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161.
An adaptation procedure of a new emission inventory of theGreater Athens Area is attempted, based on a sensitivityanalysis on the treatment of the VOC emissions. Throughthis procedure the impact that a more detailed treatment ofthe VOCs emissions might have on the atmospheric chemistrysimulations, is examined. For this analysis three differentchemical mechanisms were applied for two differentlocations (urban and city plume) with different VOC andNOx mixture characteristics. Finally, this studyrecommends new carbon fractions, reflecting the localconditions in Athens basin.  相似文献   
162.
南京东路机动车尾气污染调查和计算分析   总被引:13,自引:0,他引:13  
机动车排放的尾气是城区重要的污染,是形成光化学烟雾的直接因素。通过对南京东路王开照相馆-东海商厦断面的车流量、污染物浓度和气象要素的调查和监测,分析了南京东路交通流量的特征,估算了这一路段机动车尾气污染源源强,并利用分车道的经验公式计算了选定剖面的NOx浓度分布。结果表明:(1)南京东路的车辆构成中出租车占很大比例。一天中车流量存在明显的变化,从西到东和从东到西车道的变化趋势一致,主要集中在白天和  相似文献   
163.
The levels of roadside PM10 in 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 PMlo in Beijing correlated strongly with the PM10 background in the urban atmosphere. The levels of PM10 in street canyons were markedly higher than those along the open roads and in crossroad areas because of limited ventilation. An elevation of PM10 was observed in April, which was possibly due to the sand storms that frequently occur in the spring. Based on these observations, roadside PM10 in Beijing could have multiple origins and was to some extent dispersion- governed. In Guangzhou, the roadside PM10 did not closely relate to the background values. The PM10 pollution was greatly affected by local traffic conditions. The simulation of PM10 for different 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 sufficient for the simulation of PM10 in 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.  相似文献   
164.
Total pollution effect of urban surface runoff   总被引:2,自引:1,他引:2  
For pollution research with regard to urban surface runo , most sampling strategies to date have focused on di erences in land usage. With single land-use sampling, total surface runo pollution e ect cannot be evaluated unless every land usage spot is monitored. Through a new sampling strategy known as mixed stormwater sampling for a street community at discharge outlet adjacent to river, this study assessed the total urban surface runo pollution e ect caused by a variety of land uses and the pollutants washed o from the rain pipe system in the Futian River watershed in Shenzhen City of China. The water quality monitoring indices were COD (chemical oxygen demand), TSS (total suspend solid), TP (total phosphorus), TN (total nitrogen) and BOD (biochemical oxygen demand). The sums of total pollution loads discharged into the river for the four indices of COD, TSS, TN, and TP over all seven rainfall events were very di erent. The mathematical model for simulating total pollution loads was established from discharge outlet mixed stormwater sampling of total pollution loads on the basis of four parameters: rainfall intensity, total land area, impervious land area, and pervious land area. In order to treat surface runo pollution, the values of MFF30 (mass first flush ratio) and FF30 (first 30% of runo volume) can be considered as split-flow control criteria to obtain more e ective and economical design of structural BMPs (best management practices) facilities.  相似文献   
165.
Established research in first world urban environments has shown street sediments to be effective sinks for heavy metals and emphasises the health risks to children by its inhalation or ingestion. In third world countries with fewer pollution controls, contamination may be augmented by additional pollutants such as sewage discharge into urban streets and/or periodic inundation with sewage-laden run-off. This pollutant not only contains heavy metals and organic matter, but calcium oxalates that may derive directly from the sewage itself. To study this premise street sediments were collected from sites of varying industrialisation and sewage contamination within the city of Niteroi, Brazil. Calcium oxalate dihydrate (weddellite) was identified by X-ray diffraction, fourier transform infra red and scanning electron microscopy techniques and oxalate concentrations in <63m and colloidal (clay and organic matter) fractions, were determined by ion chromatography. Oxalate in colloidal fractions averaged 43601mgkg–1 in sewage contaminated industrialised urban zones, 4519mgkg–1 in suburban areas and 17477mgkg–1 in suburbs with favelas (shantytowns-of Niterói). Oxalate concentrations coincide with high levels of metal ions (Fe, Mn, Zn, Pb, Ni, Cr) that stabilise calcium oxalate dihydrate and prevent its dehydration to the monohydrate (whewellite). Lower levels of oxalate were found in lichen-covered roof sediment, plaster and mortar samples. Oxalate concentration coincides with sewage contamination and street sediments appear to act as a sink for calcium oxalate dihydrate derived from sewage. Previous studies have shown that low levels of exposure can damage kidneys and the nervous system, while prolonged exposure can cause severe corneal, retinal and skin damage, cyanosis and possibly gangrene. Contact with blood serum may result in hypocalcemia, muscular stimulation, convulsions and finally collapse. The conditions described are common throughout urban areas of the developing world and may suggest a particular environmental hazard in these regions.  相似文献   
166.
