微乳液增敏罗丹明B氧化褪色光度法测定微量亚硝酸根

基于微乳液对亚硝酸根催化溴酸钾氧化罗丹明B褪色反应具有增敏作用的原理,建立了催化动力学光度法测定痕量亚硝酸根的新方法。实验结果表明：该方法的最佳反应条件为1×10^-4 mol/L的罗丹明B溶液加入量0.60 mL,1 mol/L的稀磷酸加入量1.50 mL,0.1 mol/mL的溴酸钾溶液0.50 mL,反应温度20 ℃,反应时间15 min;对亚硝酸根测定的线性范围为ρ（NO₂^-）= 0.048~0.800 μg/mL,检出限为0.003 0 μg/mL;加入微乳液后催化反应的灵敏度增大了3倍。     

SMBR内气液两相流三维CFD模拟

应用CFD软件Fluent对浸没式膜生物反应器(submerged membrane bioreactor,SMBR)内气液两相流进行数值模拟研究,重点考查曝气系统的改变对气液两相流态的影响,并结合PIV实验验证模拟结果,从而为反应器的优化设计及膜污染的控制提供理论依据。模拟结果表明,SMBR内曝气强化了气液两相紊动,膜表面液相速度沿反应器高度增加且形成循环流动,有利于膜面污染物的脱落;反应器内气含率分布不均匀,出现死区,不利于微生物的生长;经实验验证,模拟结果吻合良好。     

Computational Fluid Dynamics (CFD) Simulations on the Effect of Rough Surface on Atmospheric Turbulence Flow Above Hilly Terrain Shapes

The behavioral distribution of the atmospheric turbulence flow over the terrain with changes in a rough surface has become one of the most important topics of air pollution research, among such other topics as transportation and dispersion pollutants. In this study, a computational model on atmospheric turbulence flow over a terrain hill shaped with rough surface was investigated under neutral atmospheric conditions. The flow was assumed to be 2D and modeled using computational fluid dynamics (CFD) models, which were numerically solved using Reynolds-averaged Navier-Stokes equations. Rough surface conditions were modeled using a number of windbreak fences regularly spaced on the hill. The mean velocity and turbulent structures such as turbulence intensity and turbulent kinetic energy were investigated in the upwind and downwind regions over the hill, and the numerical models were validated against the wind-tunnel results to optimize the turbulence model. The computational results agreed well with the results obtained from the wind tunnel experiments. The computational results indicate that the mean velocity was observed to increase dramatically around the crest of the upwind slope of the hill. A thick internal boundary layer was observed with a fence on the crest and downwind region of the hill. The reversed flow and recirculation zone were formed in the wake region behind the hill. It was thus determined that turbulent kinetic energy decreases as the mean velocity increases.     

内循环厌氧反应器多相流流场的三维数值分析简

利用数值模拟的方法,引入欧拉双流体多相流模型及标准k-ε紊流模型,模拟计算内循环厌氧反应器的三相流三维流场,并通过改变污泥颗粒密度及进水流量,针对固相流速及固含率的变化情况,分析条件的改变对流场的影响。研究结果表明,应用数值模拟方法可以获得内循环厌氧反应器内的流场特征;污泥颗粒密度及进水流量的改变对于反应器内污泥颗粒的流速及分布的均匀性有较为明显的影响。模拟结果对反应器的应用及优化设计具有一定的参考价值。     

连续流砂过滤器深度处理市政污水的中试研究

采用好氧/缺氧连续流砂过滤器中试实验研究深度处理北京某污水处理厂二级出水。实验结果表明,当连续流砂过滤器好氧段聚合氯化铝投量为20 mg/L,缺氧段碳源投量为32 mg/L时,COD、NH+4-N、TN和TP的平均去除率分别为34.77%、86.54%、66.94%和84.10%,最终出水均达到北京市新(改、扩)建城镇污水处理厂排放A标准(DB11/890-2012)。克隆文库法分析石英砂表面生物膜中的细菌群落结构表明,其优势菌群为β-proteobacteria,其中大部分能以废水中碳源为电子供体还原硝酸盐。     

