Volatile hydrocarbons in the atmosphere of Athens, Greece (original) (raw)
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An experimental study of the horizontal and vertical distribution of ozone over Athens
Atmospheric Environment (1967), 1987
in this study, we present measurements of ozone (0,) concentrations both on the surface and aloft, taken at sites appropriately located to give information about the effect of the local flows, such as the sea breeze circulation, on the air quality of Athens. Profiles of 0s and other meteoro\ogical parameters of the atmospheric boundary layer were obtained at a location in the center of Athens. Surface measurements of O3 were conducted in a number of other locations which included the shoreline and an island. The measurements confirmed well known models for the effect of sea breeze on photochemical pollutants and the diurnal variation of 0s in the evolving atmospheric boundary layer and showed that pollutants released in the evening and early morning hours are advected offshore where they generate O3 which in turn is advected back to the city by the sea breeze. They also showed that Athens pollutants are found in considerable concentrations in Aegina and outside the main basin to the north. The results of this study demonstrate the need to take into account advection patterns in any attempt to formulate pollution abatement strategies for sites with strong local circulations such as the Athens basin.
Surface ozone measurements and meteorological influences in the urban atmosphere of Istanbul
International Journal of Environment and Pollution, 2002
Hourly measurements of ozone concentration in the urban atmosphere of Istanbul were carried out from February 1998 to July 1999. An assessment of the annual variations and relationships of ozone concentrations and meteorological variables was made. Annual variations were first examined without considering meteorological variables, then meteorological influences on ozone seasonal values were examined. Furthermore, a typical ozone threshold period was analysed by considering meteorological variables for a case study. Meteorological conditions favourable for high ozone concentrations appeared when Istanbul and its surrounding region were dominated by an anticyclonic pressure system. During conducive ozone days, southerly and southwesterly winds with low speeds (daytime mean value <11m1s −1) influence Istanbul.
2021
Environmental Monitoring Center Station (23.12° N, 113.27° E, 51 m above sea level). It is a typical urban site located at Jixiang Road, Yuexiu District of Guangzhou, an urban area surrounded by massive residential and commercial buildings. The pillar industries are business industry, financial industry, cultural creativity industry, and health care over the area, therefore, the site is mainly subjected to traffic emissions and rarely impacted by industrial source. The site is set up on the rooftop of an eightfloor building with an altitude of ~40 m above the ground level and the data collected here can reflect urban pollution characteristics. Real-time measurements of trace gases, including O3, NO, NO2, CO, SO2, and VOCs were implemented using standard commercial techniques. O3 was measured by a UV photometric ozone analyzer (Thermo 49i) with a detection limit of 0.50 ppbv. NO and NO2 were monitored using a chemiluminescence analyzer (Thermo 42i) with a detection limit of 0.40 ppbv. CO was measured by a gas filter correlation, non-dispersive infrared analyzer (Thermo 48i) with a detection limit of 40 ppbv. SO2 was measured by a pulsed fluorescence gas analyzer (Thermo 43i) with a detection limit of 1 ppbv. The quality assurance and quality control procedures were implemented according to "Technical Specifications for Automatic Monitoring of Ambient Air Quality (HJT193-2005)". VOCs were measured using the GC866 online analyzer (Chromatotec) with a detection limit of 0.01 ppbv. The detection system consists of two analyzers: the low-carbon analyzer is responsible for the collection and detection of C2-C6 hydrocarbons, and the high-carbon analyzer is responsible for the collection and detection of C6-C12 hydrocarbons. Both analyzers use flame ionization detector for detection, and totally 57 hydrocarbons (specified by the Photochemical Assessment Monitoring Stations of US Environmental Protection Agency (USEPA)) were detected. Meteorological parameters including ambient temperature, relative humidity (RH), and pressure were obtained from a commercial meteorological station (Vaisala, Finland). 2. Model configuration The model was run based on the platform of F0AM (Framework for 0-D Atmospheric Modeling) (Wolfe et al., 2016), and the adopted chemical mechanism was the state-of-the-art Master Chemical Mechanism version 3.3.1 (MCMv3.3.1), which near-explicitly describes the atmospheric degradation of 143 VOC species and has been extensively used to elucidate the non-linear photochemistry between O3 and its precursors (NOx and VOCs) (Chen et al., 2020; Xue et al., 2014). In addition to the comprehensive chemistry, the model also considers several physical processes, including solar radiation, diurnal evolution of the PBL, dry deposition, and dilution with background air (Chen et al.,
Atmospheric Research, 1992
Surface measurements of ozone are correlated to measurements of its precursors (NOx and hydrocarbons) for the period 1986-1989, for the West Coast Air Basin of Athens. We first find that the concentrations of total hydrocarbons (THC) and non-methane hydrocarbons (NMHC) are linearly correlated. We then attempt to express the relationship of ozone to its precursors via polynomial and multiplicative regression models, to find that in all cases ozone variation is explained by the mixing ratios of NOx and non-methane hydrocarbons in conjunction with a meteorological parameter, namely the temperature at the pressure level of 850 hPa. Depending on the regression model, the correlation coefficient increases from 0.73 to 0.98. The satisfactory performance of the regression models support their application for both the assessment of air quality in urban areas and the formulation of localized environmental protection policies. RI~SUMI~ On 6tablit des corr61ations entre les mesures de l'ozone et celles de ses pr6curseurs (NOx et hydrocarbones) sur la pattie occidentale c6ti6re du bassin d'Ath6nes pour la p6riode 1986-1989. On trouve d'abord que les concentrations en hydrocarbone total et en hydrocarbone non m6than6 sont lin6airement corr616s. On exprime ensuite la relation de l'ozone ~ ses pr6curseurs par des mod61es de r6gression polynomiaux et multiplicatifs, pour trouver que darts tous les cas les variations de I'ozone s'expliquent par les taux de m61ange de NOx et d'hydrocarbone non m6than6 en relation avec un param6tre m6t6orologique, la temp6rature au niveau 850 hPa. Scion le mod61e de r6gression utilis6, le coefficient de corr61ation varie de 0,73 ~ 0,98. La bonne performance des mod61es de r6gression permet leur application aussi bien/l la d6termination de la qualit6 de rair dans les zones urbaines qu'/l la formulation de r6gles de protection de l'environnement.
