Ivo Moret

Determination of polychlorobiphenyls in Venice Lagoon sediments

Polychlorinated biphenyl (PCBs) congeners were measured in 14 sediment samples collected at five sites in the Venice Lagoon selected on the basis of a supposed diversity of inputs and of pollution levels. The PCBs were determined after a sonication assisted extraction by gas chromatography mass spectrometry (GCMS). The sum of the congener concentrations determined in the samples range from 4.05 to 239.15 ng/g on a dry weight basis. The concentration values are very variable both comparing the sites and comparing different samples from the same site and can be connected to the sand percentage in the sediment samples. The correlation matrix obtained from data matrix using the congener concentrations as variables shows high values, mostly between 0.964 and 1, suggesting that the pattern of the PCB congeners and the ratios among the concentrations in Venice Lagoon sediments are more or less constant; the samples differ only in the concentration level.

Distribution and seasonal variability of trace elements in atmospheric particulate in the Venice Lagoon

Size distribution and selected element concentrations of atmospheric particulate matter (PM) were investigated in the Venice Lagoon, at three sites characterised by different anthropogenic influence. The PM(10) samples were collected in six size fractions (10-7.2, 7.2-3.0, 3.0-1.5, 1.5-0.95; 0.95-0.49 and <0.49 μm) with high volume cascade impactors, and the concentration of 17 elements (Al, As, Ca, Cd, Co, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb, Sr, V, Zn) was determined by inductively coupled plasma quadrupole mass spectroscopy. More than 1 year of sampling activities allowed the examination of seasonal variability in size distribution of atmospheric particulates and element contents for each site. At all the stations, particles with an aerodynamic diameter <3 μm were predominant, thus accounting for more than 78% of the total aerosol mass concentration. The highest PM(10) concentrations for almost all elements were found at the site which is more influenced by industrial and urban emissions. Similarity in size distribution of elements at all sites allowed the identification of three main behavioural types: (a) elements found mainly within coarse particles (Ca, Mg, Na, Sr); (b) elements found mainly within fine particles (As, Cd, Ni, Pb, V) and (c) elements with several modes spread throughout the entire size range (Co, Cu, Fe, K, Zn, Mn). Factor Analysis was performed on aerosol data separately identified as fine and coarse types in order to examine the relationships between the inorganic elements and to identify their origin. Multivariate statistical analysis and assessment of similarity in the size distribution led to similar conclusions on the sources.

Temporal evolution of DMS and DMSP in Antarctic Coastal Sea water

The temporal evolution of concentrations of dimethylsulphide (DMS), its precursor dimethylsulphoniopropionate (DMSP) and chlorophyll a is surveyed weekly in the water column and in a landfast ice core at a coastal station of Gerlache Inlet (Terra Nova Bay, Antarctica) from 27 November 2000 to 14 February 2001. The DMS and DMSP profile concentrations in the water column are similar and show a clear temporal trend, with minimum values (<0.7 nM) at all depths occurring on 27 November 2000 and maximum values (4.8 × 102 nM for DMS and 1.8 × 102 nM for DMSP) in surface water on 27 December 2000 for DMS and on 19 December 2000 for DMSP. When the sea-ice cover is present, the temporal evolution of DMSP closely follows that of chlorophyll a in the water column, supporting the idea that DMSP, and therefore DMS, has a phytoplanktonic origin. However, when the ice cover breaks up during the late austral summer, a second phytoplankton bloom occurs, while the DMSP concentration in the sea-water column remains very low. In the ice core, the results show higher concentrations of DMSP than those of the underlying sea water, highlighting the important role of sea ice in the sulphur cycle of the Antarctic ecosystem.

The seasonal variations of dimethyl sulphide and carbon disulphide in surface waters of the Venice lagoon

