ilias kavouras - Academia.edu (original) (raw)

Papers by ilias kavouras

Journal of Geophysical Research, 2002

Polynuclear aromatic hydrocarbons (PAHs), n-alkanes, n-alkanals, n-alkanols, saturated and unsatu... more Polynuclear aromatic hydrocarbons (PAHs), n-alkanes, n-alkanals, n-alkanols, saturated and unsaturated carboxylic acids, a, w-dicarboxylic acids, and carbonyl and carboxylic photooxidation products of monoteprenes were determined in particle-sized aerosols of urban (Heraclion, Island of Crete, Greece), background marine (Island of Crete, Greece), and forest (Northern Greece and Portugal) atmospheres. The n-alkanes were mostly associated with fine particles in the urban and forest aerosol, and their mass mean aerodynamic diameter (MMAD) calculated over the whole size range (total MMAD) was 0.45 mm and 0.63 mm, respectively. In the background marine aerosol, nalkanes were more evenly distributed, and their MMAD was 2.00 mm, because of physical changes occurring during their long-range transport. Similar observations have been done for PAHs and nalkanals. Conversely, the most biogenic compound class, namely n-alkanols, were evenly associated in the urban, background marine, and forest aerosol, between fine and coarse particles, and their corresponding total MMAD was 2.45, 2.69, and 1.67 mm, respectively. The total MMAD of n-alkanoic acids was 0.71, 0.62, and 0.91 mm in the urban, background marine, and forest aerosol, respectively. Several compounds associated with photochemical reactions in the atmosphere were detected in urban marine and forests aerosol in the fine and ultrafine fraction, showing the low total MMAD (0.28-0.77 mm) in all aerosol types.

Journal of Geophysical Research: Atmospheres, 2012

We examined the chemical composition of aerosol samples collected during a prescribed fire at a G... more We examined the chemical composition of aerosol samples collected during a prescribed fire at a Great Basin Desert site in the context of samples collected from controlled combustion of vegetation clippings from the same site and resuspension of soil samples obtained prior to and after the burn event. We observed a distinct difference in the composition of organic carbon resuspended soil dust after the burn, reflecting changes caused by the heating of the soil. The relative abundances of minerals and organic carbon ...

PM10 refers to particulate matter (PM) of 10 microns or less in aerodynamic diameter. Another cla... more PM10 refers to particulate matter (PM) of 10 microns or less in aerodynamic diameter. Another class of particles, denoted as PM2. 5 (also called as fine particles), refers to particles of 2.5 microns or less in aerodynamic diameter. While fine particles originate mostly from combustion sources and secondary aerosol generation processes, coarse particles (PM10 minus PM2. 5) originate from mechanical activities and fugitive source categories. Major sources of PM10 typically include fugitive dust, open burning including wild fires, ...

Environmental Science and Pollution Research, 2011

Purpose The concentrations of PM 10 mass, PM 2.5 mass and particle number were continuously measu... more Purpose The concentrations of PM 10 mass, PM 2.5 mass and particle number were continuously measured for 18 months in urban background locations across Europe to determine the spatial and temporal variability of particulate matter. Methods Daily PM 10 and PM 2.5 samples were continuously collected from October 2002 to April 2004 in background areas in Helsinki, Athens, Amsterdam and Birmingham. Particle mass was determined using analytical microbalances with precision of 1 μg. Pre-and post-reflectance measurements were taken using smoke-stain reflectometers.

