Claudio Natali

Heavy metals in soils and sedimentary deposits of the Padanian Plain (Ferrara, Northern Italy): characterisation and biomonitoring

PurposeThis contribution investigates agricultural soils and sedimentary deposits in the province of Ferrara (Padanian alluvial plain, Northern Italy) in order to: examine their genesis; to define the geochemical background of the area; and to evaluate the existence of anthropogenic contamination. Moreover, environmental risk related to the presence of potentially toxic heavy metals that can be transferred into agricultural products (and consequently bio-accumulated in the food chain) was also assessed.Materials and methodsThe analyses (reported in an extensive supplementary dataset) include XRD, XRF and ICP-MS assessment of bulk sediments, tests of metal extraction with aqua regia, as well as analyses of local agricultural products, i.e. biomonitoring which is important in the evaluation of element mobility.Results and discussionBased on the results, GIS-based geochemical maps were produced and local background levels were defined. This approach demonstrated that high concentrations of Cr and Ni is a natural (geogenic) feature of the local alluvial terrains, which in turn is related to the origin and provenance of the sediments, as confirmed by the lack of top enrichment in all of the investigated sites. Tests of metal extraction and analyses of agricultural products provide guidelines for agricultural activities, suggesting that extensive use of sewage sludge, industrial slurry and manure (that are often rich in metals) should be minimised.ConclusionsThe dataset reported in this paper shows that the agricultural terrains of the studied alluvial plain are not characterised by anthropogenic heavy metal pollution. In spite of the elevated natural background of Cr and Ni, most of the local agricultural products do not show significant evidence of bio-magnification. Exceptions are represented by forage grass (alfalfa) and corn (maize) that tend to uptake As and Ni, respectively. This demonstrates that in agricultural areas, a geochemical risk assessment must include both soil and plant investigations.

Morphological changes during enhanced carbonation of asbestos containing material and its comparison to magnesium silicate minerals.

The disintegration of asbestos containing materials (ACM) over time can result in the mobilization of toxic chrysotile ((Mg, Fe)3Si2O5(OH)4)) fibers. Therefore, carbonation of these materials can be used to alter the fibrous morphology of asbestos and help mitigate anthropogenic CO2 emissions, depending on the amount of available alkaline metal in the materials. A series of high pressure carbonation experiments were performed in a batch reactor at PCO2 of 139atm using solvents containing different ligands (i.e., oxalate and acetate). The results of ACM carbonation were compared to those of magnesium silicate minerals which have been proposed to permanently store CO2 via mineral carbonation. The study revealed that oxalate even at a low concentration of 0.1M was effective in enhancing the extent of ACM carbonation and higher reaction temperatures also resulted in increased ACM carbonation. Formation of phases such as dolomite ((Ca, Mg)(CO3)2), whewellite (CaC2O4·H2O) and glushinskite (MgC2O4·2H2O) and a reduction in the chrysotile content was noted. Significant changes in the particle size and surface morphologies of ACM and magnesium silicate minerals toward non-fibrous structures were observed after their carbonation.

Geochemical characterization and biomonitoring of reclaimed soils in the Po River Delta (Northern Italy): implications for the agricultural activities.

This geochemical study is focused on the easternmost part of the Po River alluvial plain in Northern Italy, which is interested by widespread agricultural activities, investigating a reclaimed sector of the Province of Ferrara, known as “Valle del Mezzano” (Mezzano Low Land, hereafter reported as MLL) characterized by peat-rich soils. The chemical–mineralogical characterization of these reclaimed soils is important to compare the local geochemical backgrounds with those recorded in other sectors of the River Po plain and to monitor if the observed concentration exceeds critical thresholds. The reported analyses include (a) measurement of the soil salinity, (b) nutrient evaluation, (c) major and trace element concentrations carried out on bulk soils, (d) tests of metal extraction with both aqua regia and EDTA to highlight the distinct elemental mobility and (e) phyto-toxicological measurement of heavy metal concentrations in plants (Lactuca sativa acephala) grown on the studied soils. The results indicate (1) high soil salinity, often with drastic increase of sodium and chloride along the soil profiles, (2) high nitrogen content (in part related to anthropogenic activities) on superficial horizons and nitrate decrease along the soil profiles and (3) comparative enrichments in heavy metals with respect to other soils of the province, which indicate that peat deposits are effective in trapping metals from anthropogenic sources. This, in turn, implies potential geochemical risks for the agricultural activities. In this regard, specific concerns are related to the high nickel and arsenic content of MLL soils due to the mobility of these elements and their attitude to be taken up by plants.

