Flux measurements in the surface Marine Atmospheric Boundary Layer over the Aegean Sea, Greece

Micro-meteorological measurements within the surface Marine Atmospheric Boundary Layer took place at the shoreline of two islands at northern and south-eastern Aegean Sea of Greece. The primary goal of these experimental campaigns was to study the momentum, heat and humidity fluxes over this part of the north-eastern Mediterranean Sea, characterized by limited spatial and temporal scales which could affect these exchanges at the air-sea interface. The great majority of the obtained records from both sites gave higher values up to factor of two, compared with the estimations from the most widely used parametric formulas that came mostly from measurements over open seas and oceans. Friction velocity values from both campaigns varied within the same range and presented strong correlation with the wind speed at 10 m height while the calculated drag coefficient values at the same height for both sites were found to be constant in relation with the wind speed. Using eddy correlation analysis, the heat flux values were calculated (virtual heat fluxes varied from -60 to 40 W/m(2)) and it was found that they are affected by the limited spatial and temporal scales of the responding air-sea interaction mechanism. Similarly, the humidity fluxes appeared to be strongly influenced by the observed intense spatial heterogeneity of the sea surface temperature.

Quantification of environmental tobacco smoke contribution on outdoor particulate aliphatic and polycyclic aromatic hydrocarbons

The objective of this study was to identify and quantify the sources of fine particulate aliphatic and polycyclic aromatic hydrocarbons (PAHs) in an urban area in southeastern Europe. A total of 91 urban PM2.5 samples were analyzed by gas chromatography coupled with mass spectrometry for alkanes and PAHs. Exploratory statistical tools were applied to resolve a decreased number of components based on the variation of measurements. Molecular markers and diagnostic ratios were examined to assign retained components to specific sources. The contributions of the sources were estimated by multivariate linear regression. Sources of aliphatic and PAHs hydrocarbons included primary particles from traffic (3.9 ng/m(3) for alkanes and 240 pg/m(3) for PAHs), evaporative fugitive (4.0 ng/m(3) for alkanes and 93 pg/m(3) for PAHs), and unburnt fuels and oil residues (1.1 ng/m(3) for alkanes and 230 pg/m(3) for PAHs). For the first time, we quantified the contribution of environmental tobacco smoke (ETS), which accounted for 5.2 ng/m(3) of alkanes and 128 pg/m(3) of PAHs. The findings of this study underlined the persistence of ETS and possible exposures to significant quantities of tobacco residues outdoors. Tobacco smoke is known to induce adverse respiratory and cardiovascular illnesses and increased risk for cancer.

Temporal variations of PM2.5 in the ambient air of a suburban site in Athens, Greece

Twenty-three hour measurements of PM(2.5) particulate matter have been carried out during the period between the 1st April and the 13th November 2003 in a suburban area of Athens. The monitoring site was located in the National Research Center "DEMOKRITOS", on the foot of Hemittos Mountain and about 12 km away from the center of Athens. The site covers an area of 600 acres in a forest of pine trees close enough to the newly constructed Hemittos Mountain peripheral highway. PM(2.5) samples were collected on 47 mm filters, with the use of low volume gravimetric samplers while a meteorological station recorded meteorological data 6 m above the ground, nearby the sampling instrumentation. The daily average PM(2.5) concentration reached 21.1 microg m(-3) and all measurements were below U.S. Environmental Pollution Agency daily limit (65 microg m(-3)). A regression analysis was used to investigate the relationship among PM(2.5) concentrations and meteorological parameters. Additionally, PM(2.5) mass concentrations were correlated with other inorganic gaseous pollutants (O(3), NO, NO(2), SO(2)) while weekly and seasonal PM(2.5) variations were also investigated.

Sodar mixing height estimates and air pollution characteristics over a Mediterranean big city

Sodar systems are progressively used for quantitative and qualitative profile information on the atmospheric structure parameters. However, there is still a need for well-established relations between atmospheric physics parameters and air quality patterns, especially in urban environments. In this respect it is of importance to investigate the correlations among specific atmospheric quantities and air pollution patterns. It is the purpose of this paper to study correlations between the Sodar produced mixing height using the most recent and accurate methods, and O3, NOx and CO concentrations recorded by the Athens air quality monitoring network, during selected meteorological conditions. The continuous mixing height monitoring allows for deeper investigation of air pollution characteristics, especially during the transitional periods of the day. The obtained results indicate that there is good correlation between the pollutants concentrations and the mixing height especially during episode days. Furthermore, it is indicated that there is a strong dependence between the rate of increase of the mixing height and the concentration levels in the early morning hours as well as during the Atmospheric Boundary Layer (ABL) collapse in the afternoon. These results are of importance for urban air pollution modelling, which has recently attracted the attention of many research groups.