大气污染及其防治技术与市场

在简要论述国内外大气污染现状的基础上，对大气污染的防治技术，尤其是针对煤炭工业大气污染防治技术作了详细分析，为了使科学技术尽快转化为生产力，还对大气污染防治技术市场的发展趋势作了预测。     

工程项目大气环境影响评价的扩散模式计算

工程项目对大气污染影响的定量预测是通过大气扩散模式计算来实现的。本文根据近年实践经验，对大气扩散模式的选用、扩散参数的确定及修正、地面长短期浓度的计算和计算结果的验证等方面作了较为系统的介绍，经供环境影响评价工作者参考。     

株洲市清水塘地区大气中SO_2污染及防治对策的研究

本文全面扼要地叙述了株洲市清水塘地区大气污染控制研究的全过程。根据污染源调查以及模式的实际应用,将一些大气扩散研究的方法和大气污染防治的模式进行了比较,并提出了综合治理的防治对策。     

基于元胞自动机的大气扩散模型及GIS可视化

基于对目前常用大气扩散模型以及大气扩散特性的分析,采用通过局部转移规则实现宏观涌现的复杂系统建模工具-元胞自动机来建立时空动态的大气扩散模型。结合MATLAB的矩阵运算能力和GIS的栅格数据处理能力进行模型的实现与可视化。仿真结果表明,所建立的模型不仅能动态模拟大气污染的高斯扩散等常用扩散模式,通过合理的模型参数设定也可动态模拟非常规扩散模式,如模拟时段内风向风速发生多次变化或者模拟区域存在湍流等条件下的扩散过程,得到准确的污染物时空动态分布,可望为大气污染防治提供决策支持。     

工业点源大气污染扩散空间信息系统

开发了一个基于高斯扩散的大气污染扩散空间信息系统,用于模拟工业点源污染对区域大气质量的影响。该工业点源污染模型包括工业点源数据库、扩散参数、气象条件和大气质量评价4个主要数据库。用该模型计算上海市主要工业区的SO2排放,结果表明,该模型为模拟SO2污染扩散提供了一个有效便捷的方法。     

燃煤锅炉烟囱高度复核计算方法应用实例分析

主要结合地区大气污染状况，气象条件，污染物排放参数及环境控制目标等因素，运用大气环境影响评价中大气扩散有关模式及理论，通过实例分析对燃煤锅炉烟囱设计高度进行复核计算，使锅炉排放污染物满足地区环境控制目标需要。     

大气污染预测预报

大气污染和水污染不同,每当出现不利污染物扩散的天气形势,可能在很短时间内(几天内或甚至一夜之间),造成严重烟雾事件。因此,大气污染的预报是相当重要的工作,要预报准确,须选定适当预报指标。     

某Y型峡谷大气污染水平与气象因素初步探讨

一、引言 大气污染可看作是污染源所排出的污染物和对污染物起着扩散稀释作用的大气,以及承受污染的物体三者相互关联所产生的一种效应。污染物的浓度在时空分布上要受到气象条件的控制。目前,平原城市大气污染     

基于Fluent城市大气污染物扩散数值模拟

城市大气污染问题已经引起广泛的关注,其中对城市中大气污染物的迁移扩散过程还需进一步研究。为了探究城市复杂地形下大气污染物扩散预测的新模式,采用计算流体力学方法,建立了数值预测模型,构造出水平均匀的大气边界层模拟风场;进一步对建筑物影响下的大气污染物扩散过程进行了模拟,并与实验结果进行了对比。结果表明:数值模拟结果与实验结果基本吻合,计算流体力学方法可用于城市复杂地形下大气污染问题的研究工作;模拟结果与湍流模型的选取和湍流施密特数的设置有密切关系;采用SST k-ω湍流模型对此类问题较适宜,随着湍流施密特数的增大,扩散范围逐渐增大。     

基于GIS城市机动车尾气扩散迁移研究

中国城市大气污染日趋严重，汽车尾气污染所占比重越来越大。交通、道路、管制及气候条件等是影响城市机动车尾气排放的主要因素。本文根据机动车尾气研究的实际，研究了专题MGIS数据库结构， 并以广州为例，建立了基于GIS的城市机动车尾气扩散迁移预报系统，在此基础上实现了机动车尾气污染状况的可视化。     

