Carmine Apollaro

Characterization of granitoid profiles in the Sila Massif (Calabria, southern Italy) and reconstruction of weathering processes by mineralogy, chemistry, and reaction path modeling

PurposeThis paper concerns the development of a multidisciplinary research on weathering profiles of granitoid rocks in the Sila Massif (Calabria, southern Italy), based on field investigations, chemical and minero-petrographic data, and geochemical modeling. It aims at evaluating modes and degree of weathering and focuses on the main transformation processes of the parent rock, integrating information obtained by direct observations/analyses on samples with results of simulations of pertinent water–rock interaction processes, carried out through the reaction-path-modeling approach.Materials and methodsPhysical responses to geological hammer hitting and morphological weathering features were used to characterize increasing weathering grade (I–VI weathering classes) of a representative weathering profile. Also, the main microfabric and minero-petrographic features were observed in thin sections; XRPD and SEM-EDS were used to identify primary minerals and neoformed products. Progressive dissolution of the granitoid rock was simulated using the software package EQ3/6, 8.0 and a modified version of the thermodynamic database data0.ymp.R5. A kinetic mode under closed-system conditions was applied with respect to a defined set of secondary solid phases, which are allowed to precipitate.Results and discussionThe partial transformation of biotite and the partial destruction of feldspars, associated with the neoformation of secondary minerals and a substitution of the original rock fabric are the main mineralogical changes observed. Neoformed clay minerals and ferric products replaced feldspars and biotite during the most advanced weathering stage. Microfractures and morphological variations occur on the original rock. The final result of weathering process is a soil-like rock characterized by sand-gravel grain-size fraction. Results of geochemical modeling suggest that the chemical weathering processes occurring in the study area are relatively close to an iso-chemical transformation of the original granitoid rock, based on the small predicted changes in the concentrations of solutes from the initial to the final state of the simulation. The CO2-controlled dissolution of albite-rich plagioclase is the most important reaction, followed by the dissolution of K-feldspar, biotite, chlorite, and muscovite, in order of decreasing importance. The precipitating secondary minerals are ferrihydrite, saponite, vermiculite, illite, and kaolinite in order of decreasing pH values. The order of appearance and the quantities of secondary (product) minerals depend on the setup of geochemical modeling.ConclusionsBased on the standard thermodynamic properties of different illite endmembers, calculated in this work, it was possible to predict the varying compositions of the illite solid solution, which resulted to be similar to those observed in natural systems.

Asbestos and other fibrous minerals contained in the serpentinites of the Gimigliano-Mount Reventino Unit (Calabria, S-Italy)

Serpentinites are metamorphic rocks with good technological properties and valuable ornamental characteristics, which have been exploited since ancient times. Actually, their use is limited and monitored in several countries worldwide because they can contain fibrous asbestos minerals that may be carcinogenic. Furthermore, certain types of fibrous minerals can be confused with asbestos, and must therefore be carefully investigated. We have investigated the possible presence of the asbestos and non-asbestos fibrous phases contained in serpentinitic rocks in a meta-ophiolitic sequence from the Gimigliano-Mount Reventino Unit (Southern Italy), which had not been previously assessed. The detection and quantification of asbestos and the correct distinction of the fibrous non-asbestos minerals are very important not only from a scientific point of view, but also from a legislative one. This is especially the case for the administrative agencies that have to take decisions with regards to the implementation of public and occupational health protection measures (e.g., in road yards and quarry excavations). As a consequence of this, serpentinitic rock samples have been characterized in detail through X-ray powder diffraction, scanning and transmission electron microscopy combined with energy-dispersive spectrometry, analytical electron microscopy (SEM–EDS and TEM–AEM), differential scanning calorimetry, thermogravimetry and micro-Raman spectroscopy. Two kinds of asbestos and four kinds of non-asbestos fibrous silicates have been detected in the examined samples. In order of decreasing abundance these are polygonal serpentine, chrysotile, fibrous antigorite, tremolite, gedrite and magnesiohornblende. The size, morphology, crystallinity and chemical composition of the fibres were also discussed, in the light of the possible role these properties could play in the carcinogenic effect on human health.

