Paolo Censi

Oxygen isotope composition and rate of growth of patella coerulea, monodonta turbinata and M. articulata shells from the western coast of sicily

Abstract The oxygen-isotope composition of carbonate from the outermost portions of Patella coerulea, Monodonta turbinata and M. articulata shells has been measured from April 1979 to July 1981, with an interval during the summer of 1980, and correlated with the ambient temperature. Carbonate from M. turbinata has yielded values that, on the whole, reproduce the environmental temperature range acceptably: P. coerula and M. articulata indicate precipitation taking place at temperatures lower than those measured in seawater; this is particularly acceptuated in summer. This pattern does not necessarily exclude shell carbonate from precipitating under equilibrium conditions with seawater; rather it indicates a higher calcification rate in medium—warm periods for M. turbinata (with slower precipitation in winter), and in medium–cold periods for P. coerulea and M. articulata (with slow calcification, and even short interruptions during the warmest spells in summer).

Simultaneous determinations of zirconium, hafnium, yttrium and lanthanides in seawater according to a co-precipitation technique onto iron-hydroxide

Very low concentrations (pg mL(-1) or sub-pg mL(-1) level) along with the high salinity are the main problems in determining trace metal contents in seawater. This problem is mainly considered for investigations of naturally occurring YLOID (Y and Lanthanides) and Zr and Hf in order to provide precise and accurate results. The inductively coupled plasma mass spectrometry (ICP-MS), both in high and low resolution, offers many advantages including simultaneous analyses of all elements and their quantitative determination with detection limits of the order of pg mL(-1). However in the analysis of YLOID in seawater, a better determination needs an efficient combination of ICP-MS measurement with a pre-concentration technique. To perform an ultra-trace analysis in seawater, we have validated an analytical procedure involving an improved modified co-precipitation on iron hydroxides to ensure the simultaneous quantitative recovery of YLOID, Zr and Hf contents with measurement by a quadrupole ICP-MS. The validity of the method was assessed through a series of co-precipitation experiments and estimation of several quality control parameters for method validation, namely working range and its linearity, detection limit, quantification limit, precision and spike recoveries, and the methodological blank choice, are introduced, evaluated and discussed. Analysis of NASS-6, is the first report on the latest seawater reference material for YLOID, hafnium and zirconium.

Carbonatites from Eastern Paraguay and genetic relationships with potassic magmatism: C, O, Sr and Nd isotopes

SummaryGeochemical characteristics were systematically determined for Early Cretaceous samples of carbonatitic rocks from Eastern Paraguay (Rio Apa, Amambay and Central Provinces). The data show that all the occurrences have an enriched isotopic signature and that the carbonatites have negligible or absent crustal signature. A petrogenetic model (parent liquids, fractional crystallization, hydrothermal interactions and weathering) is proposed as a function of incompatible trace element, stable (O-C) and radiogenic (Sr-Nd) isotope variations with the aim to test the significance of carbonatitic complexes as a marker of the metasomatized subcontinental lithospheric mantle. The results indicate that the carbonatites and primary carbonates from eastern Paraguay, and those from the north eastern Paraná Basin (SE Brazil), were affected by metasomatic events distinct in time and composition.ZusammenfassungDie geochemischen Charakteristika von frühkretazischen Karbonatitproben aus Ostparaguay (Rio Alpa, Amambay und Zentrale Provinzen) wurden untersucht. Die Daten belegen, daß alle Vorkommen eine isotopische Anreicherungssignatur zeigen und daß ihnen eine entsprechende Krustensignatur fehlt. Ein Petrologisches Modell (Ausgangsschmelze, fraktionierte Kristallisation, hydrothermale Interaktion und Verwitterung) wird auf Grund der Verteilung der inkompatiblen Spurenelemente, der stabilen (C-O) und radiogenen (Sr-Nd) Isotope vorgeschlagen. Es versucht die Bedeutung der Karbonatitkomplexe als „Markerhorizonte” des metasomatischen subkontinentalen Mantels zu überprüfen. Die Ergebnisse zeigen, daß die Karbonatite und die primären Karbonate in Ostparaguay, und jene aus dem Paraná Becken SüdostBrasiliens durch zeitlich und zusammensetzungsmäßig unterschiedliche metasomatische Prozesse erfaßt wurden.