Effects of cadmium on the activities of photosystems of Chlorella pyrenoidosa and the protective role of cyclic electron flow

Cadmium (Cd) shows high toxicity to aquatic microalgae. Many studies showed that Cd inhibited activities of photosystem II (PSII) but the effects of heavy metals on photosystem I (PSI) and cyclic electron flow (CEF) were still controversial and unclear. The effects of CdCl₂ on the activities of PSI, PSII and CEF in Chlorella pyrenoidosa was measured simultaneously in the present study. In presence of 200 μM of Cd, ultrastructure of some cells was strongly modified. Cd exposure led to decrease of the activities of photosynthetic oxygen evolution and respiration. PSII was more sensitive to Cd treatment than PSI. Cd treatment showed significant inhibition on the photochemical quantum yield and electron transport rate of PSII. Cd increased the quantum yield of non-light-induced non-photochemical fluorescence quenching, indicating the damage of PSII. The activity of PSI showed tolerance to Cd treatment with concentration less than 100 μM in the experiment. Linear electron flow (LEF) made significant contribution to the photochemical quantum yield of PSI of the untreated cells, but decreased with increasing Cd concentration. The contribution of CEF to the yield of PSI increased with increasing Cd concentration. The activation of CEF after exposure to Cd played an essential role for the protection of PSI.     

地震液化流滑震害

通过地震液化的震害调查,从土种类、地形条件和坡度、液化土壤的赋存状况、地震能量和流滑的时间与空间分布等方面,简要总结了液化流滑的震害特征和规律,初步分析了液化引起流滑发生的条件、规模、剧烈程度、坡体运动规律以及流滑产生的破坏形式,分析了影响流滑的因素,可供进一步研究等参考。     

Monitoring morphological and vegetation changes and flow events in dryland river channels

Monitoring of impacts of floods in river valleys of dryland regions has become important with the onset and threats of desertification and is likely to become even more vital with predictions of increased effects of climate and land use change. It is also needed in order to conform to requirements of the EU Water Framework Directive. Monitoring in such regions sets particular challenges. This paper explains a system of low-cost monitoring of changes in morphology, vegetation and sediment cover in channels and valley floors of ephemerally flowing streams. It has been applied in SE Spain for 10 years and has proved very effective. In particular, the use of simple crest-stage recorders for measuring flow height and the use of real-time differential GPS for rapid and accurate survey and for relocating points have proved very valuable. Part of the monitoring is focused on the interaction of plants and channel processes. Small changes in and around vegetation associated with flow events have been detected by a combination of quadrat surveys and cross-profiling of the channel. A range of flow events has been measured over the period of monitoring, demonstrating their differing effects and the varying sensitivity and responsiveness of different sites. The sporadic occurrence of flood events in such an environment means that a strategy of monitoring several sites and of continuation over many years has great benefits.     

西部开发中的泥石流问题

西部地区的青、甘、陕、川、滇、黔、新、藏、宇、桂、内蒙和重庆等12个省区市内都有泥石流分布,已查明的泥石流沟计15500余条,受泥石流危害或威胁的县级以上政府驻地城镇逾百座,一场泥石流致死百人以上的灾害点达23个,泥石流及其灾害是西部大开发中必须面临的生态环境问题之一,城市建设、公路和铁路等交通建设、水利建设,西气和西电东送工程建设等西部大开发的重点领域,,在开发建设中都将要遇到泥石流问题,吸取以往这类建设中抗御泥石流灾害的经验与教训,对于减轻泥石流灾害和保障西部大开发顺利进行具有现实意义。     

泥石流灾情评估指标体系

泥石流灾情评估指标体系的建立应满足适用性、完备性、可比性、综合性和系统性原则,而指标的选取还应在一定的要求下确定。依据上述原则,在泥石流灾情网络分析结果的基础上,建立了评估指标体系的结构层次模型,进而对各类灾情评估指标进行了分析,确定出评估泥石流灾情的具体指标和因子。最后建立了以成灾度为目标层,经济损失,社会影响,环境损害为准则层。评估指标和评估因子为指标层的泥石流灾情评估指标体系。