Night-time NO emissions suppress large amounts of chlorine radical formation in Delhi

2021 ◽  
Author(s):  
Sophie Haslett ◽  
Varun Kumar ◽  
Andre Prevot ◽  
Jay Slowik ◽  
David Bell ◽  
...  
Keyword(s):  
Chemical Properties ◽  
Oxidative Capacity ◽  
Urban Environments ◽  
Diurnal Pattern ◽  
Night Time ◽  
Nitrogen Pentoxide ◽  
Chlorine Radicals ◽  
High Concentrations ◽  
The Impact ◽  
The City

<p>Concentrations of particulate chloride can reach values over 100 µg m<sup>-3</sup> during the winter in Delhi, which is among the highest levels recorded across the globe. In the presence of nitrogen pentoxide (N<sub>2</sub>O<sub>5</sub>), this chloride can form nitryl chloride (ClNO<sub>2</sub>), which photolyses in sunlight and releases the Cl radical. The Cl radical is an incredibly potent oxidant, reacting with some volatile organic compounds (VOCs) orders of magnitude faster than more common oxidants such as OH. Chlorine would therefore be expected to play a significant role in the oxidation of VOCs in Delhi.</p><p>We carried out intensive measurements of particle- and gas-phase physical and chemical properties during a field campaign in Delhi in early 2019. A suite of instruments was used, including a chemical ionisation mass spectrometer fitted with a filter inlet for aerosols and gases (FIGAERO-CIMS) to measure N<sub>2</sub>O<sub>5</sub> and ClNO<sub>2</sub>. Despite N<sub>2</sub>O<sub>5</sub> typically being considered a night-time compound, we in fact observed the highest concentrations in the mid-afternoon and almost none at all during the night. Further analysis indicated that the ubiquity of night-time NO<sub>x</sub> emissions in the city suppresses night-time production of N<sub>2</sub>O<sub>5</sub>. As a result of this unusual diurnal pattern, high concentrations of ClNO<sub>2</sub> are unable to form overnight. The morning peak in ClNO2 and the subsequent release of chlorine radicals, while large compared with some other urban environments, is therefore much smaller than might have been expected given the high levels of particulate chloride.</p><p>In this presentation, I will discuss our observations and the impact of this unusual diurnal pattern on the atmospheric chemical profile. Impacts include a shift of even typically ‘night-time’ oxidation patterns to the day and a likely overall reduced oxidative capacity in the city’s atmosphere. Our results indicate that a reduction in chlorine emissions must be considered in tandem with NO<sub>x</sub> emission reductions in efforts to reduce Delhi’s pollution.</p>

A case study of noise pollution levels during the restrictions period due to COVID-19.

2021 ◽  
Vol 263 (6) ◽  
pp. 206-214
Author(s):  
David Montes-González ◽  
Juan Miguel Barrigón-Morillas ◽  
Ana Cristina Bejarano-Quintas ◽  
Manuel Parejo-Pizarro ◽  
Guillermo Rey-Gozalo ◽  
...  
Keyword(s):  
Noise Pollution ◽  
Urban Environments ◽  
Control Measures ◽  
Acoustic Measurements ◽  
Pollution Levels ◽  
The World ◽  
The Impact ◽  
The City

The pandemic of coronavirus disease (COVID-19) led to the need for drastic control measures around the world to reduce the impact on the health of the population. The confinement of people in their homes resulted in a significant reduction in human activity at every level (economic, social, industrial, etc.), which was reflected in a decrease in environmental pollution levels. Studying the evolution of parameters, such as the level of environmental noise caused by vehicle traffic in urban environments, makes it possible to assess the impact of this type of measure. This paper presents a case study of the acoustic situation in Cáceres (Spain) during the restriction period by means of long-term acoustic measurements at various points of the city.

scholarly journals Activity density of carabid beetles along an urbanisation gradient

