Validation of temporal and spatial consistency of facility- and speed-specific vehicle-specific power distributions for emission estimation: A case study in Beijing,China

Vehicle-specific power (VSP) has been found to be highly correlated with vehicle emissions. It is used in many studies on emission modeling such as the MOVES (Motor Vehicle Emissions Simulator) model. The existing studies develop specific VSP distributions (or OpMode distribution in MOVES) for different road types and various average speeds to represent the vehicle operating modes on road. However, it is still not clear if the facility- and speed-specific VSP distributions are consistent temporally and spatially. For instance, is it necessary to update periodically the database of the VSP distributions in the emission model? Are the VSP distributions developed in the city central business district (CBD) area applicable to its suburb area? In this context, this study examined the temporal and spatial consistency of the facility- and speed-specific VSP distributions in Beijing. The VSP distributions in different years and in different areas are developed, based on real-world vehicle activity data. The root mean square error (RMSE) is employed to quantify the difference between the VSP distributions. The maximum differences of the VSP distributions between different years and between different areas are approximately 20% of that between different road types. The analysis of the carbon dioxide (CO₂) emission factor indicates that the temporal and spatial differences of the VSP distributions have no significant impact on vehicle emission estimation, with relative error of less than 3%.

Implications: The temporal and spatial differences have no significant impact on the development of the facility- and speed-specific VSP distributions for the vehicle emission estimation. The database of the specific VSP distributions in the VSP-based emission models can maintain in terms of time. Thus, it is unnecessary to update the database regularly, and it is reliable to use the history vehicle activity data to forecast the emissions in the future. In one city, the areas with less data can still develop accurate VSP distributions based on better data from other areas.     

模拟阳光下Ag／I-TiO2光催化预处理山核桃加工废水

研究了在模拟太阳光下,采用银修饰的碘掺杂二氧化钛光催化剂（Ag／I—TiO2）对某食品厂山核桃加工废水进行光催化预处理的效果。结合x射线衍射（XRD）、比表面积分析（BET）、紫外-可见漫反射光谱（uV—Vis）的表征结果,来分析催化剂结构对于废水处理效果的影响。探讨了Ag含量、废水初始pH（pHi）和光照时间等因素对化学需氧量（COD）去除及水质可生化性（B／C）提高的影响。并得出适宜的反应参数为：3％Ag含量;pHi为6;光照时间为240min。在最佳条件下,COD去除率45％,废水B／C比由0．17上升到0．31。光催化氧化法能够有效降低山核桃加工废水的COD含量,并达到显著提高废水可生化性的目的。     

化工项目环境影响评价报告编写要点

化工项目因存在环境风险大,评价要求高等特点,成为各类建设项目环境影响评价中难度较大的一类。与一般建设项目相比,化工项目环境影响评价报告中的工程分析、污染治理措施、风险评价三个专题尤显重要。通过逐步分析工艺流程、细致计算物料平衡实现有序而深入的工程分析;通过合理分类、技术经济论证来确定合理有效的污染治理措施;通过分析项目特征风险因素制定高效的风险防范措施和应急预案,可高效、准确地做好化工项目的环境影响评价工作。     

保护性耕作对土壤有机碳、氮储量的影响

以辽宁彰武县保护性耕作示范推广基地土壤为研究对象,通过实地调查和取样分析,对比研究了传统犁耕和6年免耕秸秆覆盖条件下的土壤有机碳、氮储量,为广泛评价保护性耕作的土壤碳、氮截获功能和合理选择农业耕作方式提供科学依据。研究结果表明,与犁耕相比,免耕覆盖不同程度地提高了0～5cm和5～15cm土层的有机碳、氮储量,对15cm以下土层没有影响,从而增加了0～100cm土体总的有机碳、氮储量,证明了免耕覆盖的土壤碳、氮截获功能,年均截获率分别为1.37Mg·hm-2和0.84Mg·hm-2。有机碳、氮在犁耕土壤0～30cm剖面的垂直分布较为均匀,免耕覆盖后则发生明显的分层,产生表聚现象。     

Two-stage fuzzy-stochastic robust programming: a hybrid model for regional air quality management

In this study, a hybrid two-stage fuzzy-stochastic robust programming (TFSRP) model is developed and applied to the planning of an air-quality management system. As an extension of existing fuzzy-robust programming and two-stage stochastic programming methods, the TFSRP can explicitly address complexities and uncertainties of the study system without unrealistic simplifications. Uncertain parameters can be expressed as probability density and/or fuzzy membership functions, such that robustness of the optimization efforts can be enhanced. Moreover, economic penalties as corrective measures against any infeasibilities arising from the uncertainties are taken into account. This method can, thus, provide a linkage to predefined policies determined by authorities that have to be respected when a modeling effort is undertaken. In its solution algorithm, the fuzzy decision space can be delimited through specification of the uncertainties using dimensional enlargement of the original fuzzy constraints. The developed model is applied to a case study of regional air quality management. The results indicate that reasonable solutions have been obtained. The solutions can be used for further generating pollution-mitigation alternatives with minimized system costs and for providing a more solid support for sound environmental decisions.     

