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This paper discusses the results of a study of the complexation of lead by natural organic ligands in the surface waters of Terra Nova Bay obtained by using differential-pulse anodic stripping voltammetry (DPASV) and by application of the... more
This paper discusses the results of a study of the complexation of lead by natural organic ligands in the surface waters of Terra Nova Bay obtained by using differential-pulse anodic stripping voltammetry (DPASV) and by application of the van der Berg-Ruzic procedure of linearization. The distribution of both metal and ligand concentrations in the area studied is presented and discussed
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ABSTRACT A new analytical methodology, based on inductively coupled plasma sector field mass spectrometry (ICP-SFMS) coupled with a micro-flow nebulizer and desolvation system, has been set up for the quantification of Ir and Pt down to... more
ABSTRACT A new analytical methodology, based on inductively coupled plasma sector field mass spectrometry (ICP-SFMS) coupled with a micro-flow nebulizer and desolvation system, has been set up for the quantification of Ir and Pt down to the sub-ppq level (1 ppq ~ 1 fg g 21 ~ 10 215 g g 21) in polar ice samples. Ultra-clean procedures were adopted during the pre-treatment phases in our laboratories in order to avoid possible contamination problems and a preconcentration step by evaporation at sub-boiling temperatures was necessary. A procedural detection limit of 0.02 ppq and 0.08 ppq for Ir and Pt, respectively, was obtained. The reproducibility of the analytical procedure at the ppq level was about 50% for Ir and 30% for Pt and the recoveries were 75% and 93% for Ir and Pt, respectively. Spectral interferences, which affect the determination of Ir and Pt, were reduced by using a desolvation system for sample introduction. The contribution of the interfering species was determined and subtracted. This new method allowed us to analyse Ir and Pt in remote uncontaminated ice samples from Antarctica and Greenland down to the sub-ppq level. The concentration ranges were from 0.1 up to 5 ppq for Ir and from 0.2 up to 7 ppq for Pt. These measurements represent the first data of Ir concentrations in unfiltered melted ice samples and the lowest concentrations ever recorded for Pt in environmental samples.
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Research Interests: Chemistry, Rivers, Medicine, Italy, Copper, and 7 moreAnimals, Humic Substances, Cadmium, Rats, Toxicity Tests, Lysosomes, and Titrimetry
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New photosensitive materials can be obtained by electrochemical oxidation of thiocyanate and selenocyanate salts. Using (K,Na)SCN eutectic melt, the formation of an electrodic deposit, with photoelectrochemical properties, has already... more
New photosensitive materials can be obtained by electrochemical oxidation of thiocyanate and selenocyanate salts. Using (K,Na)SCN eutectic melt, the formation of an electrodic deposit, with photoelectrochemical properties, has already been reported by us. To improve the photoelectrochemical characteristics of the deposit, futher investigations were carried out in the following sistems: selenocyanate ammoniate, KSCH-Acetamide eutectic mixture and KSCN ethylene carbonate solution:.
