Source diagnostics of polycyclic aromatic hydrocarbons in urban road runoff, dust, rain and canopy throughfall

Diagnostic ratios and multivariate analysis were utilized to apportion polycyclic aromatic hydrocarbon (PAH) sources for road runoff, road dust, rain and canopy throughfall based on samples collected in an urban area of Beijing, China. Three sampling sites representing vehicle lane, bicycle lane and branch road were selected. For road runoff and road dust, vehicular emission and coal combustion were identified as major sources, and the source contributions varied among the sampling sites. For rain, three principal components were apportioned representing coal/oil combustion (54%), vehicular emission (34%) and coking (12%). For canopy throughfall, vehicular emission (56%), coal combustion (30%) and oil combustion (14%) were identified as major sources. Overall, the PAH's source for road runoff mainly reflected that for road dust. Despite site-specific sources, the findings at the study area provided a general picture of PAHs sources for the road runoff system in urban area of Beijing.     

Distribution of heavy metal contents of urban soils in parks of Seville

Several metals in urban soils of Seville were extracted by two methods, which respectively give estimates of the available and ‘quasi total’ contents. Although the soils did not show strong heterogeneity in their general properties, high dispersion of the contents in those metals with greater relative availability, Cu, Pb and Zn, as compared to others suggested that pollution with these three metals could occur in some sampling sites. It was shown that the contents in these metals tend to increase as the historic quarters of the city are approached. Using reference values given by the Québec Ministry of Environment it was shown that those green areas closer to the historic centre present contents in Pb, Zn and particularly Cu that often exceed the acceptable limits for residential, recreational and institutional sites. From background contents for Seville soils estimated from a park located on the outskirts, a pollution load index (PLI) for each sampling site was calculated for the set of these three metals. It was shown that the PLI tends to increase as traffic density increases and as distance from main traffic decreases, but poor regressions were obtained, suggesting that other variables different from traffic should be considered.     

Contribution to biomonitoring of some trace metals by deciduous tree leaves in urban areas

Leaves of the deciduous tree species, horse chestnut (Aesculus hippocastanum L.) and Turkish hazel (Corylus colurna L.) were used as accumulative biomonitors of trace metal pollution in the urban area of Belgrade. Using differential pulse anodic stripping voltametry, trace metal concentrations (Pb, Cu, Zn, Cd) were determined at the single leaf level (ten leaves per species, per month), during two successive years with markedly different atmospheric level of trace metals. Increased trace metal concentrations in the leaves of A. hippocastanum reflected elevated atmospheric trace metal pollution, whereas C. colurna L. did not respond accordingly. The contents of Pb and Zn in soil over the same period also followed this trend. Anatomical analyses, in young as well as in old leaves of both species, indicated typical foliar injuries of plants exposed to stressful air conditions. Water relations that correspond to leaf age may have contributed to the considerable trace metal accumulation in leaves.     

Concentrations of heavy metals in urban soils of Talcahuano (Chile): a preliminary study

Concentrations of Cd, Cr, Ni, Pb, and Zn in the top-(0–10 cm) and sub-surface (10–20 cm) soils of the Talcahuano urban area were measured. The main soil properties (organic matter, CaCO₃, pH, particle sizes) were determined for a network of representative sampling sites. The mean Cr, Ni, Pb, and Zn contents in the urban topsoil samples from Talcahuano (37.8, 22.6, 35.2, 333 mg kg⁻¹, respectively) were compared with mean concentrations for other cities around the world. The results revealed higher concentrations of heavy metals in topsoil samples than in sub-surface samples. The samples from IS1, IS2, and IS3, located in the Talcahuano industrial park, had higher Cr, Ni, Pb, and Zn contents than did samples from the other sites. This was probably due to local pollution by industrial (metallurgical) dust, although other diffuse pollution throughout the entire port region (shipyards, metallurgy, the dismantling of old ships), and contributions from the wind from adjacent industrial, storage, and vessel areas clearly played a role. Heavy metals were lowest in the sample taken on school grounds (SG).     

