scholarly journals Evolution of NO<sub><i>x</i></sub> in the Denver Urban Plume during the Front Range Air Pollution and Photochemistry Experiment

2017 ◽  
Author(s):  
Carlena J. Ebben ◽  
Tamara L. Sparks ◽  
Paul J. Wooldridge ◽  
Teresa L. Campos ◽  
Christopher A. Cantrell ◽  
...  
Keyword(s):  
Air Pollution ◽  
Numerical Models ◽  
Near Field ◽  
Photochemical Oxidation ◽  
Front Range ◽  
City Center ◽  
Alkyl Nitrates ◽  
Effective Lifetime ◽  
Urban Plume ◽  
The City

Abstract. As NOx (NOx ≡ NO + NO2) is transported away from cities, it undergoes photochemical oxidation to peroxynitrates (RO2NO2, ΣPNs), alkyl nitrates (RONO2, ΣANs), and nitric acid (HNO3). These higher oxide species each have different lifetimes to permanent removal or conversion back to NOx, resulting in nitrogen oxide chemistry that evolves as plumes are transported away from cities. Here, observations from the Front Range Air Pollution and Photochemistry Experiment (FRAPPÉ) are used to describe the evolution of NOx and NOy (NOy ≡ NOx + ΣPNs + ΣANs + HNO3 + …) as the Denver urban plume flows outward from the city center. We evaluate the chemistry, dilution, and deposition rates in the plume to provide numerical constraints on the NOx and NOy,i lifetimes. We find that plume dilution with background air occurs with a lifetime of 3.5 hours. NOx concentrations decrease more rapidly with a lifetime to chemical loss and dilution of 2 hours in the near field of the city center. NOy has an effective lifetime of 3 hours and due to a combination of HNO3 deposition and dilution. The results provide a useful test of conceptual and numerical models of chemistry during the evolution of urban plumes.

scholarly journals Spatial and temporal variations of air pollution over 41 cities of India during the COVID-19 lockdown period

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Krishna Prasad Vadrevu ◽  
Aditya Eaturu ◽  
Sumalika Biswas ◽  
Kristofer Lasko ◽  
Saroj Sahu ◽  
...  
Keyword(s):  
Air Pollution ◽  
Temporal Analysis ◽  
Temporal Variations ◽  
Northeast India ◽  
New Delhi ◽  
City Center ◽  
Coastal Cities ◽  
Vegetation Fires ◽  
Spatial Differences ◽  
The City

Abstract In this study, we characterize the impacts of COVID-19 on air pollution using NO2 and Aerosol Optical Depth (AOD) from TROPOMI and MODIS satellite datasets for 41 cities in India. Specifically, our results suggested a 13% NO2 reduction during the lockdown (March 25–May 3rd, 2020) compared to the pre-lockdown (January 1st–March 24th, 2020) period. Also, a 19% reduction in NO2 was observed during the 2020-lockdown as compared to the same period during 2019. The top cities where NO2 reduction occurred were New Delhi (61.74%), Delhi (60.37%), Bangalore (48.25%), Ahmedabad (46.20%), Nagpur (46.13%), Gandhinagar (45.64) and Mumbai (43.08%) with less reduction in coastal cities. The temporal analysis revealed a progressive decrease in NO2 for all seven cities during the 2020 lockdown period. Results also suggested spatial differences, i.e., as the distance from the city center increased, the NO2 levels decreased exponentially. In contrast, to the decreased NO2 observed for most of the cities, we observed an increase in NO2 for cities in Northeast India during the 2020 lockdown period and attribute it to vegetation fires. The NO2 temporal patterns matched the AOD signal; however, the correlations were poor. Overall, our results highlight COVID-19 impacts on NO2, and the results can inform pollution mitigation efforts across different cities of India.

scholarly journals Heavy Metal Accumulation in Shrubs Used in Roadside Planting

2020 ◽  
Keyword(s):  
Heavy Metals ◽  
Air Pollution ◽  
Heavy Traffic ◽  
Emission Spectrometry ◽  
City Center ◽  
Shrub Species ◽  
Platycladus Orientalis ◽  
Buxus Sempervirens ◽  
The City ◽  
Cu And Zn

