1,720,982 research outputs found
Investigation of the contribution of emission sources to atmospheric particulate matter concentration (PM) and to its redox properties
Full text linkIn the last few years, various epidemiological studies were conducted to estimate the health effects of particulate matter (PM) on human population, placing at the core the association between exposure to PM and several adverse outcomes, especially on cardiovascular and respiratory systems. PM mass concentration is typically used to estimate population exposure. However, this indicator misestimate the overall impact of PM, since it does not consider the multiple toxicological effects of the different pollutants that constitute and determine the intrinsic properties of PM. In fact, the complexity and variability of PM can lead to different responses in biological systems. The hypothesis of the mechanisms of PM-related diseases include oxidative stress, inflammatory responses, and genotoxicity. All of them can be mediated by PM-related reactive oxygen species (ROS).
To assess the particles’ oxidative capacity, several acellular methods, defined as oxidative potential (OP) assays, have been developed and proposed as relevant and valid metric for addressing biological exposure to PM. There is still no agreement regarding the most representative assay to measure the OP of PM, but methods mostly used on the PM filter extracts are the dithiothreitol (OPDTT), the 2′,7′-dichlorofluorescin (OPDCFH), and the ascorbic acid (OPAA) assays. Each assay gives different results and probably simulates just a small part of the many potential mechanisms of oxidative stress induction. Therefore, the synergic application of the three assays on the same PM samples is strongly recommended to have a complete characterization of their redox properties. The study of PM composition and toxicity represents a particularly interesting field of research, aimed to a better understanding of the existing relationships between the chemical composition and sources of PM and its adverse effects on human health and environment, useful to plan the appropriate mitigation measures. It is also worth considering the heterogeneity of emission sources and the role that they play on PM physical and chemical properties. The analysis of PM coming from different sources could allow associating specific chemical composition, which depends on the pollutant origin, with a given biological response. In fact, the role of each chemical component on PM toxicity is still to be fully defined.
One of the goals of this PhD thesis is to improve the knowledge about the existing relationships between PM chemical composition and sources and, therefore, to attempt to estimate PM adverse effects on health and environment through the investigation of PM redox properties.
To this aim, a multidisciplinary study based on the synergic application of traditional and innovative approaches to PM was carried out in this PhD research.
PM field samples were collected at monitoring sites differently impacted by anthropic activities by using different techniques, such as traditional monitoring equipment, cascade impactors, biomonitoring methods and very-low volume samplers allowing spatially-resolved determination of PM chemical components. Furthermore, widespread components of PM produced by specific emission sources and characterized by very different chemical compositions were used to compare different experimental procedures on PM from defined emission sources.
Chemical characterization of PM samples was obtained by applying advanced and robust analytical procedures for the determination of inorganic ions, water-soluble and insoluble elements, water-soluble organic carbon (WSOC) and levoglucosan (LVG). PM water-soluble and insoluble fraction were separately analyzed through a well-established fractionation procedure to increase the selectivity of elements as source tracers and to estimate the environmental mobility and bio-accessibility of toxic elements.
Much of the PhD experimental research has focused on the investigation of redox properties of PM since in the last few years, the oxidative potential appears to be the central paradigm in the assessment of PM toxicity. However, there are still operative criticisms affecting its relevance as effective realistic metric to quantify the effects of ambient particles on human health, such as the influence of multiple operative conditions on OP obtained results, as well the lack of standardized operative conditions, which make a challenge to representatively compare inter-laboratory data. Therefore, one of the goals of this research was to explore in depth redox equilibria between PM reactive species.
During the PhD research various monitoring campaigns aimed to improve knowledge about the existing relationships between sources of PM and its related chemical composition were conducted under different conditions and in different geographical areas (i.e. during the national lockdown imposed by Italian government to counter the Covid-19 pandemic). Valuable information for PM source apportionment through a chemical/size fractionation procedure and OP measurements were obtained.
Potential effects of PM composition on biological systems were studied by using an in vitro approach based on the cytotoxic, genotoxic, oxidative, and inflammatory response of bronchial epithelial cell line BEAS-2B after the exposure to PM coming from different sources.
