Aerosol indirect effects on glaciated clouds. Part I: Model description

Various improvements were made to a state-of-the-art aerosol–cloud model and comparison of the model results with observations from field campaigns was performed. The strength of this aerosol–cloud model is in its ability to explicitly resolve all the known modes of heterogeneous cloud droplet activation and ice crystal nucleation. The model links cloud particle activation with the aerosol loading and chemistry of seven different aerosol species. These improvements to the model resulted in more accurate prediction especially of droplet and ice crystal number concentrations in the upper troposphere and enabled the model to directly sift the aerosol indirect effects based on the chemistry and concentration of the aerosols. In addition, continental and maritime cases were simulated for the purpose of validating the aerosol–cloud model and for investigating the critical microphysical and dynamical mechanisms of aerosol indirect effects from anthropogenic solute and solid aerosols, focusing mainly on glaciated clouds. The simulations showed that increased solute aerosols reduced cloud particle sizes by about 5 μm and inhibited warm rain processes. Cloud fractions and their optical thicknesses were increased quite substantially in both cases. Although liquid mixing ratios were boosted, there was however a substantial reduction of ice mixing ratios in the upper troposphere owing to the increase in snow production aloft. These results are detailed in the subsequent parts of this study

Carbonaceous PM2.5 and secondary organic aerosol across the Veneto region (NE Italy)

Organic and elemental carbon (OC-EC) were measured in 360 PM2.5 samples collected from April 2012 to February 2013 at six provinces in the Veneto region, to determine the factors affecting the carbonaceous aerosol variations. The 60 daily samples have been collected simultaneously in all sites during 10 consecutive days for 6months (April, June, August, October, December and February). OC ranged from 0.98 to 22.34μg/m3, while the mean value was 5.5μg/m3, contributing 79% of total carbon. EC concentrations fluctuated from 0.19 to 11.90μg/m3 with an annual mean value of 1.31μg/m3 (19% of the total carbon). The monthly OC concentration gradually increased from April to December. The EC did not vary in accordance with OC. However the highest values for both parameters were recorded in the cold period. The mean OC/EC ratio is 4.54, which is higher than the values observed in most of the other European cities. The secondary organic carbon (SOC) contributed for 69% of the total OC and this was confirmed by both the approaches OC/EC minimum ratio and regression. The results show that OC, EC and SOC exhibited higher concentration during winter months in all measurement sites, suggesting that the stable atmosphere and lower mixing play important role for the accumulation of air pollutant and hasten the condensation or adsorption of volatile organic compounds over the Veneto region. Significant meteorological factors controlling OC and EC were investigated by fitting linear models and using a robust procedure based on weighted likelihood, suggesting that low wind speed and temperature favour accumulation of emissions from local sources. Conditional probability function and conditional bivariate probability function plots indicate that both biomass burning and vehicular traffic are probably the main local sources for carbonaceous particulate matter emissions in two selected cities

Long-term trends of PM10-bound arsenic, cadmium, nickel, and lead across the Veneto region (NE Italy)

Since the mid-90s, the European Community has adopted increasingly stringent air quality standards. Consequently, air quality has generally improved across Europe. However, current EU standards are still breached in some European hotspots. The Veneto region (NE Italy) lies in the eastern part of the Po Valley, a major European hotspot for air pollution, where EU standards for particulate matter, nitrogen oxides and ozone are still breached at some sites. This study aims to analyse the PM10-bound arsenic, cadmium, nickel, and lead concentrations over a 10 years-long period (2010-2020) in the Veneto Region by using data collected by the local environmental protection agency (ARPAV) in 20 sampling stations mostly distributed across the plain areas of the region and categorized as rural (RUR), urban (URB), and suburban (SUB) background, industrial (IND) and traffic (TRA) hotspots (Figure 1). The comprehensive dataset discussed in this study was statistically investigated to detect the seasonal trends, their relationship with other air pollutants and meteorological parameters and their spatial variations at a regional scale. This study completes previous air quality studies over the Veneto region for gaseous pollutants and bulk PM10 (Masiol et al. 2017). Samplings were carried out according to CEN EN 12341:1998 standard on quartz fibre filters and were continuous for 24 h, starting at midnight. The gravimetric determination of PM10 mass was measured following the CEN EN 12341:2014 standard. The elemental analysis was performed using an ICP-MS (Agilent 7700) after acid digestion (EN 14902:2005). The trends were analysed using different approaches on the monthly-averaged data. The shape of trends and their seasonal variations were assessed through the seasonal-trend decomposition time series procedure based on “Loess” (STL). The linear trends were computed by the Mann-Kendall trend test (p < 0.05) and the Theil-Sen nonparametric estimator of slope (MK-TS). Since this latter analysis assumes monotonic linear trends and does not consider the shape of trends, the presence of possible breakpoints was investigated using the piecewise regression. Generally, monthly patterns of all analysed elements show higher concentrations during winter, following PM10 concentrations. Some exceptions were detected and discussed. Results of trend analysis indicate statistically significant negative (decreasing) or null linear trends in almost all stations. A few positive (increasing) but not statistically significant trends were also detected. Some sites showed rapid decreases occurred in short periods and linked to peculiar events or local causes. Among others, several sites across the Venice area showed significant drops of arsenic concentrations after the REACH (Registration Evaluation Authorisation of Chemicals) implementation (Formenton et al., 2021). Data used in this study are provided by ARPAV (Agenzia Regionale per la Prevenzione e Protezione Ambientale del Veneto, https://www.arpa.veneto.it/)