城市街道峡谷中气态污染物扩散数值计算方法研究   总被引:1,自引:3,他引:1  
选用不同的差分格式(Upwind, Hybrid, Hquick)对城市街道峡谷内部汽车污染物排放浓度进行了预测,并于风洞实验结果对比。研究表明,三种格式的计算结果和实验结果总体趋势一致,即背风面建筑物附近浓度远高于迎风面建筑物附近的浓度,地面附近浓度高于峡谷上方的浓度。相比之下,Hquick格式的预测性能最佳,应为首选。  相似文献   
167.
This paper presents thedifferential impacts of flood hazards amongstreet children, the urban poor andresidents of wealthy neighborhoods in MetroManila, Philippines. It argues that beingpoor is not the only reason why certainsectors are more vulnerable to floods orany environmental hazards – spatialisolation and lack of participation indecision making intensify their presentand future vulnerability, as well. Archival research, interviews, focusedgroup discussion, participant observationand surveys of populations at risk areemployed to delineate the flood experiencesand coping strategies of street childrenand residents of poor urban settlements andwealthy neighborhoods in Metro Manila atthe household and community levels. Theconcept of entitlement, the ContextualHazards Model, and the Access Model areused in the data analysis andinterpretation. Several policyrecommendations on hazard management anddisaster mitigation are identified toreduce flood losses in Metro Manila.  相似文献   
168.
城市街口规划设计与城市空气环境的关系   总被引:6,自引:1,他引:6       下载免费PDF全文
 城市大气环境同时涉及到大气科学和城市规划理论.本文从建筑与生态环境协调的角度出发,通过对典型实测数据的分析,考虑建筑物与风的相互作用特点,论述了街口形式对街道污染物扩散效果的影响,并对街口的生态设计原则提出了建议.  相似文献   
169.
应用火焰原子吸收光谱法,对长春市14条主要街路交通密集地段两侧绿化带中采集到的12种代表性植物叶片的铅含量进行了分析。结果表明,植物叶片的铅含量范围在8.20 mg/kg~58.5 mg/kg之间,平均值为19.7 mg/kg。木本植物叶片的平均铅富集能力略低于草本植物,并且木本植物叶片平均铅含量的空间变异性较大;木本植物中杨树叶片的平均铅富集能力最强而榆树最低,草本植物中绣线菊的叶片平均铅富集能力最强而八宝景天最低;草本植物中绣线菊的叶片在所有供试植物叶片中平均铅富集能力最强,其次为木本植物中杨树的叶片,而草本植物中八宝景天的叶片平均铅富集能力最低。不同植物在同一街路以及同种植物在不同街路之间其叶片的铅含量都不同。  相似文献   
170.
为有效控制深谷型湖泊内源污染,构建底泥活性覆盖系统,以脱碱赤泥为主料,粉煤灰、黏土和Ca CO3为辅料,制作了不同配比的底泥覆盖材料,并评价其在厌氧条件下对湖泊内源污染物的控制效果。结果表明:底泥覆盖后上覆水体水质总体趋于稳定,DO水平能够得到改善,TP和COD的释放受到抑制,对NH3-N虽有一定控制作用但短期效果不理想;3种材料覆盖后,上覆水体中均低检出或未检出Cu、Pb、Zn、Cr、Cd,Fe、Mn、Ca、Mg的含量也较对照组低,削弱了金属元素的释放迁移;结合底泥内源污染物的控制效果和上覆水体水质的稳定性两方面因素,3种材料中,材料2(配料为赤泥38.9%,黏土14.4%,粉煤灰38.9%,Ca CO37.8%)最适于深谷型湖泊底泥覆盖。该覆盖方法原料获取方便、材料制作简单、经济成本低廉、操作方法简易、污染控制效果优良,可用于深谷型湖泊底泥原位控制。  相似文献   
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