Extremely dry and warm conditions in northern Italy during the year 2015: effects on the Po river water

The presented research highlights relationships between the climatic anomalies that occurred in northern Italy in 2015 and the water system of Po river. We investigated the effect of anomalous high temperature and paucity of meteoric precipitation on the Po river discharge and water geochemistry. The new geochemical data, carried out on river water sampled at Pontelagoscuro (close to the city of Ferrara) and in the delta, have been compared with an extended dataset collected since 2009. The comparison emphasizes that water samples of 2015 were characterized by a high electrical conductivity due to high concentrations of conservative ionic species (e.g. Na, Cl, SO4) and nutrients such as nitrate. Oxygen and hydrogen isotopes, particularly sensitive to the observed climatic changes, reveal in a δ18O-δD diagram evaporative trends (highlighted by displacement from the Meteoric Water Lines) with a magnitude that was not recorded in the last years. The monitoring is currently in progress to develop functions that relate geochemical parameters to the evolving meteo-hydrological conditions.

Geochemical and isotopic analyses on the Po delta water: insights to understand a complex riverine ecosystem

This contribution was preliminarily presented with an oral communication during the “Water Day 2015” conference organized in Rome the 20th of March 2015 by the Accademia Nazionale dei Lincei. It implements a recent paper that studied the Po river water from the Alpine springs toward the Adriatic Sea (Marchina et al. Environ Sci Pollut Res 22, 5184–5203, 2015), specifically focussing on its deltaic part. The new geochemical analyses are useful to evaluate the extent of salinization (due to mixing with sea-water) and to monitor the flux of nutrients that are conveyed by the river toward the coastal environment. The paper also contains oxygen/hydrogen water isotopes that represent a snapshot of the current climatic conditions to be compared with the literature data and with the future composition to set up a hydro-archive that should be updated to evaluate on-going climatic changes. Moreover, the paper reports preliminary nitrogen isotopes composition of Po river water that trace the impact of human activities, to be monitored in the future to understand possible on-going pollutions. We conclude that geochemical researches on Po river should consider with particular attention the delta because it is an extremely fragile ecosystem where biogeochemical variations are more relevant.

Natural and anthropogenic variations in the Po river waters (northern Italy): insights from a multi-isotope approach

ABSTRACT Po is the main Italian river and the δ18O and δ2H of its water reveal a similarity between the current meteoric fingerprint and that of the past represented by groundwater. As concerns the hydrochemisty, the Ca–HCO3 facies remained constant over the last 50 year, and only nitrate significantly increased from less than 1 mg/L to more than 10 mg/L in the 1980s, and then attenuated to a value of 9 mg/L. Coherently, δ13CDIC and δ34SSO4 are compatible with the weathering of the lithologies outcropping in the basin, while extremely variable δ15NNO3 indicates contribution from pollutants released by urban, agricultural and zootechnical activities. This suggests that although the origin of the main constituents of the Po river water is geogenic, anthropogenic contributions are locally significant. Noteworthy, the associated aquifers have the same nitrogen isotopic signature of the Po river, but are characterized by significantly higher NO– 3 concentration. This implies that aquifers’ pollution is not ascribed to inflow of current river water, and that the attenuation of the nitrogen load recorded in the river is not occurring in the aquifers, due to their longer water residence time and delayed recovery from anthropogenic contamination.

Comment on Manuella et al. "The Hyblean xenolith suite (Sicily): an unexpected legacy of the Ionian-Tethys realm"

Manuella et al. (2015) emphasize that the Hyblean xenolith suite includes only ultramafic (peridotites and pyroxenites) and mafic (gabbros s.l.) lithotypes, whereas felsic rocks are not observed. On this ground, they attest that rocks having a “continental” affinity are totally absent within the Hyblean basement. This statement can be criticized for various reasons because the representativeness of the crust provided by the xenoliths is often biased, as xenolith populations worldwide are often monotonous, i.e., mainly represented by a limited number of lithologies (see also Rudnick and Fountain 1995; Coltorti et al. 2011). The observation suggests that: host magmas entrained xenoliths at a specific depth, and not all along the path toward the surface. The restricted type of lithologies is generally ascribed to the mechanism of xenolith uptake, which is related to the fluid (mainly CO2) release and bubble nucleation, which trigger discrete event of crack formation and breaking of the surrounding host rocks; in other words, fluid nucleation leads to “explosion,” fracturing the wall rocks and forming the xenoliths (Lensky et al. 2006); the specific depth of xenolith formation is distinctive of each magma type, and usually Cenozoic alkaline basalts of the Mediterranean region entrain xenoliths from either the uppermost lithospheric mantle or the lower crust (at ca 30–50 km depth), whereas sampling of shallower depths is rarer (Beccaluva et al. 2005); basic magmas easily resorb and assimilate felsic rocks as indicated by experimental and numerical modeling (Sachs Introduction

