Quantification and characterization of microplastics in the Thermaic Gulf, in the North Aegean Sea.

The abundance and distribution of microplastics has largely increased during last years and the respective implications on the environment and human health is an emerging field in research. In addition, recent studies in the enclosed Mediterranean Sea in Spain and Italy have shown an extended occurrence of microplastics (MPs) in different sediments of environmental samples. This study is focused on the quantification and the characterization of MPs in the Thermaic Gulf in northern Greece. Briefly, samples from different environmental compartments such as seawater, local beaches and seven commercially available fish species collected and analyzed. MPs particles extracted and classified by size, shape, colour and polymer type. A total of 28,523 microplastic particles recorded in the surface water samples, with their numbers ranging from 189 to 7714 particles per sample. The mean concentration of MPs recorded on the surface water was 1.9 ± 2 items/m3 or 750,846 ± 838,029 items/km2. Beach sediment sample analysis revealed 14,790 microplastic particles, of which 1825 were large microplastics (LMPs, 1-5 mm) and 12,965 were small microplastics (SMPs, <1 mm). Furthermore, beach sediment samples showed a mean concentration of 733.6 ± 136.6 items/m2, with the concentration of LMPs being 90.5 ± 12.4 items/m2 and the concentration of SMPs being 643 ± 132 items/m2. Concerning fish deposition, microplastics were detected in intestines and mean concentrations per species ranged from 1.3 ± 0.6 to 15.0 ± 1.5 items/individual. The differences in microplastic concentrations between species were statistically significant (p < 0.05) and showed that mesopelagic fish contained the highest concentrations, followed by epipelagic species. The most common size fraction found in the data-set was 1.0-2.5 mm, and polyethylene and polypropylene were the most abundant polymer types recorded. This is the first detailed investigation of MPs in Thermaic Gulf, which raises concerns on their potential negative effects.

Magnetic nanoparticles: An indicator of health risks related to anthropogenic airborne particulate matter.

Due to their small dimensions, airborne particles are able to penetrate through inhalation into many human organs, from the lungs to the cardiovascular system and the brain, which can threaten our health. This work establishes a novel approach of collecting quantitative data regarding the fraction, the composition and the size distribution of combustion-emitted particulate matter through the magnetic characterization and analysis of samples received by common air pollution monitoring. To this end, SQUID magnetometry measurements were carried out for samples from urban and suburban areas in Thessaloniki, the second largest city of Greece, taking into consideration the seasonal and weekly variation of airborne particles levels as determined by occurring traffic and meteorological conditions. The level of estimated magnetically-responding atmospheric particulate matter was at least 0.5 % wt. of the collected samples, mostly being present in the form of ultrafine particles with nuclei sizes of approximately 14 nm and their aggregates. The estimated quantities of magnetic particulate matter show maximum values during autumn months (0.8 % wt.) when increased commuting takes place, appearing higher in the city center by up to 50% than those in suburban areas. In combination with high-resolution transmission electron imaging and elemental analysis, it was found that Fe3O4 and similar ferrites, some of them attached to heavy metals (Co, Cr), are the dominant magnetic contributors arising from anthropogenic high-temperature processes, e.g. due to traffic emissions. Importantly, nasal cytologic samples collected from residents of both central and suburban areas showed same pattern in what concerns magnetic behavior, thus verifying the critical role of nanosized magnetic particles in the assessment of air pollution threats. Despite the inherent statistical limitations of our study, such findings also indicate the potential transmission of infectious pathogens by means of pollution-derived nanoparticles into the respiratory system of the human body.

Multi-city comparative PM2.5 source apportionment for fifteen sites in Europe: The ICARUS project.

PM2.5 is an air pollution metric widely used to assess air quality, with the European Union having set targets for reduction in PM2.5 levels and population exposure. A major challenge for the scientific community is to identify, quantify and characterize the sources of atmospheric particles in the aspect of proposing effective control strategies. In the frame of ICARUS EU2020 project, a comprehensive database including PM2.5 concentration and chemical composition (ions, metals, organic/elemental carbon, Polycyclic Aromatic Hydrocarbons) from three sites (traffic, urban background, rural) of five European cities (Athens, Brno, Ljubljana, Madrid, Thessaloniki) was created. The common and synchronous sampling (two seasons involved) and analysis procedure offered the prospect of a harmonized Positive Matrix Factorization model approach, with the scope of identifying the similarities and differences of PM2.5 key-source chemical fingerprints across the sampling sites. The results indicated that the average contribution of traffic exhausts to PM2.5 concentration was 23.3% (traffic sites), 13.3% (urban background sites) and 8.8% (rural sites). The average contribution of traffic non-exhausts was 12.6% (traffic), 13.5% (urban background) and 6.1% (rural sites). The contribution of fuel oil combustion was 3.8% at traffic, 11.6% at urban background and 18.7% at rural sites. Biomass burning contribution was 22% at traffic sites, 30% at urban background sites and 28% at rural sites. Regarding soil dust, the average contribution was 5% and 8% at traffic and urban background sites respectively and 16% at rural sites. Sea salt contribution was low (1-4%) while secondary aerosols corresponded to the 16-34% of PM2.5. The homogeneity of the chemical profiles as well as their relationship with prevailing meteorological parameters were investigated. The results showed that fuel oil combustion, traffic non-exhausts and soil dust profiles are considered as dissimilar while biomass burning, sea salt and traffic exhaust can be characterized as relatively homogenous among the sites.

Monitoring of air pollution levels related to Charilaos Trikoupis Bridge.

Charilaos Trikoupis bridge is the longest cable bridge in Europe that connects Western Greece with the rest of the country. In this study, six air pollution monitoring campaigns (including major regulated air pollutants) were carried out from 2013 to 2015 at both sides of the bridge, located in the urban areas of Rio and Antirrio respectively. Pollution data were statistically analyzed and air quality was characterized using US and European air quality indices. From the overall campaign, it was found that air pollution levels were below the respective regulatory thresholds, but once at the site of Antirrio (26.4 and 52.2µg/m3 for PM2.5 and ΡΜ10, respectively) during the 2nd winter period. Daily average PM10 and PM2.5 levels from two monitoring sites were well correlated to gaseous pollutant (CO, NO, NO2, NOx and SO2) levels, meteorological parameters and factor scores from Positive Matrix Factorization during the 3-year period. Moreover, the elemental composition of PM10 and PM2.5 was used for source apportionment. That analysis revealed that major emission sources were sulfates, mineral dust, biomass burning, sea salt, traffic and shipping emissions for PM10 and PM2.5, for both Rio and Antirrio. Seasonal variation indicates that sulfates, mineral dust and traffic emissions increased during the warm season of the year, while biomass burning become the dominant during the cold season. Overall, the contribution of the Charilaos Trikoupis bridge to the vicinity air pollution is very low. This is the result of the relatively low daily traffic volume (~10,000 vehicles per day), the respective traffic fleet composition (~81% of the traffic fleet are private vehicles) and the speed limit (80km/h) which does not favor traffic emissions. In addition, the strong and frequent winds further contribute to the rapid dispersion of the emitted pollutants.