Assessment of a procedure to determine trace and major elements in Atmospheric Aerosol

The determination of trace elements in atmospheric particulate is affected by a number of problems that arise from some critical points such as the blank of the filters, sample heterogeneity and pre-analytical treatments. In the framework of a monitoring campaign conducted in the Venice Lagoon the analytical methodology for the determination of 20 trace elements (Al, As, Ca, Cd, Co, Cr, Cs, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb, Rb, Sr, V, Zn) in atmospheric particulate samples by inductively coupled plasma quadrupole mass spectroscopy (ICP-QMS) has been optimized taking into account the individual critical points. Tests were carried out to estimate the blank contributions, and minimize the detection limit (LOD), measurements were also carried out to evaluate the accuracy and the repeatability. To obtain a complete dissolution of aerosol dust material and good recoveries of the elements, the acid mixture and the microwave assisted digestion program were optimized. The blank contributions from membrane filter manipulation and transportation prior to exposure were tested for the slotted and back filters by placing them on the sampling device for some minutes without air flowing to obtain field blanks (FBs). The contribution to the blank values of passive deposition and by contact with the samplers (quoted as campaign blanks, CBs) was measured by exposing the membranes throughout the sampling session (fifteen days) without any air flow. Instrumental ICP-QMS parameters were optimized and calibration curve intervals were selected on the basis of the necessity of simultaneous determination of the elements present at different levels of concentration. The limits of detection for each elements and the investigated method were suitable to determine the 20 elements reported above in the atmospheric aerosol fractionated in 6 classes ranging between 10 to 0.49 mm. It allows the determination of trace elements in aerosol in a large range of concentrations that can be observed in areas characterized by remarkable variability and regions with different levels of contamination

Impact of maritime traffic on polycyclic aromatic hydrocarbons, metals and particulate matter in Venice air

Harbours are important hubs for economic growth in both tourism and commercial activities. They are also an environmental burden being a source of atmospheric pollution often localized near cities and industrial complexes. The aim of this study is to quantify the relative contribution of maritime traffic and harbour activities to atmospheric pollutant concentration in the Venice lagoon. The impact of ship traffic was quantified on various pollutants that are not directly included in the current European legislation for shipping emission reduction: (i) gaseous and particulate PAHs; (ii) metals in PM10; and (iii) PM10 and PM2.5. All contributions were correlated with the tonnage of ships during the sampling periods and results were used to evaluate the impact of the European Directive 2005/33/EC on air quality in Venice comparing measurements taken before and after the application of the Directive (year 2010). The outcomes suggest that legislation on ship traffic, which focused on the issue of the emissions of sulphur oxides, could be an efficient method also to reduce the impact of shipping on primary particulate matter concentration; on the other hand, we did not observe a significant reduction in the contribution of ship traffic and harbour activities to particulate PAHs and metals

Aerosol and snow transfer processes: An investigation on the behavior of water-soluble organic compounds and ionic species

The concentrations of water-soluble compounds (ions, carboxylic acids, amino acids, sugars, phenolic compounds) in aerosol and snow have been determined at the coastal Italian base "Mario Zucchelli" (Antarctica) during the 2014-2015 austral summer. The main aim of this research was to investigate the air-snow transfer processes of a number of classes of chemical compounds and investigate their potential as tracers for specific sources.The composition and particle size distribution of Antarctic aerosol was measured, and water-soluble compounds accounted for 66% of the PM10 total mass concentration. The major ions Na+, Mg2+, Cl- and SO42- made up 99% of the total water soluble compound concentration indicating that sea spray input was the main source of aerosol. These ionic species were found mainly in the coarse fraction of the aerosol resulting in enhanced deposition, as reflected by the snow composition.Biogenic sources were identified using chemical markers such as carboxylic acids, amino acids, sugars and phenolic compounds. This study describes the first characterization of amino acids and sugar concentrations in surface snow. High concentrations of amino acids were found after a snowfall event, their presence is probably due to the degradation of biological material scavenged during the snow event. Alcohol sugars increased in concentration after the snow event, suggesting a deposition of primary biological particles, such as airborne fungal spores. (C) 2017 Elsevier Ltd. All rights reserved

Distribuzione e speciazione di metalli in traccia nell'acqua di mare superficiale del bacino delle isole Eolie

