Measurements of atmospheric aerosol in the Salentum Peninsula and its correlation with local meteorology

In this paper the results of measurements of Total Suspended Particles (TSP), PM10 and PM2.5 and their correlation with meteorological parameters are presented. The samplings were carried out with a mobile laboratory in seven locations in the Salentum Peninsula located in the southeastern part of Italy in Puglia. Measurements were taken discontinuously during the period 2002-2005. Up to now no systematic analyses of aerosol concentrations in the Salentum Peninsula have been presented in the scientific literature. This study is therefore a useful basis for assessing the local situation and for planning future monitoring. Measurements have been performed, on a daily basis, using standard European inlet (CEN-EN12341, 1998) and successive gravimetric detection of aerosol deposited on filters. The measurement sites can be considered representative of urban background for all the cases investigated. An analysis of the random uncertainties (LOQ and LOD) for the different types of filters used is reported. Results show concentrations in good agreement with lognormal distributions, indicating that the PM10 fraction is about 66% of TSP and PM2.5 is about 67% of PM10, which allows us to evaluate that the fraction of PM2.5 is about 44% of TSP. Concentration levels were correlated with local meteorological parameters, especially with wind velocity and precipitations. Results indicate that during rainy days the average concentration is reduced of about 70% and the reduction is larger for TSP and PM10 with respect to PM2.5. There is, on average, a substantial decrease of concentration levels in high wind conditions. Results also suggest the possibility of a significant contribution of African dust to PM10 and TSP, especially in the spring and summer season, which could be responsible for some days with concentrations above the threshold imposed by the European legislation on PM10

Measurements of atmospheric aerosol in the Salentum Peninsula and its correlation with local meteorology

In this paper the results of measurements of Total Suspended Particles (TSP) and PM10 are presented. The samplings were carried out with a mobile laboratory in five locations on the Salentum peninsula situated in the southeastern part of Italy in Puglia. Measurements were taken discontinuously during the period 2002?2004. Some results of PM2.5 measurements taken only in 2004 are also presented. Up to now no systematic analyses of aerosol concentration in the Salentum peninsula have been presented in the scientific literature. This study is therefore a useful basis for assessing the local situation and for planning future monitoring and investigations. Measurements were performed using a standard European PM10 inlet (CEN?EN12341, 1998) and successive gravimetric detection of aerosol deposited over 24 hours periods on filters. The measurement sites can be considered representative of urban background for all the cases investigated. Results show concentrations in good agreement with lognormal distributions, indicating that the PM10 fraction is about 69% of TSP and PM2.5 is about 81% of PM10, which allows us to evaluate that the fraction of PM2.5 is about 56% of TSP. Concentration levels were correlated with local meteorological parameters, such as wind velocity, wind direction and precipitations. Results indicate that there is, on average, a substantial decrease of concentration levels in high wind conditions and on rainy days. They also suggest the possibility of a significant contribution 1 of African Dust to PM10 and TSP, especially in the summer season, which could be responsible for some periods of concentrations above the threshold imposed by the European legislation on PM10

