道路绿化带对街道峡谷内污染物扩散的影响研究

研究了道路绿化带对街道峡谷内流场与机动车尾气扩散的影响特征.假设绿化带树冠为均匀多孔介质,采用压力损失系数表征树冠对空气流动的阻碍作用,建立可用于数值模拟的绿化带多孔介质物理模型.采用稳态k-ε湍流模型结合组分输运方程模拟道路中央有绿化带街道峡谷内的尾气扩散过程,模拟结果与风洞试验数据对比吻合较好.分析发现,有绿化带街道峡谷内存在一个围绕树冠的顺时针旋涡,旋涡中心略偏向右上方,背风面污染物浓度显著增大,较无绿化带的污染物平均浓度增长46.0%.进一步模拟了不同绿化带树冠高度情况下街道峡谷内流场与浓度场,发现随着树冠位置的上升,峡谷内流场旋涡中心逐步上移且偏向迎风建筑物,峡谷内整体气流速度下降,污染物浓度逐步升高,树冠底部高度为8 m时其污染物浓度可达4 m时的2倍多;尤其是当树冠顶部超过屋顶高度时,峡谷内污染物总体浓度增长迅速.     

8种植物叶片对城市大气苯并（a）芘（BaP）的吸收比较

城市化及汽车的发展导致城市大气中多环芳烃（PAHs）含量较高,强致癌作用污染物苯并（a）芘（BaP）含量也相应增高。植物是大气环境天然的过滤器,能滞留、吸附和累积空气中多种污染物。选择广州市8种常见行道树,4种乔木：红花羊蹄甲（Bauhiniablakeana）、腊肠树（Cassiafistula）、高山榕（Ficus...     

Estimation of PM_(10) in the trafc-related atmosphere for three road types in Beijing and Guangzhou,China

The levels of roadside PM10in Beijing, China, were investigated in 2011 and 2012 on a seasonal basis to estimate the population exposure to particulates for three road types. The measurements of PM10 were also conducted in the southern Chinese megacity of Guangzhou for comparison purposes. The results showed that roadside PM10in Beijing correlated strongly with the PM10background in the urban atmosphere. The levels of PM10in street canyons were markedly higher than those along the open roads and in crossroad areas because of limited ventilation. An elevation of PM10was observed in April, which was possibly due to the sand storms that frequently occur in the spring. Based on these observations, roadside PM10in Beijing could have multiple origins and was to some extent dispersiongoverned. In Guangzhou, the roadside PM10did not closely relate to the background values. The PM10 pollution was greatly afected by local trafc conditions. The simulation of PM10 for diferent road types was completed during the study period using the Motor Vehicle Emissions Factor Model(MOBILE6.2) as an emission model and the California Line Source Dispersion Model(CALINE4) and Operational Street Pollution Model(OSPM) as dispersion models. The MOBILE6.2/CALINE4 software package was demonstrated to be sufcient for the simulation of PM10in the open roads and crossroad areas in both Beijing and Guangzhou, and the simulation results of roadside PM10 in the street canyons by the MOBILE6.2/OSPM package were in close agreement with those of the measurements.     

Dynamic street environment

The research examines the street's physical characteristics that are influenced by the culture in the city of Mashhad, Iran as a case study. It is evident that new developments in the traditional street have mostly eroded the cultural value of the urban environment. The techniques used for data collection include literature review, in-depth interview, questionnaire and field observation. The research outcome indicated, firstly, the street's physical characteristics which were influenced by culture and shaped the street form and function as a corridor to the Holy Shrine, a significant Iranian landmark. It is indicated that culture is a way of life influencing the physical appearance, activities and behavioural aspects that these are important to support human needs, therefore to create a sense of place. Secondly, culture, in line with the physical characteristics, would enhance the uniqueness of the street and its cultural value to support distinctiveness of the street environment. The third finding proves that cultural aspects have a significant role in activating public life and increasing the attractiveness of the street.     

兰州市街道尘埃粒度空间变化特征

采用Mastersizer2000激光粒度仪对2006年3月采集的兰州市街道尘埃进行了粒度分析。结果表明,兰州市街道尘埃中颗粒物平均粒径范围在46．83μm-266．59μm,平均值为118．73μm;其中〉2μm的颗粒占总量的92％-99．5％,〈2μm的颗粒占10％以下。受地形因素影响,兰州市西部和东部地区粒径较粗,中间地段粒径相对较细;进一步分析发现在风动能大的区域,尘埃主要以较粗物质为主;在风动能相对较弱区域,细颗粒和粗颗粒含量差别不大,而在风动能小的区域,街道尘埃主要以细颗粒物为主。由此可见,兰州市街道尘埃中的颗粒物的主要来源是由于风力和人为活动产生的土壤尘和人为排放的污染物所共同贡献的;粒度分布特征受到风动力条件和物源（污染源）两方面因素的控制。     

城市低矮街道峡谷汽车排放NOx扩散模式的初探

通过对武汉市珞狮路路段的车流量、NOx 浓度和气象要素的调查与监测 ,分析了珞狮路交通流量的特征 ,给出了源强的计算公式 ,并重点讨论了街道两侧环境中 NOx 浓度与各种影响因素之间的关系 ,发现城市低矮峡谷中 NOx 扩散不同于以往的研究结果 ,有其自己的特殊性。最后提出了扩散模式参数的处理方法 ,为建立城市低矮街道峡谷排放 NOx 扩散模式提供了基础     

The variation of street air levels of PAH and other mutagenic PAC in relation to regulations of traffic emissions and the impact of atmospheric processes

The occurrence of particle associated PAH and other mutagenic PAC was determined in 1996 in the street air of Copenhagen. In addition, particle extracts were tested for mutagenicity. The measurements were compared with previous measurements in 1992/1993. The levels had decreased in this period. The decrease was caused by an implementation of light diesel fuels for buses and the exchange of older petrol-driven passenger cars with catalystequipped new ones. About 65% of the reduction was caused by the application of the light diesel fuels. Under special conditions, chemical processes in the atmosphere produced many more mutagens than the direct emissions. The concentrations of S-PAC and N-PAC were 10 times lower than those of PAH, while the levels of oxy-PAH were in the same order of magnitude as those of PAH. Benzanthrone, an oxy-PAH, is proposed to be formed in the atmosphere in addition to direct emissions. Benzo(a)pyrene, often applied as an air quality criteria indicator, was photochemically degraded in the atmosphere. A strong increase in the mutagenic activities was observed to coincide with a depletion of benzo(a)pyrene.     

基于DEMATEL/ISM的地下商业街火灾风险影响因素研究

为研究某地下商业街火灾风险影响因素，针对该地下商业街火灾的复杂性和特殊性，建立了包括人员、设备、环境、管理等4个大类下的16个影响因素的火灾风险影响因素指标体系，运用DEMATEL方法分析影响火灾风险的关键因素，并结合ISM方法建立影响因素多层次递阶解释结构模型。结果表明：火灾风险由多种影响因素耦合而成，消防人员工作能力、地下建筑结构复杂度、消防资金投入大小和消防安全规程的执行力度是影响地下商业街火灾的关键因素。