不同因素对街谷内污染物扩散的影响研究

近年来,机动车尾气排放已经成为大气颗粒物的主要来源之一.某些类型的城市街道布局不利于污染物的扩散.街道峡谷是最典型的污染物聚集地和对人类危害最大的形态之一,影响污染物扩散的因素包括高架桥、隔声屏障、绿色植被、太阳辐射、风向、建筑物屋顶形状等六个方面.本文主要根据现有的一些研究,系统地回顾了近年来学者们对于影响街道峡谷内...     

AERMOD模型中城市效应对某化工项目大气预测的影响规律

本文主要研究大气预测模型AERMOD的参数城市效应对大气环境影响预测结果的影响。按照考虑城市效应、未考虑城市效应两种情景进行模拟预测,结果表明,考虑城市效应的大气模拟预测结果比未考虑城市效应的高,城市效应对最大地面浓度有一定的影响。环评预测时应当根据项目周边实际情况进行考虑,才能真实客观反映大气环境影响程度。     

污染源位置对街道峡谷内污染物扩散分布的影响研究

文章采用CFD(计算流体力学)数值模拟的研究方法,探究了孤立街道峡谷内不同屋顶形状和污染源位置的数值仿真模型。针对平顶-三角形屋顶和三角形-平顶屋顶,以及3种污染源,共6种工况进行研究。结果表明相同屋顶形状的污染源位置变化对于气流运动无改变,对于污染物浓度相对低的壁面浓度值改变很小,但对污染物浓度相对高的壁面浓度有较大影响,街谷上部靠近屋顶位置受污染源位置的影响逐步减小。     

北京城区机动车道降雨径流水质调研及特性分析

机动车道径流污染是城市面源污染的重要组成部分。通过对北京城区机动车道径流进行调研,对径流水质状况及特性进行了分析。结果表明：路面径流中常规污染物的平均浓度均超出《地表水环境质量标准》GB3838--2002）中V类水体标准,各污染物与ss的相关性较好,径流可生物降解性较差,沉淀性较好;降雨特性、交通流量、道路周围土地利用类型及环境特征对径流水质存在影响;污染物的浓度初期效应明显;污染负荷排放的初期效应程度较小,且易溶性污染物更易产生。研究结论可为城市路面径流污染控制技术的实施及路面径流资源化利用提供依据。     

垃圾衍生燃料在流化床焚烧时NO和N_2O排放特性研究

在实验室规模的内循环流化床内进行城市垃圾焚烧实验,在线测量焚烧过程中NO和N_2O的排放特性,研究空气过量系数、添加钙基脱硫剂及城市垃圾与半焦混烧时不同混烧率对NO和N_2O排放特性的影响。研究结果表明,城市垃圾在流化床焚烧过程中随空气过量系数增加,NO和N_2O排放浓度都增加,且NO增加幅度大于N_2O;随Ca/(S+0.5 Cl)摩尔比增加,N_2O生成量逐渐下降;随着混烧燃料中城市垃圾混烧率增加,烟气中NO排放浓度增加,N_2O排放浓度逐渐下降。     

汽油车CO和HC排放浓度超标的影响因数分析

近些年,我国城市的大气污染达到了较为严重的程度。在机动车保有量持续快速增长的情况下,机动车污染物排放对我国大气质量,特别是城市大气质量形成了严重威胁。这些大气污染问题与汽车尾气排放具有较高的相关性。大量的汽车尾气排放导致空气中污染物浓度过高,不仅影响了城市居民的身体健康,也对全球气候产生了不利影响。因此汽油车经检测,当CO和HC排放浓度超过标准规定的限值时,要查找出具体的影响因素并进行调整。其影响因数分析如下：     

人为源氨排放系数的研究

氨的产生、迁移、清除和净化一直是人们关注和研究的课题,近年来广东省珠江三角洲城市人为源氨的排放情况将不容忽视。通过开展珠江三角洲一城市全面的氨排放源调查研究,建立涉及氨排放的各个源的氨排放清单和计算氨的排放系数,为制定地区空气质量保障方案做充分的准备,具有十分重要的意义。     