Clinically relevant investigation of flattening filter-free skin dose

As flattening filter-free (FFF) photon beams become readily available for treatment delivery in techniques such as SBRT, thorough investigation of skin dose from FFF photon beams is necessary under clinically relevant conditions. Using a parallel-plate PTW Markus chamber placed in a custom water-equivalent phantom, surface-dose measurements were taken at 2 × 2, 3 × 3, 4 × 4, 6 × 6, 8 × 8, 10 × 10, 20 × 20, and 30 × 30 cm2 field sizes, at 80, 90, and 100 cm source-to-surface distances (SSDs), and with fields defined by jaws and multileaf collimator (MLC) using multiple beam energies (6X, 6XFFF, 10X, and 10XFFF). The same set of measurements was repeated with the chamber at a reference depth of 10 cm. Each surface measurement was normalized by its corresponding reference depth measurement for analysis. The FFF surface doses at 100 cm SSD were higher than flattened surface doses by 45% at 2 × 2 cm2 to 13% at 20 × 20 cm2 for 6 MV energy. These surface dose differences varied to a greater degree as energy increased, ranging from +63% at 2 × 2 cm2 to -2% at 20 × 20 cm2 for 10 MV. At small field sizes, higher energy increased FFF surface dose relative to flattened surface dose; while at larger field sizes, relative FFF surface dose was higher for lower energies. At both energies investigated, decreasing SSD caused a decrease in the ratios of FFF-to-flattened surface dose. Variability with SSD of FFF-to flattened surface dose differences increased with field size and ranged from 0% to 6%. The field size at which FFF and flattened beams gave the same skin dose increased with decreasing beam energy. Surface dose was higher with MLC fields compared to jaw fields under most conditions, with the difference reaching its maximum at a field size between 4 × 4 cm2 and 6 × 6 cm2 for a given energy and SSD. This study conveyed the magnitude of surface dose in a clinically meaningful manner by reporting results normalized to 10 cm depth dose instead of depth of dose maximum

Multi-Year Concentrations, Health Risk, and Source Identification, of Air Toxics in the Venice Lagoon

This work presents and discusses the results of multi-year measurements of air toxics concentrations from different sites of Venice Lagoon. The aim of the study is the characterization of the air quality of the area, in terms of PM10, PM10-bound metals, and polycyclic aromatic hydrocarbons (PAHs) concentrations, even with the individuation of the related inhalation risk and the identification of the main contaminants' sources. The study moreover provides an important multi-years trend of chemical characterization of the Venice Lagoon. Sampling for PM10 and its metal content was carried out between 2010 and 2015, using low volume sequential aerosol samplers; V, Cr, Fe, Co, Ni, Cu, Zn, As, Mo, Cd, Sb, Tl, and Pb were measured by ICP-MS. Samples for PAHs concentration in gas and particle phases were collected from 2010 to 2014, using a high-volume air sampler that allows to sample both phases simultaneously. Samples for PAHs determinations were analyzed by GC-HRMS. Concentrations of air toxics have been studied with the use of enrichment factor, the coefficient of divergence, and the Mann-Kendal test, to individuate eventual local divergences, seasonal and other temporal trends. The inhalation risk assessment has been achieved by the calculation of the cumulative incremental carcinogenic risk for all the air toxics analyzed. The sources' identification and impact evaluation have been carried out using the atmospheric vanadium concentration, to calculate the primary contribution of ship traffic to PM10, the Positive Matrix Factorization, and the Diagnostic Ratios, with the aim of evaluating the impact of construction activities of M.o.S.E, (Modulo Sperimentale Elettromeccanico-Electromechanical Experimental Module) as well as of ship traffic and other possible air toxics' sources. Temporal trends indicate a slight decrease of PAHs and PM10 and of its content of Pb, Zn, Sb. Sharp increases of As and Cd during 2014 and 2015 may be due to local sources like emissions from the construction yard, ship, and road traffic. The cumulative incremental carcinogenic risk was below the unconditionally acceptable risk; Co and As are the most important contributors among metals, followed by Cd and Ni while the PAH congeners that most contribute to the carcinogenic risk were benzo(a)pyrene and dibenzo(A,H)anthracene