机动车不同速度下外噪声变化与衰减关系研究

通过在机动车测试场进行单辆机动车行驶状况的实验,研究机动车车型大小、行驶速度快慢与噪声量大小的关系,同时研究不同距离下机动车行驶外噪声的衰减规律。数据结果显示,测试条件下,噪声量随着速度提升而增加,呈线性关系或对数关系;相同速度下,大型车的噪声量比小型车的高8.1～11.0dB;在一定距离范围内,距离每增加3.5m,机动车噪声量将衰减2.2～3.0dB。     

辽宁省朝阳市城市污水BOD与COD关系的探讨

从BOD与COD的构成及降解动力学出发,探讨了BOD与COD的相关关系,得到了BOD5与COD的相关模型,应用朝阳市城市污水的实测数据和数理统计模型进行了检验。     

城市土壤吸附重金属动力学特征及其与土壤理化性质的关系

以长春市土壤为对象,既研究了长春市土壤理化性质特征,又采用间歇法研究了城市土壤吸附重金属Pb、Cd和Cu动力学特征及其两者之间的关系。结果表明：长春市土壤pH接近于中性或者偏碱性;土壤碳酸钙、有机质含量升高;土壤砂粒化;土壤CEC和Eh具有逐渐降低的趋势。土壤吸附重金属动力学过程包括快速阶段和慢速阶段,不同重金属在不同吸附阶段吸附速率明显不同。双常数速率方程和Elovich方程基本上可以描述土壤对Pb、CA和Cu吸附的动力学过程。pH、碳酸钙和砂粒含量是影响Pb吸附速率的主要因子;碳酸钙含量是影响CA吸附速率的主要因子。     

沈阳市城市污水中的热能回收及利用研究

以北部污水处理厂为例,结合沈阳城市污水源热泵系统规划思路,对沈阳市7座污水处理厂及污水特征参数进行了论述及推算。通过调查分析供暖企业的燃煤现状及供暖情况,推算出了采用污水供暖取代燃j采供暖后的环境效益及经济效益,提出了沈阳建立污水源热泵系统的对策及建议。     

Pedestrian distraction: The effects of road environment complexity and age on pedestrian’s visual attention and crossing behavior

Introduction: Little is known about how characteristics of the environment affect pedestrians’ road crossing behavior. Method: In this work, the effect of typical urban visual clutter created by objects and elements in the road proximity (e.g., billboards) on adults and children (aged 9–13) road crossing behavior was examined in a controlled laboratory environment, utilizing virtual reality scenarios projected on a large dome screen. Results: Divided into three levels of visual load, results showed that high visual load affected children’s and adults’ road crossing behavior and visual attention. The main effect on participants’ crossing decisions was seen in missed crossing opportunities. Children and adults missed more opportunities to cross the road when exposed to more cluttered road environments. An interaction with age was found in the dispersion of the visual attention measure. Children, 9–10 and 11–13 years old, had a wider spread of gazes across the scene when the environment was highly loaded—an effect not seen with adults. However, unexpectedly, no other indication of the deterring effect was found in the current study. Still, according to the results, it is reasonable to assume that busier road environments can be more hazardous to adult and child pedestrians. Practical Applications: In that context, it is important to further investigate the possible distracting effect of causal objects in the road environment on pedestrians, and especially children. This knowledge can help to create better safety guideline for children and assist urban planners in creating safer urban environments.     

Urban afforestation and infant health: Evidence from MillionTreesNYC

This paper examines the impact of urban afforestation on infant health outcomes by exploiting a quasi-experimental setting where one million new trees were planted in New York City (NYC), but not in counties surrounding NYC over the same time period. Using a near-universal birth record of NYC and surrounding counties over 2004–2015 and employing both the synthetic control method and a difference-in-differences model, we find that an approximately 20% increase in urban forest cover decreased prematurity and low birth weight among mothers in NYC by 2.1 and 0.24 percentage points, respectively, relative to similar mothers outside of NYC. The low birth weight finding is equivalent to getting a mother smoking two cigarettes a day during pregnancy to quit. An internal validity test suggests that changes in the composition of NYC mothers cannot explain the observed effects. Additionally, we find evidence that declines in PM_2.5 concentrations and increases in outdoor walks are potential causal mechanisms. Results suggest that urban afforestation may be able to complement existing policies aimed at improving infant health.