Source and Nature of Inhaled Atmospheric Dust from Trace Element Analyses of Human Bronchial Fluids

Rapid volcanic eruptions quickly ejecting large amounts of dust provoke the accumulation of heavy metals in people living in surrounding areas. Analyses of bronchoalveolar lavage samples (BAL) collected from people exposed to the paroxysmal 2001 Etna eruption revealed a strong enrichment of many toxic heavy metals. Comparing the BAL to the dust composition of southeastern Sicily, we found that only V, Cr, Mn, Fe, Co, and U enrichment could be related to the volcanic event, whereas Ni, Cu, Cd, and Pb contents come from the dissolution of particles of anthropogenic origin. Furthermore, the nature of these inhaled anthropogenic particles was revealed by anomalous La and partially Ce concentrations in BAL that were consistent with a mixture of road dust and petroleum refinery emissions. Our results indicate that trace element distribution in BAL is a suitable tracer of human exposure to different sources of inhaled atmospheric particulates, allowing investigations into the origin of source materials inhaled by people subjected to atmospheric fallout.

Geochemical behaviour of rare earths in Vitis vinifera grafted onto different rootstocks and growing on several soils

The geochemical behaviour of lanthanides and yttrium (Rare Earth Elements, REEs) has been investigated mainly in geological systems where these elements represent the best proxies of processes involving the occurrence of an interface between different media. This behaviour is assessed according to features recorded in sequences of REE concentrations along the REE series normalised with respect to a reference material. In this study, the geochemical behaviour of REE was investigated in different parts of Vitis vinifera specimens grown off-soil, on soils of different nature and grafted onto several rootstocks in order to evaluate effects induced by these changes. The results indicated that roots are the plant organs where REEs are preferentially concentrated, in particular elements from Sm to Ho (middle REE, MREE) whereas Eu enrichments occur in aerial parts. The geochemical behaviour of REE suggests that MREE enrichments in roots are due to preferential MREE interactions with biological membranes or to surface complexation with newly formed phosphates. Eu-positive anomalies suggest that Eu(3+) can form stable organic complexes in place of Ca(2+) in several biological processes in xylem fluids. The possibility that Eu mobility in these fluids can be enhanced by its reductive speciation as Eu(2+) cannot be ruled out. The assessment of the geochemical behaviour of REE according to the theory of the Tetrad Effect carried out confirms that REEs coming from soil are scavenged onto root tissues or mineral surfaces whereas their behaviour in aerial parts of V. vinifera is driven by dissolved complexation.

Influence of dissolved organic matter on rare earth elements and yttrium distributions in coastal waters

Data collected during this study indicate that dissolved Y and REE (rare earth element) behaviour can be monitored through shale-normalised ratios. Relationships occurring between these ratios suggest that leaching from lithogenic materials is the main source of REE in the studied area. This process involves riverine detrital matter in the inner area of the Gulf of Palermo. Features of shale-normalised patterns and the relationship recognised between dissolved Fe and Y/Ho suggest that REE are released from Fe-rich coatings of atmospheric dust. Observed similarities between dissolved Fe and chlorophyll-α content suggest that leaching of Fe-rich atmospheric particulates induces a fertilisation of shallow water layers influencing the dissolved organic content. In turn, the increasing chlorophyll-α content causes a progressive decrease in amplitude of the negative Ce anomaly in seawater that is also observed in water in the Central Mediterranean Sea, suggesting that organic matter generally plays a key role in REE behaviour at the solid–liquid interface. Shale-normalised REE features recognised in suspended particulate matter (SPM) indicate the occurrence of three different fractions from lithogenic matter, biogenic carbonates and authigenic components, respectively. The latter is formed during REE scavenging onto the surface of detrital biogenic particles and is mainly recognised in inner gulf waters.