Summary - The distribution and speciation of cadmium, lead and copper in the Eolian Basin (South Tyrrhenian Sea) was studied by analysis of surface sea water samples using anodic stripping voltammetry (DPASV). Samples were analyzed to determine the total metal content (after acid digestion), the metal distribution between free fraction (or ASVlabile, mainly ionic and inorganically complexed metal) and bound fraction (organically complexed metal). The complexing capacity of the water was also evaluated by determination of the content of strong organic ligands complexing metals and the related conditional stability constants

High Performance Size Exclusion Chromatography-Inductively Coupled Plasma-Mass Spectrometry to Study the Copper and Cadmium Complexation with Humic Acids

Dissolved organic matter (DOM) plays an important role in the environment by influencing the transport and distribution of organic and inorganic components through different processes: the retention, mobilization, and bio-availability of potentially toxic elements (PTEs). The aim of the present study is to examine the dimensional characterization of humic acids (HA) extracted from soil matrix, as well as to analyze the metal distribution among different ligand classes. The molecular size distribution of the HA extract from soil showed three dimensional classes: 52 KDa, 4.5 KDa, and 900 Da. HPSEC-ICP-MS measurements demonstrated that the dimensional classes, relative to first two fractions, bind the largest part of metals. The complexing capacity of HA was evaluated to assess the pollutants mobility in the environmental system. In particular, cadmium (Cd) and copper (Cu) complexation was investigated due to the great concern regarding their bio-availability and toxicity in natural waters. The complexing capacity of HA solution (20 mg/L) was measured by titration using a high-performance size exclusion chromatography (HP-SEC) coupled to an inductively coupled mass spectrometry (ICP-MS). Results obtained by this technique are compared with those obtained by anodic stripping voltammetry (ASV) to investigate the effects of kinetic lability of complexes on measurements carried by HPSEC-ICP-MS. In this study, results of ligand concentrations and stability constants obtained via the two techniques are assessed considering the detection window associated to the applied analytical methodology. Results obtained using the two analytical techniques showed that Cd is complexed by two classes of ligands. However, the ligand concentration values obtained using the two techniques are different, because the detection window associated to the two methodologies; the complexing capacity, which was obtained as sum of the two classes of ligands, were 33 nmol/L and 9 nmol/L for ASV and HPSEC-ICP-MS, respectively. The copper complexing capacities determined by the two methodologies are comparable: 166 and 139 nmol/L for ASV and HPSEC-ICP-MS, respectively. However, the results of Cu titration differ for the two techniques, highlighting only one class of ligands when ASV was used, and two classes when HPSEC-ICP-MS was employed. Differences on results obtained by the two techniques are explained considering the kinetic lability of complexes; the results show that, differently from previous studies, also Cu complexes can be kinetically labile, if one technique with high reaction time is used, as well some cadmium complexes are sufficient stable to be determined by HPSEC-ICP-MS

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 (ICPORS- 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

HPLC-HRMS simultaneous determination of salicylic, shikimicand jasmonicacids in wild and transgenic NicotianaLangsdorffiiplants exposed to abioticstresses

When dealing with adverse or limiting growth conditions, plants respond by specific-stress mechanisms which are regulated by the phytohormonal network. Salicylic acid (SA) and Jasmonic acid (JA) are hormones involved in plant growth and development, which also take part in plant response towards different kind of stresses. Shikimic acid (SHA) is an important plant intermediate and a key molecule in the biosynthesis of many secondary metabolites implicated in the stress response mechanisms. The Nicotiana genus includes small, well characterized plants, traditionally used as biological models for genetic and physiological studies; the insertion of the rolC gene from Agrobacterium rhizogenes and the rat glucocorticoid receptor (GR) gene in Nicotiana plants have been previously investigated, demonstrating interesting results for the production of resistant plants. In this study, a new HPLC-ESI-LTQ Orbitrap method for the simultaneous quantification of SA, JA and SHA in N. Langsdorffii is presented. The method was developed and validated by estimating matrix effect, accuracy, precision and the detection limits. The method, which, to our known, is the first which permit the simultaneous quantification of these three compounds, was then applied to 82 wild and transgenic plants, exposed to chemical, water and heat stresses. The results showed a differential regulation of the phytohormones’ levels in the wild and genetically modified plants, as a clear indication of the activation of stress response processes. A differential induction of the shikimic acid pathway in stressed plants was moreover observed, highlighting the mechanisms the plant behavior against different abiotic stresses