P. D. Kalabokas

Atmospheric concentrations of saturated and aromatic hydrocarbons around a Greek oil refinery

Petroleum refineries are large industrial installations that are responsible for the emission of several pollutants into the atmosphere. Hydrocarbons are among the most important air pollutants that are emitted by petroleum refineries, since they are involved in almost every refinery process. The ambient air concentrations of many saturated and aromatic hydrocarbons were measured in several sites around an oil refinery, near the city of Corinth in Greece, during 1997. At the same time several meteorological parameters were also recorded. The seasonal, diurnal and spatial variations of the ambient air concentrations of these hydrocarbons were investigated and analyzed. An estimation of the contribution of the refinery to the measured atmospheric levels of hydrocarbons was also performed. The ambient air mixing ratios of the saturated and aromatic hydrocarbons in a large area outside the refinery were generally low, in ppbv range, much lower than the ambient air quality standards or the ambient air concentrations in the two largest urban centers in Greece, Athens and Thessaloniki.

Quasi-continuous measurements of non-methane hydrocarbons (NMHC) in the Greater Athens area during medcaphot-trace

Abstract During the comprehensive field campaign MECAPHOT-TRACE (20 August to 20 September 1994) quasi-continuous measurements of NMHC in the range of C 4 –C 12 were carried out for the first time in the Greater Athens area simultaneously at two sites, by means of on-line gas-chromatographic methods. The results show a heavy load of hydrocarbons in ambient air, especially during stagnant weather conditions that favour the development of land–sea-breeze circulations. Overall the urban hydrocarbon mix reflects the emission of traffic. This influence is confirmed through correlation analyses of hydrocarbon ratios, especially aromatic compound ratios, and their dependence on both wind direction and wind velocity at a suburban receptor site. The ethylbenzene/ m -xylene-ratio turned out to be a good indicator for the impact of anthropogenically related hydrocarbon chemistry leading to the formation of secondary pollutants. Episodes will be discussed that elucidate the importance of hydrocarbons in the course of ozone formation.

Field studies of aldehyde chemistry in the Paris area

Abstract Measurements of carbonyl compound concentrations at different sites in the Paris area have been carried out. Interpretation of the results made use of the following data: general meteorological conditions, wind field analysis and type of primary pollutant sources. The principal phenomena observed were: a sharp formaldehyde decrease during rainfall; concentration levels of lower aldehydes in rural sites comparable to those found in the literature; an important variation in the ratio of primary aldehydes to secondary aldehydes depending on meteorological conditions; a significant increase in lower aldehyde concentrations downwind from the urban center despite vertical dispersion of the pollutants.

Vertical ozone measurements in the troposphere over the Eastern Mediterranean and comparison with Central Europe

Vertical ozone profiles measured in the period 1996–2002 in the framework of the MOZAIC project (Measurement of Ozone and Water Vapor by Airbus in Service Aircraft) for flights connecting Central Europe to the Eastern Mediterranean basin (Heraklion, Rhodes, Antalya) were analysed in order to evaluate the high rural ozone levels recorded in the Mediterranean area during summertime. The 77 flights during summer (JJAS) showed substantially (10– 12 ppb, 20–40%) enhanced ozone mixing ratios in the lower troposphere over the Eastern Mediterranean frequently exceeding the 60 ppb, 8-h EU air quality standard, whereas ozone between 700 hPa and 400 hPa was only slightly (3– 5 ppb, 5–10%) higher than over Central Europe. Analysis of composite weather maps for the high and low ozone cases, as well as back-trajectories and vertical profiles of carbon monoxide, suggest that the main factor leading to high tropospheric ozone values in the area is anticyclonic influence, in combination with a persistent northerly flow in the lower troposphere during summertime over the Aegean. On the other hand the lowest ozone levels are associated with lowpressure systems, especially the extension of the Middle East low over the Eastern Mediterranean area.

On the temporal and spatial variation of ozone in Cyprus.

More than sixteen years (1997-2013) of continuous ozone concentrations at the rural Agia Marina (EMEP, 532 ma.s.l.) station in Cyprus, together with a number of ancillary chemical and meteorological parameters have been analyzed on a multiannual, annual and diurnal basis. The observations reveal a) the presence of a prominent seasonality with maxima observed during summer (54±5 ppbv) and the minima in winter (39±3 ppbv) b) a relatively small diurnal variability with the noon levels (50±9 ppbv) being higher by ~4 pbbv compared to nighttime (46±9 ppbv) and c) a non-significant upward trend over the 16 years of 0.11±0.12 ppbv y(-1). To assess the spatial variability over Cyprus, simultaneous measurements in 2011-2012 have been performed at Inia, Stavrovouni and Cavo Greco, three remote marine monitoring sites located to the west, central and the east of the Island, respectively. Our results show that ambient ozone levels over Cyprus are mostly influenced by regional/transported ozone while the local precursor emissions play a minor role in ozone formation. On an annual basis a net ozone reduction of 1.5 and 1.0 ppbv occurs when the air masses originate from northerly and westerly directions, respectively, while this is 2.4 ppbv during southerly wind. This suggests continuous net ozone loss controlled by surface deposition and photochemical destruction, and highlights the importance of long-range transport in controlling ozone levels in Cyprus.