The ozone increments in urban plumes
Science of The Total Environment, 1995
The role of urban plumes in the exposure of suburban/rural areas to pollution by ozone is discussed, and literature on direct measurement of ozone within plumes reviewed. There is a virtual absence of reports of ozone destruction within a NOx-rich urban plume and reasons are given for this gap in the current published data. These negative ozone increments are important because the particular air quality problems encountered downwind of a city will depend on its character as a source or sink of ozone. Simple plume reconstruction methods are used to verify and extend data from measurements in the London plume. There is an optimum time for air-parcel release with respect to increased plume ozone, and a change in the typical diurnal variation of ground-level ozone concentrations when the receptor site is situated within an urban plume. On a surface constructed from air parcel emission times and times travelled downwind of London, a major peak in plume ozone increment is observed 6-8 h downwind of a post rush-hour release in the urban centre. A secondary maximum in the surface is also apparent for air parcels 2-3 h after release in the early afternoon. These are not the emission and travel times usually adopted in modelling studies of the urban plume from London. Sites in the urban plume are also found to have a statistically different diurnal variation compared to rural/suburban sites which are not influenced by the plume. This is due to the titration of ozone mixing into the plume from aloft by plume NO.
Atmospheric Environment, 2021
Volatile organic compounds (VOCs) and oxygenated VOCs (OVOCs) were measured in Ho Chi Minh City (HCMC) and Hanoi, the two largest and most populous cities in Vietnam. The purpose of this study is to better understand the VOC atmospheric composition and their role in ground-level ozone formation. Online measurements of a wide range of VOCs and other pollutants were conducted using numerous instruments during different seasons (dry and rainy) in HCMC and Hanoi (spring). Our results show that the mean mixing ratio of total measured VOCs in Hanoi was 80.8 ± 40.7 ppb (mean ± standard deviation), and was similar to that observed during the rainy season (75.2 ± 44.8 ppb) in HCMC. During the dry season campaign in HCMC, which was coincident with the Hanoi campaign, total VOC was around 50% lower (40.7 ± 19.5 ppb), largely a result of increased planetary boundary layer (PBL) height and the direction of the prevailing wind. VOC profiles in both cities were dominated by alkanes (31-35%) and OVOCs (27-33%) and the proportion of alkenes (13-17%) and aromatics (12-19%) were comparable. Similarities in diurnal variation for most VOC species (except for isoprene) are seen in both cities with two clear peaks during the morning (7:00-8:00 am) and evening (18:00 pm) rush hours, as observed for vehicular-combustion tracers (acetylene and CO). Comparisons of the ambient ratios of paired VOCs, namely i/n-pentane, and toluene/benzene, with those reported in motorcycle exhaust, roadside and gasoline samples indicate that motorcycle-related emission is likely a major contributor to VOC pollution. According to the propylene-equivalent concentration (PE conc.) and maximum incremental reactivity (MIR) methods, alkenes and aromatics were determined to be the main contributors to reactivity and ozone potential formation. Furthermore, the initial mixing ratio of VOC species was estimated based on the photochemical age method. The consumed VOCs (initial VOCs minus measured VOCs) has a similar variation trend to ground-level ozone, and a good correlation is observed in HCMC. In contrast, this result was not seen in Hanoi despite relatively high levels of PE conc. and MIR.
