The Development of a Model to Examine Source-Receptor Relationships for Visibility on the Colorado Plateau

This paper describes the development and application of the Visibility and Haze in the Western Atmosphere (VISHWA) model to understand the source-receptor relationships that govern chemical species relevant to visibility degradation in the western United States. The model was developed as part of a project referred to as Visibility Assessment for Regional Emission Distributions (VARED), the objective of which is to estimate the contributions of various geographical regions, compounds, and emission

sources to light scattering and absorption by particles on the Colorado Plateau.

The VISHWA model is a modified version of a comprehensive Eulerian model, known as the Acid Deposition and Oxidant Model.1 The modifications were designed to obtain the computational efficiency required to simulate a one-year period at about 1/25th of real time, and at the same time incorporate mechanistic features relevant to realistic modeling of the fate and transport of visibility degrading species. The modifications included use of a condensed chemical mechanism; incorporation of reactions to simulate the formation of secondary organic particles; and use of a semi-Lagrangian advection scheme to preserve concentration peaks during advection.

The model was evaluated with 1992 air quality data from Project MOHAVE (Measurements of Haze and Visual Effects) intensive experiments. An important conclusion of this evaluation is that aqueous-phase oxidation of SO2 to sulfate in nonprecipitating clouds makes a significant contribution to observed sulfate levels during winter as well as summer. Model estimates of ambient sulfate

for the winter intensive were within a factor of 2 of the observations for 75% of the values. The corresponding statistic for the summer intensive was 90%. Model estimates of carbon were within a factor of 2 of the limited set of observations.     

Evaluation of Wind Fields Used in Grand Canyon Visibility Transport Commission Analyses

ABSTRACT

The Grand Canyon Visibility Transport Commission (GCVTC) was established by the U.S. Congress to assess the potential impacts of projected growth on atmospheric visibility at Grand Canyon National Park and to make recommendations to the U.S. Environmental Protection Agency on what measures could be taken to avoid such adverse impacts. A critical input to the assessment tool used by the commission was three-dimensional model-derived wind fields used to transport the emissions. This paper describes the evaluation of the wind fields used at various stages in the assessment. Wind fields evaluated included those obtained from the Colorado State University Regional Atmospheric Modeling System (RAMS), the National Meteorological Center's Nested Grid Model (NGM), and the National Oceanic and Atmospheric Administration's Atmospheric Transport and Dispersion (ATAD) trajectory model. The model-derived wind fields were evaluated at multiple vertical levels at several locations in the southwestern United States by determining differences between model predicted winds and winds that were measured using radiosonde and radar wind profiler data. Model-derived winds were also evaluated by determining the percent of time that they were within acceptable differences from measured winds.

All models had difficulties, generally meeting the acceptable criteria for less than 50% of the predictions. The RAMS model had a persistent bias toward southwesterly winds at the expense of other directions, especially failing to represent channeling by north-south mountain ranges in the lower levels. The NGM model exhibited a substantial bias in the summer months by extending northwesterly winds in the eastern Pacific Ocean well inland, in contrast to the observed southwesterlies at inland locations. The simpler ATAD trajectory model performed somewhat better than the other models, probably because of its use of more upper air sites. The results of the evaluation indicated that these wind fields could not be used to reliably predict source-receptor impacts on a particular day; thus, seasonally averaged impacts were used in the GCVTC assessment.     

从循环经济视角看高职院校的专业长负责制

循环经济作为一种新的、科学的发展观,要求高等职业教育必须建立全新的适应循环经济发展的人才培养模式,在专业建设中凸显循环经济理念,用专业长负责制实现专业建设与社会需求的联通。以中国环境管理干部学院为例,以精品课建设为载体,从循环经济视角探讨了专业长负责制的推行,以及取得的成效。     

十三种农村水资源保护措施适宜性评价

依据“源头—过程—末端”防控体系对13种常见的农村水资源保护措施进行分类,在此基础上,建立AHP评价模型,根据影响水资源保护措施适宜性的13个指标对各项措施进行适宜性评价.结果表明:污染物去除率、出水水质、建设成本及运行维护这4个因素具有较高权重值,应在实际运用中优先考虑.源头控制措施中保护性耕作与“一池三改”技术可以作为首选措施;在过程控制措施中,土地处理技术措施具有较好的适宜性;在选取末端处理措施的时候,必须优先考虑温度及建设成本的影响.     

Particulate matter modeling in the Los Angeles basin using SAQM-AERO

The SARMAP air quality model, enhanced with aerosol modeling capability, and its associated components were developed to understand causes of ozone (O3) and particulate matter exceedances in the San Joaquin Valley of California. In order for this modeling system to gain increasing acceptance and use in guiding air quality management, it is important to assess how transportable this modeling system is across geographic domains. We describe the first application of the modeling system outside the "home" domain for which it was developed and evaluated. We have chosen the August 27-28, 1987, intensive monitoring period of the Southern California Air Quality Study to evaluate the performance of the modeling system and to assess its sensitivity to emission control options. The predicted surface concentrations of O3 and other gas-phase species were spatially and temporally correlated with measured data. The fractional normalized absolute error was 0.32 to 0.36 for O3, and somewhat larger for other species. The fractional normalized bias for O3 on August 27 and 28, 1987, was 0.02 to 0.04. The simulated PM2.5 mass and constituent species concentrations reproduced the magnitude and variability of the observed daytime concentrations at most locations; however, nighttime PM2.5 concentrations were overpredicted by the model. The model's response to emission control options was consistent with other models of the same genre.     

普通话与口才训练教学中应加强人文素质教育

经济社会的飞速发展并没有带来人文精神的匹配升华,新生代大学生无法和社会历史融合最重要的原因就是人文素质教育的缺乏。应使普通话与口才训练成为大学生人文素质教育的有效载体和实践途径,输送给学生口语交际知识和人文素质的双重养分。     

朋辈教育在高校思想政治工作中的应用实践

朋辈群体是影响大学生思想形成和发展的重要因素。在大学生思想政治工作中构建朋辈教育体系,通过设立班主任导生、政治导生、心理辅导员等形式,依靠朋辈群体开展学生思想政治教育工作,是做好学生教育和管理工作的一个独特而有效的切入点。     

Analysis of organic nitrogen removal in municipal wastewater by reverse osmosis

The results of a pilot study that was conducted to determine the total nitrogen removal by the reverse osmosis process are presented. The organic nitrogen removal rates are compared with removals observed from three full-scale reverse osmosis facilities and four pilot studies. The results of this analysis suggest that organic nitrogen removal is variable and that reverse osmosis may not consistently produce total nitrogen levels less than 1.0 mg/L without additional treatment. Three hypotheses to explain the variability in organic nitrogen removal in the different data sets are presented.     

硅酸钙微粉吸附预处理焦化废水中COD和NH3-N的实验研究

首次将固体废弃物硅酸钙微粉用于焦化废水的预处理,通过静态和动态吸附实验评价了硅酸钙微粉对COD和NH3-N的去除效果。结果表明:对COD和NH3-N产生吸附作用的有效组分为硅酸钙微粉的水解产物H2SiO3电离产生的HSiO3-和SiO23-;pH通过影响硅酸钙微粉水解反应以及水解产物H2SiO3和有机物、NH3的电离反应来影响去除率。在进水pH=7.00、硅酸钙微粉投加量为170g/L、振荡时间为75min的条件下,静态吸附实验中COD和NH3-N的去除率分别达16.1%和27.1%;经直径为10mm、高度为300mm的硅酸钙吸附柱预处理,动态吸附实验中COD和NH3-N的去除率分别可达58.9%和35.9%。