三峡澎溪河回水区消落带岸边土壤重金属污染分布特征

在对澎溪河回水区消落带及岸边土样品中重金属含量和样品理化性质测定的基础上,重点分析了该区域内重金属分布特征,并对重金属元素间的相关性展开研究.同时,应用地累积指数对研究区域污染现状进行评价.结果表明,消落带样品中Cu、Cr、Zn、As、Cd、Pb、Hg的平均含量分别为28.17、59.21、108.98、4.77、2.02、28.85、0.52 mg·kg-1;岸边土样品中重金属的含量范围分别为22.32、54.90、98.05、7.87、0.77、22.97、0.94 mg·kg-1.Cd是三峡库区污染较严重的重金属元素.相关性分析表明:在消落带样品中,Cd与Zn显著相关(p<0.01),Pb、Hg和Cu、As都存在显著的正相关关系,说明这4种重金属元素在接受外来污染时可能存在相似性;在岸边土样品中,Cd与Zn、Cr与Cu、As与Hg显著相关(p<0.01),Pb与Cu、Cr、Zn、Cd显著正相关,表明这几种重金属可能有着相似的来源.消落带样品重金属污染程度评价结果为:Cd>Hg>Zn>Pb>Cu>As>Cr,岸边土样品重金属污染程度评价结果为:Hg>Cd>Zn>As>Pb>Cu>Cr,Cd和Hg在个别站位达到了严重污染水平.消落带土壤受人为扰动后会成为水体的二次污染源,因此,消落带土壤重金属对水体的潜在影响不容忽视.     

半干法烟气脱硫除尘多级功能处理装置技术与应用

文中介绍了一种炉窑烟气调质、烟气除尘、烟气脱硫在一个单体结构中的一体化装置和在烟气除尘脱硫技术上的应用,并对该脱硫除尘装置与传统的半干法烟气脱硫除尘装置进行了比较。     

袋式除尘器入口烟道流场数值模拟与优化设计

采用计算流体动力学（CFD）方法,对某热电厂350 MW机组袋式除尘器入口烟道及除尘器内部的气流流场分布进行了数值模拟实验研究。识别了原烟道设计结构存在的问题,分析了造成各除尘器单元流量分配不均匀和除尘器喇叭口进口断面速度分布不均匀的原因,并提出了改变进口烟道形状,在入口烟道布置导流板的优化方案。经过模拟仿真对比,优化后并联的5个除尘器单元流量分配不均匀性得到明显改善,最大流量偏差由10.79%减小至-2.29%,且5个喇叭口进口断面速度相对均方根值均不大于0.25,满足技术规范要求。     

南水北调中线清河溶解性有机物的光降解行为

溶解性有机物(dissolved organic matter, DOM)在水环境中普遍存在,其光降解行为与种类和来源密切相关。近年来,南水北调中线工程沿线中DOM含量过高问题逐渐引起了人们对饮用水水源水质的关注。利用三维荧光光谱与紫外可见吸收光谱表征了清河段DOM在水(Water DOM, W-DOM)、底泥(sediment-derived DOM, S-DOM)、藻胞内(intracellular DOM, I-DOM)和胞外(extracellular DOM, E-DOM)这4种典型来源中的光学性质和光降解行为。结果表明,W-DOM的主要来源是藻类代谢产生的E-DOM;S-DOM的主要形成原因是藻细胞破裂释放I-DOM。DOM的光漂白主要发生在紫外区,且UV-B波段的光漂白效率大于UV-A波段。W-DOM、S-DOM和E-DOM中有色DOM(chromophoric DOM, CDOM)的降解率基本相同,为40%~50%;I-DOM中CDOM降解率相对较低,约为25%。光照可以将W-DOM、S-DOM和E-DOM中复杂的大分子物质分解成结构简单的小分子物质。CDOM中类腐殖质的光降解率比类蛋白质更高,W-DOM、S-DOM和E-DOM中CDOM与类腐殖质的光降解速率在相同时间下基本保持一致;S-DOM和E-DOM中CDOM与类蛋白质的光降解速率在相同时间下基本保持一致。以上结果反映了太阳辐射对水环境中DOM的转化和去除机理,为河流水质保护提供了理论依据。