence and proximity of tour vessels to dolphins relative to research vessels, tour-vessel activity contributed more to declining dolphin numbers within the tourism site than research vessels. Although this trend may not jeopardize the large, genetically diverse dolphin population of Shark Bay, the decline is unlikely to be sustainable for local dolphin tourism. A similar decline would be devastating for small, closed, resident, or endangered cetacean populations. The substantial effect of tour vessels on dolphin abundance in a region of low-level tourism calls into question the presumption that dolphin-watching tourism is benign.     

Effects of Warming Conditions in Eastern North American Forests on Red-Backed Salamander Morphology

Abstract:  Several studies have reported climate-associated changes in phenotypically plastic traits of amphibians, yet it remains unknown whether amphibians can manifest an evolutionary response to global climate change at the rate and magnitude that it is occurring. To assess this issue, we examined temporal change in the morphology of the red-backed salamander ( Plethodon cinereus ), a small, abundant woodland salamander distributed widely in eastern North America with two distinct morphotypes: striped individuals associated with cooler microclimates and unstriped individuals associated with warmer microclimates. We compiled morph frequencies for 50,960 individual salamanders from 558 sites as recorded in the published literature and in unpublished field notes of herpetologists between 1908 and 2004. We observed that striping probability increased with increasing latitude, longitude, and elevation and decreased (from 80% to 74% range wide) with time. The combined forces of regional climate warming and, particularly, forest disturbance have evidently been sufficient to cause morphological evolution in this amphibian over the last century.     

南洞庭湖湿地鱼类生境景观变化及其人为驱动

通过实地调查和制图分析,研究1983~2013年南洞庭湖区万子湖湿地和鱼类生境景观变化及其人为驱动,结果表明:湿地洲滩面积由1.410×104 hm2增加到2.135×104 hm2,敞水面面积由1.363×104 hm2减少到0.631×104 hm2;芦苇洲减少,但林地由0.056×104 hm2增加到0.728×104 hm2并扩展到保护区核心区;新增泥围21个、网围10个,引淤、沥水排水设施长度增加了201.71km。人为干扰对景观变化有极大影响,其中引种意大利杨及芦苇改变了地形和群落结构,挤占了自然演替条件下应有的草洲景观空间,使鱼类产卵、索饵的适宜生境减少;泥围作为有害渔法,与网围都处于建设发展阶段,占据了草洲、洼地等鱼类产卵、索饵的适宜生境;引淤渠建设使大面积湖泊快速淤积成洲,将水生生态景观转变为大多数时间干露的以陆相生态景观为主的水陆相生态景观,鱼类生境被压缩,并对南洞庭自然保护区核心区继续发挥促淤作用。     

铸铁还原氯乙酸的影响因素与机制研究

氯乙酸是地表水与饮用水中一种常见的微量氯代有机污染,具有致癌性,浓度较高时对人体健康会产生一定的危害.为了更经济地去除水体中的氯乙酸,研究了铸铁废料去除氯乙酸的可行性,讨论了铁类型、预处理方法,振荡方式以及溶解氧等条件对还原效果的影响.结果表明传质过程比铁类型与酸处理对氯乙酸还原速率的影响更大.铸铁无氧去除三氯乙酸(TCAA)的主要产物为二氯乙酸(DCAA)而有氧存在时为一氯乙酸(MCAA).在纵向翻转下铸铁对氯乙酸的去除过程符合伪一级动力学,TCAA、DCAA与MCAA的无氧速率常数分别为0.46 h-1、0.03 h-1与0,有氧速率常数依次为1.24 h-1、0.79 h-1与0.28 h-1.不同氧含量环境中铸铁对氯乙酸的去除机制不同,无氧时为连续氢解,有氧时可能包括连续氢解与直接转化过程.     

石化工业园区有毒废水来源识别研究

针对石化废水对综合污水处理厂的毒性冲击问题,采用耗氧速率抑制试验评价不同石化废水对活性污泥的毒性,评价对象包括石化工业园区内不同生产装置和装置内不同生产节点的废水.试验发现废水的有机质含量与毒性效应之间没有直接的相关性,并不能单从废水的有机质含量预测其毒性.同时,研究中针对活性污泥敏感性在不同批次试验之间的差异问题,将各废水对活性污泥的毒性数据转化为标准毒性物质3,5-二氯苯酚的浓度,提高了数据之间的可比性.在此基础上,根据废水流量和对应3,5-二氯苯酚浓度,计算废水对应标准毒性物质质量排放负荷,作为评价废水毒性排放贡献的指标.对不同装置和节点石化废水的毒性贡献进行排序,有效识别了该石化工业园区内有毒废水的产生来源,为从生产源头控制废水毒性提供有效指导.     

溶解氧对Biolak型A2O工艺脱氮除磷性能的影响

通过对Biolak型A2O工艺处理生活污水工程应用的研究,考察了好氧段溶解氧(DO)浓度对该工艺脱氮除磷的影响.试验结果表明,DO浓度变化对系统COD、NH+4-N处理效果的影响不大,而对系统总氮及总磷的去除效果影响显著.当DO浓度控制在0.80~1.50 mg·L-1之间时,系统总氮去除效果最佳,可以达到69.5%,系统好氧段可实现同步硝化反硝化除氮.通过对系统氮进行物料衡算发现,23.7%的总氮通过好氧段多级A/O反硝化脱氮去除.当DO浓度为1.00~3.00 mg·L-1时,总磷(TP)去除率较高,可以达到74.0%.DO浓度控制在1.00~1.50 mg·L-1之间时,系统脱氮除磷效果最佳,此时TN、TP的去除率分别为68.9%、73.7%,二级生化处理段出水TN、TP分别为12.02、0.95 mg·L-1.