Ambient atmospheric trace gas concentrations and meteorological parameters during the first BEMA measuring campaign on May 1994 at Castelporziano, Italy

Abstract During the first measuring campaign of the BEMA project, carried out in May 1994 at Castelporziano, near Rome, Italy, one of the tasks was to measure continuously meteorological parameters and tropospheric trace gas concentrations. The atmospheric species measured were ozone, NO x , anthropogenic and biogenic hydrocarbons, carbonyl compounds, hydrogen peroxide, organic peroxides and PAN. Another goal was the characterization of the atmospheric circulation patterns. The results showed that anthropogenic pollution is present at the Castelporziano site originating mainly from the Rome metropolitan area but also from other directions. The average concentration levels of NO x were about 9 ppb, the average total measured anthropogenic hydrocarbon concentration was 67 ppbC and the average ozone mixing ratio was 36 ppb. The possible role of naturally emitted VOCs in tropospheric ozone formation is discussed.

A study on the atmospheric concentrations of primary and secondary air pollutants in the Athens basin performed by DOAS and DIAL measuring techniques

In this work an analysis of continuous Differential Optical Absorption Spectroscopy (DOAS) measurements of primary and secondary air pollutants (SO(2), NO(2) and O(3)) in the Athens basin is performed combined with Differential Absorption Lidar (DIAL) vertical ozone measurements obtained inside the Planetary Boundary Layer (PBL) and the lower free troposphere. The measurements took place during the period May 2005-February 2007, at the National Technical University of Athens Campus (200 m above sea level (asl.), 37.96 °N, 23.78 °E). The SO(2) and NO(2) DOAS measurements showed maximum 1-hour mean values (around 20 μg/m(3) and 74 μg/m(3), respectively) in winter and did not exceed the current European Union (EU) air quality standards (European Council Directive 2008/50/EC), in contrast to ozone, which shows its maximum (around 128 μg/m(3)) in summer and frequently exceeds the EU standard for human health protection (120 μg/m(3)). If the measurements are classified according to the two most frequent flow-patterns of the air masses in the Athens basin (northern-southern circulation), it is observed that in general the atmospheric concentrations of all measured pollutants including ozone are higher when the southern circulation occurs, in comparison to the corresponding values under the northern circulation. The vertical ozone profiles obtained by DIAL were also higher under the southern circulation. During the summer months a mean difference (between the southern-northern circulations) of the order of 15-20 μg/m(3), maximized at the 0.9-1.1 km and 1.7-1.8 km height, was observed within the PBL. It was also observed that the summer surface ozone levels remained relatively high (around 80-110 μg/m(3)) even during strong northerly winds, verifying the high levels of rural surface ozone in the surrounding area reported by previous studies.

ATMOSPHERIC LEVELS OF NITROGEN OXIDES AT A GREEK OIL REFINERY COMPARED WITH THE URBAN MEASUREMENTS IN ATHENS

Oil refining is among the industrial activities that emit considerable amounts of air pollutants into the atmosphere. Nitrogen oxides are important air pollutants that are emitted by oil refineries as products of combustion processes. The ambient air concentrations of nitrogen oxide (NO) and nitrogen dioxide (NO2) were monitored continuously at a site close to an oil refinery, near the city of Corinth in Greece, during autumn 1997 together with the main meteorological parameters. The contribution of the oil refinery to the measured atmospheric levels of nitrogen oxides was estimated. The ambient air concentration of nitrogen oxides in the area surrounding the oil refinery were generally lower than the ambient air concentrations in the urban area of Athens in Greece, and the NO2 levels were always below the existing air quality standards. The influence of the refinery emitted NOx in the photochemical production of ozone seems to be more important in terms of human and vegetation exposure given the high ozone backgrounds measured in the area.

Quelques Aspects de la Chimie des Aldehydes dans la Basse Troposphere

L’etude de la chimie des aldehydes dans la basse troposphere a ete abordee par deux voies complementaires : d’une part, la determination de la reactivite des aldehydes vis-a-vis des radicaux hydroxyles et nitrates sous conditions atmospheriques simulees en vue de l’estimation de leur temps de residence tropospherique et d’autre part l’etude des facteurs sources et puits d’aldehydes dans les masses d’air transitant au-dessus de la region parisienne.