Modeling of air sparging of VOC-contaminated soil columns

Air sparging is a remediation technology currently being applied for the restoration of sites contaminated with volatile organic compounds (VOCs). Attempts have been made by various researchers to model the fate of VOCs in the gas and liquid phase during air sparging. In this study, a radial diffusion model with an air–water mass transfer boundary condition was developed and applied for the prediction of VOC volatilization from air sparging of contaminated soil columns. The approach taken was to use various parameters such as mass transfer coefficients and tortuosity factors determined previously in separate experiments using a single air channel apparatus and applying these parameters to a complex system with many air channels. Incorporated in the model, is the concept of mass transfer zone (MTZ) where diffusion of VOCs in this zone was impacted by the volatilization of VOCs at the air–water interface but with negligible impact outside the zone. The model predicted fairly well the change in the VOC concentrations in the exhaust air, the final average aqueous VOC concentration, and the total mass removed. The predicted mass removal was within 1% to 20% of the actual experimental mass removed. The results of the model seemed to suggest that air-sparged soil columns may be modeled as a composite of individual air channels surrounded by a MTZ. For a given air flow rate and air saturation, the VOC removal was found to be inversely proportional to the radius of the air channel. The approach taken provided conceptual insights on mass transfer processes during air sparging operations.     

Analysis of policy options for promotion of clean and energy efficient technologies in the transport sector in Beijing

As a extra-large city in China, Beijing faces a serious problem with air pollution. In 1998, a package of air pollution control measures was announced by local government. However in order to reach environment target, further policy options have to be explored. Based on previous studies on technology choices for urban transport in Beijing, this paper presents a policy assessment to examine these options. A methodology framework using criteria for policy evaluation was used in the assessment. Here diesel-car, Compressed Natural Gas (CNG) vehicle and Mass Railway based Transport (MRT) were selected, and barriers to their diffusion were identified. For each barrier, a group of policy options to remove the barrier was evaluated by five criteria. A ranking of these policy options is given in this paper.     

International Diffusion of Open Path FTIR Technology and Air Monitoring Methods: Taiwan (Republic of China)

Abstract

International cooperation and diffusion of environmental technologies is a central goal of the U.S. EPA Environmental Technology Initiative, and is of great interest to many countries. One objective is to exchange knowledge and skills concerning new monitoring technologies. In this case, the technology was open path Fourier Transform Infrared Spectrometry (op-FTIR).

Taiwan is a high-technology, newly industrialized country. Because of air pollution problems, it is interested in obtaining skills, knowledge, and instrumentation for monitoring air pollutants. In April 1994, the Industrial Technology Research Institute, Center for Industrial Safety and Health Technology (ITRI/CISH) in Hsinchu, Taiwan, requested intensive training in op-FTIR. Training was held between September 30,1994 and October 29,1994.

During the stay, the instructor provided intensive training on op-FTIR theory as well as an introduction to available instrumentation and software. The training concluded with a field demonstration of the instrumentation in a manufacturing facility. This report gives an overview of the training methods, structure, and materials in the op-FTIR training course. It will also address various problems encountered while teaching this course. In addition, the potential use for this technology in industry as well as by the Taiwanese government will be explained.     

海岸地区基于AERMOD的热力内边界层对大气污染物扩散影响的模拟研究

海岸地区热力内边界层(TIBL)对大气污染物扩散具有重要影响。选取杭州湾地区某区域为模拟区,采用一个TIBL高度的简单计算模式模拟模拟区的TIBL高度,将其耦合到空气质量模式AERMOD中,并对AERMOD的相关模块和参数进行了相应的修改,再分别利用原AERMOD和改进后的AERMOD,模拟了不同污染源情景下的大气污染物地面浓度分布。结果表明,在多数情况下,由于TIBL对于大气污染物扩散空间的限制,大气污染物的地面最大浓度有所升高,地面浓度的高值区范围也有所增加,具体影响特征取决于污染源与TIBL的相对高度以及污染源距离海岸的相对位置。     

Numerical Modeling of the Transport Diffusion and Deposition of Pollutants For Regions and Extended Scales

There is an emerging need to develop understanding and predictive capability for the transport, diffusion, and deposition of pollutants on regional and extended spatial scales. Some recent developments in the numerical simulation of pollutant transport and diffusion are reviewed and summarized herein, including case studies of model validation whenever’available. The efforts reported include: (a) the development and verification of a Lagrangian large-cloud diffusion code for intermediate to extended scales; (b) a hybrid Lagrangian-Eulerian transport-diffusion code for simulating pollutant distributions in transient stratified shear flow; (c) a meteorological submodel for determining a mass-consistent wind field on a regional scale suitable as input to a regional air pollution model; and (d) the development and initial verification of a multi-box regional air pollution model for the San Francisco Bay Area utilizing a mass-consistent wind field submodel.     

