Commute mode diversity and income inequality: an inter-urban analysis of 148 midsize US cities

Little is known about the relationship between multi-modal transportation environments and aspects of sustainable urban development, such as reduced income inequality and affordable housing. This study, adapted from Molotch and Appelbaum's inter-city differential method, studied 148 semi-isolated mid-size cities. Using U.S. Census data from 2013, we found that increased diversity in commute modality is associated with less income inequality between white and African-American households, as well as between men and women. Commute mode diversity is also associated with higher earnings for white women and African-American men. Our study also shows that cities with more commuter mode diversity are associated with higher home property values and affordable rental markets compared to automobile dependent cities. These results undercut the notion that increasing automobile ownership is a reasonable policy response to urban poverty, and suggest that sustainable transportation policy can produce positive economic gains for cities. This work adds to the growing literature identifying fundamental differences between multimodal and automobile dependent cities.     

佛山市南海城区环境空气中铅污染现状分析研究

为了解佛山市南海城区环境空气中铅污染现状,在南海城区中心设置空气质量监测点,采用重量法和电感耦合等离子体质谱法分别对空气颗粒物及不同粒径颗粒物的铅含量进行定量分析,测定结果为:TSP、PM10、PM2.5平均浓度分别是150 ug/m3、99 ug/m3、67 ug/m3,其中铅平均浓度分别是214 ng/m3、175 ng/m3、156 ng/m3.结论为:南海城区环境空气中的铅浓度达到国家环境空气质量二级标准,铅污染水平处于珠江三角洲的中游;大气中的铅主要分布在PM2.5中,机动车尾气是其主要来源.     

Characteristic levels of heavy metals in soil profiles of automobile mechanic waste dumps in Nigeria

The characteristic levels of heavy metals (Cd, Cr, Cu, Pb, Ni and Zn) of soil profiles of automobile mechanic waste dumps were studied. The concentration of heavy metals decreased with the depth of the profile and lateral distance from the dumpsites. The levels found in this study exceeded background concentrations and limits for agricultural and residential purposes. The distribution pattern of heavy metals in the soil profiles were in the following order Pb > Zn > Cu > Cd > Ni > Cr. The mechanic waste dumps represent potential sources of heavy metal pollution to environment. The elevated levels of heavy metals in these soil profiles constitute a serious threat to both surface and groundwater.     

负载型金催化剂在汽车尾气中的应用

金催化剂能在常温下能够催化CO、NOx生成无害的物质越来越受到科学家的重视,现在倍受关注的负载型金催化剂的研究已经开始向着汽车尾气消除的方面发展,文章主要综述了在汽车尾气催化剂的发展历史、制备方法以及应用前景。     

机动车尾气污染控制的对策建议

近年来,南通市机动车保有量大幅增长。受机动车尾气污染影响,城市空气污染已由煤烟型污染向交通尾气型污染转变。控制机动车尾气污染,已成为大气污染防治的重点工作之一。本文根据第一次全国污染源普查结果,分析南通市机动车尾气污染和治理现状,从而提出加强机动车尾气污染控制的对策和建议。     

典型城市机动车排气污染防治研究

机动车尾气污染日益加剧,对城市环境空气质量造成严重影响。文中分析了江苏省几个重点城市机动车排气污染的现状及原因,从政策、技术等多方面提出了一系列具体的防治对策。     

汽车尾气超标原因分析与防治

通过对烟台市近几年的尾气检测与治理的经验分析,简要论述了汽车尾气超标的原因,并针对不同的超标情况提出相应的解决方案.     

关于中国在用汽车排污控制的若干问题--柴油车部分

文章结合《点燃式发动机汽车排气污染物排放限值及测量方法（双怠速法及简易工况法）》（GB18285—2005）修订中的重大问题阐述中国在用汽油车排气烟度控制方面的新要求。主要包括：增加高怠速排污检测、对电喷汽车增加过量空气系数（λ）的限定、新规定了国1以来的在用汽油车双怠速排放限值、双燃料车要对两种燃料分别检测、对简易工况检测法作了规定、制定简易工况检测法排放限值的基本原则和方法、供地方参考的排放限值等。     

青岛市机动车排放源强与排放量研究

阐述了青岛市城市机动车的发展现状和道路交通状况,采集典型交通状况的车流量和车速数据,对评价区域进行了移动线源、面源的源强分析计算,得到了该区域内机动车排放网格数据,通过修正的排放因子计算了青岛市机动车主要尾气污染物的年排放量,目的是为机动车污染治理提供了理论数据。研究表明从排放源源强分析机动车道路污染状况和污染区域分布,不受扩散模式的影响,可以简单有效的评价机动车排放污染程度;青岛市城市主干道以成为机动车污染物的主要排放源,针对青岛市机动车尾气污染情况提出了合理的污染物治理建议。     

Instrumental and bio-monitoring of heavy metal and nanoparticle emissions from diesel engine exhaust in controlled environment

In the present article we characterized the emissions at the exhaust of a Common Rail (CR) diesel engine, representative of lightduty class, equipped with a catalyzed diesel particulate filter (CDPF) in controlled environment. The downstream exhausts were directly analyzed (for PM, CO, CO2, O2, HCs, NOx) by infrared and electrochemical sensors, and SEM-EDS microscope; heavy metals were chemically analyzed using mosses and lichens in bags, and glass-fibre filters all exposed at the engine exhausts. The highest particle emission value was in the 7–54 nm size range; the peak concentration rose until one order of magnitude for the highest load and speed. Particle composition was mainly carbonaceous, associated to noticeable amounts of Fe and silica fibres. Moreover, the content of Cu, Fe, Na, Ni and Zn in both moss and lichen, and of Al and Cr in moss, was significantly increased. Glass-fibre filters were significantly enriched in Al, B, Ba, Cu, Fe, Na, and Zn. The role of diesel engines as source of carbonaceous nanoparticles has been confirmed, while further investigations in controlled environment are needed to test the catalytic muffler as a possible source of silica fibres considered very hazardous for human health.