Chemical composition and shape of snow crystals in Antarctica

Fresh snow samples collected in a coastal Antarctic site (Terra Nova Bay) were examined by considering both the chemical composition and ice Crystal shape. Measured concentrations in snow samples show that nucleation is the dominant aerosol scavenging process. An additional contribution from phoretic forces to aerosol scavenging during growth of ice crystals can be deduced from the correlation between non sea-salt sulphate (nss-SO2−4) and methanesulfonic acid (MSA) measured in snow samples. The sea-salt contribution is dominant, as usually observed in the coastal Antarctic stations. By determining sea-salt from Na+ concentration, the values of 4400 μg l−1; 2400 μg l−1; 2900 μg l−1; 650 μg l−1 were obtained for the examined samples. The NO−3 /Na+ ratio in fresh snow (range 0.1–0.6), much higher than the value in sea-water (about 10−4), excludes a marine origin for NO−3 ion, suggesting a continental and/or stratospheric source. Organic compounds (propionate, acetate, formate, MSA and glycolate) were in addition measured in snow samples. Ice crystal replicas were made by collecting crystals on microscope slides, previously covered with a thin layer of 2% formvar in chloroform. Samples were analyzed by a scanning electron microscope (SEM). A large variety of ice crystal habits (needles, hexagonal plates, crystals with branches, dendritic crystals, etc.) were observed. In the examined replicas of different events, cases are noted in which simple plates are prevalent, others in which prevalently complex crystal shapes are observed, and others again in which simple and complex crystal shapes are present simultaneously

Application of the Soft X-Ray TSI Advanced Aerosol Neutralizer to Aerosol Measurements Made by a Grimm SMPS

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Atmospheric Deposition of Inorganic Elements and Organic Compounds at the Inlets of the Venice Lagoon

The Venice Lagoon is subjected to long-range transport of contaminants via aerosol from the near Po Valley. Moreover, it is an area with significant local anthropogenic emissions due to the industrial area of Porto Marghera, the urban centres, and the glass factories and with emissions by ships traffic within the Lagoon. Furthermore, since 2005, the Lagoon has also been affected by the construction of the MOSE (Modulo Sperimentale Elettromeccanico—Electromechanical Experimental Module) mobile dams, as a barrier against the high tide. This work presents and discusses the results from chemical analyses of bulk depositions, carried out in different sites of the Venice Lagoon. Fluxes of pollutants were also statistically analysed on PCA with the aim of investigating the spatial variability of depositions and their correlation with precipitations. Fluxes of inorganic pollutants depend differently on precipitations, while organic compounds show a more seasonal trend. The statistical analysis showed that the site in the northern Lagoon has lower and almost homogeneous fluxes of pollutants, while the other sites registered more variable concentrations. The study also provided important information about the annual trend of pollutants and their evolution over a period of about five years, from 2005 to 2010

Characterisation of PM2,5 concentrations and turbulent fluxes on a island of the Venice Lagoon using high temporal resolution measurements

This work presents an analysis of PM2.5 concentrations and vertical turbulent fluxes on an island of the Venice lagoon. Data were collected during three measurement campaigns in spring, summer and winter periods. Measurements were taken with a high-resolution optical PM2.5 detector, coupled with a micrometeorological station that allowed the evaluation of the vertical turbulent fluxes of PM2.5 using the eddy-correlation technique. The main objective of this paper is to analyse the daily and seasonal pattern in PM2.5 concentrations and fluxes and to discuss their correlation with the main meteorological and micrometeorological parameters using high temporal resolution measurements. Observed data showed a seasonal pattern in turbulent fluxes with daytime average positive value during winter and negative during summer. Deposition velocities, ranged from –60 to 20 mm/s, appeared to be mainly influenced by atmospheric stability. There were larger emissions in cases of high wind velocities blowing from water sector indicating a significant potential contribution of sea spray to PM2.5 fluxes. The local atmospheric circulation, due to the orography of the area, was characterised by diurnal winds coming from the Adriatic Sea and nocturnal wind coming from the Alps. This circulation influenced deposition velocity creating an increase of negative fluxes in the morning at the starting of the sea breeze. A diurnal pattern in concentration has been observed and it is similar for all three measurement campaigns, with higher concentrations in nocturnal periods. The daily pattern was investigated in terms of its correlation with meteorological and micro-meteorological parameters, and was found highly correlated with the diurnal pattern of boundary layer height (BLH) and with relative humidity