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The problem of contamination during the collection of samples of environmental interest to detect trace metal is discussed. Attention is focused on the leaching of metals from sampling devices used to collect surface and deep seawater. A... more
The problem of contamination during the collection of samples of environmental interest to detect trace metal is discussed. Attention is focused on the leaching of metals from sampling devices used to collect surface and deep seawater. A procedure to test metal release is applied to emphasize the importance of conditioning samplers before use. The procedure for checking the contamination extent
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Research Interests: Environmental Science, Principal Component Analysis, Environmental Monitoring, Medicine, Multidisciplinary, and 14 moreEnvironmental science and technology, Italy, Cities, Trajectory, Industry, Polycyclic Aromatic Hydrocarbon, Seawater, Seasonal variation, Polycyclic aromatic hydrocarbons (PAHs), Gases, Seasons, Soil Pollutants, Air Pollutants, and Troposphere
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Research Interests: Ecotoxicology, Biology, Medicine, Italy, Cities, and 15 moreEnvironmental Sciences, Bivalvia, Animals, Male, Seawater, Ammonia, Metals, CHEMICAL SCIENCES, Crassostrea gigas, Mytilus galloprovincialis, Paracentrotus lividus, Spermatozoa, Geologic Sediments, Pore Water, and Medical and Health Sciences
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The concentrations of gas-phase PCBs were measured from March 2002 to June 2003 at two sites of the Venice Lagoon and at one site of the Euganei hills. The aims of this study were to evaluate the various gas-phase PCB sources, the spatial... more
The concentrations of gas-phase PCBs were measured from March 2002 to June 2003 at two sites of the Venice Lagoon and at one site of the Euganei hills. The aims of this study were to evaluate the various gas-phase PCB sources, the spatial and temporal variability of PCB concentrations in the gas-phase that enter the Venice Lagoon atmosphere and the influence of the air temperature on PCB trends. The highest annual average concentration of summation PCBs was observed at the station directly influenced by "urban" sources with values about 3 and 1.5 times higher compared to the concentrations found at the stations where "marine" sources and "not subjected to direct local sources" were respectively sampled from. The temporal trends of summation PCBs concentrations were similar at the three sampling stations corresponding to seasonal temperature changes. Greater concentrations occurred in the summer and first autumn months while the lower ones occurred in late autumn and winter. The temperature dependences were investigated using plots of the natural logarithm of the summation PCBs concentrations vs. reciprocal mean temperatures.
Research Interests: Environmental Science, Environmental Monitoring, Medicine, Multidisciplinary, Italy, and 12 moreSeasonality, Air, Polychlorinated Biphenyls, Seasonal variation, Polychlorinated Biphenyl, Temperature Dependence, Air Temperature, Spatial Variation, Gases, Seasons, Temporal Variability, and Air Pollutants
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Abstract: The project SESAMO focusing on the development of an autonomous catamaran for data acquisition and sampling for biological, chemical and physical investigations on the air-sea interface is presented. In particular, the SESAMO... more
Abstract: The project SESAMO focusing on the development of an autonomous catamaran for data acquisition and sampling for biological, chemical and physical investigations on the air-sea interface is presented. In particular, the SESAMO platform will be equipped with modules for the collection of surface microlayer, sampling of subsurface water, and survey in situ of water column and atmosphere parameters, along paths specified by the scientific end-users. At the end of the project, which is funded in the framework of the Italian National ...
ABSTRACT The electrochemical oxidation of selenocyanate in ammoniate solution was studied by potentiostatic, voltammetric, and galvanostatic measurements on Pt electrodes. The formation of both an anodic deposit, possibly a (SeCN)x matrix... more
ABSTRACT The electrochemical oxidation of selenocyanate in ammoniate solution was studied by potentiostatic, voltammetric, and galvanostatic measurements on Pt electrodes. The formation of both an anodic deposit, possibly a (SeCN)x matrix with trapped (SeCN)−3, and a soluble species, (SeCN)−3, was observed at current densities below 0.3 mA cm−2. At higher current densities only deposit formation was observed. A theoretical treatment and experimental evidence are given for the kinetic mechanism of deposit formation. The mechanism explains the impossibility experienced in both obtaining a massive deposit and enhancing its photoelectrochemical properties.
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Research Interests: Engineering, Chemistry, Microfluidics, Mass Spectrometry, Medicine, and 15 moreBiological Sciences, Flow Injection Analysis, Isotopes, Analytical, Laminar Flow, Seawater, Contamination, Accuracy, CHEMICAL SCIENCES, Reproducibility of Results, Microchemistry, Precision, Certified Reference Material, Direct Method, and Mass Spectrometer
Changes in the lead concentration in Antarctic snow over the past 30 years are considered as a response of the environment to a well-documented environmental change (decrease of lead emissions into the atmosphere). New data confirm the... more
Changes in the lead concentration in Antarctic snow over the past 30 years are considered as a response of the environment to a well-documented environmental change (decrease of lead emissions into the atmosphere). New data confirm the recent decreasing trend of lead concentration in snow as revealed by previous studies. Furthermore, comparing changes in the lead concentration in Antarctic snow layers with lead emissions from different anthropic sources, we can hypothesise that under present-day climatic conditions, lead-enriched aerosols reaching the Atlantic and Pacific sectors of East Antarctica originate mainly in South America and Australia, respectively.