基于故障树方法的机动车燃油大气环境风险评价：以杭州市为例

由于城市化、工业化和机动车数量的快速增长,灰霾天气已成为中国许多大城市亟待解决的严重环境污染问题。大量石油燃料消耗产生的机动车尾气排放可能是引起城市灰霾污染的一个关键因素。以长江三角洲的代表性城市杭州市为具体案例,探索将安全工程领域的故障树方法应用在机动车燃油尾气排放大气环境风险评价和与灰霾天气的致因机理分析上。通过辨识导致城市机动车尾气过量排放的关键风险因子,构建了杭州市“灰霾天气–机动车尾气过量排放”的故障树。另外采用结构、概率以及临界重要度分析,对关键风险因子对顶上事件“灰霾天气–机动车尾气过量排放”的贡献和影响程度进行了定性和定量分析。分析结果表明,过量机动车使用,严重的交通堵塞、高污染机动车的不当使用以及监管不严是对杭州市机动车尾气过量排放影响较大的关键风险因子。可为城市机动车燃油环境风险因子评价以及管理提供一种简洁有效的方法和思路。     

基于环境统计分析的全国主要城市空气质量浅析

文章利用2009年全国31个主要城市年平均空气质量数据,运用主成分法评价各城市空气质量,得到海口、拉萨、南宁空气质量最好,乌鲁木齐最差;运用因子分析法影响各城市空气质量的主要污染源得出北方城市以燃煤排放为主,南方城市以汽车尾气排放为主;运用Bayes判别法得到深圳2009年空气质量为二级。     

基于故障树方法的机动车燃油大气环境风险评价:以杭州市为例

由于城市化、工业化和机动车数量的快速增长,灰霾天气已成为中国许多大城市亟待解决的严重环境污染问题。大量石油燃料消耗产生的机动车尾气排放可能是引起城市灰霾污染的一个关键因素。以长江三角洲的代表性城市杭州市为具体案例,探索将安全工程领域的故障树方法应用在机动车燃油尾气排放大气环境风险评价和与灰霾天气的致因机理分析上。通过辨识导致城市机动车尾气过量排放的关键风险因子,构建了杭州市"灰霾天气–机动车尾气过量排放"的故障树。另外采用结构、概率以及临界重要度分析,对关键风险因子对顶上事件"灰霾天气–机动车尾气过量排放"的贡献和影响程度进行了定性和定量分析。分析结果表明,过量机动车使用,严重的交通堵塞、高污染机动车的不当使用以及监管不严是对杭州市机动车尾气过量排放影响较大的关键风险因子。可为城市机动车燃油环境风险因子评价以及管理提供一种简洁有效的方法和思路。     

Long-term sensor measurements of lung deposited surface area of particulate matter emitted from local vehicular and residential wood combustion sources

Abstract

Lung deposited surface area (LDSA) is a relatively new metric that has been argued to be more accurate at predicting health effects from aerosol exposure. For typical atmospheric aerosol, the LDSA concentration depends mainly on the concentration of ultrafine particles (e.g. vehicular exhaust emissions and residential wood combustion) and therefore optical methods cannot be used to measure and quantify it. The objective of this study was to investigate and describe typical characteristics of LDSA under different urban environments and evaluate how a diffusion charging-based Pegasor AQ Urban sensor (Pegasor Ltd., Finland) can be used as an alternative to optical sensors when assessing local combustion emissions and respective LDSA concentrations. Long-term (12?months) sensor measurements of LDSA were carried out at three distinctly different measurement sites (four sensor nodes) in the Helsinki metropolitan area, Finland. The sites were affected mainly by vehicular exhaust emission (street canyon and urban background stations) and by residential wood combustion (two detached housing area stations). The results showed that the accuracy of the AQ Urban was good (R² = 0.90) for the measurement of LDSA when compared to differential mobility particle sizer. The mean concentrations of LDSA were more than twice as high at the street canyon (mean 22 µm² cm^?3) site when compared to the urban background site (mean 9.4 µm² cm^?3). In the detached housing area, the mean concentrations were 12 µm² cm^?3, and wood combustion typically caused high LDSA peaks in the evenings. High correlations and similar diurnal cycles were observed for the LDSA and black carbon at street canyon and urban background stations. The utilization of a small-scale sensor network (four nodes) showed that the cross-station variability in hourly LDSA concentrations was significant in every site, even within the same detached housing area (distance between the two sites ～670?m).     