<p>The aim of this study is to determine the shrub species which can be used as the biomonitor of air pollution originating mainly from the traffic and could provide the opportunity to increase the air quality in urban areas. To this end, Berberis thunbergii, Buxus sempervirens, Juniperus horizontalis, and Platycladus orientalis, mostly preferred species for roadside plantations, were chosen for the study. First, three regions with heavy traffic intensities were determined. Next, the levels of 4 heavy metals were examined by using Inductively Coupled Plasma–Optical Emission Spectrometry. The results obtained indicate that since the deposition of Cu and Zn is more in the leaves and barks of four species, these shrub species are more effective in the accumulation of Cu and Zn. Furthermore, the results of the study show that Platycladus orientalis is more effective in Cu and Pb accumulation, while Buxus sempervirens is more effective in terms of Ni and Zn accumulation. Determining high levels of traffic-originated heavy metals of Cu, Pb and Zn, particularly in the leaves of Platycladus orientalis in the city center indicates that air pollution is more intense in the city center and that Platycladus orientalis can be used as a biomonitor for traffic-originated air pollution.</p>

scholarly journals Car Free Zone as Planning Vision to Enhancements Transportation in City Centers (Holy Najaf City Center-Iraq)

2022 ◽  
Vol 961 (1) ◽  
pp. 012074
Author(s):  
Zahraa Saeb Mohialdeen ◽  
Mustafa Abduljalil Ebrageem
Keyword(s):  
Air Pollution ◽  
Public Transportation ◽  
Research Problem ◽  
Transportation System ◽  
Easy Access ◽  
City Center ◽  
Pedestrian Movement ◽  
Free Zone ◽  
The City ◽  
Holy City

Abstract The idea of a car-free city represents a solution to the problem of fuel consumption and air pollution caused by the use of cars and replaces the idea of owning and using private cars with an efficient transportation system, and it doesn’t mean living without cars, because cars have become an integral part of a modern city. On the contrary, people can still drive in city but will not park their cars at home. Instead, they park elsewhere on their way home. Research problem: Weak regulation of the movement of vehicles in the center of the holy city of Najaf, which leads to the danger of pedestrian movement in the city center. The aim of the research: to provide a safe and effective movement for pedestrians in the center of the holy city of Najaf. Research hypothesis: The use of the car-free zone strategy in the city center transportation system achieves security for the population in the old city. The research examines reasons behind suggesting free-of-vehicle areas It gives a number of policies to achieve the strategy in the center of the holy city of Najaf, including the provision of public transportation, furniture and comfort for pedestrians in the streets, as well as easy access for the residents of the area. Thus, it is possible to draw the conclusion that there is a possibility to achieve this strategy in religious centers according to a number of policies that suit the specificity of the area.

Accuracy of On-site Consistent Origin-Destination Estimation Method for Measuring the Actual Numbers of Consumer Shop-around Movements within the City Center of Hanoi, Vietnam

2012 ◽  
Vol 42 (2) ◽  
pp. 439-455 ◽  
Author(s):  
Saburo SAITO ◽  
Tran Ngoc HUY ◽  
Masakuni IWAMI ◽  
Takahiro SATO ◽  
Kosuke YAMASHIRO ◽  
...  
Keyword(s):  
Estimation Method ◽  
City Center ◽  
The City

Urban Development Strategies of City Centers: The Case of Rafah City, Palestinian Territories

2014 ◽  
Vol 8 (3) ◽  
pp. 195
Author(s):  
Omar S. Asfour ◽  
Samar Abu Ghali
Keyword(s):  
Urban Development ◽  
Gaza Strip ◽  
Geographic Location ◽  
Development Strategies ◽  
Functional Requirements ◽  
City Center ◽  
Palestinian Territories ◽  
The Gaza Strip ◽  
The City ◽  
Commercial Center

City centers worldwide are perceived as essential parts of the city, where city memories are preserved and its identity is expressed. They are planned to satisfy the functional requirements and pleasurable qualities of the city. Under the accelerating urbanization of the modern city, several challenges face these centers including demographic, economic, and environmental challenges. This requires a continuous and incremental urban development process based on clear strategy and action plans. Thus, this study focuses on urban development strategies of city centers, with a focus on Rafah city located in the Gaza Strip, Palestinian Territories. The geographic location of this city near the Palestinian-Egyptian borders makes it a promising commercial city at local and regional levels. Thus, the current situation of Rafah city center has been analyzed, and several development strategies have been proposed. This has been done through a field survey based on observation and a questionnaire directed to city center users. It has been found that there is a great potential of Rafah city center to be developed as a commercial center. In this regard, several strategies and required actions have been proposed in the fields of transportation, environmental quality, shopping activities, investment opportunities, and visual perception.