We examined the chemical composition of aerosol samples collected during a prescribed fire at a ... more We examined the chemical composition of aerosol samples collected during a prescribed fire at a Great Basin Desert site in the context of samples collected from controlled combustion of vegetation clippings from the same site and resuspension of soil samples obtained prior to and after the burn event. We observed a distinct difference in the composition of organic carbon resuspended soil dust after the burn, reflecting changes caused by the heating of the soil. The relative abundances of minerals and organic carbon fractions in aerosols collected during the first period of the burn were identical to those measured in soil dust. For aerosol samples collected for the remaining two periods of the burn event, the profiles of both minerals and organic carbon matched quite well those observed for vegetation combustion. Reconstruction of aerosol samples collected during the burn event showed that vegetation combustion dominated emissions but mineral soil dust may account for about 10% of PM10emissions (reconstructed) during the early stages of the fire. A large fraction of emissions during the first two hours was also unaccounted mainly because of the insufficient conversion of organic carbon to organic mass. The abundance of heavier non-volatile organics in soil dust suggested the presence of humic/fulvic acids that exhibit higher OM-to-OC ratios and thus, account for a proportion of the unaccounted emissions. These findings indicated that soil dust may be released into the air during a fire event, probably due to the enhanced turbulent mixing near the burn front.

Journal of The Air & Waste Management Association, 2007

The associations between residential outdoor and ambient particle mass, fine particle absorbance,... more The associations between residential outdoor and ambient particle mass, fine particle absorbance, particle number (PN) concentrations, and residential and traffic determinants were investigated in four European urban areas (Helsinki, Athens, Amsterdam, and Birmingham). A total of 152 nonsmoking participants with respiratory diseases, not exposed to occupational pollution, were included in the study, which comprised a 7-day intensive exposure monitoring period of both indoor and home outdoor particle mass and number concentrations. The same pollutants were also continuously measured at ambient fixed sites centrally located to the studied areas (fixed ambient sites). Relationships between concentrations measured directly outside the homes (residential outdoor) and at the fixed ambient sites were pollutant-specific, with substantial variations among the urban areas. Differences were more pronounced for coarse particles due to resuspension of road dust and PN, which is strongly related to traffic emissions. Less significant outdoor-to-fixed variation for particle mass was observed for Amsterdam and Birmingham, predominantly due to regional secondary aerosol. On the contrary, a strong spatial variation was observed for Athens and to a lesser extent for Helsinki. This was attributed to the overwhelming and time-varied inputs from traffic and other local sources. The location of the residence and traffic volume and distance to street and traffic light were important determinants of residential outdoor particle concentrations. On average, particle mass levels in suburban areas were less than 30% of those measured for residences located in the city center. Residences located less than 10 m from a street experienced 133% higher PN concentrations than residences located further away. Overall, the findings of this multi-city study, indicated that (1) spatial variation was larger for PN than for fine particulate matter (PM) mass and varied between the cities, (2) vehicular emissions in the residential street and location in the center of the city were significant predictors of spatial variation, and (3) the impact of traffic and location in the city was much larger for PN than for fine particle mass.

Journal of Hazardous Materials, 2006

As part of the Megacities Initiative: Local and Global Research Observations (MILA-GRO) study in ... more As part of the Megacities Initiative: Local and Global Research Observations (MILA-GRO) study in the Mexico City Metropolitan Area in March 2006, we measured particulate polycyclic aromatic hydrocarbons (PAHs) and other gaseous species and particulate properties at six locations throughout the city. The measurements were intended to 5 support the following objectives: to describe spatial and temporal patterns in PAH concentrations, to gain insight into sources and transformations of PAHs, and to quantify the relationships between PAHs and other pollutants. Total particulate PAHs at the Instituto Mexicano del Petróleo (T0 supersite) located near downtown averaged 50 ng m −3 , and aerosol active surface area averaged 80 mm 2 m −3 . PAHs were also measured on 10 board the Aerodyne Mobile Laboratory, which visited six sites encompassing a mixture of different land uses and a range of ages of air parcels transported from the city core. Weak intersite correlations suggest that local sources are important and variable and that exposure to PAHs cannot be represented by a single regional-scale value. The relationships between PAHs and other pollutants suggest that a variety of sources and 15

