Agnese Giacomino

Accumulation of heavy metals from contaminated soil to plants and evaluation of soil remediation by vermiculite

We evaluated the distribution of 15 metal ions, namely Al, Cd, Cu, Cr, Fe, La, Mn, Ni, Pb, Sc, Ti, V, Y, Zn and Zr, in the soil of a contaminated site in Piedmont (Italy). This area was found to be heavily contaminated with Cu, Cr and Ni. The availability of these metal ions was studied using Tessiers sequential extraction procedure: the fraction of mobile species, which potentially is the most harmful for the environment, was much higher than that normally present in unpolluted soils. This soil was hence used to evaluate the effectiveness of treatment with vermiculite to reduce the availability of the pollutants to two plants, Lactuca sativa and Spinacia oleracea, by pot experiments. The results indicated that the addition of vermiculite significantly reduces the uptake of metal pollutants by plants, confirming the possibility of using this clay in amendment treatments of metal-contaminated soils. The effect of plant growth on metal fractionation in soils was investigated. Finally, the sum of the metal percentages extracted into the first two fractions of Tessiers protocol was found to be suitable in predicting the phytoavailability of most of the pollutants present in the investigated soil.

Parameters affecting the determination of mercury by anodic stripping voltammetry using a gold electrode.

The electrochemical determination of aqueous Hg(II) by anodic stripping voltammetry (ASV) at a solid gold electrode is described. The aim of this work is to optimise all factors that can influence this determination. Potential wave forms (linear sweep, differential pulse, square wave), potential scan parameters, deposition time, deposition potential and surface cleaning procedures were examined for their effect on the mercury peak shape and intensity. Five supporting electrolytes were tested. The best responses were obtained with square wave potential wave form and diluted HCl as supporting electrolyte. Electrochemical and mechanical surface cleaning, aimed at removing the amount of mercury deposited onto the gold surface, were necessary for obtaining a good performance of the electrode. Response linearity, repeatability, accuracy and detection limit were also evaluated.

The role of chemometrics in single and sequential extraction assays: A review: Part I. Extraction procedures, uni- and bivariate techniques and multivariate variable reduction techniques for pattern recognition

Element mobility and availability in natural solid matrices can be studied with single and sequential extraction procedures; such procedures provide reliable and useful information only if the experiments are correctly planned and executed and the results are properly interpreted. Chemometrics can be a valuable tool for these aims, especially taking into account the large amounts of data generated with extraction essays and the complexity of the processes under investigation. This review deals with the application of chemometrics in research studies involving single and sequential extractions on soils or sediments, for several purposes: the development and optimization of the extraction conditions, the calculation of element fractionation, the visual illustration of the experimental results, the acquisition of different areas of information, including relationships among variables, similarities and differences among samples, causes of the observed behaviour (e.g. source identification), risk assessment, models and predictions of future events. In Part I of the review, following an overview on extraction procedures, the applications of univariate and bivariate chemometric methods are reported; then the principles of multivariate techniques for pattern recognition based on variable reduction, their applications and the main findings obtained are addressed.

The role of chemometrics in single and sequential extraction assays: a review. Part II. Cluster analysis, multiple linear regression, mixture resolution, experimental design and other techniques.

Single and sequential extraction procedures are used for studying element mobility and availability in solid matrices, like soils, sediments, sludge, and airborne particulate matter. In the first part of this review we reported an overview on these procedures and described the applications of chemometric uni- and bivariate techniques and of multivariate pattern recognition techniques based on variable reduction to the experimental results obtained. The second part of the review deals with the use of chemometrics not only for the visualization and interpretation of data, but also for the investigation of the effects of experimental conditions on the response, the optimization of their values and the calculation of element fractionation. We will describe the principles of the multivariate chemometric techniques considered, the aims for which they were applied and the key findings obtained. The following topics will be critically addressed: pattern recognition by cluster analysis (CA), linear discriminant analysis (LDA) and other less common techniques; modelling by multiple linear regression (MLR); investigation of spatial distribution of variables by geostatistics; calculation of fractionation patterns by a mixture resolution method (Chemometric Identification of Substrates and Element Distributions, CISED); optimization and characterization of extraction procedures by experimental design; other multivariate techniques less commonly applied.

An approach for arsenic in a contaminated soil: speciation, fractionation, extraction and effluent decontamination.

The fractionation and speciation of As in a contaminated soil were investigated, and a remediation strategy was tested. Regarding speciation, we found that As(V) prevails over As(III) whereas more than 40% of total arsenic is in organic form. The fractionation of As was investigated with two sequential extraction methods: a low mobility was found. Then we tested the possibility of using phosphoric acid to extract As from the soil and cleaning the washing effluents by sorption onto montmorillonite. The efficiency of the extraction and of the adsorption onto the clay were also investigated for Cr, Cu, Fe, Mn, Ni, Pb and Zn, whose total concentrations and fractionation in the soil are reported here. The extraction percentages for As and metals ranged from 30 to 65%; the residual proportions in the soil are presumably in very unreactive forms. Montmorillonite showed a good uptake capacity towards the investigated pollutants.

Determination of As(III) by anodic stripping voltammetry using a lateral gold electrode: experimental conditions, electron transfer and monitoring of electrode surface.