基于波理论的涡街流量计雾状流测量模型

建立了雾状流条件下涡街流量计的修正模型。雾状流中液相的存在会导致涡街流量计的测量误差,通过将以往研究者在单相流中对Karman涡街现象的认识及取得的研究成果作为基础,并结合实验流体本身所具有的动力特点,利用Karman涡街波传递的理论分析了非定常不稳定的雾状流流场中的Karman涡街现象,构建了双向耦合的气液两相流动力学模型。试验结果显示,当液相体积含率从0～0.13%变化时,模型修正后的结果与实际值较为接近。     

城市道路栏杆清洁机的研制

国内外城市道路栏杆多为铁栅栏 ,长度数公里到数百公里不等 ,形状各异 ,清洁工作十分困难 .目前多为人工擦洗 ,劳动强度大、效率低、费用高 .提出了一种机械化清洗城市道路栏杆的新方法———道路栏杆清洁机 ,清洁机由清水冲洗系统和旋转毛刷系统两部分组成 .压力水通过一组喷嘴首先冲掉栏杆上的浮尘 ,旋转毛刷擦去栏杆上的附着物 ,再用压力水对刷过的栏杆进行冲洗 ,达到比较完全清洁道路栏杆之目的 .研究表明 ,本清洁机原理可行 ,工作可靠 ,结构简单 ,使用方便 ,效果好 ,可作为配套设备安装在洒水车或高压清洗车上 ,在全国各大、中城市具有广阔的推广应用前景 .     

Dynamics and dispersion modelling of nanoparticles from road traffic in the urban atmospheric environment—A review

Reducing exposure to atmospheric nanoparticles in urban areas is important for protecting public health. Developing new or improving the capabilities of existing dispersion models will help to design effective mitigation strategies for nanoparticle rich environments. The aims of this review are to summarise current practices of nanoparticle dispersion modelling at five local scales (i.e. vehicle wake, street canyons, neighbourhood, city and road tunnels), together with highlighting associated challenges, research gaps and priorities. The review begins with a synthesis of available information about the flow and mixing characteristics in urban environments which is followed by a brief discussion on dispersion modelling of nanoparticles. Further sections cover the effects of transformation processes in dispersion modelling of nanoparticles, and a critical discussion on associated structural and parametric uncertainties in modelling. The article concludes with a comprehensive summary of current knowledge and future research required on the topic areas covered.Appropriate treatment of transformation processes (i.e. nucleation, coagulation, deposition and condensation) in existing dispersion models is essential for extending the applicability of gaseous dispersion models to nanoparticles. Some modelling studies that consider the particles down to 1 nm size indicate importance of coagulation and condensation processes on street-scale modelling whereas others neglecting either sub-10 nm particles or Van der Waals forces along with fractal geometry suggest to discard these processes due to negligible effects on particle number and size distributions. Further, it is important to consider those transformation processes e.g. at city scale or in road tunnels because of the much longer residence time or much higher concentration levels compared to the street scale processes. Structural and parametric uncertainties affect the modelled results considerably. In particular, parametric uncertainty in the form of particle number emission factors appears to be the most significant due to considerably large variations in their estimates. A consistent approach to the use of emission factors, appropriate treatment of transformation processes in particle dispersion models and the evaluation of model performance against measured data are essential for producing reliable modelled results.     

