Evaluation of the Efficiency of Arundo donax L. Leaves as Biomonitors for Atmospheric Element Concentrations in an Urban and Industrial Area of Central Italy

Washed and unwashed Arundo donax L. (A. donax) leaves were analyzed for elements, and results were compared with element concentrations detected in river water and particulate matter (PM) Samples were collected along a river in an urban and industrial hot spot of Central Italy, where element concentrations show relevant spatial gradients both in air and river water. The aim of this study is to identify the role of the two environmental matrices on leaves composition. Element concentrations of washed and unwashed leaves were compared to differentiate between the superficial deposition and the uptake into leaf tissues of elements. Water-soluble and -insoluble element concentrations were measured in PM10 samples collected on membrane filters by using innovative high spatial resolution samplers. The comparison among leaf and atmospheric concentrations of PM10 elements showed a similar trend for Ni, Mo, Cr, Ti, and Fe, which are reliable tracers of the PM10 contribution by steel plant and vehicular traffic. Soluble species appeared to be mainly bounded into leaf tissues, while insoluble species were deposited on their surface. On the other hand, element concentrations detected in washed A. donax leaves were poorly correlated with those measured in river water samples. The obtained results proved that A. donax leaves can be used as reliable biomonitors for the evaluation of the atmospheric concentrations of some PM10 elemental components

Toxicological profile of PM from different sources in the bronchial epithelial cell line BEAS-2B

The toxicity of particulate matter (PM) is strictly associated with its physical-chemical characteristics, such as size or chemical composition. While these properties depend on the origin of the particles, the study of the toxicological profile of PM from single sources has rarely been highlighted. Hence, the focus of this research was to investigate the biological effects of PM from five relevant sources of atmospheric PM: diesel exhaust particles, coke dust, pellet ashes, incinerator ashes, and brake dust. Cytotoxicity, genotoxicity, oxidative, and inflammatory response were assessed in a bronchial cell line (BEAS-2B). BEAS-2B cells were exposed to different concentrations (25, 50, 100, and 150 g/mL medium) of particles suspended in water. The exposure lasted 24 h for all the assays performed, except for reactive oxygen species, which were evaluated after 30 min, 1 h, and 4 h of treatment. The results showed a different action of the five types of PM. All the tested samples showed a genotoxic action on BEAS-2B, even in the absence of oxidative stress induction. Pellet ashes seemed to be the only ones able to induce oxidative stress by boosting the formation of reactive oxygen species, while brake dust resulted in the most cytotoxic. In conclusion, the study elucidated the differential response of bronchial cells to PM samples generated by different sources. The comparison could be a starting point for a regulatory intervention since it highlighted the toxic potential of each type of PM tested

Seasonal variations in the chemical composition of indoor and outdoor PM10 in university classrooms

In the VIEPI project (Integrated evaluation of the exposure to indoor particulate matter) framework, we carried out a 1-year study of the concentration and chemical composition of particulate matter (PM) in a 5 story building in the Sapienza University of Rome (Italy). Each sampling had a duration of 1 month and was carried out indoors and outdoors in six classrooms. The chemical analyses were grouped to obtain information about the main PM sources. Micro-elements in their soluble and insoluble fractions were used to trace additional sources. Indoor PM composition was dominated by soil components and, to a lesser extent, by the organics, which substantially increased when people crowded the sites. The penetration of PM components was regulated by their chemical nature and by the dimensions of the particles in which they were contained. For the first time in crowded indoor environments, three different chemical assays aimed to determine PM redox properties complemented chemical composition measurements. These preliminary tests showed that substantially different redox properties characterised atmospheric particles in indoor and outdoor sites. The innovative characteristics of this study (time duration, number of considered environments) were essential to obtain relevant information about PM composition and sources in indoor academic environments and the occupants’ role

Food Waste Materials as Low-Cost Adsorbents for the Removal of Volatile Organic Compounds from Wastewater

The aim of this work was to study the potential of food waste materials (banana peel, potato peel, apple peel, lemon peel, coffee waste, decaf coffee waste, grape waste, and carob peel) as low-cost adsorbents for the removal of aliphatic and aromatic volatile organic compounds (VOCs) from wastewater. The ability of examined food waste materials to adsorb VOCs from synthetic multi-component standard solutions was evaluated and the examined food waste materials showed high removal efficiency. Performances of coffee waste, grape waste, and lemon peel were detailed by using Trichloroethylene and p-Xylene in mono-component standard solutions. The adsorption capacity of the three selected food wastes was determined by using linear Langmuir and Freundlich isotherm models. Two errors functions, average percentage error (APE) and the chi-square test (χ2), were used for isotherm optimization prediction. Freundlich isotherm well described the adsorption of VOCs on the considered materials. According to the obtained results, a multilayer, physical, and cooperative adsorption process was hypothesized, particularly evident when the VOCs’ concentrations are high. This was confirmed by the high adsorption efficiency percentages (E% > 80%) of VOCs from a real polluted matrix (urban solid waste leachate), containing high concentrations of total organic content

Progetti per Avvio alla Ricerca - Tipo 1

L'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

Investigation of the contribution of emission sources to atmospheric particulate matter concentration (PM) and to its redox properties

In 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

Optimization and application of the DPPH assay for evaluating reducing properties of particulate matter