Re-evaluation of surface ozone over Athens, Greece, for the period 1901–1940
Atmospheric Research, 1991
Surface ozone mixing ratio was monitored in Athens, Greece from 1901 to 1940. This historic ozone series is unique for southeastern Europe. The series provides ozone mixing ratio values for that period and therefore allows comparison with recent ones. The measurements were obtained using the De James colometric papers, which scale from 0 to 21. A re-evaluation of the data is attempted considering the dependence of the measurements' conversion on both the relative humidity and the exposure time. The newly estimated surface daily ozone values in Athens (1901-1940) vary around 20 ppb and reach their maximum and minimum values during the periods April-June and October-December respectively. RESUMI~ La concentration au sol en ozone a 6t6 mesurre/t Athrnes, Grrce, de 1901 /1 1940. La srrie de mesures, unique pour l'Europe du sud-est, donne les valeurs du taux de mrlange pour cette prriode, ce qui permet une comparaison avec de mesures rrcentes. Les mesures ont 6t6 faites en utilisant des papiers colorimrtriques De James sur une 6chelle de 0/l 21. On procrde h une r66valuation des donnres en considrrant l'influence sur la conversion des donnres/t la fois de l'humidit6 relative et du temps d'exposition. Les nouvelles valeurs journalirres estimre de rozone au sol (1901-1940) tournent autour de 20 ppb et atteignent leurs valeurs maximales et minimales respectivement d'avril/l juin et d'octobre/t drcembre.
Impact of VOCs and NOx on Ozone Formation in Moscow
Atmosphere, 2020
Volatile organic compounds (VOCs), ozone (O3), nitrogen oxides (NOx), carbon monoxide (CO), meteorological parameters, and total non-methane hydrocarbons (NMHC) were analyzed from simultaneous measurements at the MSU-IAP (Moscow State University—Institute of Atmospheric Physics) observational site in Moscow from 2011–2013. Seasonal and diurnal variability of the compounds was studied. The highest O3 concentration in Moscow was observed in the summer daytime periods in anticyclonic meteorological conditions under poor ventilation of the atmospheric boundary layer and high temperatures (up to 105 ppbv or 210 μg/m3). In contrast, NOx, CO, and benzene decreased from 8 a.m. to 5–6 p.m. local time (LT). The high positive correlation of daytime O3 with secondary VOCs affirmed an important role of photochemical O3 production in Moscow during the summers of 2011–2013. The summertime average concentrations of the biogenic VOCs isoprene and monoterpenes were observed to be 0.73 ppbv and 0.53 p...
Regional ozone and urban plumes in the southeastern United States: Birmingham, A case study
Journal of Geophysical Research, 1995
Aircraft measurements of ozone and the oxides of nitrogen have characterized the horizontal and vertical extent of the urban plume downwind of Birmingham, Alabama. Derived NOx emission rate estimates of 0.6 x 1025 molecules s -1, with an uncertainty of a factor of 2, for this metropolitan area are in reasonable accord with the 1985 National Acid Precipitation Assessment Program inventory, which gives 1.2 x 1025 molecules s -1 for daytime emissions. These estimates are from two flights in 1992 when the urban plume was well separated from the plumes from two power plants northwest of the city. During three flights in 1990 the plumes of the Birmingham metropolitan area and the two power plants were combined; good agreement was found between the estimated fluxes1)(2.0 to 5.5 x 102s molecules s -1) and the emission inventory (3.7 x 1025 molecules s-for the combined sources. The enhancement of 03 in the urban plume indicates photochemical formation and shows that during the summertime, approximately seven 03 molecules can be formed per NOx molecule added by the urban and power plant emissions. This production efficiency applies both to the isolated urban plume and to the combined urban-power plant plumes and is similar to that derived for rural areas from surface studies. Comparison of the results from several flights indicates the contribution of the regional ozone levels to the 0 3 concentrations observed within the urban plumes. The aircraft measurements, in combination with surface measurements of ozone, show that the interaction of ozone concentrations entering the urban area, the photochemical formation of ozone during the oxidation of the urban emissions, and the wind speed and direction determine the location and the magnitude of the peak ozone concentrations in the vicinity of this metropolitan area. Paper number 95JD01641. 0148-0227/95/95JD-01641505.00 the urban center [White et al., 1976]. By following the chemical development at successive interceptions of urban plumes, estimates of the oxidation rate of sulfur dioxide [Gillani et al., 1978], the rate of removal of NOx [Spicer, 1982], and the oxidation rate of hydrocarbons [Calvert, 1976; Blake et al., 1993] have been derived. The amount of ozone formed per oxidation of NOx has been estimated in the plumes of large metropolitan areas [White et al., 1983; Altshuller, 1986, and references therein]. Studies of the enhancement of ozone in urban plumes have been summarized by Altshuller [1986].
Evaluation of Ozone Levels in Volos, Greece. The Weekend Effect
2010
The results presented in this work were derived from an analysis of hourly surface ozone concentrations, measured at the urban station of Volos, a coastal medium-sized city at the eastern seaboard of Central Greece, during the eight-year period 2001-2008. The regional climate, which is characterized by hot and dry summers with intense sunshine, plays an important role in the observed exceedances of the air quality ozone limits. The analysis showed that, ozone diurnal patterns depict daytime photochemical ozone built up, during the sunlight hours of the day. A weekend effect was observed, which is likely attributed to working days/weekend differences with respect to nitrogen oxide emissions, and the complex non-linear ozone's photochemistry.