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.

East Siberian Arctic background and black carbon polluted aerosols at HMO Tiksi.

Assessment of Arctic pollution is hampered by a lack of aerosol studies in Northern Siberia. Black carbon observations were carried out at the Hydrometeorological Observatory Tiksi, a coast of Laptev sea, from September 2014 to September 2016. Aerosol sampling was accompanied by physico-chemical characterization. BC climatology showed a seasonal variation with highest concentrations from January to March (up to 450ng/m3) and lowest ones for June and September (about 20ng/m3). Stagnant weather and stable atmosphere stratification resulted in accumulation of pollution, in dependence on the wind direction and air mass transportation. Carbon fractions, functionalities, ions, and elements are associated to marine, biogenic, and continental sources. In September low OC, aliphatic, carbonyls, amines, and hydroxyls characterize background aerosols. Na+/Cl- ratio much higher than in sea-salt indicates a strong Cl depletion. Increased OC, aromatic, carbonyls, and nitrocompounds as well as waste burning markers K+, Cl-, and PO42- confirm impacts from Tiksi landfill burns. BC pollution episodes are differentiated through increased EBC and sulfates, related to gas flaring, industrial and residential emissions transported from Western Siberia while the increase of carbonyls, hydroxyl, and aromatic indicate emissions sources from Yakutia and Tiksi urban area. Arctic Haze aerosols are characterized by increased concentrations of SO42- in comparison with OC, much higher abundance of oxygenated compounds with respect to alkanes of anthropogenic origin. In summer rich organic chemistry indicates impacts of biogenic, local urban, and shipping sources as well as secondary aerosol formation influenced by emissions from low latitude Siberia.

Source apportionment of indoor PM10 in Elderly Care Centre.

Source contribution to atmospheric particulate matter (PM) has been exhaustively modelled. However, people spend most of their time indoors where this approach is less explored. This evidence worsens considering elders living in Elderly Care Centres, since they are more susceptible. The present study aims to investigate the PM composition and sources influencing elderly exposure. Two 2-week sampling campaigns were conducted-one during early fall (warm phase) and another throughout the winter (cold phase). PM10 were collected with two TCR-Tecora(®) samplers that were located in an Elderly Care Centre living room and in the correspondent outdoor. Chemical analysis of the particles was performed by neutron activation analysis for element characterization, by ion chromatography for the determination of water soluble ions and by a thermal optical technique for the measurement of organic and elemental carbon. Statistical analysis showed that there were no statistical differences between seasons and environments. The sum of the indoor PM10 components measured in this work explained 57 and 53 % of the total PM10 mass measured by gravimetry in warm and cold campaigns, respectively. Outdoor PM10 concentrations were significantly higher during the day than night (p value < 0.05), as well as Ca(2+), Fe, Sb and Zn. The contribution of indoor and outdoor sources was assessed by principal component analysis and showed the importance of the highways and the airport located less than 500 m from the Elderly Care Centre for both indoor and outdoor air quality.

Organic and elemental carbon associated to PM10 and PM 2.5 at urban sites of northern Greece.

Organic carbon (OC) and elemental carbon (EC) concentrations, associated to PM10 and PM2.5 particle fractions, were concurrently determined during the warm and the cold months of the year (July-September 2011 and February-April 2012, respectively) at two urban sites in the city of Thessaloniki, northern Greece, an urban-traffic site (UT) and an urban-background site (UB). Concentrations at the UT site (11.3 ± 5.0 and 8.44 ± 4.08 14 µg m(-3) for OC10 and OC2.5 vs. 6.56 ± 2.14 and 5.29 ± 1.54 µg m(-3) for EC10 and EC2.5) were among the highest values reported for urban sites in European cities. Significantly lower concentrations were found at the UB site for both carbonaceous species, particularly for EC (6.62 ± 4.59 and 5.72 ± 4.36 µg m(-3) for OC10 and OC2.5 vs. 0.93 ± 0.61 and 0.69 ± 0.39 µg m(-3) for EC10 and EC2.5). Despite that, a negative UT-UB increment was frequently evidenced for OC2.5 and PM2.5 in the cold months possibly indicative of emissions from residential wood burning at the urban-background site. At both sites, cconcentrations of OC fractions were significantly higher in the cold months; on the contrary, EC fractions at the UT site were prominent in the warm season suggesting some influence from maritime emissions in the nearby harbor area. Secondary organic carbon, being estimated using the EC tracer method and seasonally minimum OC/EC ratios, was found to be an appreciable component of particle mass particularly in the cold season. The calculated secondary contributions to OC ranged between 35 and 59 % in the PM10 fraction, with relatively higher values in the PM2.5 fraction (39-61 %). The source origin of carbonaceous species was investigated by means of air parcel back trajectories, satellite fire maps, and concentration roses. A local origin was mainly concluded for OC and EC with limited possibility for long range transport of biomass (agricultural waste) burning aerosol.

Highly entangled ground States in tripartite qubit systems.

We investigate the creation of highly entangled ground states in a system of three exchange-coupled qubits arranged in a ring geometry. Suitable magnetic field configurations yielding approximate Greenberger-Horne-Zeilinger and exact W ground states are identified. The entanglement in the system is studied at finite temperature in terms of the mixed-state tangle tau. By generalizing a conjugate gradient optimization algorithm originally developed to evaluate the entanglement of formation, we demonstrate that tau can be calculated efficiently and with high precision. We identify the parameter regime for which the equilibrium entanglement of the tripartite system reaches its maximum.

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.

Coulomb scattering in a 2D interacting electron gas and production of EPR pairs.

We propose a setup to generate nonlocal spin Einstein-Podolsky-Rosen pairs via pair collisions in a 2D interacting electron gas, based on constructive two-particle interference in the spin-singlet channel at the pi/2 scattering angle. We calculate the scattering amplitude via the Bethe-Salpeter equation in the ladder approximation and small r(s) limit and find that the Fermi sea leads to a substantial renormalization of the bare scattering process. From the scattering length, we estimate the current of spin-entangled electrons and show that it is within experimental reach.