The effect of air pollution in the city of Krasnodar on health

2017 ◽  
pp. 22-25
Author(s):  
S.P. Kukkoev ◽  
T.F. Nikishina ◽  
P.N. Nikolaevich
Keyword(s):  
Air Pollution ◽  
The City ◽  
Main Factor

The results of in-depth studies of the effect of air pollution in the city of Krasnodar on the health of the population, which showed that the main factor affecting the health of the population of Krasnodar, is air pollution.

Impact of Proposed Burlington and Hamilton Sewage Discharges in Western Lake Ontario

2003 ◽  
Vol 38 (4) ◽  
pp. 627-645 ◽  
Author(s):  
Yerubandi R. Rao ◽  
Raj C. Murthy ◽  
Fausto Chiocchio ◽  
Michael G. Skafel ◽  
Murray N. Charlton
Keyword(s):  
Action Plan ◽  
Near Field ◽  
Lake Ontario ◽  
Zone Model ◽  
Hamilton Harbour ◽  
Western Lake ◽  
Treated Sewage ◽  
Treated Effluents ◽  
Typical Summer ◽  
The City

Abstract The alternate strategy of open-lake discharge may alleviate the need for unusually stringent treatment needed to meet water quality goals of the Hamilton Harbour Remedial Action Plan (RAP). The latest update of the RAP recommended a study of the possibility of offshore discharges. A study conducted for the City of Burlington has proposed a location for outfall in Lake Ontario. This paper utilizes a combination of physical limnological data and mathematical models to predict the waste plume characteristics for the proposed outfall in the lake. Near-field dilutions obtained from a mixing zone model show that, for treated effluents with a discharge condition of 2 m3/s at the proposed outfall site at Burlington, the dilution ratios are in the range of 13:1 to 28:1 for weak to moderate currents during summer stratification. Winter dilution ratios increased to 21:1 to 96:1 for moderate currents. The recommended site for open-lake outfall provides acceptable near-field dilutions for treated effluents under typical lake currents and density structure. The extension of outfall to a location farther offshore is only marginally beneficial. With the proposed Burlington outfall location and discharge conditions, no far-field contamination is observed near the beaches or nearby water intakes for typical summer and winter conditions. Thus, this study indicates that by discharging the treated sewage from an outfall in Lake Ontario it is possible to achieve the Hamilton Harbour RAP goals.

Spatial and Temporal Differences in Weekday Travel Durations Between Private-for-Hire Transportation Services and Transit in the City Center

2021 ◽  
pp. 036119812110197
Author(s):  
Baxter Shandobil ◽  
Ty Lazarchik ◽  
Kelly Clifton
Keyword(s):  
Transportation Network ◽  
Central City ◽  
Temporal Analysis ◽  
Time Of Day ◽  
City Center ◽  
Transportation Services ◽  
Regulatory Frameworks ◽  
Transit Services ◽  
Level Information ◽  
The City

There is increasing evidence that ridehailing and other private-for-hire (PfH) services such as taxis and limousines are diverting trips from transit services. One question that arises is where and when PfH services are filling gaps in transit services and where they are competing with transit services that are publicly subsidized. Using weekday trip-level information for trips originating in or destined for the city center of Portland, OR from PfH transportation services (taxis, transportation network companies, limousines) and transit trip data collected from OpenTripPlanner, this study investigated the temporal and spatial differences in travel durations between actual PfH trips and comparable transit trips (the same origin–destination and time of day). This paper contributes to this question and to a growing body of research about the use of ridehailing and other on-demand services. Specifically, it provides a spatial and temporal analysis of the demand for PfH transportation using an actual census of trips for a given 2 week period. The comparison of trip durations of actual PfH trips to hypothetical transit trips for the same origin–destination pairs into or out of the central city gives insights for policy making around pricing and other regulatory frameworks that could be implemented in time and space.

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