In parallel with the described activity, the reliability of PM biomonitoring techniques for the assessment of atmospheric element concentrations was estimated. To this aim, leaf deposition on riparian species (Arundo donax (L.)) and lichen transplants (Evernia prunastri (L.) Ach.) were used. Furthermore, an integrated approach to assess the effects of PM on functional traits of Quercus ilex (L.) in an urban area was carried out comparing results from OP assays when applied on PM deposited on Q. ilex leaves, and on filters (traditional monitoring system).
Another line of research was the analysis of PM samples in indoor environments of private dwellings and University classrooms, to study the concentration, the chemical composition, and the OP of indoor and outdoor PM to obtain information about the main indoor and outdoor PM emission sources and exposure of occupants.
Lastly, another important study included in the PhD research was related to the project Redox-activity and Health-effects of Atmospheric Primary and Secondary aerosol (PRIN 2017-RHAPS project) in which our groups participated with OP measurements and elemental analysis of PM samples. RHAPS aims to identify specific properties of PM from anthropogenic sources that are responsible for toxicological effects and can be used as new metrics for health-related outdoor pollution studies. The main goal of RHAPS project was to provide a new assessment of the sources and nature of PM components responsible for adverse health
effects in real-world conditions. The experimental field monitoring campaigns have been recently completed and data elaboration is still ongoing.
Supplementary research activities were focused on the evaluation of the capability of food waste materials as low-cost adsorbents for the removal of Volatile Organic Compounds (VOC) from wastewater, and on the analytical characterization of biological matrices (i.e. bees and beehive products, olive oil) to evaluate their potential of accumulating toxic elements, allowing the monitoring of this kind of pollutants concentrations in the environment for integrated measurements. Rapid analytical methods for routinely analyzing a significant number of biological samples were developed and validated
Effects of operating conditions on PM oxidative potential assays
No full textOxidative potential (OP) has been suggested as a biologically relevant exposure metric for estimating particulate matter (PM) capacity to induce oxidative stress in living organisms. However, standardized experimental pro-cedures are not yet available. This study explores how a variety of operating conditions influences responses of several different assays for measuring OP: the 2′,7′-dichlorofluorescein (OPDCFH), the ascorbic acid (OPAA) and the dithiothreitol (OPDTT) assays. A recently optimized method for the evaluation of PM reducing properties, based on the 2,2-diphenyl-1-picrylhydrazyl assay (RPDPPH), was also included in the study. Two monitoring campaigns were carried out in Central Italy by using co-located PM10 samplers working in parallel, for comparing results obtained from different operating procedures simultaneously applied on equivalent samples. Extraction efficiency and repeatability of three different water-extraction methods (rotating agitator, ultra-sonic bath, and vortex), and the influence of storage duration and conditions on OP results were examined. OPDCFH values were found to be significantly higher when ultrasonic bath (US) was used for extraction, probably due to the formation of free radicals induced by US; for all the OP assays, the highest repeatability was obtained by extracting samples with rotating agitator (RA). Sample storage was confirmed to be a very critical issue as all the assays, except OPDTT, showed a marked dependence on storage time and conditions. The influence of membrane filters used to collect PM was also assessed. No significant differences were observed between samples collected on quartz and polytetrafluoroethylene (PTFE) membrane filters, except for OPAA, that gave significantly higher results for samples collected on PTFE membranes. Lastly, the contribution of water-insoluble PM com-ponents to OP was examined and warrants further investigations
Air quality biomonitoring in an urban and industrial hot-spot of Central Italy