Natural vs anthropogenic components in sediments from the Po River delta coastal lagoons (NE Italy)

The Sacca di Goro and Sacca di Scardovari are two coastal lagoons of the Po River delta facing the northern Adriatic Sea. They are sensitive ecosystems both from the naturalistic and socio-economic point of view, since they are included in a natural park and are high productivity shellfish sites. Bottom sediments from the two lagoons have been analysed for their textural and geochemical (major and trace elements by XRF) composition in order to identify natural backgrounds and anthropogenic inputs. OC, N and δ13COC data have been also carried out by EA-IRMS to highlight the association of heavy metals with inorganic or organic sedimentary components. Results show that abundances of siderophile (Cr, Ni, Co) heavy metals in samples from the two lagoons are generally in the range of those recorded in alluvial sediments from the neighbours and are associated with the finest (clayey) fraction. Among chalcophile heavy metals, Pb and Zn display significant enrichments relative to the local geochemical backgrounds suggesting anthropogenic sources. They appear to be preferentially associated with the sedimentary organic matter that, according to the isotopic composition, is mainly formed by the incorporation of different proportions of macroalgae and macrophytes that have a significant bioaccumulation capacity. Taking into consideration that the extent of the algal biomass is sensitive to anthropogenic pressure and climatic changes, the trace element budget of sediments from these lagoons has to be monitored in the future, also to assess the impact of heavy metals on shellfish production.

Oxalate Patinas on Stone Monuments in the Venetian Lagoon: Characterization and Origin

Calcium oxalate patinas have been sampled on architectural elements of two ancient churches located on Torcello Island (Venetian Lagoon) and subsequently analyzed. The site had been selected presenting patinas of exceptional amount and thickness, elsewhere generally found as thin alteration layers covering stone surfaces or within black crusts on monuments in urban environments. Optical and mineralogical analyses suggest that these patinas are not the result of a simple deposition process, but originate as surface “transformations” of the substrate, and are mainly composed of dihydrate calcium oxalate (weddellite) and gypsum. Among the experimental techniques, isotope analyses (C and S) have been specifically carried out aiming at achieving a better understanding of their origin and possible causes of formation. The observed carbon isotopic fingerprint reveals in fact a strong biological fractionation recorded in the oxalate patina (δ13C ranging from −22.3‰ to −28.0‰), almost exclusively attributable to C3 pathway photosynthesis processes. Slightly negative sulfur isotope ratio values seem to be inversely correlated with patina exposure to atmospheric agents and pollutants. The results obtained prove that calcium oxalate originates from a biomineralization process induced by lichen colonization in specific environmental conditions.

Water–Rock Interaction and Lake Hydrochemistry in the Main Ethiopian Rift

This study investigates the halogen budget of the Main Ethiopian Rift (MER) lithologies and water, and on the basis of new laboratory experiments gives insights on the water–rock interaction processes which ultimately mobilize fluoride in the environment. The halogen composition, and in particular, the chloride content of MER lakes is also taken into consideration to evaluate compositional variation occurred during the last 80 years that have to be mainly related evaporative effects. The evaporation trends are also investigated on the basis of new analyses of stable isotopes of oxygen and hydrogen that are compared with those available in the literature since the 1970s. In such complex scenario, although the average annual temperature increased ~1 °C in 30 years, we did not observe systematic trends valid for all the investigated lakes. The record defined for the last 30 years by δ18O–δD denote fluctuations of the climatic parameters with extreme evaporation preceding the year 2005, then declining to more “normal” conditions. The relation between the observed climatic parameters and the water isotopic composition suggests that the study lakes quickly respond to the environmental changes, possibly within one (or two) year(s). We therefore suggest to continue the data acquisition of climatic and hydrochemical parameters in order to implement the existing hydro-archive that could be useful to point out possible environmental changes.