2020 ◽  
Vol 66 (Suppl.) ◽  
pp. 21-36
Author(s):  
Simone Fattorini ◽  
Cristina Mantoni ◽  
Davide Bergamaschi ◽  
Lorenzo Fortini ◽  
Francisco J. Sánchez ◽  
...  
Keyword(s):  
Intermediate Disturbance Hypothesis ◽  
Urban Environments ◽  
Carabid Beetles ◽  
City Centre ◽  
Intermediate Disturbance ◽  
Rural Environments ◽  
Activity Density ◽  
Urban Rural ◽  
The Impact ◽  
The City

Several works have investigated the impact of urbanisation on carabid activity density using urban-rural gradients. Such works compared activity density recorded from green spaces located in different parts of a city and assigned to categories of increasing urban intensity, which poses two problems: (1) since the gradient is divided into categories, it is impossible to model continuous variations in biotic responses, and (2) sites representative of different urbanisation levels are not true segments of the same ecological continuum. To surpass these problems, we modelled variations in carabid activity density along an urban-rural transect within a single green space extending from the city centre of Rome to rural environments. Carabids were sampled by pitfall traps from sites distributed along the entire gradient. We used breakpoint regressions to model how (1) carabid activity density, (2) carabids/beetles ratio, (3) carabids/insects ratio and (3) carabids/arthropods ratio varied along the gradient. As already observed for various organisms in urban environments, we found that activity density of carabids and their contribution to the abundance of beetles, insects and arthropods, peaked in the middle of the gradient. This supports the intermediate disturbance hypothesis, according to which moderate urbanisation may favour diversity by increasing habitat heterogeneity.

scholarly journals Effect of isoprene emissions from major forests on ozone formation in the city of Shanghai, China

2011 ◽  
Vol 11 (6) ◽  
pp. 18527-18556 ◽  
Author(s):  
F. Geng ◽  
X. Tie ◽  
A. Guenther ◽  
G. Li ◽  
J. Cao ◽  
...  
Keyword(s):  
Ozone Production ◽  
Ozone Formation ◽  
Emission Model ◽  
Peroxy Radicals ◽  
Forest Regions ◽  
High Concentrations ◽  
The Impact ◽  
The City ◽  
Continuous Oxidation ◽  
Ho2 Radical

Abstract. Ambient surface level concentrations of isoprene (C5H8) were measured in the major forest regions located south of Shanghai, China. Because there is a large coverage of broad-leaved trees in this region, high concentrations of isoprene were measured, ranging from 1 to 6 ppbv. A regional dynamical/chemical model (WRF-Chem) is applied for studying the effect of such high concentrations of isoprene on the ozone production in the city of Shanghai. The evaluation of the model shows that the calculated isoprene concentrations agree with the measured concentrations when the measured isoprene concentrations are lower than 3 ppb, but underestimate the measurements when the measured values are higher than 3 ppb. Isoprene was underestimated only at sampling sites near large bamboo plantations, a high isoprene source, indicating the need to include geospatially resolved bamboo distributions in the biogenic emission model. The assessment of the impact of isoprene on ozone formation suggests that the concentrations of peroxy radicals (RO2) are significantly enhanced due to the oxidation of isoprene, with a maximum of 30 ppt. However, the enhancement of RO2 is confined to the forested regions. Because the concentrations of NOx were low in the forest regions, the ozone production due to the oxidation of isoprene (C5H8 + OH →→ RO2 + NO →→ O3) is low (less than 2–3 ppb/h). The calculation further suggests that the oxidation of isoprene leads to the enhancement of carbonyls (such as formaldehyde and acetaldehyde) in the regions downwind of the forests, due to continuous oxidation of isoprene in the forest air. As a result, the concentrations of HO2 radical are enhanced, resulting from the photo-disassociation of formaldehyde and acetaldehyde. Because the enhancement of HO2 radical occurs in regions downwind of the forests, the enhancement of ozone production (6–8 ppb/h) is higher than in the forest region, causing by higher anthropogenic emissions of NOx. This study suggests that the biogenic emissions in the major forests to the south of Shanghai have important impacts on the levels of ozone in the city, mainly due to the carbonyls produced by the continuous oxidation of isoprene in the forest air.