No full textParticulate matter (PM) is a complex mixture of solid and liquid airborne particles, characterized by different size, shape, chemical composition, solubility and origin [1]. The high costs associated to the definition of a traditional monitoring network determine an increasing demand for new and low-cost techniques for air pollution monitoring [2]. In this context, leaves are often described as efficient passive biomonitors for airborne pollutants such as particulate matter [3]. Deposition of PM on vegetation is influenced by species-specific characteristic and also by chemical and physical characteristics of PM (dimension, composition, morphology and solubility) [4]. This study reports the evaluation of PM deposition on giant reed leaves (A. donax (L.)), in Terni city, an industrial and urban hotspot of Central Italy. Leaves were collected in six different collection sites along the river Nera that cross the city, in order to evaluate the role of the different emission sources present in this area. The chemical characterization of washed and unwashed leaves allows us to estimate PM deposition on leaf surface. Thanks to the utilization of new and innovative PM samplers (HSRS, Fai Instruments, Fonte Nuova, Italy) it was possible to build an extensive air monitoring network, useful to compare the airborne elemental concentrations with the PM deposition on A. donax (L.) leaves data. The comparison between leaves deposition results and atmospheric concentrations of PM10 elemental components allowed us to evaluate the efficiency of A. donax leaves as biomonitors for PM pollution. Deposition data confirmed to be reliable for elements such as Ni, Mo and Cr emitted at high concentrations by the steel plant. The obtained results proved the influence of chemical and physical characteristics on the deposition efficiency of each elemental component
Sphagnum moss and peat comparative study: metal release, binding properties and antioxidant activity
Full text linkPeat is the main constituent of cultivation substrates and a precious non-renewable fossil material. Peatlands provide important ecosystem services and allow the absorption and storage of carbon. Protecting peatlands helps tackle climate change and contributes to biodiversity conservation. Due to its importance, it is necessary to implement strategies to reduce the use of peat, such as replacing it with biomass-based alternative growing media constituents, such as Sphagnum moss. In this study, we compared the metal release and binding properties at two different pH, antioxidant activity, and total phenolic content of peat and Sphagnum moss from the Tierra del Fuego (TdF) region of southern Patagonia. Levels of the elements were determined by inductively coupled plasma mass spectrometry (ICP-MS), while the types and amounts of functional groups were characterized and compared using Fourier transform infrared (FTIR) spectroscopy. The total phenol level and antioxidant capacity were assessed using the Folin-Ciocalteu method and 2,2-diphenyl-1-picrylhydrazyl test. There are generally higher concentrations of leachable elements in peat than in Sphagnum moss at pH = 2, except Cs, Rb, Ti, and Zr. In contrast, at pH = 5, levels of all leached elements are highest in Sphagnum moss. Sphagnum moss shows a higher metal adsorption capacity than peat, except for Be, Mn, Tl, and Zn. Finally, the results showed that both matrices contained similar total phenolic contents: 0.018 ± 0.011 mg gallic acid equivalent (GAE) per gram dry sample for peat and 0.020 ± 0.007 mg GAE g-1 for Sphagnum moss. Instead, Sphagnum moss extracts showed a significantly higher antioxidant activity [0.026 ± 0.028 mmol Trolox equivalents (TE) g-1] than that estimated in peat (0.009 ± 0.005 mmol TE g-1). Humic acids, carboxylic acids, and phenolic and lignin groups were identified as the functional groups that mainly determined the antioxidant activity of the Sphagnum moss compared to peat. The present study resulted in an advancement of knowledge of these materials for more thoughtful future use and possible replacements
A New Method for the Assessment of the Oxidative Potential of Both Water-Soluble and Insoluble PM
Full text linkWater-soluble and insoluble fractions of airborne particulate matter (PM) exhibit different toxicological potentials and peculiar mechanisms of action in biological systems. However, most of the research on the oxidative potential (OP) of PM is focused exclusively on its water-soluble fraction, since experimental criticisms were encountered for detaching the whole PM (soluble and insoluble species) from field filters. However, to estimate the actual potential effects of PM on human health, it is essential to assess the OP of both its water-soluble and insoluble fractions. In this study, to estimate the total OP (TOP), an efficient method for the detachment of intact PM10 from field filters by using an electrical toothbrush was applied to 20 PM10 filters in order to obtain PM10 water suspensions to be used for the DCFH, AA and DTT oxidative potential assays (OPDCFH, OPAA and OPDTT). The contribution of the insoluble PM10 to the TOP was evaluated by comparing the TOP values to those obtained by applying the three OP assays to the water-soluble fraction of 20 equivalent PM10 filters. The OP of the insoluble fraction (IOP) was calculated as the