Journal of Geophysical Research, 2009

1] Aerosol data from the Interagency Monitoring of Protected Visual Environments (IMPROVE) networ... more 1] Aerosol data from the Interagency Monitoring of Protected Visual Environments (IMPROVE) network, air mass backward trajectories, land use maps, soil characteristics maps, diagnostic ratios of elemental composition, and multivariate linear regression were utilized as part of a semi-quantitative analysis. The purpose of the analysis was to determine the types of dust-causing events that contribute to low visibility at a given site when the sum of extinction from coarse mass (CM) and fine soil (FS) was larger than any other aerosol component and the reconstructed aerosol extinction coefficient was among the 20% highest (calculated on a calendar

Journal of Geophysical Research, 2007

1] We estimated the contributions of windblown dust from nearby area sources to dust concentratio... more 1] We estimated the contributions of windblown dust from nearby area sources to dust concentrations at Class I areas in the western United States including Alaska and Hawaii. The approach utilized multivariate linear regression of dust concentrations against categorized wind conditions (wind direction and speed) for all 2001-2003 data for 70 Interagency Monitoring of Protected Visual Environments sites. Statistically significant associations between dust concentrations and at least one of the wind variables were found at 41 sites with correlation coefficients as high as 0.97. At some sites, primarily in New Mexico and Texas, windblown dust from nearby sources accounted for up to 3 mg m À3 over the 2001-2003 period. In addition, the impact of local windblown dust sources during the 20% worst visibility days when dust was the major component of visibility reduction (worst dust days) was examined. A total of 608 worst dust days were identified for 2001-2003, mostly at Class I areas in southwestern states during spring and summer with 24-h average dust concentrations as high as 153 mg m À3 . Windblown dust from local sources was present with statistical confidence on many of the worst dust days at sites in New Mexico, Utah, Colorado, southern Texas, and Death Valley in California. A smaller percentage of worst dust days were associated with local windblown dust in Arizona and other sites in southern California, suggesting either nonwindblown or distant sources of dust. The methods discussed can serve as a useful, semiquantitative tool for identifying sites where local wind conditions affect dust concentrations. Citation: Kavouras, I. G., V. Etyemezian, J. Xu, D. W. DuBois, M. Green, and M. Pitchford (2007), Assessment of the local windblown component of dust in the western United States,

Geophysical Research Letters, 1999

By using adequate sampling techniques we studied the chemical pathways, the gas-to-particle parti... more By using adequate sampling techniques we studied the chemical pathways, the gas-to-particle partition and the conversion processes leading to the formation of organic aerosols via the photo-oxidation of biogenic hydrocarbons in the atmosphere over a conifer forest. Photo-oxidation products of monoterpenes such as pinonic acid, nor-pinonic acid, pinic acid, pinonaldehyde and nopinone were detected in the gas and particulate phases of all forest aerosol samples. Considering the diurnal concentration pattern of the photo-oxidation products of a-and 13-pinene and Aitken nuclei concentration measured during the same periods, we observed that the acidic photo-oxidation products of monoterpenes play a more important role in the formation of new particles than the corresponding carbonyl compounds. '

Indoor Air, 2002

The gas and particulate phase of semi-volatile organic compounds (six samples) and the compositio... more The gas and particulate phase of semi-volatile organic compounds (six samples) and the composition of organic aerosol as a function of particle size (six samples) were studied in two public buildings in Greece. The objectives of this study were: i) to chemically characterize the organic content of indoor gas and particulate phases; ii) to classify indoor organic aerosol constituents as a function of particle size; and iii) to reconcile the sources of organic compounds indoors. Non-polar, semi-polar, polar, and acidic compounds were identified in both gas and particulate phases by using gas chromatography/mass spectrometry (GC/MS). Branched iso- and anteiso-alkanes were used to trace environmental tobacco smoke (ETS) concurrently with other compounds. Polycyclic aromatic hydrocarbons (PAHs) in the gas phase gave a pattern more characteristic to ETS than the corresponding pattern in the particulate phase. The chemical composition observed for n-alkanols and n-alkanoic acids in both gas and particulate phases indicated ETS as one of their main sources indoors. PAHs and n-alkanols were evenly associated between fine and coarse particles and their corresponding total mean mass median aerodynamic diameter (MMAD) was 1.27 and 1.38 microns respectively, indicating a mixed origin. Conversely, the MMAD of n-alkanes, unresolved complex mixture (UCM), iso- and anteiso-alkanes and free fatty acids varied from 0.30 to 0.62 micron denoting a stronger association with indoor sources.