Effects of acidic aerosol, fog, mist and rain on crops and trees

1984 ◽  
Vol 305 (1124) ◽  
pp. 327-338 ◽  
Keyword(s):  
Wind Velocity ◽  
Chemical Properties ◽  
Acute Injury ◽  
Acidic Precipitation ◽  
Transfer Rates ◽  
Lack Of Information ◽  
Leaf Surfaces ◽  
Number Frequency ◽  
High Concentrations ◽  
The Impact

The most important factors to consider for a complete determination of the toxicity to vegetation of acidic precipitation are: settling velocity, mass transfer rates, capacity to wet surfaces; number, frequency, and duration of events; and chemical composition and concentration. Meteorological factors, such as wind velocity and humidity, also must be considered because they affect the physical, temporal, and chemical properties of precipitation. Climate is important because it influences the capacity of plants to adjust, recover, or compensate for exposure to acidic precipitation. Genotype affects the efficiency of capture and capacity to tolerate acidic conditions. Aerosol and fog droplets generally are more acidic than mist and rain but they may be less phytotoxic because smaller droplets are deposited and captured less readily by leaf surfaces except when wind velocity is high. Concentrations of acids, mainly sulphuric and nitric acids, in aerosols, fog, mist, and rain in polluted regions, appear to be insufficient to produce acute injury on vegetation except perhaps in the immediate vicinity of intense sources of emissions. Chronic effects of repeated exposure to acidic precipitation, such as the impact on plant nutrition or on processes occurring at the leaf surface-atmosphere interface, and interactions with gaseous pollutants such as ozone, cannot be evaluated at present owing to the lack of information.

scholarly journals Building Stability On Permafrost In Vorkuta, Russia

2019 ◽  
Author(s):  
P. I. Kotov ◽  
V. Z. Khilimonyuk
Keyword(s):  
Climate Change ◽  
Housing Stock ◽  
Residential Buildings ◽  
Open Data ◽  
Urban Environments ◽  
The Arctic ◽  
Residential Housing ◽  
Infrastructure Stability ◽  
The Impact ◽  
The City

The Infrastructure stability on permafrost is currently an important topic as the Arctic countries are developing climate change adaptation and mitigation programs. Assessing the sustainability of infrastructure facilities (especially in urban environments) is a difficult task as it depends on many parameters. This article discusses the city of Vorkuta, which is located in the northwest of Russia. This city differs from many others built on permafrost because most of buildings were built according to Principle II (The Active Method) of construction on permafrost with thawing soil prior to construction. Assessments of the engineering and geocryological conditions, basic principles of construction in the city, and reasons for building failures, were carried out within this study. The research is based on publications, open data about buildings, and visual observations in Vorkuta. About 800 buildings are in use in Vorkuta in 2020 (43% of what it was 50 years ago). According to the analysis, about 800 houses have been demolished or disconnected from utility lines over the past 50 years (about 250 of these are still standing, pending demolition). Since 1994, the construction of new residential buildings has almost stopped. Therefore, buildings that have been in use for over 50 years will account for 90% of the total residential housing stock by 2040. The effects of climate change in the city will depend primarily on the principle of construction employed and on the geocryological conditions of the district. Buildings constructed according to Principle I (The Passive Method) were found to be more vulnerable due to a decrease in permafrost bearing capacity. The impact of increasing air temperature on some of the buildings built on bedrock (the central part of the city) and some built on thawing soil will be minimal, as other factors are more significant.

The Impact of Spatial Organization on Locating the Friday Mosques in the Traditional Islamic City-The Old Mosul City as a Case Study

2014 ◽  
Vol 71 (1) ◽  
Author(s):  
Faris A. Matloob ◽  
Ahmad B. Sulaiman
Keyword(s):  
Urban Space ◽  
Spatial Organization ◽  
Urban Environments ◽  
Urban Structure ◽  
Analytical Technique ◽  
People Movement ◽  
The Impact ◽  
The City ◽  
Early Islamic