Experimental investigation of pneumatic soil vapor extraction

Soil Vapor Extraction (SVE) is a common remediation technique for removing volatile organic compounds from unsaturated contaminated soils. Soil heterogeneities can however cause serious limitations to the applicability of SVE due to air bypassing low permeable areas of the soil, leading to diffusion limitation of the remediation. To enhance removal from areas subject to diffusion limitation a new remediation technique, pneumatic soil vapor extraction, is proposed. In contrast to traditional SVE, in which soil vapor is extracted continuously by a vacuum pump, pneumatic SVE is based on enforcing a sequence of large pressure drops on the system to enhance the recovery from the low-permeable areas. The pneumatic SVE technique was investigated in the laboratory using TCE as a model contaminant. 2D-laboratory tank experiments were performed on homogeneous and heterogeneous sand packs. The heterogeneous packs consisted of a fine sand lens surrounded by a coarser sand matrix. As expected when using traditional SVE, the removal of TCE from the low permeable lens was extremely slow and subject to diffusion limitation. In contrast when pneumatic venting was used removal rates increased by up to 77%. The enhanced removal was hypothesized to be attributed to mixing of the contaminated air inside the lens and generation of net advective transport out of the lens due to air expansion.     

Removal ratio of gaseous toluene and xylene transported from air to root zone via the stem by indoor plants

This work was designed to investigate the removal efficiency as well as the ratios of toluene and xylene transported from air to root zone via the stem and by direct diffusion from the air into the medium. Indoor plants (Schefflera actinophylla and Ficus benghalensis) were placed in a sealed test chamber. Shoot or root zone were sealed with a Teflon bag, and gaseous toluene and xylene were exposed. Removal efficiency of toluene and total xylene (m, p, o) was 13.3 and 7.0 μg·m^?3·m^?2 leaf area over a 24-h period in S. actinophylla, and was 13.0 and 7.3 μg·m^?3·m^?2 leaf area in F. benghalensis. Gaseous toluene and xylene in a chamber were absorbed through leaf and transported via the stem, and finally reached to root zone, and also transported by direct diffusion from the air into the medium. Toluene and xylene transported via the stem was decreased with time after exposure. Xylene transported via the stem was higher than that by direct diffusion from the air into the medium over a 24-h period. The ratios of toluene transported via the stem versus direct diffusion from the air into the medium were 46.3 and 53.7 % in S. actinophylla, and 46.9 and 53.1 % in F. benghalensis, for an average of 47 and 53 % for both species. The ratios of m,p-xylene transported over 3 to 9 h via the stem versus direct diffusion from the air into the medium was 58.5 and 41.5 % in S. actinophylla, and 60.7 and 39.3 % in F. benghalensis, for an average of 60 and 40 % for both species, whereas the ratios of o-xylene transported via the stem versus direct diffusion from the air into the medium were 61 and 39 %. Both S. actinophylla and F. benghalensis removed toluene and xylene from the air. The ratios of toluene and xylene transported from air to root zone via the stem were 47 and 60 %, respectively. This result suggests that root zone is a significant contributor to gaseous toluene and xylene removal, and transported via the stem plays an important role in this process.     

On efficient numerical solution of one-dimensional convection–diffusion equations in modelling atmospheric processes

A new approach is proposed to the numerical solution of one-dimensional convection–diffusion equations that arise in modelling atmospheric processes and air pollution modelling. The technique is based on upstream-type difference approximations for first-order derivatives and non-standard difference approximations for second-order derivatives of convection–diffusion equations. This approach leads to the significant qualitative improvements in the numerical solutions behaviour. The relative contribution of convection and diffusion is directly incorporated into the corresponding numerical scheme in such a way that large spatial grids can be taken without affecting solution stability. The method is compared with the contemporary computational schemes for solving problems with severe internal and boundary gradients and is shown to be stable and computationally efficient. The results of a numerical experiment are given.     

Numerical simulation of air pollution in urban areas: Model development

A three-dimensional, grid-based numerical air pollution model for the estimation of air pollutant concentrations in an urban area is developed. Based on the continuity equation, the modeling system incorporates the combined influences of advective transport, turbulent diffusion, chemical transformation, source emissions and surface removal of air contaminants. Recent developments in plume rise and plume penetration processes, objective wind field analysis procedures and numerical solution techniques incorporated into the model are described.     

Deposition of particulate matter in diffusion tube samplers for the determination of NO2 and SO2

The applicability of tube-like diffusion samplers for the determination of ambient air concentrations of sulfur dioxide and nitrogen dioxide was evaluated. The diffusion tubes were made from polyethylene and triethanolamine was used as an absorbent. Artifacts due to the deposition of gaseous or particulate compounds to the tube walls were considered. With respect to sampling of nitrogen dioxide no interference by the tube walls could be observed. The determination of sulfur dioxide was strongly biased by the collection of particulate sulfate at the entrance part of the tube and along the tube walls. This effect leads to a large overestimation of the average air concentrations compared with fluorescence monitors.