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The chemical composition and size distribution of marine aerosols constitute an important parameter to investigate the latter's impact on global climate change. Amino acids are an important component of organic nitrogen in aerosols... more
The chemical composition and size distribution of marine aerosols constitute an important parameter to investigate the latter's impact on global climate change. Amino acids are an important component of organic nitrogen in aerosols and have the ability to activate and act as cloud condensation nuclei, with important effects on the radiation balance. <br><br> In order to understand which physical and chemical transformations occur during transport processes, aerosol samples were collected during four different Antarctic austral summer campaigns. <br><br> The mean amino acids concentration detected at the Italian coastal base was 11 pmol m<sup>−3</sup>. The main components were fine fractions, establishing a local marine source. Once produced on the sea surface, marine aerosols undergo an ageing process, due to various phenomena such as coagulation, or photochemical transformations. This was demonstrated by using the samples collected on t...
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The methodology for using DPASV to study cadmium complexation in seawater is evaluated using EDTA as a model ligand and by analysing natural samples. The results show that the methodology gives an accurate evaluation of metal complexation... more
The methodology for using DPASV to study cadmium complexation in seawater is evaluated using EDTA as a model ligand and by analysing natural samples. The results show that the methodology gives an accurate evaluation of metal complexation when inert complexes are studied, both as regards the ligand concentration and the conditional stability constant; the error for both the parameters is lower than 10% at a ligand concentration of about 10(-8) M and a conditional stability constant of 10(9) M-1. Cadmium complexes with ligands present in natural seawater show an evident kinetic lability that may lead to underestimation of the conditional stability constant when a working electrode characterised by a very thick diffusion layer is used. The conditional stability constant in one water sample of the Adriatic coast ranged between 0.14 and 1.4 l/nmol using a rotating disk electrode at rotation rates of 300 and 6000 rpm. The results of cadmium complexation obtained for samples collected in ...
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Trace heavy metal (Cd, Pb and Cu) and nitrogen species (N-NO3, N-NO2 and N-NH4) fluxes between sediment and water were examined for approximately 4 days, in a coastal marine station located in the northern Adriatic Sea in front of the... more
Trace heavy metal (Cd, Pb and Cu) and nitrogen species (N-NO3, N-NO2 and N-NH4) fluxes between sediment and water were examined for approximately 4 days, in a coastal marine station located in the northern Adriatic Sea in front of the River Po outflow. An in situ benthic chamber, equipped with electronic devices for monitoring and adjustment of oxygen and pH and with a temperature detector, was used. The benthic chamber experiment enabled study of the temporal trend of metals and nutrients when oxygen concentration varied in a controlled environment. Although particular care was devoted to chamber deposition and parameter control, sediment resuspension occurred at the beginning of the experiment and O2 fluctuations were observed during the course of the experiment. Pb concentration was affected by both resuspension and oxic conditions in bottom water, which prevented determination of any reasonable Pb flux value. Cd and Cu, not influenced by oxygen fluctuations, reached an equilibrium phase in a short period with initial positive fluxes from sediment of 0.68 (S.D. = 0.07) and 6.9 (S.D. = 5.6) pmol cm(-2) h(-1), respectively. With regard to nitrogen species, the highest positive flux was that of N-NH4 (10.5, S.D. = 2.4, nmol cm(-2) h(-1)) whose concentration increased in the chamber, while nitrate concentration (initial flux of -5.7, S.D. = 1.5, nmol cm(-2) h(-1)) immediately decreased after the beginning of the experiment. Nitrite concentration was almost constant throughout the experiment and its flux was generally low (initial flux 0.1, S.D. = 0.9, nmol cm(-2) h(-1)).