difference between the TOP and the WSOP. Moreover, each PM10 sample was analyzed for the water-soluble and insoluble fractions of 10 elements (Al, Cr, Cs, Cu, Fe, Li, Ni, Rb, Sb, Sn) identified as primary elemental tracers of the main emission sources in the study area. A principal component analysis (PCA) was performed on the data obtained to identify the predominant sources for the determination of TOP, WSOP, and IOP. Results showed that water-soluble PM10 released by traffic, steel plant, and biomass burning is mainly responsible for the generation of the TOP as well as of the WSOP. This evidence gave strength to the reliability of the results from OP assays performed only on the water-soluble fraction of PM. Lastly, the IOPDCFH and IOPDTT were found to be principally determined by insoluble PM10 from mineral dust
Progetti per Avvio alla Ricerca - Tipo 1
No full textL'esposizione al particolato atmosferico (PM) è strettamente collegata all'insorgenza di patologie della salute umana. Lo studio del PM
è fondamentale per una comprensione più dettagliata delle sue caratteristiche e per l'attuazione di strategie per il miglioramento della
qualità dell'aria. Ultimamente, la ricerca scientifica nel campo in questione si è concentrata sullo studio dello stress ossidativo indotto
dal PM in organismi biologici, ritenuto uno dei meccanismi biologici chiave nella generazione di effetti negativi. Tale capacità del PM è
definita potenziale ossidativo (OP), generalmente misurata mediante l¿applicazione di saggi acellulari su campioni di PM. Tuttavia,
numerosi studi hanno evidenziato la variabilità delle risposte in funzione delle condizioni operative di esecuzione dei test e, quindi, la
necessità di protocolli standardizzati per rendere affidabili i confronti inter-laboratorio e ottenere dati rappresentativi. Il progetto di
ricerca presentato si pone l'obiettivo di approfondire gli equilibri redox delle specie native del PM che si instaurano durante le diverse
fasi di trattamento e analisi dei campioni. Diverse procedure sperimentali saranno applicate su campioni identici di PM, raccolti in
parallelo durante diverse campagne di monitoraggio, le cui prestazioni saranno confrontate per identificare l'influenza delle condizioni
operative di applicazione dei test sui risultati ottenuti. La capacità di queste misure acellulari di simulare la reale induzione di stress
ossidativo in sistemi biologici verrà valutata mediante confronto con endpoints biologici su organismi modello e bioindicatori.
Un'ulteriore finalità del presente progetto di ricerca è la valutazione delle tecniche di biomonitoraggio attraverso il confronto con le
convenzionali tecniche di campionamento attivo di PM, con l'obiettivo di validarne l'efficienza e, di conseguenza, costruire reti di
monitoraggio che forniscano raccolte di dati a elevata risoluzione spaziale e temporale
An analytical method for the biomonitoring of mercury in bees and beehive products by cold vapor atomic fluorescence spectrometry
Full text linkBees and their products are useful bioindicators of anthropogenic activities and could overcome the deficiencies of air quality networks. Among the environmental contaminants, mercury (Hg) is a toxic metal that can accumulate in living organisms. The first aim of this study was to
develop a simple analytical method to determine Hg in small mass samples of bees and beehive products by cold vapor atomic fluorescence spectrometry. The proposed method was optimized for about 0.02 g bee, pollen, propolis, and royal jelly, 0.05 g beeswax and honey, or 0.1 g honeydew with 0.5 mL HCl, 0.2 mL HNO3, and 0.1 mL H2O2 in a water bath (95 ◦C, 30 min); samples were made up to a final volume of 5 mL deionized water. The method limits sample manipulation and the reagent mixture volume used. Detection limits were lower than 3 μg kg−1 for a sample mass of 0.02 g, and recoveries and precision were within 20% of the expected value and less than 10%, respectively, for many matrices. The second aim of the present study was to evaluate the proposed method’s performances on real samples collected in six areas of the Lazio region in Italy
Lichen transplants for high spatial resolution biomonitoring of persistent organic pollutants (POPs) in a multi-source polluted area of Central Italy
