Formation of metal-cyanide complexes in deliquescent airborne particles: a new possible sink for HCN in urban environments

Hydrogen cyanide is a ubiquitous gas in the atmosphere and a biomass burning tracer. Reactive gasses can be adsorbed onto aerosol particles where they can promote heterogeneous chemistry. In the present study, we report for the first time on the measurement and speciation of cyanides in atmospheric aerosol. Filter samples were collected at an urban background site in the city center of Padua (Italy), extracted and analyzed with headspace gas chromatography and nitrogen-phosphorous detection. The results showed that strongly bound cyanides were present in all aerosol samples at a concentration ranging between 0.3 and 6.5 ng/m3 in the PM2.5 fraction. The concentration of cyanides strongly correlates with concentration of total carbon and metals associated with combustion sources. The results obtained bring evidence that hydrogen cyanide can be adsorbed onto aerosol liquid water and can react with metal ions to form stable metal-cyanide complexes

Characterization and preliminary risk assessment of road dust collected in Venice airport (Italy)

Road dust is a non-exhaust source that can significantly contribute to atmospheric particulate by resuspension. Beside the issue of the overcoming of guidelines limits for the air quality, the characterization of this matrix is of crucially high interest for the inherent toxicity of resuspended particles, that can act as carriers of heavy metals and toxic-carcinogenic components. In this paper, road dust collected in the Venice international airport is characterized with a multi-technique approach in order to identify the main pollutant sources and to highlight the differences between airside/landside places. The most polluted sites are identified and a preliminary risk assessment is performed taking into account ingestion, dermal intake and inhalation of fugitive particulate pathways. Specifically, the main sources are related to construction activities, anti-icing safety procedures, and brake, tire and road wear; streets are the most polluted landside places; PAHs, Na, Al, Cu, Zn, Ag, Cd are more concentrated in airside area; as regards the risk assessment As, BaP, Cr, Sb, BaA, and BbF are the most critical pollutants. Considering the high number of people passing or working in this airport and the ongoing works related to its enlargement which promotes the emission and the resuspension of fugitive dusts, this research addresses a fundamental step for the protection of potential receptors

Hybrid multiple-site mass closure and source apportionment of PM2.5 and aerosol acidity at major cities in the Po Valley

This study investigates the major chemical components, particle-bound water content, acidity (pH), and major potential sources of PM2.5 in major cities (Belluno, Conegliano, Vicenza, Mestre, Padua, and Rovigo) in the eastern end of the Po Valley. The measured PM2.5 mass was reconstructed using a multiple-site hybrid chemical mass closure approach that also accounts for aerosol inorganic water content (AWC) estimated by the ISORROPIA-II model. Annually, organic matter accounted for 31-45% of the PM2.5 at all sites, followed by nitrate (10-19%), crustal material (10-14%), sulfate (8-10%), ammonium (5-9%), elemental carbon (4-7%), other inorganic ions (3-4%), and trace elements (0.2-0.3%). Water represented 7-10% of measured PM2.5. The ambient aerosol pH varied from 1.5 to 4.5 with lower values in summer (average in all sites 2.2±0.3) and higher in winter (3.9±0.3). Six major PM2.5 sources were quantitatively identified with multiple-site positive matrix factorization: secondary sulfate (34% of PM2.5), secondary nitrate (30%), biomass burning (17%), traffic (11%), re-suspended dust (5%), and fossil fuel combustion (3%). Biomass burning accounted for ∼90% of total PAHs. Inorganic aerosol acidity was driven primarily by secondary sulfate, fossil fuel combustion (decreasing pH), secondary nitrate, and biomass burning (increasing pH). Secondary nitrate was the primary driver of the inorganic AWC variability. A concentration-weighted trajectory (multiple-site) analysis was used to identify potential source areas for the various factors and modeled aerosol acidity. Eastern and Central Europe were the main source areas of secondary species. Less acidic aerosol was associated with air masses originating from Northern Europe owing to the elevated presence of the nitrate factor. More acidic particles were observed for air masses traversing the Po Valley and the Mediterranean, possibly due to the higher contributions of fossil fuel combustion factor and the loss of nitric acid due to its interaction with coarse sea-salt particles

Late time response analysis in UWB radar for concealed weapon detection : feasibility study

Remote detection of body-worn concealed weapons or explosives (CWE) is a field of ongoing research. In this Thesis the feasibility of CWE detection by using the UWB radar is explored. The CWE detection is based on the analysis of the Late Time Response (LTR) of the human which has been illuminated by the UWB signal. A specific set of LTR parameters characterizes the target signature. Therefore the existence of a CWE attached on the human body will influence the LTR characteristics and give the composite object i.e. human-CWE a different signature than the simple object i.e. human. The CWE detection methodology is verified by theoretical analysis, modelling and extensive laboratory experimentation. Investigation of the way the LTR parameters are influenced by the existence of the CWE signifies the differences of the LTR signature between the human and human-CWE. So the resolution of the differences in the LTR of a human with and without a CWE as the main objective of the research, are presented in the Thesis. The results verify that CWE detection with the use of LTR is feasible under the experimental conditions presented. Furthermore consideration of all possible detection scenarios is out of the scope of this Thesis.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

