Numerical Investigation of the Effects of Boundary-Layer Evolution on the Predictions of Ozone and the Efficacy of Emission Control Options in the Northeastern United States

This paper examines the effects of two different planetary boundary-layer (PBL) parameterization schemes – Blackadar and Gayno–Seaman – on the predicted ozone (O₃) concentration fields using the MM5 (Version 3.3) meteorological model and the MODELS-3 photochemical model. The meteorological fields obtained from the two boundary-layer schemes have been used to drive the photochemical model to simulate O₃ concentrations in the northeastern United States for a three-day O₃ episodic period. In addition to large differences in the predicted O₃ levels at individual grid cells, the simulated daily maximum 1-h O₃ concentrations appear at different regions of the modeling domain in these simulations, due to the differences in the vertical exchange formulations in these two PBL schemes. Using process analysis, we compared the differences between the different simulations in terms of the relative importance of chemical and physical processes to O₃ formation and destruction over the diurnal cycle. Finally, examination of the photochemical model's response to reductions in emissions reveals that the choice of equally valid boundary-layer parameterizations can significantly influence the efficacy of emission control strategies.     

上流式厌氧污泥床滤层反应器处理鸡粪混合液离心出水

本研究采用上流式厌氧污泥床滤层反应器对蛋鸡场鸡粪混合液离心出水进行处理,试验结果:在中温25℃,进水COD_(cr)18000mg/L和氨氮1600mg/L的条件下,COD_(cr)去除率74.08%,BOD_5去除率83.78%,水力停留时间26.15h,容积负荷15.60kg·COD_(cr)/m~3·d,产气率0.52m~3/去除km·COD_(cr).反应器运行状况良好.     

基于CFD的卧式高固厌氧消化混合策略优化

高固厌氧消化(High solid anaerobic digestion,HSAD)在实际生产运行中,与传统厌氧消化相比,存在混合效果差、能量转换效率低等缺点。基于计算流体力学(Computational Fluid Dynamics,CFD)研究了不同桨叶角度的搅拌桨对生产规模反应器混合效率的影响。并根据不同工况下的能量转换效率和能量消耗,确定了最佳工况。结果表明,随着桨叶角度从30°增加到60°,径向和轴向混合均有明显改善,但在高转速下的改善效果不明显。考虑到实际工程应用,建议采用低转速和大桨叶角度。因此,建议反应器采用桨叶角度为60°的搅拌桨,转速为1 r·min⁻¹(净能量产出为0.023 GJ·d⁻¹·m⁻³)。本研究结果可为实际工程中HSAD反应器的混合策略提供参考。     

磷酸铵镁结晶技术处理模拟氨氮废水

从工程应用角度出发,考察了不同氨氮起始浓度、反应温度、搅拌速率及搅拌时间对磷酸铵镁化学结晶技术沉氨效果的影响。研究结果表明,当氨氮起始浓度超过200 mg/L时,氨氮去除率达到90%以上。不同温度条件下,氨氮去除率超过80%。随着温度升高,氨氮去除率明显上升,最高可达90%以上。搅拌是晶粒生长的一个重要影响因素;搅拌速率对晶粒生长作用复杂,当搅拌速率低于150 r/min时,加速了晶粒生长,达2.25 nm;提高搅拌速率,晶粒大小降至1.54 nm。而搅拌时间对晶粒生长起着非常明显的促进作用;随着搅拌时间的延长,晶粒出现明显的增长,从5 min的0.47 nm长至120 min的1.71 nm。     

南京江北新区大气单颗粒来源解析及混合状态

利用单颗粒气溶胶飞行时间质谱（SPAMS）于2015年12月1~31日对南京江北新区大气单颗粒进行了测量,共采集到同时含有正负离子谱图的颗粒747.8万个.结果表明,监测期间南京江北新区总体空气质量较差,污染天气占比为49.2%,SPAMS所捕获的颗粒数与PM_2.5质量浓度的相关性达到0.83,因此颗粒物数浓度在一定程度上能够用来反映大气污染状况,监测点主要污染源包括燃煤源以及机动车尾气源,工业工艺源污染占比居第3位,3种源的总贡献率达到63.5%.从整体上看,PM_2.5质量浓度的升高大多伴随着燃煤及机动车尾气占比的升高,EC、混合碳（ECOC）与OC在生物质燃烧、扬尘、汽车尾气排放、燃煤燃烧以及工业源中均与NO₂^-、NO₃^-以及SO₄^-有较高的混合程度.     

