Marta Radaelli

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 summation operatorPCB 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.

Metabolomic analysis of wild and transgenic Nicotiana langsdorffii plants exposed to abiotic stresses: unraveling metabolic responses

AbstractNicotiana langsdorffii plants, wild and transgenic for the Agrobacterium rhizogenes rol C gene and the rat glucocorticoid receptor (GR) gene, were exposed to different abiotic stresses (high temperature, water deficit, and high chromium concentrations). An untargeted metabolomic analysis was carried out in order to investigate the metabolic effects of the inserted genes in response to the applied stresses and to obtain a comprehensive profiling of metabolites induced during abiotic stresses. High-performance liquid chromatography separation (HPLC) coupled to high-resolution mass spectrometry (HRMS) enabled the identification of more than 200 metabolites, and statistical analysis highlighted the most relevant compounds for each plant treatment. The plants exposed to heat stress showed a unique set of induced secondary metabolites, some of which were known while others were not previously reported for this kind of stress; significant changes were observed especially in lipid composition. The role of trichome, as a protection against heat stress, is here suggested by the induction of both acylsugars and glykoalkaloids. Water deficit and Cr(VI) stresses resulted mainly in enhanced antioxidant (HCAs, polyamine) levels and in the damage of lipids, probably as a consequence of reactive oxygen species (ROS) production. Moreover, the ability of rol C expression to prevent oxidative burst was confirmed. The results highlighted a clear influence of GR modification on plant stress response, especially to water deficiency—a phenomenon whose applications should be further investigated. This study provides new insights into the field of system biology and demonstrates the importance of metabolomics in the study of plant functioning. Graphical AbstractUntargeted metabolomic analysis was applied to wild type, GR and RolC modified Nicotiana Langsdorffii plants exposed to heat, water and Cr(VI) stresses. The key metabolites, highly affected by stress application, were identified, allowing to outline the main metabolic responses to stress in each plant genotype.

A new exploration of licorice metabolome

The roots and rhizomes of licorice plants (genus Glycyrrhiza L.) are commercially employed, after processing, in confectionery production or as sweetening and flavouring agents in the food, tobacco and beer industries. G. glabra, G. inflata and G. uralensis are the most significant licorice species, often indistinctly used for different productions. Licorice properties are directly related to its chemical composition, which determines the commercial values and the quality of the derived products. In order to better understand the characteristics and properties of each species, a chemical characterization of three species of licorice (G. glabra, G. inflata, G. uralensis) is proposed, through an untargeted metabolomic approach and using high-resolution mass spectrometry. The statistical analysis reveals new possible markers for the analyzed species, and provides a reliable identification of a high number of metabolites, contributing to the characterization of Glycyrrhiza metabolome.

Electrochemical single-cell reactor for treatment of industrial wastewater composed of a spent textile bath

Abstract In the paper the electro‐oxidation of a spent dyeing bath, mediated by the Cl−/Cl2 redox couple, was studied and proposed for the treatment of textile wastewater as a technology alternative to hypochlorite oxidation. The work focused on the optimization of the electrochemical reactor. Particular attention was paid to the dependence of transport mechanisms and reaction rates on temperature, applied current, and hydrodynamic conditions in the reactor. The simultaneous production of H2O2 from the cathodic reduction of O2, which could also react with the dye, was also assessed. The regime which controlled the reaction was determined from the Hatta number.

Five primary sources of organic aerosols in the urban atmosphere of Belgrade (Serbia)

Biomass burning and primary biological aerosol particles (PBAPs) represent important primary sources of organic compounds in the atmosphere. These particles and compounds are able to affect climate and human health. In the present work, using HPLC-orbitrapMS, we determined the atmospheric concentrations of molecular markers such as anhydrosugars and phenolic compounds that are specific for biomass burning, as well as the concentrations of sugars, alcohol sugars and d- and l-amino acids (D-AAs and L-AAs) for studying PBAPs in Belgrade (Serbia) aerosols collected in September-December 2008. In these samples, high levels of all these biomarkers were observed in October. Relative percentages of vanillic (V), syringic compounds (S) and p-coumaric acid (PA), as well as levoglucosan/mannosan (L/M) ratios, helped us discriminate between open fire events and wood combustion for domestic heating during the winter. L-AAs and D-AAs (1% of the total) were observed in Belgrade aerosols mainly in September-October. During open fire events, mean D-AA/L-AA (D/L) ratio values of aspartic acid, threonine, phenylalanine, alanine were significantly higher than mean D/L values of samples unaffected by open fire. High levels of AAs were observed for open biomass burning events. Thanks to four different statistical approaches, we demonstrated that Belgrade aerosols are affected by five sources: a natural source, a source related to fungi spores and degraded material and three other sources linked to biomass burning: biomass combustion in open fields, the combustion of grass and agricultural waste and the combustion of biomass in stoves and industrial plants. The approach employed in this work, involving the determination of specific organic tracers and statistical analysis, proved useful to discriminate among different types of biomass burning events.