The aim of this work is to evaluate the efficiency of the determination of As(III) by anodic stripping voltammetry (ASV) using a lateral gold electrode and to study the modifications of the electrode surface during use. Potential waveforms (differential pulse and square wave), potential scan parameters, deposition time, deposition potential and surface cleaning procedure were examined for they effect on arsenic peak intensity and shape. The best responses were obtained with differential pulse potential wave form and diluted 0.25 M HCl as supporting electrolyte. The repeatability, linearity, accuracy and detection limit of the procedure and the interferences of cations and anions in solution were evaluated. The applicability of the procedure for As(III) determination in drinking waters was tested. Cyclic voltammetry (CV) was used to study the electrochemical behaviour of As(III) and for the daily monitoring of electrode surface. Also scanning electron microscopy (SEM) analysis was used to control the electron surface. Finally we evaluated the possibility to apply the equations valid for flow systems also to a stirred system, in order to calculate the number of electrons transferred per molecule during the stripping step.

Spatial distribution and potential sources of trace elements in PM10 monitored in urban and rural sites of Piedmont Region

The results on elemental composition of aerosol (PM10) sampled during 2011 in Piedmont region (Italy) are interpreted using meteorological data, Enrichment Factors (EF), chemometric processing by Principal Component Analysis (PCA), Factor Analysis (FA) and Hierarchical Cluster Analysis (HCA). Daily concentrations of about 30 elements were measured using HR-ICP-MS in five monitoring sites. A clear seasonal pattern, with higher concentrations in autumn and winter, was observed, particularly in the urban sites. Levels of As, Cd, Ni and Pb in most of the samples were within the limits imposed by the European legislation. Spatial differences in PM10 and metal concentrations were significant, with rural and urban sites showing different metal patterns, indicating different sources. K and Ca were used, respectively, as marker of biomass burning and industrial marker (cement plant); EFs showed that Ca was enriched just in one area and K was enriched only in the winter period considered and in some stations. Data analysis through PCA, FA and HCA allowed us to identify correlations among the investigated elements and similarities between sampling sites in order to individuate specific emission sources, such as non-exhaust vehicle emission.

Metal Content in Dandelion (Taraxacum officinale) Leaves: Influence of Vehicular Traffic and Safety upon Consumption as Food

The widespread distribution of the common dandelion, that is, Taraxacum officinale, along with its ability to tolerate a wide range of environmental conditions, makes this plant a good candidate as biological monitor of environmental metal contamination. Taraxacum officinale leaves growing spontaneously in meadows and along the streets are traditionally picked up and eaten in Italy as salad, so it is important to know the concentrations of potentially toxic elements contained in them from the point of view of food safety. For these reasons the concentrations of Cd, Cr, Cu, Fe, Mn, Pb, and Zn were determined in dandelion leaf and underlying soil samples collected at 12 sites in the province of Cuneo (Piedmont, Italy) in the vicinity of streets or roundabouts. The concentrations were compared with reference values for plant and soils and with maximum allowable concentrations in edible vegetables. Neither dandelion nor soil samples were found to be polluted by metals, but the comparison with limits for vegetables suggests that caution should be used in consuming spontaneously growing vegetables.

Determination of the total and bioaccessible contents of essential and potentially toxic elements in ayurvedic formulations purchased from different commercial channels

Abstract Ayurveda is a major traditional system of Indian medicine that is still being successfully used in many countries. It advocates the use of both herbal and metallic preparations, in which herbs are deliberately combined with metals, minerals and gems. This study aimed to identify possible risks associated with the presence of toxic elements in ayurvedic formulations. We determined the concentrations of 25 elements (Al, As, Ag, Au, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, P, Pb, Pd, Pt, Sb, Si, Sn and Zn) in 17 ayurvedic products manufactured in India and sold in different distribution channels: Indian ayurvedic medical shops, an Italian pharmacy and on the Internet. After sample mineralization, concentrations were determined by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). We calculated daily intake of each element and compared the obtained concentrations with the maximum tolerable intake levels or recommended nutrient amounts. Element content found in the products purchased on the Internet and in the Italian pharmacy was lower than the safety limits fixed by the international authorities. Five medicines purchased in India contained potentially dangerous amount of As, Cu, Hg, and Pb. Metal bioaccessibility was studied by extraction with solutions simulating gastric and intestinal fluids. The concentration of As potentially adsorbed during the digestion of two products was greater than the maximum admissible daily intake for this element. The obtained results were treated with chemometric techniques.

Temporal trends of elements in Turin (Italy) atmospheric particulate matter from 1976 to 2001

The temporal trends of major, minor and trace elements in the total atmospheric particulate sampled in the urban area of Turin (Italy) were determined for the following years: 1976, 1986, 1996 and 2001. The wavelength dispersive X-ray fluorescence (WD-XRF) technique was adopted to determine the concentrations of Ba, Br, Ca, Cl, Cr, Cu, Fe, K, Mg, Mn, Ni, Pb, S, Ti and Zn. A smaller number of samples was also analysed by ICP atomic emission spectroscopy (ICP-AES) and the results were compared with those obtained by WD-XRF to confirm their validity. A clear seasonal pattern with higher concentrations of the aforementioned elements in the cold periods was observed. Moreover, a change in the chemical composition of atmospheric particulate matter was evidenced, particularly between the first (1976 and 1986) and the last (1996 and 2001) years. This change can be attributed both to the greater contribution of Pb and Br to atmospheric pollution in the past and, in recent years, to the higher level of pollutants associated with increased vehicular traffic and industrial activities. The application of chemometric techniques (Principal Component Analysis and Cluster Analysis) allowed us to speculate about the main emitting sources influencing the total atmospheric particulate in these years.