A. Bourliva

PM10 composition during an intense Saharan dust transport event over Athens (Greece)

The influence of Saharan dust on the air quality of Southern European big cities became a priority during the last decade. The present study reports results on PM(10) monitored at an urban site at 14 m above ground level during an intense Saharan dust transport event. The elemental composition was determined by Energy Dispersive X-ray Fluorescence Spectrometry (EDXRF) for 12 elements: Si, Al, Fe, K, Ca, Mg, Ti, S, Ni, Cu, Zn and Mn. PM(10) concentrations exceeded the EU limit (50 μg/m(3)) several times during the sampling period. Simultaneous maxima have been observed for the elements of crustal origin. The concentrations of all the elements presented a common maximum, corresponding to the date where the atmosphere was heavily charged with particulate matter permanently for an interval of about 10h. Sulfur and heavy metal concentrations were also associated to local emissions. Mineral dust represented the largest fraction of PM(10) reaching 79%. Seven days back trajectories have shown that the air masses arriving over Athens, originated from Western Sahara. Scanning Electron Microscopy coupled with Energy Dispersive X-ray analysis (SEM-EDX) revealed that particle agglomerates were abundant, most of them having sizes <2 μm. Aluminosilicates were predominant in dust particles also rich in calcium which was distributed between calcite, dolomite, gypsum and Ca-Si particles. These results were consistent with the origin of the dust particles and the elemental composition results. Sulfur and heavy metals were associated to very fine particles <1 μm.

Study of road dust magnetic phases as the main carrier of potentially harmful trace elements

Mineralogical and morphological characteristics and heavy metal content of different fractions (bulk, non-magnetic fraction-NMF and magnetic fraction-MF) of road dusts from the city of Thessaloniki (Northern Greece) were investigated. Main emphasis was given on the magnetic phases extracted from these dusts. High magnetic susceptibility values were presented, whereas the MFs content of road dust samples ranged in 2.2-14.7 wt.%. Thermomagnetic analyses indicated that the dominating magnetic carrier in all road dust samples was magnetite, while the presence of hematite and iron sulphides in the investigated samples cannot be excluded. SEM/EDX analyses identified two groups of ferrimagnetic particles: spherules with various surface morphologies and textures and angular/aggregate particles with elevated heavy metal contents, especially Cr. The road dusts (bulk samples) were dominated by calcium, while the mean concentrations of trace elements decreased in the order Zn > Mn > Cu > Pb > Cr > Ni > V > Sn > As > Sb > Co > Mo > W > Cd. MFs exhibited significantly higher concentrations of trace elements compared to NMFs indicating that these potentially harmful elements (PHEs) are preferentially enriched in the MFs and highly associated with the ferrimagnetic particles. Hazard Index (HI) obtained for both adults and children through exposure to bulk dust samples were lower or close to the safe level (=1). On the contrary, the HIs for the magnetic phases indicated that both children and adults are experiencing potential health risk since HI for Cr was significantly higher than safe level. Cancer risk due to road dust exposure is low.

Ceramic building materials for electromagnetic interference shielding using metallurgical slags

Abstract Abstract The technological properties and the electromagnetic shielding efficiency of clay based ceramic building products prepared by using electric arc furnace slag (EAFS) and ladle furnace slag (LFS) as admixtures and fired at various temperatures were investigated. Chemical and mineralogical analyses were performed to characterise EAFS and LFS. The results showed that the ceramic specimens prepared by the addition of EAFS to the clayey material presented better shielding efficiency than the relevant of LFS, both tested in the same X-band frequency range (8–12 GHz). The prepared specimens showed water absorption, flexural and compressive strengths and firing shrinkage within accepted limits. Modulus of rupture and compressive strength values were slightly decreased by increasing the addition of EAFS and LFS. The technological characteristics were found to be affected by both the percentage of EAFS and LFS added as well as their grain size. Finally, the leaching test performed showed stabilisation of all studied toxic elements within the sintered ceramic structure.

Lead removal from aqueous solutions by natural Greek bentonites

Abstract Three bentonite samples (B1, B2, B3) from Milos Island, Greece, were investigated by XRD, AAS, DTA-TG, FTIR and specific surface area measurement techniques. A laboratory batch study has been performed to investigate the adsorption characteristics of lead ions (Pb2+) onto natural bentonite samples. The effect of various physicochemical factors that influence adsorption, such as solution pH (2-6), adsorbent dosage (1-10 g L-1), contact time (20-360 min), and initial metal ion concentration (5-150 mg L-1) was studied. A number of available models like the Lagergren pseudo first-order kinetic model, the pseudo second-order kinetic model and intra-particle diffusion were utilized to evaluate the adsorption kinetics. The adsorption of Pb2+ was modelled with the Langmuir, Freundlich and D-R isotherms. The maximum Pb2+ adsorption capacities for B1, B2 and B3 were 85.47 mg g-1, 73.42 mg g-1 and 48.66 mg g-1, respectively.

Seasonal and spatial variations of magnetic susceptibility and potentially toxic elements (PTEs) in road dusts of Thessaloniki city, Greece: A one-year monitoring period

A one-year sampling campaign of road dusts was carried out at 10 distinct sites in the broader area of the city of Thessaloniki, Greece and concentrations of heavy metals (HMs) along with magnetic susceptibility were evaluated. The concentrations of HMs in road dusts were higher than their local background values, while magnetic parameters indicated a significant anthropogenic load. Principal component analysis (PCA) identified non-exhaust vehicular emissions, oil/fuel combustion and industrial activities as major sources of heavy metals accounted for approximately 73% of the total variance. A significant seasonal variability for Cr, Cu, Mn, and χlf was observed with constantly higher values during summer. Moreover, variations among urban and industrial sites were more pronounced for Cr, Cu, Zn, and χlf, while they displayed insignificant variations across all urban sites. On the contrary, concentration peaks in the urban cluster were observed for Cd, Mn, and Ni coinciding with the port area. Based on multiple pollution indices, a severe polluted area was revealed, while potential ecological risk index (RI) indicated a high potential ecological risk with Cd being regarded as the pollutant of high concern. The health risk assessment model indicated ingestion as the major exposure pathway. For both adults and children, Cr and Pb had the highest risk values, mainly recorded in the urban cluster underscoring the need of potential measures to reduce road dust in urban environments.