Air quality during uncontrolled fires: a multi-years case of study

Exposure to high level of pollutant as a consequence of uncontrolled fire is a issue that must be managed in the right way in order to protect environment and ensure a safe habitat for humans, flora and fauna, because is well know that emissions occurred during those events could serious contaminate air soil and water, and some pollutant could be hazardous for the human health (Lemieux, 2002). During uncontrolled fires a lot of contaminants may be emitted, but in high concern for the human health are persistent organic pollutants (POPs) and PAHs (Coudon et al., 2019, Zhang et al., 2008). Moreover uncontrolled burning could release polychlorinated biphenyls dioxin-like (PCB dl), that are generated as by-product during industrial combustions. Those pollutants are all of high concern for human health because they have well-known carcinogenic and mutagenic properties, e.g. is well known that PAHs is the main carcinogenic constituent of ambient aerosol (Zhang et al., 2008, Fent et al., 2018; Ravindra et al., 2008). Moreover, PCDD/PCDF, frequently referred as dioxin, are recognized as toxic chemical pollutant, with endocrine proprieties and toxic dioxin congener is classified as group1 carcinogen by the international agency for research in cancer (IARC). The aim of this study is evaluate how uncontrolled fires can affect air quality by characterizing persistent organic pollutant emitted from some events occurred from 2015 to 2018 in Veneto region (northern Italy). This area is one of the most polluted and urbanized areas in Europe (Larsen et al., 2012)and uncontrolled fire can further enhance this severe situation, leading air pollution to critical level. During those accidental events the Environmental Protection Agency of Veneto (ARPAV), in order to monitoring the effect of fires, and ensure public health, collected some air samples using Hi-vol samplers equipped with quartz fiber filter (QFF) for collecting “particulate” phase compounds and a polyurethane foam plug (PUF) for retaining “gas-phase” compounds. Subsequently, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/PCDF), polychlorinated biphenyls dioxin-like (PCB dl) and Polycyclic aromatic hydrocarbons (PAHs), were analysed using a High Resolution Gas Chromatography (HRGC), coupled with High Resolution Mass Spectrometry (HRMS). As expected results show large increase of PCDD/PCDF, PCB dl and PAHs during and immediately after incidental fires, with differences in pollutant composition. It’s noticeable how, in a few time (hours to days) pollutant concentration presented a clear and strong drop, leading air quality to better conditions. This drop is probably due to meteorological factors, that will be investigated

The disinfection by-products are in the air: Aerosol measurements in the urban area of Venice

Haloacetic acids (HAAs) are usually taken to be man-made, regularly determined in drinking water as disinfection by-products; yet they have been demonstrated as a probable photooxidation products from atmospheric halogenated hydrocarbons. Here we determined a total of fourteen HAAs, including for the first time iodinatedHAAs, in aerosol samples collected from April to June 2023 at Parco Bissuola (urbanized area of Venice) and Rio Novo (Venice island). The study provides a first insight and source identification about the anthropogenic or natural origin of HAAs. To fulfil this aim, we improved existing methods with a highly sensitive technique by using high pressure anion exchange chromatography coupled to a triple quadrupole mass spectrometer. Five HAAs have been found to be above the detection limits at both sites, and the major source should be attributed to a mixed contribution from atmospheric oxidation of both organic precursor, sea spray and a minor contribution of an external swimming pool located near the Parco Bissuola site. Considering the presence of iodinated HAAs and their cytotoxicity, the present study also provides a basis for the assessment of risks for humans

Seasonal trends and spatial variations of PM10-bounded polycyclic aromatic hydrocarbons in Veneto Region, Northeast Italy