Abstract The seasonal variation in the concentration of dimethyl sulphide (DMS) and carbon disulphide (CS2) in the surface water of the Venice lagoon was determined at two stations in the period from 3 June 1996 (3 March 1997 for CS2) to 26 November 1997. Other parameters such as chlorophyll a, water temperature, and wind speed were also measured. DMS concentration (ranges 0.85–15.0 nmol S l−1 at Stn. 1 and 0.40–16.3 nmol S l−1 at Stn. 2) showed two relative maxima in the spring–summer period, probably connected to phytoplanktonic and macro-algal blooms. Low and constant values were observed in autumn, whereas the maximum concentration was observed in the late winter period. The CS2 concentration (ranges 0.17–2.8 nmol S l−1 at Stn. 1 and 0.08–2.0 nmol S l−1 at Stn. 2) increased in the spring, was maximal in summer and then decreased in autumn, with a different trend from that of DMS, suggesting that the production and the fate of CS2 and DMS in water are different. Interpretation of the seasonal trends, based on current knowledge of possible formation and transformation processes, is reported. The mean flux of DMS to the atmosphere is estimated to be 0.34 μmol S (DMS) m−2 day−1, which is about one order of magnitude lower than that observed in the open sea, due mainly to lower wind speed. The CS2 flux (March to November average 0.086 μmol S(CS2) m−2 day−1) may represent, at least in lagoon environments, an appreciable fraction of the total natural reduced sulphur emitted to the atmosphere.

Chemometric studies in the Lagoon of Venice, Italy. 1. The environmental quality of water and sediment matrices

Water, particulate, and sediments were collected at a few sites in the Venice Lagoon (Italy) in order to evaluate the quality of these components through a number of mainly chemical measurements. Trace elements (mainly heavy metals), nutrients, PCBs, a toxicity test, and other general constituents were the main features considered. Principal component analysis was applied as a multivariate statistical technique for dimensionality reduction, for the formulation of a multivariate quality criterion, and for identification of the most significant variables. The first few (2−3) principal components have proven useful in summarizing the information available in all the observed variables, supplying a link between the different classes of chemical substances detected in the water matrix and the different polluting inputs (industrial, agricultural, urban) to which the Venice Lagoon is subject (water matrix) and between the chemical composition (speciation of trace elements) of the sediment matrix and its toxicity.

Statistical evaluation of the group structures of five Venetian wines from chemical measurements

Exploratory statistical methods are used to elucidate the group structures pertaining to a chemical data set obtaned from 184 samples of five typical white wines from the Venetian Region: Soave Classico, Presecco di Conegliano-Valdobbiadene, Verduzzo del Piave, Tocai di Lison, Tocai delle Grave del Friuli. Analytical data included 19 classical parameters and 9 aroma components. Correlation matrices showed that the same three sets of intercorrelated variables were present in all the groups, and that aroma components were nearly uncorrelated with classical parameters. Principal components analysis allowed a subspace of reduced dimensionality to be derived for each group. However, because of similar pattern of the correlation matrices, a high degree of similarity was also observed among the subspaces. An efficient differentiation of the groups was obtained by canonical variates analysis. The most important chemical parameters were potassium, ash content, total nitrogen, cis-3-hexen-1-o1 and 1-hexanol. Classification of samples by the Euclidean distances from the centroids in the canonical space gave on average 94% correct results.

Heavy metal distribution and speciation in the Northern Adriatic Sea

In the present study the concentrations of cobalt, copper, iron, manganese, zinc were analysed and the speciation of copper and zinc performed, with a summer and winter sampling, for two areas in the Northern Adriatic Sea and crossing at the farthest zones of the Po river-sea water interface. Results show that when salinity increases the concentrations of all investigated metals (with the exception of cobalt) present some degree of biogeochemical cycling. Copper is the element whose dissolved phase has the highest importance in metal transport across the salinity gradient. Results of speciation analysis demonstrate that the presence of excess amounts (5-8 fold) of unbound ligands confers a buffering capacity for potential inputs of dissolved metals into the Northern Adriatic Sea. The speciation of both copper and zinc in the dissolved phase was dominated by organic complexation.

The interactions of cetyltrimethylammonium with mitochondria: an uncoupler or a detergent?

The interactions of cetyltrimethylammonium (CTA) with mitochondria have been investigated. We confirm, as already observed in a previous paper, that this compound behaves as proton carrier (or uncoupler) of the oxidative phosphorylation, but evidences suggest that this compound enhances the membrane permeability to many other compounds such as sucrose. We conclude therefore that CTA as a detergent enhances membrane permeability to all ions including protons. Some evidences are also given that the inhibitory effect of CTA on the mitochondrial respiratory chain is a consequence of the swelling induced.

Electrochemical determination of the contamination of sea water samples during storage and filtration

Abstract Samples of sea water collected near the coast of an industrial area were analyzed by anodic stripping voltammetry in order to investigate the contamination by cadmium, lead and copper during filtration and storage. Sea water leaches metals from uncleaned membrane filters until 1 l of water has passed through. Samples can be stored in conventional polyethylene containers (properly cleaned and conditioned) at 4°C and natural pH for at least 3 months.