Naturally occurring asbestos: potential for human exposure, San Severino Lucano (Basilicata, Southern Italy)

In recent years, environmental exposure to naturally occurring asbestos (NOA) has been shown to be a cause of several types of lung disease, which may occur when NOA outcrops are in proximity to residential areas. In this study, we present the results of our investigation of NOA hosted in outcrops of serpentinites in Basilicata region (Southern Italy), which could be potentially harmful to human health. For this purpose, fifteen serpentinite rock samples collected within and near the village of San Severino Lucano were characterized in detail by optical microscope (OM), X-ray powder diffraction (XRPD), thermal analysis (TG/DSC/DTG/DDSC), scanning and transmission electron microscopy combined with energy-dispersive spectrometry, analytical electron microscopy (SEM/EDS and TEM/AEM). Chrysotile and asbestos tremolite or asbestos actinolite were identified in all samples. The NOA in these outcrops could be subject to weathering processes and/or human activities, which generate airborne particles, thus exposing the neighbouring populations to a series of health risks. The size and morphology of NOA are also discussed, regarding the carcinogenic effect that these factors may have on human health. Due to the health risks associated with disturbing NOA-bearing rock, an asbestos exposure control plan must be instituted.

Modelling seasonal variations of natural radioactivity in soils: A case study in southern Italy

The activity of natural radionuclides in soil has become an environmental concern for local public and national authorities because of the harmful effects of radiation exposure on human health. In this context, modelling and mapping the activity of natural radionuclides in soil is an important research topic. The study was aimed to model, in a spatial sense, the soil radioactivity in an urban and peri-urban soils area in southern Italy to analyse the seasonal influence on soil radioactivity. Measures of gamma radiation naturally emitted through the decay of radioactive isotopes (potassium, uranium and thorium) were analysed using a geostatistical approach to map the spatial distribution of soil radioactivity. The activity of three radionuclides was measured at 181 locations using a high-resolution ?-ray spectrometry. To take into account the influence of season, the measurements were carried out in summer and in winter. Activity data were analysed by using a geostatistical approach and zones of relatively high or low radioactivity were delineated. Among the main processes which influence natural radioactivity such as geology, geochemical, pedological, and ecological processes, results of this study showed a prominent control of radio-emission measurements by seasonal changes. Low natural radioactivity levels were measured in December associated with winter weather and moist soil conditions (due to high rainfall and low temperature), and higher activity values in July, when the soil was dry and no precipitations occurred.

Preliminary geochemical and geological characterization of the thermal site of Spezzano Albanese (Calabria, South Italy)

Waters discharging at the Spezzano Albanese spring come from a deep circuit hosted in the Ophiolitic rocks of the Diamante Unit (phyllites and metabasalts, Liberi et al., 2006; Vespasiano et al., 2012b). The unit contains a warm deep aquifer acting as a sort of well-mixed reservoir; during the ascent the waters interact with Tertiary and Quaternary deposits (conglomerates, sands, gypsum and clays with levels of halite) that give them a characteristic composition with near neutral pH value of 7.05 to 7.57, outlet temperatures of 20.16° to 26.6°C, variable redox potentials (–0.25 to 0.28 V) and total dissolved solids from 848 to 9720 ppm.During deep circulation, the waters extract heat from reservoir rocks, attaining thermo-chemical equilibrium and rise relatively quickly to the surface, along sub-vertical faults and fractures, preserving part of their physical and chemical characteristics (Vespasiano et al., 2014).Water chemistry was discussed by means of the triangular diagrams among major anionic/cationic constituents and correlation plots. Triangular diagrams show a Na-Cl composition characterized by high bacterial sulfate reduction. Correlation diagrams attest a high calcite and silica precipitation (likely scaling effect) and show a 1:1 ratio between sodium and chlorine that underline an interaction with halite. This represents only a preliminary study that demonstrates the importance of the geochemical characterization as powerful tool to improve the knowledge of natural environment and to predict and avoid problems linked to the study of thermal sites (Gurrieri et al., 1984; Duchi et al., 1991; Italiano et al., 2010).

Preliminary geochemical characterization of the thermal waters of Caronte SPA springs (Calabria, South Italy)

Literature data with new geological, hydrogeological and geochemical investigations have been used to model the thermal spring waters of Caronte. Waters come from a deep hydrogeological circuit, which is chiefly hosted in the carbonate rocks and evaporites belonging to the Upper Triassic Verbicaro Unit (Iannace et. al., 2007). In particular, the warm deep reservoir has a temperature of ± 45 °C, as indicated by the chalcedony solubility and the SO4–F geothermometers. The warm reservoir is probably located at depths close to 0.9 km, assuming a geothermal gradient of 33 °C km-1. Water leaves the deep reservoir discharges at the surface at 37.3 ± 1.2 °C, with a SO4-Ca composition, after a relatively fast upflow and limited cooling.The upward part of hydrogeological circuit is controlled by local high-angle fault systems as well as by the tectonic window of Sambiase, where the Verbicaro Unit crops out.