Combined effects of arsenic, salinity and temperature on Crassostrea gigas embryotoxicity

The combined effects of different salinity and temperature levels on the toxicity of Arsenic (As) were studied on the embryonic development of the oyster Crassostrea gigas. A standardized embryotoxicity test was performed to assess the interactive effects of these stressors, in a full factorial design experiment including a range of salinities (15, 19, 24, 28 and 32), temperatures (16, 20, 24, 28 and 32°C) and As concentrations (100, 300, 600, 1200, 2400µgL-1). The embryotoxicity endpoint was about the determination of normal larvae development rates at various conditions, and median effect concentration (EC50) determination for each As exposure condition. Results showed that toxicity induced by As was characterized by retardation of embryonic development observing toxic effects at lower concentrations than previously reported studies. The presence of As in seawater resulted in a narrower range of tolerance to both salinity and temperature. These findings bring new insights on the impacts of a common contaminant on an important shellfish species having a planktonic early life stage development, with potential implications for population survival and ecosystem functioning in a changing environment.

Assessing the potential phytotoxicity of digestate from winery wastes

In this study, digestate from winery wastes was investigated focusing on phytotoxicity using macrophytes and evaluating the potential contribution of ammonium and copper. Spreading of digestate on soil could represent a suitable approach to recycle nutrients and organic matter, creating an on site circular economy. In this study, digestate quality was evaluated considering both chemical-physical characteristics and biological toxicity applying germination test. The effluent did not meet the entire amendment quality standard defined by Italian law (Decree 75/2010 germination index > 60% with solution of 30% v/v of digestate), but bio-stimulation was observed at low doses (3.15-6.25% v/v) for S. alba and S. saccharatum. The beneficial concentration agreed with Nitrate Directive dose and suggested that limited addition of digestate could have several positive effects on soil characteristics and on crop growth. Specific test using ammonium and copper solutions showed that these pollutants were not directly correlated to observed phytotoxicity.

Nicotiana langsdorffiiwild type and genetically modified exposed to chemical and physical stress: changes in element content

The concentrations of 19 elements in wild and genetically modified Nicotiana langsdorffii (N. langsdorffii) exposed to Chromium (VI) and to water deficit were determined and compared to provide new information about their response to abiotic stress. Genetic modifications by GR and RolC genes (encoding for the rat glucocorticoid receptor and for Agrobacterium rhizogenes RolC, respectively) were investigated because they induce significant, but only partially known changes in the plant response to stress. Simultaneous determination of Al, As, Ba, Ca, Cd, Co, Cr, Cs, Cu, Fe, K, Mg, Mn, Na, Pb, Rb, Sr, V and Zn was carried out by ICP-MS equipped with a collision/reaction cell (ICP-ORS-MS). The methodology was optimised by testing the grinding, homogenisation, digestion and analysis procedures, to reduce the uncertainty of the experimental results and to identify statistically significant differences between nine sample pools, for a total of 75 samples. The quality control procedure was carried out by blank control and by evaluating the detection limits and repeatability. Trueness was assessed by analysing certified reference material, NIST 1573a. Significant differences were observed in the uptake and accumulation of several elements in the wild-type N. langsdorffii samples, either with respect to the plants submitted to water deficit and exposure to Cr(VI) or with respect to the genetically modified plants. The differences were highlighted by principal component analysis (PCA). The analysis of the element content of the whole plant, combined with the data found in the literature, allows us to hypothesise effects on the metabolic mechanism controlling the uptake and translocation of elements inside the vegetal organism. Because genetic and chemical stress decreases the nutrient concentration in the whole plant, we can say that the uptake at root level is affected. The increase in concentration of elements such as As, Sr and Al indicates a decreased selectivity in the uptake of potentially toxic elements and, consequently, highlights the effects on the plant’s metabolic processes.

Application of electro-catalytic mediated oxidation for the treatment of a spent textile bath in a membrane reactor

Electrochemical mediated oxidation can be considered a very efficient alternative to the commonly used pretreatment of textile wastewater by hypochlorite oxidation, but the process still needs to be optimized. In view of this, the study on the influence of the membrane reactor operating conditions on the kinetics of elimination of color from a spent textile bath was undertaken and is here presented. Experimental runs were carried out in a reactor equipped with a Ti/Pt-Ir anode and a stainless steel cathode, and the results of measurements designed to assess for an eventual risk of generating air pollutants during the electrolysis are also presented.

Temporal evolution of cadmium, copper and lead concentration in the Venice Lagoon water in relation with the speciation and dissolved/particulate partition

In order to study the role of sediment re-suspension and deposition versus the role of organic complexation, we investigated the speciation of cadmium (Cd), copper (Cu) and lead (Pb) in samples collected in the Venice Lagoon during several campaigns from 1992 to 2006. The increment in Cd and Pb concentration in the dissolved phases, observed in the central and northern basins, can be linked to important alterations inside the lagoon caused by industrial and urban factors. The study focuses on metal partition between dissolved and particulate phases. The analyses carried out in different sites illustrate the complex role of organic matter in the sedimentation process. While Cd concentration in sediments can be correlated with organic matter, no such correlation can be established in the case of Pb, whose particulate concentration is related only to the dissolved concentration. In the case of Cu, the role of organic complexation remains unclear.