The Veneto Region extends for ~18.4·103km2 in the northeastern part of the Po Valley and includes mountains, hills, plain and coastal environments with very different and discontinuous anthropogenic pressures. Although many efforts have been made to mitigate air pollution, the European air quality standards for atmospheric pollutants are frequently breached. This study investigates the levels of eight PM10-bound PAHs collected in 21 stations categorized as rural background, urban and suburban backgrounds, traffic and industrial hot-spots during one year (2011). Data were statistically processed to detect the PAH seasonal trends, their relationship with other air pollutants and micro-meteorological parameters and the space variations at a regional scale. Results show that PAHs levels are relatively high in the largest part of the region, with 10 sites exceeding the levels of BaP targeted by the European legislation. Two sites exhibited anomalously high PAHs concentrations and this anomaly became even more evident when considering the population density as a surrogate for the potential anthropogenic pressure. The PAHs levels were found directly proportional to other gaseous pollutants (CO, NO, NOx, SO2) suggesting common polluting sources. The analysis of time trends of PAH concentrations reveals significant coincidences throughout the region, i.e. simultaneous changes are observed in most sites as a consequence of similar emission sources and accumulation/removal processes. In this scenario, the control strategies currently imposed at local level (e.g. traffic limitations) have proven scarcely effective in mitigating air pollution and a real coordination at regional or even interregional level cannot be further postponed. Peculiar features of the PAHs pollution in the Veneto were also identified and some measures for protecting the human health were suggested

Novel Applications of State-of-the-Art Gamma-Ray Imaging Technique: From Nuclear Decommissioning and Radioprotection to Radiological Characterization and Safeguards

Gamma-ray imaging is a powerful technique subjected to important research efforts in nonmedical fields, providing information about the possible spatial distribution of radioactive materials emitting photons and potential contamination spots, in generic area survey or to specific component analyses. This capability opens up a range of possible applications in nuclear installations and radioactive waste management sites, where radiation survey protocols and radiological characterization of items may be highly and positively impacted by this technique. In this work, a new-generation 3-D pixelated CdZnTe gamma-ray imaging and spectrometry detector has been used in the context of the TRIGA RC-1 Research Reactor at the ENEA Casaccia Research Centre to test several applications where gamma-ray imaging can provide valuable information otherwise unknown (with equivalent level of accuracy and effort). Experiments carried out range from radiological survey, where hotspots are identified and radioactive items are sorted from conventional waste to improvements in the quantification of gamma emitters via gamma-spectrometry analysis, and from safeguards and nonproliferation purposes (e.g., providing methods to assess the amount of special nuclear material (SNM), which remains fixed and unchanged in time) up to radiation protection issues (e.g., identification of unexpected contributions to personnel total exposure). The results obtained in this experimental campaign, as well as the validations provided by comparison with 'traditional' methods, demonstrate the applicability of state-of-the-art gamma-ray imaging systems to the presented tasks, with consequences that could positively impact the current radiation survey routines and radiological characterization protocols followed at ENEA TRIGA RC-1 as well as other installations

Identification of a defected fuel rod in the TRIGA R.C.-1 facility of the ENEA Casaccia Research Center: radiation protection aspects

The nuclear facility TRIGA RC-1 is located at the ENEA Casaccia Research Center in Rome. It is a thermal spectrum research reactor with a thermal power of 1 MW and a Mark III containment. The failure of the fuel cladding of the General Atomic TRIGA is a well-known phenomenon in the literature and is normally expected during its lifetime. Depending on the severity of the cracking, this results in the transfer of radioactivity from inside the fuel rods to the demineralized moderation and cooling water of the primary circuit. This occurs especially when the fuel is heated, as the temperature rise leads to an increase in the internal pressure inside the rods, causing fission products, especially gaseous ones, to be released through the cracks. The sustained release of these fission products over time causes impurities with longer half-lives (e.g., Cs-137) to accumulate in the primary water purification system and, in particular, in the ion exchange resin tank. Therefore, the detection of Cs-137 in the ion exchange resins of the primary water purification system of the reactor is a sufficiently clear indication of the occurrence of such disturbances. Indeed, Cs-137 is not only a direct fission product of U-235, but is also produced by the decay of Xe-137 (one of the major fission noble gasses), which, because of its physical nature, readily escapes through the rod cladding. To ensure worker protection from ionizing radiation during the identification and replacement of defective fuel rods, a special program of physical, environmental, and personal radiation protection monitoring was conducted. In addition to a brief description of the work performed, this report presents the results of radiometric measurements and associated individual dose assessment performed before, during, and after the identification and replacement of the defected fuel elements