Relationship between lanthanide contents in aquatic turtles and environmental exposures

Trace elements released in the environment during agricultural practices can be incorporated and accumulated in biological fluids and tissues of living organisms. The assessment of these exposures were carried out investigating lanthanide distributions in blood and exoskeleton samples collected from Emys trinacris turtle specimens coming from sites with anthropogenic discharge in western and south Sicily, along migration paths of many bird species from Africa to Europe. The data show a significant (Rxy=0.72; Rxy>0.67; α=0.025) linear relationship between the size of turtle specimens and the lanthanide contents in blood lower than 0.4 μg L(-1) whereas this relationship disappears in blood with higher lanthanide contents. Comparative evaluations of normalised concentrations show that lanthanides fractionate between blood and exoskeleton inducing antithetical lanthanide patterns therein. These features are more evident in specimens with high lanthanide contents in blood, suggesting that lanthanide accumulations in the exoskeleton can represent the physiological response of E. trinacris to environmental and the further confirmation of relationship occurring between the environmental and the biological fluids.

RARE EARTHS AND TRACE ELEMENTS CONTENTS IN LEAVES: A NEW INDICATOR OF THE COMPOSITION OF ATMOSPHERIC DUST

The relationship between the trace element distribution in atmospheric particles and leaves of some exposed plants in the environment was recently demonstrated. This indication would suggest that the trace element analysis of leaves in these plants could provide information about the composition, nature and origin of the atmospheric dust dispersed in the environment. In order to corroborate this hypothesis, the distribution of trace elements and Rare Earths were studied in leaves of some endemic plants, in the atmospheric fallout and in soils of rural, urban and industrial ecosystems in Sicily. These elements have been chosen to discriminate the source and nature of different source on atmospheric dust and the larger capability of the composition of the latter materials to influence the metal ion distribution in leaves of studied plants rather than the soil composition. These evidences are related to the recognition both of positive La anomaly and trace element enrichments in studied leaves and to their particular V/Th and Co/Ni signature. On the other hand, some particular normalised REE features recognised in leaves suggest that a limited contribution to the REE budget in studied leaves is provided by the REE migration from roots.

Medical geochemistry: Geological materials and health

Preface.- How trace element contents in bronchoalveolar lavages can probe the human exposure to inhaled particulates.- Geochemistry and Biochemistry - insights into the fate and transport of Pt-based chemotherapy drugs.- Atmospheric Particulate Matter (PM) in the Middle East: Toxicity, trans-boundary transport and influence of synoptic conditions.- Reaction path modeling: theoretical aspects and applications.- An observation on the composition of urinary calculi: environment influence.- Magnetite minerals in the human brain: whats their role?.- Chemometrics and Medical Geochemistry: A brief tutorial.- Dust, metals and metalloids in the environment: from air to hair.- Metal Geochemistry of a Brackish Lake: Etang Saumatre, Haiti.- Trace Element Composition of Modern Human Bone.

Zr, Hf and REE distribution in river water under different ionic strength conditions

The Platani River flowing in south-central Sicily, interacting with evaporite rocks, generates a wide range of ionic strength in the water catchment from 0.1 to 5.0molkg-1. We sampled 38 river sites and analysed the composition for the dissolved fraction filtered through 0.45μm, the truly dissolved fraction obtained through ultrafiltration (10kDa) and the relative included colloidal fraction. This study was focused on the recognition of Zr, Hf and REE behaviour under changing ionic strength conditions, since this is one of parameters responsible for colloid stability in natural waters. In turn, this phenomenon leads to REE release from the colloidal fraction and their scavenging onto surfaces of suspended particles or sediment, or their complexation with dissolved ligands. Our results indicated that in both dissolved and ultra-filtrated fractions REE increases either in the middle (Sm - Dy) or in the heavier (Ho - Lu) part of the PAAS-normalised distribution, while the Zr/Hf ratio value ranges from sub-chondritic to super-chondritic. Scanning Electron Microscopic and Energy Dispersive X-ray Spectrometric (SEM-EDS) analyses and dissolved Mg, Al and Fe concentrations suggested that the studied colloids consist of aggregations of Al-oxyhydroxides, carbonate nanoparticles and clays where organic traces were not found. The studied colloids showed greater affinity with dissolved Zr than Hf determining Zr/Hf values larger than the chondritic values. The largest Zr/Hf values were found in colloidal fractions from waters with ionic strength larger than 0.6molkg-1. These Zr/Hf values up to 280 (w/w) are provided by the faster removal of Hf relative to Zr from coagulating colloids and its preferential scavenging onto authigenic Fe-oxyhydroxides in bottom sediment. Further studies are needed to clarify is this suggested process can represent a suitable starting point for the Zr-Hf decoupling observed in seawater.