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ABSTRACT
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To assess the exchange and the mobility of trace metals between sediments and water and their geochemical behaviour, experiments were carried out within the sphere of the CORILA project for the safeguarding of the Venice lagoon. Trace... more
To assess the exchange and the mobility of trace metals between sediments and water and their geochemical behaviour, experiments were carried out within the sphere of the CORILA project for the safeguarding of the Venice lagoon. Trace element exchanges were examined for approximately 60 h at two sites in the central part of the Venice lagoon (Italy): the first one
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The Antarctic surface seawater of Terra Nova Bay (Ross Sea) was investigated by anodic stripping voltammetry (ASV) to study the distribution and complexation of lead and cadmium in an extremely remote region. Samples were analyzed to... more
The Antarctic surface seawater of Terra Nova Bay (Ross Sea) was investigated by anodic stripping voltammetry (ASV) to study the distribution and complexation of lead and cadmium in an extremely remote region. Samples were analyzed to determine the total metal content (after acid digestion), the metal distribution between free fraction (or ASV labile, mainly ionic and inorganically complexed metal) and bound fraction (organically complexed metal), the content of ligands complexing metal, and the related conditional stability constants. Metal complexation was studied separately by titrating the sample with each of the metals and detecting the labile fraction by differential pulse anodic stripping voltammetry. Voltammetric titration data were processed according to the van den Berg-Ruzic procedure to determine metal complexation parameters. Results for lead and cadmium revealed the presence of one class of ligands. To evaluate the possible anthropic influence in metal content and speciation in seawater, Antarctic results were compared to data obtained from different geographical areas, i.e., the Pacific Ocean, the Atlantic Ocean, and the Mediterranean Sea (Adriatic Sea). The more significant findings include the generally high proportion of bound fractions of metals (70-80% in the Adriatic Sea compared to about 50% in Oceanic and Antarctic waters) and a general agreement between values of conditional stability constants observed in different areas, leading to the hypothesis that the ligands are Of natural origin.
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Research Interests: MARINE POLLUTION, Environmental Monitoring, Water Pollution, Multidisciplinary, Italy, and 11 moreGC-MS, Surface Water, Polychlorinated Biphenyls, Polycyclic Aromatic Hydrocarbon, Seawater, Polychlorinated Biphenyl, Polycyclic aromatic hydrocarbons (PAHs), Enrichment factor, Coastal Zone, Gas Chromatography/mass Spectrometry, and Volatilization
Water bodies are important storage media for persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs) and this function is increased in coastal regions because their inputs are higher than those to the open sea. The... more
Water bodies are important storage media for persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs) and this function is increased in coastal regions because their inputs are higher than those to the open sea. The air-water interface is extensively involved with the global cycling of PCBs because it is the place where they accumulate due to depositional processes and where they may be emitted by gaseous exchange. In this work the parallel collection of air, microlayer and sub-superficial water samples was performed in July 2005 at a site in the Venice lagoon to evaluate the summer gaseous flux of PCBs. The total concentration of PCBs (sum of 118 congeners) in air varies from 87 to 273 pg m(-3), whereas in the operationally defined dissolved phase of microlayer and sub-superficial water samples it varies from 159 to 391 pg L(-1). No significant enrichment of dissolved PCB into the microlayer has been observed, although a preferential accumulation of most hydrophobic congeners occurs. Due to this behaviour, we believe that the modified two-layer model was the most suitable approach for the evaluation of the flux at the air-sea interface, because it takes into account the influence of the microlayer. From its application it appears that PCB volatilize from the lagoon waters with a net flux varying from 58 to 195 ng m(-2)d(-1) (uncertainty: +/-50-64%) due to the strong influence of wind speed. This flux is greater than those reported in the literature for the atmospheric deposition and rivers input and reveals that PCB are actively emitted from the Venice lagoon in summer months.