Environmental Science & Technology, 1999

In a Eucalyptus forest in Portugal were investigated (a) the formation of secondary organic aeros... more In a Eucalyptus forest in Portugal were investigated (a) the formation of secondary organic aerosol formed through the condensation of low vapor pressure products of monoterpenes (α-and β-pinene) photooxidation and (b) the chemical structure of these products related to their ...

Environmental Science & Technology, 2002

Atmospheric aerosols play a central role in climate and atmospheric chemistry. Organic matter fre... more Atmospheric aerosols play a central role in climate and atmospheric chemistry. Organic matter frequently composes aerosol major fraction over continental areas. Reactions of natural volatile organic compounds, with atmospheric oxidants, are a key formation pathway of fine particles. The gas and particle atmospheric concentration of organic compounds directly emitted from conifer leaf epicuticular wax and of those formed through the photooxidation of alpha- and beta-pinene were simultaneously collected and measured in a conifer forest by using elaborated sampling and GC/ MS techniques. The saturation concentrations of acidic and carbonyl photooxidation products were estimated, by taking into consideration primary gas- and particle-phase organic species. Primary organic aerosol components represented an important fraction of the atmospheric gas-phase organic content Consequently, saturation concentrations of photooxidation products have been lowered facilitating new particle formation between molecules of photooxidation products and semi-volatile organic compounds. From the measured concentrations of the above-mentioned compounds, saturation concentrations (Csat,i) of alpha- and beta-pinene photooxidation products were calculated for nonideal conditions using a previously developed absorptive model. The results of these calculations indicated that primarily emitted organic species and ambient temperature play a crucial role in secondary organic aerosol formation.

Aerosol Science and Technology, 2001

Open pore polyurethane foam (PUF) can be used effectively as a substrate for conventional inertia... more Open pore polyurethane foam (PUF) can be used effectively as a substrate for conventional inertial impactors with both high particle collection ef ciency and minimal vaporizationof semi-volatile particle components. The collection characteristics of PUF as an impaction substrate were studied as a function of PUF density, Reynolds number, impaction substrate diameter, and nozzle-toplate distance. The conventional impaction substrate of the PM 2:5 Harvard Impactor sampler was replaced with the PUF substrate. The use of PUF resulted in signi cant changes in the collection efciency curve, with the 50% cut-off size (d 50 ) decreasing from 2.48 to 1.12 ¹m, corresponding to p Stk = 0:24. While the theory for conventional at impaction substrates accurately predicts d 50 values (at p Stk = 0:49), for PUF substrates this same theory predicts d 50 values much larger than the experimentally determined values.

Atmospheric Environment, 1999

Using a novel sampler, particulate organic compounds were collected in Santiago de Chile from Jun... more Using a novel sampler, particulate organic compounds were collected in Santiago de Chile from June 9 to August 10, 1997. This sampler consists of a di!usion denuder to remove gas-phase organics prior to particle collection, a Te#on "lter, and a PUF cartridge downstream of the "lter. PAHs and n-alkanes were measured using gas chromatography/mass spectrometry analysis. Volatilization of particles collected on the Te#on "lter varied from 15 to 85% for both n-alkanes and PAHs, with strong dependence on molecular weight. The relative distribution of n-alkanes and the values of molecular diagnostic ratios, such as Carbon preference index, indicated a mixed origin with strong anthropogenic input. Indeed, CPI values ranged from 0.66 to 1.96 (for the whole range of n-alkanes). The percent contribution of leaf`waxa n-alkanes (4.55}20.83%) indicated the low contribution of biogenic sources. In addition, the distribution pattern of PAHs was characteristic of anthropogenic emissions. The dominant contribution of combustion-related PAHs (CPAHs), 74}84%, indicated that vehicular emissions was the major source of PAHs.