Color‐emotion associations,designing color schemes for urban environment‐architectural settings

Color in urban design has become an important issue, each city may present different colors which help to define and describe its architectural features. In the study, color in urban design with architectural setting is studied, façade colors are analyzed with a specific emphasis on the following research questions; “Can color schemes be designed in respect to color‐emotion associations? ” and “Are color‐emotion associations affective while designing architectural setting‐urban environment?.” Non‐color experts, 170 people, from different European and non‐European countries were asked to match the most appropriate adjectives with the given street views in accordance to their color schemes. In the first step, the effect of color is identified in relation to architectural environment‐urban setting, second the relative effect of color is studied as a component of the material. A categorical specification on color cognition and linguistic level of representation is attempted. The results can be a starting point to highlight the importance of preparing color schemes in regard to color‐emotion associations. Abstract color schemes may also provide us an idea about image setting, especially at design process stage. In the study, keywords are linked as environment‐response pairs; such as quiet, calming, lively, exclusive, reserved, and natural. Human psychophysical structure such as “warm‐cool,” “heavy‐light” in regard to visualizing certain colors are evaluated and described in terms of building materials.     

基于双MCU结构的路灯远程监控终端设计

设计一种双MCU结构的路灯远程监控终端。该终端利用GPRS和电力载波通信技术,实现路灯监控的远程通信连接;并采用复合控制策略实现路灯精准控制。现场应用测试表明该监控终端性能稳定,实现了路灯监控的动态化远程管理。     

冻融作用对土壤中氨氮的影响

我国对土壤冻融作用研究主要集中在自然环境条件下冻土环境变化.本文是对齐齐哈尔市南郊污水处理厂附近的氧化塘中的冻融土壤进行研究,论述了冻融作用对土壤中氨氮的影响.研究表明,季节性冻融作用对土壤氨氮有较大影响.     

离散液相对涡街流量计测量误差影响的实验研究

研究雾状流条件下,离散液相对涡街流量计测量误差的影响。对实验结果的进一步分析表明,均相流模型并不适合于涡街流量计在雾状流中的测量。实验在多相流装置上口径为50mm的水平管段上进行,在保证气相流量不变的条件下,研究了0-0．1％液相含率范围内涡街流量计的测量误差,涡街产生的频率值是通过对模拟信号进行傅立叶变换来获取的。利用数值仿真的方法研究了旋涡发生体上涡量场的变化,理论上解释了雾状流中涡街流量计测量误差产生的原因。     

生态城市的研究进展

随着社会发展,城市环境日益恶化,如何实现可持续发展是全球的重要议题。介绍了生态城市的主要内容、发展过程、国内外关于生态城市的理论研究与实践、国外生态城市发展对国内的影响,并展望了其发展前景。     

几种理化因子对狂犬病病毒分离株感染力影响的再检测

目的 分析几种理化因子对狂犬病病毒街毒分离株感染力的影响。方法将2006年分离的1株狂犬病街毒BD06株适应细胞后的第18代毒株暴露于不同的理化条件下,通过接种BHK-21细胞测定其病毒滴度(TCID50),观察其感染力的变化。结果 BD06株狂犬病病毒在100℃作用10 s和56℃作用2 min可以完全灭活,在37℃可存活6 d,4℃可存活2周,-20℃以下可存活半年以上;病毒置紫外线灯下30 cm处2 min内全部被灭活;在pH 6～10的中性环境下能够存活,在pH 5以下的弱酸性和pH 11以上的碱性环境中,10 min内可完全灭活;病毒对胰酶稳定;30%以上的丙酮在20 min,2倍体积的氯仿在5 min,75%的乙醇在2 min,0.05%的甲醛在6 h,10%的甲醛在5 min内均可将病毒全部灭活。结论分析了几种理化因子对狂犬病病毒BD06株感染力的影响,为生产实践中灭活狂犬病病毒或消毒提供了参考。