The dark side of the tradition: The polluting effect of Epiphany folk fires in the eastern Po Valley (Italy)

In the Veneto Region (Po Valley, Northeastern Italy) on the eve of Epiphany, an important religious celebration, during the night between January 5th and 6th thousands of folk fires traditionally burn wooden material. The object of this study is to characterize the 2013 episode, bymonitoring the effects on the air quality in the region's lowlands. The daily concentrations ofPM2.5 and PM10 exceeded 250 and 300 μg m−3, respectively and the PM10 hourly values were above 600 μg m−3 in many sites. The levels of total carbon, major inorganic ions, polycyclic aromatic hydrocarbons and biomass burning tracers (levoglucosan and K+)weremeasured in 84 samples of PM10 and 38 of PM2.5 collected at 32 sites between January 4th and 7th. Total carbon ranged from 11 μg m−3 before the pollution episode to 131 μg m−3 a day afterwards, K+ from 0.6 to 5.1 μg m−3, benzo(a)pyrene from 2 to 23 ng m−3, and levoglucosan from 0.5 to 8.3 μg m−3. The dispersion of the particulate matter was traced by analyzing the levels of PM10 and PM2.5 in 133 and 51 sites, respectively, in the Veneto and neighboring regions. In addition to biomass burning the formation of secondary inorganic aerosol was revealed to be a key factor on a multivariate statistical data processing. By providing direct information on the effects of an intense and widespread biomass burning episode in the Po Valley, this study also enables some general considerations on biomass burning practices

Variabilit\ue0 della componente carboniosa del particolato atmosferico fine in stazioni di pianura e montane del Veneto

Su 170 campioni di PM2.5 raccolti nel periodo estivo ed in quello invernale del 2019 presso tre stazioni della rete di monitoraggio del Veneto, due di pianura (Venezia citt\ue0 e zona industriale di Marghera) ed una montana (Feltre), \ue8 stata determinata la concentrazione di carbonio organico (OC), carbonio elementare (EC), carbonio idrosolubile e levoglucosano. La componente idrosolubile risulta quella maggiormente presente tra le specie carboniose. Mediante strumenti statistici si \ue8 cercato di individuare le sorgenti del particolato, evidenziando come la componente dovuta alla combustione da biomassa risulta preponderante, soprattutto nel periodo invernale e nella stazione montana. Altre differenze si sono notate tra le stazioni di campionamento, in particolare una marcata influenza del traffico acqueo nella stazione di Venezia. Data l\u2019elevata stabilit\ue0 atmosferica verificatasi nel corso delle campagne di campionamento, si \ue8 inoltre potuto verificare come le sorgenti locali di inquinamento contribuiscano in modo determinante alla componente carboniosa del particolato

Thirteen years of air pollution hourly monitoring in a large city: Potential sources, trends, cycles and effects of car-free days

Thirteen air pollutant concentrations were measured hourly for 13 years (2000-2013) at an urban background site of a large city in the eastern Po Valley (Italy) and results were chemometrically analysed. The pollutant list includes CO, NO, NO2, NOx, O-3, SO2, benzene, toluene, ethylbenzene, o-, m- and p-xylenes and PM10, all known or suspected of having adverse effects on human health. The hourly data were statistically processed to detect the long-term trends in relation to the changes in the emission scenarios occurred in the last decade. The most probable emission sources and atmospheric photochemical processes were investigated by analyzing the seasonal, weekly, diurnal cycles of pollutants and the lagged correlations amongst pollutants. The role of micrometeorological factors upon the air quality was assessed by analyzing the relationships with key weather parameters, while the location of the potential sources was studied by matching atmospheric circulation and pollution data through bivariate polar plots and conditional probability functions. In addition, a new statistical procedure is presented and tested to analyze the periods when common mitigation measures were adopted in the city (e.g., the total stop of traffic and car-free days) and to evaluate their real effect upon the air quality. By providing direct information on the levels and trends of key pollutants, this study finally enables some general considerations about air pollution in an important hotspot of Southern Europe, the eastern Po Valley, where the levels of some key pollutants are still far from meeting the EC limit and target values. It may help policy-makers to take successful mitigation measures

Source apportionment of PAHs and n-alkanes bound to PM1 collected near the Venice highway

n-Alkanes and polycyclic aromatic hydrocarbons (PAHs) bound to atmospheric particulate matter (PM1) were investigated in a traffic site located in an urban area of Venice Province (Eastern Po Valley, Italy) during the cold season. Considering the critical situation affecting the Veneto Region concerning the atmospheric pollution and the general lack of information on PM1 composition and emission in this area, this experimental study aims at determining the source profile, their relative contributions and the dispersion of finer particles. Four sources were identified and quantified using the Positive Matrix Factorization receptor model: (1) mixed combustions related to the residential activities, (2) agricultural biomass burning in addition to the resuspension of anthropogenic and natural debris carried by the wind, (3) gasoline and (4) diesel traffic-related combustions. The role of local atmospheric circulation was also investigated to identify the pollutant sources