Different 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

Evaluation of antioxidant properties of particulate matter by DPPH assay

Several acellular methods, defined as oxidative potential (OP) assays, have been developed to assess the particulate matter (PM) oxidative capacity and they are considered as predictors of the ability of dust to generate oxidative stress in living organisms. There is no agreement regarding the most representative assay to measure the OP of PM (Ayres et al., 2008), but methods mostly used on the PM filter extracts are the dithiothreitol (DTT; Cho et al., 2005), the 2′,7′-dichlorofluorescin (DCFH; Hung et al., 2001) and the ascorbic acid (AA; Stoeger et al., 2008) assays. The application of those assays to PM samples collected in field suggests the possible presence of reducing species, naturally present in PM, that compete with oxidizing species, altering OP values. This issue merits to be further investigated. While the use of acellular methods for the assessment of the OP values has been receiving great scientific attention in recent years, there is still a literature gap about acellular assays for identifying reducing species in particulate matter. One of the antioxidant capacity assays, that is currently in use for various matrices, is based on the use of the stable free radical DPPH (2,2-Diphenyl-1-picrylhydrazyl). In this work, this assay was tailored and applied to PM. Both PM2.5/PM10 field samples and dusts produced by specific sources (i.e. brake dust, Saharan dust, road dust, soil dust, coke and certified material NIST1648a) were considered in the work. The effect of the antioxidants on DPPH· radical is estimated according to the procedure described by Chen et al. (2016) with slight modifications. The collected dust and the PM filters are put into 5 ml of DPPH 0.1 mM in ethanol (96%) prepared daily and, then, they are extracted at room temperature for 30 minutes, by shaking the solutions inside glass vials. Then, spectrophotometric measurements are done at 517 nm. The same samples were analysed also for elements, inorganic ions and oxidative potential (AA, DTT and DCFH assays). The comparison between obtained data by OP assays and DPPH assay performed in parallel, allowed us to gain more knowledge on redox properties of PM. The values are interpreted and linked to the chemical composition of the samples. The study of the redox properties of PM may help to deepen the relationship between the composition of PM and its toxicity

Air quality biomonitoring in an urban and industrial hot-spot of Central Italy

Particulate 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

Valutazione dell’efficienza dell’utilizzo di foglie di A. donax L. per il biomonitoraggio delle concentrazioni atmosferiche di componenti elementari di PM10

Numerosi studi hanno evidenziato la possibilità di utilizzare le foglie come alternativa low-cost per il biomonitoraggio dell’inquinamento atmosferico da PM in ambiente urbano. Nello specifico, tramite la caratterizzazione chimico-fisica delle particelle depositate sulle foglie è possibile ottenere informazioni sul ruolo e l’impatto di diverse sorgenti emissive di PM. Infatti, queste caratteristiche sono direttamente influenzate dal tipo di processo e di sorgente emissiva. Il presente studio è focalizzato sulla valutazione dell’efficienza di foglie di Arundo donax L. per il biomonitoraggio dell’inquinamento da PM e la valutazione dell’impatto di sorgenti emissive nella conca ternana. A. donax è già largamente conosciuta in letteratura per il suo utilizzo nel fitorimedio e il biomonitoraggio di acque e suoli contaminati, legato alla sua elevata tolleranza nei confronti di contaminanti ambientali come metalli pesanti quali Cd, Cr e Ni. Per valutare la sua efficacia, per il biomonitoraggio del PM, campioni fogliari di A. donax sono stati prelevati mensilmente e in parallelo al campionamento di filtri di PM10 da sei siti, caratterizzati dal diverso impatto di sorgenti emissive di PM e localizzati lungo il corso del fiume Nera che attraversa la conca ternana. Inoltre, prendendo in considerazione la capacità di bioaccumulo di questa specie nei confronti di metalli pesanti, campioni di acqua di fiume sono stati prelevati dai sei siti durante la campagna di cinque mesi, da Marzo a Luglio 2017. Le concentrazioni elementari rinvenute nei campioni di foglie lavate con acqua deionizzata sono state sottratte a quelle delle foglie non lavate per ottenere una stima della deposizione fogliare (SD, deposizione superficiale) di componenti elementari del PM10. I risultati relativi alla deposizione fogliare sono stati successivamente confrontati con i risultati della caratterizzazione chimica dei filtri di PM10, sottoposti alla procedura di frazionamento chimico per l’individuazione delle concentrazioni nella componente solubile e insolubile del PM10, per valutare la rappresentatività dei risultati nello studio dell’impatto di sorgenti presenti nella conca. I risultati ottenuti e relativi alla SD sono stati successivamente confrontanti con le concentrazioni elementari rinvenute nei campioni di acqua fluviale per discriminare l’influenza della contaminazione di questa matrice. Il confronto tra deposizione fogliare e concentrazioni su filtri di PM10 ha evidenziato la stessa variabilità tra siti per elementi come Ni, Mo, Cr, Ti e Fe, conosciuti e utilizzati come traccianti dell’emissione dell’acciaieria e del traffico veicolare, evidenziando l’affidabilità di questo approccio di biomonitoraggio per la valutazione dell’impatto di queste sorgenti nella conca. Nello specifico, i valori di deposizione fogliare relativi a questi traccianti, fatta eccezione per il molibdeno, sono risultati significativamente correlati alle concentrazioni nella componente insolubile del PM10. Al contrario, specie solubili come il molibdeno hanno evidenziato minori valori di deposizione fogliare, sottolineando l’influenza di caratteristiche chimico-fisiche delle particelle sull’interazione con le foglie, confermata anche dai risultati delle analisi di microscopia a scansione elettronica accoppiata a spettroscopia a raggi X (SEM/EDX) delle particelle depositate