Preliminary geochemical characterization of a carbonate aquifer: the case of Pollino massif (Calabria, South Italy)

Groundwater is a very significant water source used for irrigation and drinking purposes in many region, and therefore understanding the hydrogeochemistry of karst water is extremely important. In this study, surface water and groundwater were collected, and major chemical compositions in the water were measured in order to determine the hydro-chemical processes governing the evolution of the groundwater.Water chemistry was discussed by means of the triangular diagrams among major anionic/cationic constituents and correlation plots. Triangular diagrams show that groundwater is typically characterized by Ca–Mg-HCO3 composition in a shallow aquifer, and Ca-SO4 composition in a deeper aquifer. The active geochemical processes in aquifers, with their corresponding time sequence are: dissolution of CO2, dissolution of calcite and dissolution of dolomite.This represents only a preliminary study that demonstrates the importance of the geochemical characterization as powerful tool to improve the knowledge of natural environment.

Hydrogeological and isotopic study of the multi-aquifer system of the Sibari Plain (Calabria, Southern Italy)

Geochemical study allowed to recognize four groups of groundwater for the Sibari Plain (Southern Italy): Ca–HCO3, Na–Cl, Ca–Cl and Na–HCO3. Chloride-rich waters are located close to the Crati mouth that could be a preferential path for seawater ingression. In fact, seawater and brackish waters could move inland along the stream channel and enter the nearby aquifers due to excessive pumping of wells positioned near the river. In alternative, the occurrence of processes, such as ion exchange or dissolution of halite-bearing Miocene evaporite deposits can generate aqueous solutions with similar characteristics to those produced by seawater ingression. Moreover, was calculated the infiltration average (Hi, m a.s.l.) for groundwater of the Sibari Plain by the following equations:The data showed a lower average of the infiltrations in the inner part of the Sibari Plain, with values between 550 and 870 m a.s.l., and higher values (1000/1500 m a.s.l.) moving to NW and SE.

Geochemical modeling as a tool to investigate the release and fate of Cr in the ophiolitic aquifers of Northern Calabria (S-Italy)

The study of the weathering process of ophiolitic rocks represents an important process due the high toxicity of Cr(VI) with environmental and social consequences and health effects.Since this topic is not well understood, a preliminary study on the release of Cr and other constituents during the weathering of the meta-ophiolitic rocks outcropping in Northern Calabria (Fuscaldo zone) has been carried out using the reaction path modeling.In this work, the EQ3/6 software package, version 8.0 was used together with its data0.ymp.R5 thermodynamic database (Apollaro et al., 2013a, b), upon acquisition of the necessary information such as the stability constants of the aqueous complexes of Cr(VI).Preliminary results showed that the geochemical modeling is an important tool to investigate the phenomena which control the redox state of Cr in near-surface environment and the release and fate of Cr and other chemical constituents in these peculiar environments since during the progressive dissolution of the considered lithotypes, the aqueous solution may attain saturation with respect to different secondary solid phases, potentially acting as sinks of various elements and species.

Geochemical and mineralogical characterization of tremolite asbestos contained in the Gimigliano-Mount Reventino Unit (Calabria, south Italy)

In the recent years, many studies have focused on rocks containing naturally occurring asbestos (NOA) with the purpose of determining the potential health risks to exposed neighboring populations. Environmental exposure to NOA has been shown to be a cause of several types of lung disease. The toxicity of asbestos fibres should also depend on the concentration of trace elements and their release in the environment. In this regard the aim of the present work was to characterize four samples of pure tremolite asbestos belonging to Gimigliano-Mount Reventino Unit (Calabria, south Italy). Through a several analytical techniques such as X-ray powder diffraction (XRPD), scanning electron microscopy combined with energy dispersive spectrometry (SEM–EDS), differential scanning calorimetry (DSC), derivative thermogravimetric (DTG) and atomic absorption spectroscopy (AAS), the size, morphology, crystallinity and chemical composition of tremolite samples were discussed to define the impact on the environment and human health.