Islamic city has its own character that distinguishes it from other urban environments. This is because it followed the Islamic ideology related to building the land. This led to that all cities built during early Islamic ages had followed the same principles in any part of the Islamic world. It is argued that the characteristics of the urban space configuration have a big role in making these cities successful environments. The key aspect in this matter is the distribution of land uses within the urban structure as it is directly associated with people movement and the distribution of their activities. The Friday mosques as the most important components of the Islamic city was located in a way that gave the city its own character. This study supposes that the distribution of the Friday mosques was affected by the way in which the urban space was configured. It aimed to find out to what extent this configuration influenced locating the Friday mosques in the urban fabric. Using space syntax as an analytical technique and the Old Mosul city as a case study, this research analyzed the spatial structure against several spatial characteristics with mosques locations to meet its goal.  

scholarly journals Urban Lighting Research Transdisciplinary Framework—A Collaborative Process with Lighting Professionals

2021 ◽  
Vol 18 (2) ◽  
pp. 624
Author(s):  
Catherine Pérez Vega ◽  
Karolina M. Zielinska-Dabkowska ◽  
Franz Hölker
Keyword(s):  
Urban Environments ◽  
Practice Research ◽  
Night Time ◽  
Research Knowledge ◽  
Research Production ◽  
Wide Range ◽  
Terrestrial Habitats ◽  
Dual Perspective ◽  
Micro Organisms ◽  
The Impact

Over the past decades, lighting professionals have influenced the experience of the night by brightly illuminating streets, buildings, skylines, and landscapes 24/7. When this became the accepted norm, a dual perspective on night-time was shaped and the visual enjoyment of visitors after dusk was prioritized over natural nightscapes (nocturnal landscapes). During this time, researchers of artificial light at night (ALAN) observed and reported a gradual increase in unnatural brightness and a shift in color of the night-time environment. As a consequence, ALAN has been identified as a relevant pollutant of aquatic and terrestrial habitats, and an environmental stressor, which may adversely affect a wide range of organisms, from micro-organisms to humans. Unfortunately, lighting professionals and ALAN researchers usually attempt to solve today’s sustainable urban lighting problems distinctive to their fields of study, without a dialogue between research and practice. Therefore, in order to translate research knowledge as an applicable solution for the lighting practice and to minimize the impact on the environment, a collaborative framework involving a transdisciplinary process with lighting professionals is crucial to potentially bring the practice, research, production, decision-making, and planning closer to each other. This paper presents a framework to help reduce the existing gap of knowledge, because appropriate lighting applications depend upon it. Access to less light polluted nightscapes in urban environments is just as important as access to unpolluted water, food, and air. This call for action towards sustainable urban lighting should be included in future lighting policies to solve the urgent environmental and health challenges facing our world.

scholarly journals Viscosity controls humidity dependence of N<sub>2</sub>O<sub>5</sub> uptake to citric acid aerosol

2015 ◽  
Vol 15 (15) ◽  
pp. 21983-22011 ◽  
Author(s):  
G. Gržinić ◽  
T. Bartels-Rausch ◽  
T. Berkemeier ◽  
A. Türler ◽  
M. Ammann
Keyword(s):  
Citric Acid ◽  
Aerosol Particles ◽  
Organic Matrix ◽  
Oxidative Capacity ◽  
Uptake Kinetics ◽  
Kinetic Regime ◽  
Night Time ◽  
Polycarboxylic Acids ◽  
Humidity Dependence ◽  
The Impact

Abstract. The heterogeneous loss of dinitrogen pentoxide (N2O5) to aerosol particles has a significant impact on the night time nitrogen oxide cycle and therefore the oxidative capacity in the troposphere. Using a 13N short lived radioactive tracer method we studied the uptake kinetics of N2O5 on citric acid aerosol particles as a function of relative humidity (RH). The results show that citric acid exhibits lower reactivity than similar di- and polycarboxylic acids, with uptake coefficients between ~ 3 × 10−4–~ 3 × 10−3 depending on humidity (17–70 % RH). This humidity dependence can be explained by a changing viscosity and, hence, diffusivity in the organic matrix. Since the viscosity of highly concentrated citric acid solutions is not well established, we present four different parameterizations of N2O5 diffusivity based on the available literature data or estimates for viscosity and diffusivity. Above 50 % RH, uptake is consistent with the reacto-diffusive kinetic regime whereas below 50 % RH, the uptake coefficient is higher than expected from hydrolysis of N2O5 within the bulk of the particles, and the uptake kinetics may be limited by loss on the surface only. This study demonstrates the impact of viscosity in highly oxidized and highly functionalized secondary organic aerosol material on the heterogeneous chemistry of N2O5 and may explain some of the unexpectedly low loss rates to aerosol derived from field studies.