A two-component parameterization of marine ice-nucleating particles based on seawater biology and sea spray aerosol measurements in the Mediterranean Sea

Ice-nucleating particles (INPs) have a large impact on the climate-relevant properties of clouds over the oceans. Studies have shown that sea spray aerosols (SSAs), produced upon bursting of bubbles at the ocean surface, can be an important source of marine INPs, particularly during periods of enhanced biological productivity. Recent mesocosm experiments using natural seawater spiked with nutrients have revealed that marine INPs are derived from two separate classes of organic matter in SSAs. Despite this finding, existing parameterizations for marine INP abundance are based solely on single variables such as SSA organic carbon (OC) or SSA surface area, which may mask specific trends in the separate classes of INP. The goal of this paper is to improve the understanding of the connection between ocean biology and marine INP abundance by reporting results from a field study and proposing a new parameterization of marine INPs that accounts for the two associated classes of organic matter. The PEACETIME cruise took place from 10 May to 10 June 2017 in the Mediterranean Sea. Throughout the cruise, INP concentrations in the surface microlayer (INPSML) and in SSAs (INPSSA) produced using a plunging aquarium apparatus were continuously monitored while surface seawater (SSW) and SML biological properties were measured in parallel. The organic content of artificially generated SSAs was also evaluated. INPSML concentrations were found to be lower than those reported in the literature, presumably due to the oligotrophic nature of the Mediterranean Sea. A dust wet deposition event that occurred during the cruise increased the INP concentrations measured in the SML by an order of magnitude, in line with increases in iron in the SML and bacterial abundances. Increases in INPSSA were not observed until after a delay of 3 days compared to increases in the SML and are likely a result of a strong influence of bulk SSW INPs for the temperatures investigated (T=−18 ∘C for SSAs, T=−15 ∘C for SSW). Results confirmed that INPSSA are divided into two classes depending on their associated organic matter. Here we find that warm (T≥−22 ∘C) INPSSA concentrations are correlated with water-soluble organic matter (WSOC) in the SSAs, but also with SSW parameters (particulate organic carbon, POCSSW and INPSSW,−16C) while cold INPSSA (T<−22 ∘C) are correlated with SSA water-insoluble organic carbon (WIOC) and SML dissolved organic carbon (DOC) concentrations. A relationship was also found between cold INPSSA and SSW nano- and microphytoplankton cell abundances, indicating that these species might be a source of water-insoluble organic matter with surfactant properties and specific IN activities. Guided by these results, we formulated and tested multiple parameterizations for the abundance of INPs in marine SSAs, including a single-component model based on POCSSW and a two-component model based on SSA WIOC and OC. We also altered a previous model based on OCSSA content to account for oligotrophy of the Mediterranean Sea. We then compared this formulation with the previous models. This new parameterization should improve attempts to incorporate marine INP emissions into numerical models

Organic micropollutants in wet and dry depositions in the Venice Lagoon

Atmospheric transport is an important route by which pollutants are conveyed from the continents to both coastal and open sea. The role of aerosol deposition in the transport of polycyclic aromatic hydrocarbons (PAHs), polychlorobiphenyls (PCBs) and polybromodiphenyls ethers (PBDEs) to water and soil systems has been evaluated by measuring their concentrations in wet and dry depositions to the Venice Lagoon. The organic micropollutant flux data indicate that they contribute to the total deposition flux in different ways through wet and dry deposition, showing that the prevalent contribution derives from wet deposition. The fluxes calculated for PBDEs, showed the prevalence of 47, 99, 100 and 183 congeners, both in dry and wet fluxes. With regard to PCBs, the flux of PPCB for wet deposition is in the same order of magnitude of the diffusive flux at the air–water interface. The PAH fluxes obtained in the present study are similar to those obtained in previous studies on the atmospheric bulk deposition to the Venice Lagoon. The ratios between Phe/Ant and Fl/Py indicate that the pollutants sources are pyrolytic, deriving from combustion fuels