基于高斯线源模式的主要尾气扩散模型综述

机动车排放污染扩散模式口可分为高斯模式、经验模式、数值模拟模式和箱式模式。而目前世界各国环保部门推荐应用于污染浓度预测的模式大多属于高斯扩散模式。主要介绍了基于高斯模式的几个主要扩散模型，并比较了它们的优劣，指出开发新模犁需解决的问题。     

武汉地区医疗废物处理现状及对策分析

从医疗废物的来源及其对人体健康和环境的危害入手,结合医疗废物在收集、储存、运输、处理处置过程中的特殊要求,对武汉地区医疗废物管理现状进行了全面分析.针对存在的问题,对武汉地区医疗废物的全程管理和环境无害化处理处置进行了探讨,提出了相应的建议和对策.     

湖北省环境质量和生态环境现状及防治对策

依据监测资料 ,分析了湖北的大气环境、地表水环境、降水与酸雨及城市噪声环境和生态环境的现状。并根据全省环境污染物及排放的特点 ,提出治理的对策建议。大气环境应着重二氧化硫排放负荷量大的电力、冶金等行业重点治理。水污染的治理应着重于工业污染源和生活污染源并重的特点进行治理 ,重点是汉江支流水域及“三河”、“三湖”COD的治理。生态环境保护应坚决贯彻执行湖北生态环境保护纲要 ,加大生态环境建设的投资力度     

关于规划环境影响评价的思考

环境影响评价法的实施,使中国的环境影响评价制度从建设项目环境影响评价拓展到规划环境影响评价层面,是从微观到宏观、从点到面的环境保护措施,是环境影响评价制度的最新发展.该法设专章对规划的环境影响评价做了明确的规定,要求规划和建设项目一样,必须进行环境影响评价,并规定了违反规划环评的相关法律责任.经过三年多的实施,针对实施过程中暴露出来的问题,文章从法律的角度提出了建议和对策.     

解决压载水微生物入侵性传播研究的国际动态

船舶压载水排放造成了地理性隔离水体间的生物入侵，是有害微生物传播的最主要途径。有害水生生物和病原体通过压载水传播，严重威胁侵入国的经济、环境及人类健康，已引起世界范围的广泛关注，许多国家都已开始着手调查外来生物入侵现状，研究管理措施、治理对策及方法。文中对此作一综述。     

Experiments on vertical transverse mixing in a large-scale heterogeneous model aquifer

Vertical transverse mixing is known to be a controlling factor in natural attenuation of extended biodegradable plumes originating from continuously emitting sources. We perform conservative and reactive tracer tests in a quasi two-dimensional 14 m long sand box in order to quantify vertical mixing in heterogeneous media. The filling mimics natural sediments including a distribution of different hydro-facies, made of different sand mixtures, and micro-structures within the sand lenses. We quantify the concentration distribution of the conservative tracer by the analysis of digital images taken at steady state during the tracer-dye experiment. Heterogeneity causes plume meandering, leading to distorted concentration profiles. Without knowledge about the velocity distribution, it is not possible to determine meaningful vertical dispersion coefficients from the concentration profiles. Using the stream-line pattern resulting from an inverse model of previous experiments in the sand box, we can correct for the plume meandering. The resulting vertical dispersion coefficient is approximately approximately 4 x 10(-)(9) m(2)/s. We observe no distinct increase in the vertical dispersion coefficient with increasing travel distance, indicating that heterogeneity has hardly any impact on vertical transverse mixing. In the reactive tracer test, we continuously inject an alkaline solution over a certain height into the domain that is occupied otherwise by an acidic solution. The outline of the alkaline plume is visualized by adding a pH indicator into both solutions. From the height and length of the reactive plume, we estimate a transverse dispersion coefficient of approximately 3 x 10(-)(9) m(2)/s. Overall, the vertical transverse dispersion coefficients are less than an order of magnitude larger than pore diffusion coefficients and hardly increase due to heterogeneity. Thus, we conclude for the assessment of natural attenuation that reactive plumes might become very large if they are controlled by vertical dispersive mixing.     

Indoor pollutant mixing time in an isothermal closed room: an investigation using CFD

We report on computational fluid dynamics (CFD) predictions of mixing time of a pollutant in an unventilated, mechanically mixed, isothermal room. The study aims to determine: (1) the adequacy of the standard Reynolds Averaged Navier Stokes two-equation (k−) turbulence model for predicting the mixing time under these conditions and (2) the extent to which the mixing time depends on the room airflow, rather than the source location within the room. The CFD simulations modeled the 12 mixing time experiments performed by Drescher et al. (Indoor Air 5 (1995) 204) using a point pulse release in an isothermal, sealed room mechanically mixed with variable power blowers. Predictions of mixing time were found in good agreement with experimental measurements, over an order of magnitude variation in blower power. Additional CFD simulations were performed to investigate the relation between pollutant mixing time and source location. Seventeen source locations and five blower configurations were investigated. Results clearly show large dependence of the mixing time on the room airflow, with some dependence on source location. We further explore dependence of mixing time on the velocity and turbulence intensity at the source location. Implications for positioning air-toxic sensors in rooms are briefly discussed.     

The influence of meteorological conditions and stringent emission control on high TSP episodes in istanbul

Istanbul has faced serious air pollution problems since the mid-80s. This is mainly due to particulate air pollution coming from poor quality lignite in areas, which are heavily populated and industrialized. As a consequence of severe air pollution problems, stringent control on the emissions in the city started in the year of 1994. In this work, in order to study the relationship between emissions and meteorological conditions, an assessment of air pollution episodes and air pollution potential in the city is presented for the terms at the changed emission schedule as the influence of an emission reduction strategy. The influence of meteorological conditions on the TSP (total suspended particulates) levels is considered for two consecutive winter periods. On this occasion, the city has faced different TSP levels and episode characteristics depending on stringent emission reductions covering the banned, poor-quality lignite and fuel switching. For this purpose, climatological conditions and air quality analyses were performed.     

The Modelling of Turbulence from Traffic in Urban Dispersion Models — Part I: Theoretical Considerations

The modelling of pollutant dispersion at the street scale in an urban environment requires the knowledge of turbulence generated by the traffic motion in streets. In this paper, a theoretical framework to estimate mechanical turbulence induced by traffic in street canyons at low wind speed conditions is established. The standard deviation of the velocity fluctuations is adopted as a measure of traffic-produced turbulence (TPT). Based on the balance between turbulent kinetic energy production and dissipation, three different parameterisations for TPT suitable for different traffic flow conditions are derived and discussed. These formulae rely on the calculations of constants that need to be estimated on the basis of experimental data. One such estimate has been made with the help of a wind tunnel data set corresponding to intermediate traffic densities, which is the most common regime, with interacting vehicle wakes.     

On the estimation of overwater buoyancy length from routine measurements

The stability parameter (z/L, where z is the height and L the buoyancy length) is an essential parameter in atmospheric boundary layer studies. From routine measurements, the bulk Richardson number (R_b) is usually computed. On the basis of appropriate field measurements at sea, it is shown that z/L = A R_b where A = 10.2 (with R ² = 0.97) for unstable and 6.3 (with R ² = 0.97) for stable conditions, respectively. It is also demonstrated that the proposed simplified equations are in excellent agreement with those more complicated formulations.