When the City Begins to Talk

2020 ◽  
pp. 22-56
Author(s):  
Kristian Kloeckl
Keyword(s):  
Information Technologies ◽  
Design Research ◽  
Ad Hoc ◽  
Urban Environments ◽  
Urban Life ◽  
Urban Condition ◽  
Current Design ◽  
Virtual City ◽  
The Impact ◽  
The City

This chapter introduces the digitally augmented city as a major focus of current design research and practice. It critically examines the impact that the entanglement of networked information technologies with the urban realm has produced and discusses this in reference to extant literature. The entanglement of networked information technologies and urban environments has changed cities and urban life, and it has changed how we think about cities. Over the past two decades, a profusion of terms have been coined by scholars and practitioners to describe aspects of this changing urban condition. Networked city, real-time city, virtual city, smart city, hybrid city, responsive city, and ad hoc city are terms that are at times used lightly but that have underlying concepts that can help us capture more of the current urban condition and point to ways of working with it.

scholarly journals Are Heteroptera communities able to be bioindicators of urban environments?

2020 ◽  
Vol 28 (2) ◽  
pp. 195-202
Author(s):  
O. M. Kunakh ◽  
I. O. Fedyay
Keyword(s):  
Environmental Factors ◽  
Large City ◽  
Ecological Factors ◽  
Urban Ecosystems ◽  
Urban Environments ◽  
Ecological Groups ◽  
Similar Character ◽  
High Level ◽  
The Impact ◽  
The City

The Heteroptera is a group of animals associated with the vegetation cover. The conducted analysis indicates that groups of heteropterans in the urban environment have a pattern of reaction to the environmental factors, determined using the phytoindication method. In the study, we considered the following hypotheses: 1) phytoindicational assessments of ecological factors may explain the patterns of variation of the groups of heteropterans; 2) among Heteroptera species, comparatively homogenous ecological groups could be distinguished which are characterized by similar character of response to the effect of certain environmental factors; 3) these groups could be used for bioindication of the conditions of environment in urban ecosystems. Stationary collection of heteropterans was performed during three years from May to October of 2017–2019 on six plots in Kharkiv. The article describes factors which affect the structure of groups of Heteroptera within the ecosystem of the large city and assess the bioindication possibilities. The data presented in the article, as well as the conclusions drawn, are to a large extent associated with stenotopic species, most of which could be used as bioindicators of the condition of one or another biocenosis. According to the results of a taxonomical survey in the territory of Kharkiv, 180 species of Heteroptera were found, belonging to 120 genera and 17 families. The highest species diversity was seen for the family Miridae, accounting for 50 species (27.0% of the total number of counted species). Fewer species were identified as the representatives of families Lygaeidae – 46 species (24.9%) and Pentatomidae – 23 (12.4%). Family Rhopalidae was represented by 11 species (5.9%). Nabidae and Tingidae – 10 species each (5.4%). Families Coreidae – 8 (4.3%), Cydnidae and Scutelleridae – 4 species each (2.2%), Anthocoridae – 3 (1.6%). The families Berytidae, Piesmatidae, Pyrrhocoridae and Reduviidae were represented by only 2 species each (1.1%). Families Acanthosomatidae, Alydidae and Aradidae were represented by 1 species each, in total accounting for 1.5%. The reasonably high level of species and ecological diversities of Heteroptera in the territory of the city allows them to be used in bioindication studies. We determined comparatively homogenous ecological groups of heteropterans which have a similar pattern of response to the impact of certain environmental factors. The study demonstrates that phytoindicatory assessments of the ecological factors can explain the patterns of variation in groups of heteropterans, We determined the factors which have effects on the structure of the group of heteropterans within the metropolitan ecosystem. The level of their effect on groups of heteropterans within the city is different. The most influential were light and humidity. Comparison of potential and realized projections of ecological space allows us, to a certain extent, to generate hypotheses about the orientations of transformation of the group heteropterans.

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