Just Add Water and the Colorado River Still Reaches the Sea

A recent article in Environmental Management by All argued that flood flows in North America’s Colorado River do not reach the Gulf of California because they are captured and evaporated in Laguna Salada, a below sea-level lakebed near the mouth of the river. We refute this hypothesis by showing that (1) due to its limited area, the Laguna Salada could have evaporated less than 10% of the flood flows that have occurred since 1989; (2) low flow volumes preferentially flow to the Gulf rather than Laguna Salada; (3) All’s method for detecting water surface area in the Laguna Salada appears to be flawed because Landsat Thematic Mapper images of the lakebed show it to be dry when All’s analyses said it was flooded; (4) direct measurements of salinity at the mouth of the river and in the Upper Gulf of California during flood flows in 1993 and 1998 confirm that flood waters reach the sea; and (5) stable oxygen isotope signatures in clam shells and fish otoliths recorded the dilution of seawater with fresh water during the 1993 and 1998 flows. Furthermore, All’s conclusion that freshwater flows do not benefit the ecology of the marine zone is incorrect because the peer-reviewed literature shows that postlarval larval shrimp populations increase during floods, and the subsequent year’s shrimp harvest increases. Furthermore, freshwater flows increase the nursery area for Gulf corvina (Cynoscion othonopterus), an important commercial fish that requires estuarine habitats with salinities in the range of 26–38‰ during its natal stages. Although flood flows are now much diminished compared to the pre-dam era, they are still important to the remnant wetland and riparian habitats of the Colorado River delta and to organisms in the intertidal and marine zone. Only a small fraction of the flood flows are evaporated in Laguna Salada.     

Chaotic Behavior and Pollution Dispersion Characteristics in Engineered Tidal Embayments: A Numerical Investigation1

Abstract: This paper presents a numerical investigation of approaches to enhance the mixing and dispersion processes in tidal areas by effecting changes in the natural estuary system. It compares the impact of various estuary modifications stemming from human intervention to pollutant dispersion and chaotic flow within the estuary including the implications of alteration of the original channel shape, change of the channel bathymetry, and modification of the tidal signal. Our findings indicate that chaotic flow analysis is similar in many regards, but not all, to conventional dispersion analysis. Specifically, we conclude that (1) simplification of the flow regime reduces chaotic flow patterns and tracer particle dispersion, (2) creation of extensively protruding barriers and/or installation of barriers on opposite sides of the main stem of the estuary enhances particle dispersion and chaotic mixing, (3) installation of underwater berms has relatively minor beneficial, but highly localized, effects on chaotic regime and particle dispersion, and (4) increasing the tidal signal amplitude was shown to increase chaotic and dispersion properties of the estuarine system. A parametric study investigating the effect of several geometrical configurations and tidal signals on characteristics of chaotic flows concludes the paper.     

凌钢52 m2烧结机混料系统除尘设计

对58m^2烧结机混料系统原除尘状况进行了详细分析，对新建52m^2烧结机混料系统通风除尘设备选型、设计方案及效果进行了详尽的阐述。     

唐山市区大气环境容量研究

为确定唐山市区的大气环境容量,根据唐山市自然环境、污染气象特征、大气环境过程、区域污染源分布等现有信息,利用飞机场探空气象资料研究了唐山市大气混合层高度,并建立了用于大气环境质量预测的多维多箱与高斯复合模型,结合大气环境质量标准计算了不同达标率下唐山市的大气环境容量.研究结果表明,复合模型能够综合考虑各类影响因素,对污染物浓度具有较高的预测准确度,能有效地应用于大气环境容量计算中.     

水泥土搅拌桩复合地基静载试验检测法的安全度分析

在检测水泥土搅拌桩复合地基的承载力能否达到设计要求时 ,最常用的方法是单桩静载试验法和复合地基静载试验法。工程实践中发现 ,采用这两种静载试验方法得到的检测结果存在较大差异。笔者根据水泥土搅拌桩的基本特性 ,结合工程实例 ,对这两种静载试验检测结果存在的差异及其安全度进行比较分析 ,得出单桩静载试验法结果的安全度高于复合地基试验法结果的结论 ,因此 ,提出了一些合理化建议