No full textThe ability of lichen transplant Evernia prunastri (L.) Ach. to reflect air concentration and spatial distribution of 7 polychlorinated dibenzodioxins (PCDDs), 10 polychlorinated dibenzofurans (PCDFs), and 23 polychlorinated biphenyls (PCBs) was evaluated through the construction of a wide and dense biomonitoring network. For this purpose, 23 lichen transplants were placed in a highly polluted area in Central Italy, characterized by the presence of different local emission sources such as a power plant, a steel plant, vehicular traffic, and domestic heating. The high spatial resolution data obtained from lichens were used to map the spatial distribution of the studied compounds, useful to identify the location and strength of target compounds sources over the territory. The maps showed that the highest concentrations of the pollutants were detected, as expected, in the sites close to the power plant and to the steel plant, confirming their important role as persistent pollutants emission sources. The statistical analysis performed on the spatially resolved data allowed us to identify the steel plant as the main source of PCDD/Fs, while PCBs were emitted by both the steel plant and the power plant. Finally, the efficiency of lichen transplants to reflect PCDD/Fs and PCBs atmospheric concentrations was assessed by comparing lichen data with POPs deposition measured by bulk deposition samplers at sites impacted by intensive emission sources; good results were achieved from the comparison (R2 > 0.79). Lichen transplants have demonstrated to be suitable biomonitors of POPs, allowing to obtain a high spatial monitoring network. The lowcost biomonitoring and experimental approach described in this study can be applied to other monitoring campaigns for identifying localizing emission sources of POPs in areas contaminated by several disaggregated sources
Multielement characterization and antioxidant activity of Italian extra-virgin Olive oils
Full text linkFood product safety and quality are closely related to the elemental composition of food. This study combined multielement analysis and chemometric tools to characterize 237 extra-virgin olive oil (EVOO) samples from 15 regions of Italy, and to verify the possibility of discriminating them according to different quality factors, such as varietal or geographical origin or whether they were organically or traditionally produced. Some elements have antioxidant properties, while others are toxic to humans or can promote oxidative degradation of EVOO samples. In particular, the antioxidant activity of oils’ hydrophilic fraction was estimated and the concentrations of 45 elements were determined by inductively coupled plasma mass spectrometry (ICP-MS). At first, univariate and multivariate analyses of variance were used to compare the element concentrations, and statistically significant differences were found among samples from different regions. Successively, discriminant classification approaches were used to build a model for EVOO authentication, considering, in turn, various possible categorizations. The results have
indicated that chemometric methods coupled with ICP-MS have the potential to discriminate and characterize the different types of EVOO, and to provide “typical” elemental fingerprints of the various categories of samples
Optimization and application of the DPPH assay for evaluating reducing properties of particulate matter
No full textDifferent acellular assays were recently developed to measure particulate matter (PM) oxidative potential (OP) [1]. Common OP methods include dithiothreitol assay (OPDTT), ascorbic acid assay (OPAA) and 2′,7′-dichlorofluorescin (OPDCFH). OP assays can provide observations on the relationship between PM characteristics and its ability to generate oxidative stress. However, along with oxidizing species, experimental OP values suggest the possible presence of reducing species in PM. Therefore, the obtained data drives the need to deepen knowledge on redox properties of PM. The DPPH (2,2-Diphenyl-1-picrylhydrazyl; Figure 1) assay is a commonly used spectrophotometric method to estimate antioxidant activity of several matrices (e.g. food [2], plants [3]) by measuring the decrease of absorbance at 517 nm over time. This assay estimates the overall antioxidant capacity of the samples and offers the advantages of being simple and rapid [2] and easily applicable to intensive PM monitoring campaigns. For these reasons, in this work the DPPH procedure was tailored and optimized to be applied to both PM field samples and to dusts produced by specific sources (e.g. brake dust, incinerator dust, urban dust). To the best of our knowledge, this is the first study describing the application of an antioxidant capacity assay on PM.
The optimized procedure shows good analytical performance and allows the analysis of conventional 24-h airborne PM samples with a repeatability included in the range 5-10%. The assay was applied to samples (Figure 2) and compared with OP results in order to gain more knowledge about the redox properties of PM and to deepen the relationship between the composition of PM and its toxicity. First results suggest a competition between oxidizing and reducing processes during the extraction step, which needs to be carefully evaluated in interpreting the results
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