Atmospheric Environment, 2002

Fine particle (PM 2.5 ) samples were collected, using a charcoal diffusion denuder, in two urban ... more Fine particle (PM 2.5 ) samples were collected, using a charcoal diffusion denuder, in two urban areas of Chile, Santiago and Temuco, during the winter and spring season of 1998. Molecular markers of the organic aerosol were determined using GC/MS. Diagnostic ratios and molecular tracers were used to investigate the origin of carbonaceous aerosols. As main sources, road and non-road engine emissions in Santiago, and wood burning in Temuco were identified. Cluster analysis was used to compare the chemical characteristics of carbonaceous aerosols between the two urban environments. Distinct differences between Santiago and Temuco samples were observed. High concentrations of isoprenoid (30-69 ng m À3 ) and unresolved complex mixture (UCM) of hydrocarbons (839-1369 ng m À3 ) were found in Santiago. High concentrations of polynuclear aromatic hydrocarbons (7517304 ng m À3 ) and their oxygenated derivatives (472 ng m À3 ), and of n-alk-1-enes (16713 ng m À3 ) were observed in Temuco. r

Journal of The Air & Waste Management Association, 2001

Chile is a fast-growing country with important industrial activities near urban areas. In this st... more Chile is a fast-growing country with important industrial activities near urban areas. In this study, the mass and elemental concentrations of PM 10 and PM 2.5 were measured in five major Chilean urban areas. Samples of particles with diameter less than 10 µm (PM 10 ) and 2.5 µm (PM 2.5 ) were collected in 1998 in Iquique (northern Chile), Valparaíso, Viña del Mar, Rancagua (central Chile), and Temuco (southern Chile). Both PM 10 and PM 2.5 annual mean concentrations (PM 10 : 56.9-77.6 µg/m 3 ; PM 2.5 : 22.4-42.6 µg/m 3 ) were significantly higher than the corresponding European Union (EU) and U.S. Environmental Protection Agency (EPA) air quality standards. Moreover, the 24-hr PM 10 and PM 2.5 U.S. standards were exceeded infrequently for some of the cities (Rancagua and Valparaíso).

Environmental Science & Technology, 1998

Branched isoand anteiso-alkanes were conjointly used, with n-alkanes and PAHs, as specific molecu... more Branched isoand anteiso-alkanes were conjointly used, with n-alkanes and PAHs, as specific molecular markers to trace environmental tobacco smoke (ETS) in particlesized aerosols collected in the indoor and outdoor urban atmosphere. GC/MS and GC-FID were used for the determination of iso-, anteiso-, and n-alkanes and PAHs. The branched alkanes (ranging from C 29 to C 33 ) were detected only in particles in the accumulation range mode (<1.5 µm) in both indoor and outdoor samples. The concentrations of isoand anteiso-alkanes in the indoor aerosols (0.75-8.53 ng/m 3 ) were higher than those measured in outdoor samples (0.77-1.51 ng/m 3 ). The indoor aerosol pattern of iso-, anteiso-, and their calculated diagnostic concentration ratios were characteristic for ETS. The compound distribution pattern of indoor n-alkanes (ranging from C 21 to C 33 ) was of biogenic origin, and the use of odd-toeven predominance running ratio curves indicated their cigarette smoke origin. The corresponding outdoor pattern and concentration ratios, although less characteristic than the indoor ones, also indicated ETS as the main source of these compounds. The distribution study of the branched alkanes between gas and particulate phase in indoor aerosol demonstrated their presence only in the particles. On the other hand, PAHs in the gas phase gave a compound pattern more characteristic of ETS components than the PAHs present in the particulate phase. Isoand anteiso-alkanes, due to their specificity, their nonreactive character, their association with the accumulation range mode particles, and therefore, their long atmospheric residence time, are the most suitable tracers for particulate ETS emissions in the indoor and outdoor urban atmosphere.

Inhalation Toxicology, 2000

ABSTRACT