Geochemical Modeling of Water-Rock Interaction in the Granulite Rocks of Lower Crust in the Serre Massif (Southern Calabria, Italy)

To simulate the evolution of groundwaters interacting with granulitic rocks of the lower crust exposed in the southern sector of the Calabrian region, reaction path modeling was performed by means of the EQ3/6 software package version 8.0a. Low-salinity waters issuing from granulite have Na–Cl to Na-HCO3 composition, about neutral pH (mean value of 6.7), outlet temperatures of 7.7 to 14.2°C, oxidant redox potentials from 100 to 182 mV, and electrical conductivity from 72.1 to 196.9 μS/cm. The mineral constituents of local granulite are plagioclase, amphibole, biotite, clinopyroxene, garnet, and orthopyroxene. Simulations were carried at constant temperature of 11.8°C (which reproduces the average temperature of local groundwaters) fixing the fugacity of CO2 at 10-2.4 bar (mean value), 10-2.0 bar (mean value +1 σ), and 10-2.8 bar (mean value -1 σ). The analytical contents of major elements in groundwaters were satisfactorily reproduced by modeling and are fully consistent with the secondary minerals produced by weathering processes affecting the same rocks

The Role of Water-Rock Interaction Processes in Soil Formation: Geochemical, Mineralogical, Geomorphological, and Engineering-Geological Aspects

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Mineralogical and Geochemical Characterization of Asbestiform Todorokite, Birnessite, and Ranciéite, and Their host Mn-Rich Deposits from Serra D'Aiello (Southern Italy)

Manganese ores, especially the oxyhydroxides in their different forms, are the dominant Mn-bearing minerals that occur in marine and terrestrial environments, where they are typically found as poorly crystalline and intermixed phases. Mn oxyhydroxides have a huge range of industrial applications and are able to exert a strong control on the mobility of trace metals. This paper reports the results of a detailed study on the Mn oxyhydroxides occurring in the manganiferous deposit outcropping in the Messinian sediments from Serra D'Aiello (Southern Italy). Nine Mn samples were characterized in detail using X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), thermogravimetry (TG), transmission electron microscopy combined with energy dispersive spectrometry (TEM/EDS), and X-ray fluorescence (XRF). The results indicated that the Mn deposit included the oxyhydroxide mineral species birnessite, todorokite, and rancièite. The size, morphology, and chemical composition of Mn oxyhydroxide samples were investigated in order to define their impact on the environment and human health. Todorokite displayed asbestiform shapes and could disperse fibers of breathable size in the air. Furthermore, since in-depth characterization of minerals within Mn deposits may be the first step toward understanding the genetic processes of manganese deposits, hypotheses about the genesis of the Mn oxyhydroxide deposits were discussed

Geochemical modeling of water-rock interaction in the ophiolitic aquifers of Northern Calabria

Scuola di Dottorato "Archimede" in Scienze ,Comunicazione e Tecnologie, Ciclo XXVI Ciclo XXVI, a.a. 2007-2013This study was developed in two distinct parts with the ultimate aim to investigate the weathering processes of the metabasalts and serpentinites of Northern Calabria, taking into account the dissolution kinetics of relevant mineral phases. In the first part, a laboratory experimental work has been carried out on two suitably characterized rock samples, a metabasalt and a serpentinite, to determine the whole-rock dissolution rates and, consequently, the kinetic parameters of each constituting mineral in these specific rocks, at 25 °C and different pH values. Mixed-flow reactors were used to perform this experimental work. Incidentally, it must be recalled that: (i) although there are many laboratory studies aimed at the determination of the dissolution rates of separate (single) minerals, less is known about the dissolution rates of individual minerals in multimineralic rocks and (ii) in geochemical modeling, the dissolution rates measured on separate mineral are customarily utilized to estimate the dissolution path of the overall rock, assuming that the dissolution rate of a separate mineral is equal to that of the same mineral in a given rock. However, the experimental results of in this study contradict this hypothesis. Indeed, it turned out that: (i) dissolution rates of individual minerals obtained from the dissolution experiments of whole rocks are significantly different from those of separate minerals and (ii) the dissolution rates of individual minerals exhibit minor differences to each other and appear to be close to the whole-rock rate. This behavior is probably constrained by the sufficiently abundant mineral(s) of lowest dissolution rate, preventing the dissolution of other faster-dissolving mineral grains as long as these do not come in contact with the aqueous phase. The second part of the study has been devoted to simulate the rock-to-water release of elements and their fate in the groundwaters interacting with metabasalts and serpentinites by means of two different reaction-path-modeling approaches. In the first approach, kinetic parameters of relevant minerals were taken from the geochemical literature and the progressive dissolution of metabasalts and serpentinites cropping out in Northern Calabria (Italy) was simulated by means of the EQ3/6 software package, version 8.0, adopting the Double Solid Reactant Method (DSRM). In the second approach, the whole-rock kinetic parameters, retrieved from the dissolution experiments on the metabasalt were used in the modeling exercise. The results of the two reaction-path-modeling approaches are in agreement with analytical data for natural waters but the second approach appears to be more accurate than the first one. The main lesson learned from this study is that the dissolution rates of individual minerals retrieved from the dissolution experiments of whole rocks are significantly different from those of separate minerals. This invalidate the assumption on the equality of these rates which is commonly adopted in geochemical modeling. These findings have important consequences on the understanding of the rock-to-water release of chemical elements and their fate in natural waters.Università della Calabri

Mobility of REE from a hyperacid brine to secondary minerals precipitated in a volcanic hydrothermal system: Kawah Ijen crater lake (Java, Indonesia)

info:eu-repo/semantics/publishe

Caratterizzazione idrogeochimica, isotopica e geologica delle aree termali della Calabria Settentrionale

Dottorato di Ricerca in Scienze della Terra, XXVII Ciclo, a.a. 2008-2011Università della Calabri

Fluoride Polluted Groundwaters in Calabria Region (Southern Italy): Natural Source and Remediation

Excessive ingestion of fluoride through the consumption of F−-rich drinking water could cause adverse effects to human health. For this reason, the WHO has fixed 1.5 mg/L as the maximum F- concentration for drinking water. In this work, a detailed geochemical characterization was performed to define the source of natural pollution of two groundwaters (samples Pc and Bg) coming from deep crystalline aquifers located in the Calabria region (southern Italy) and to define and optimize the most appropriate water treatment strategy. The samples were classified as a F− enriched NaHCO3 type of water. In particular, the F− concentrations observed were 30 mg/L and 8.9 mg/L for the Pc and Bg samples, respectively. Based on the acquired geochemical characterization knowledge, the groundwaters were treated by two thin-film composite NF membranes, namely SPR 10113 and SPR 10114 which have so far not been used for water defluoridation. It was found that the SPR 10114 membrane was able to guarantee water permeates with F− contents lower than the threshold value of 1.5 mg/L for both treated waters, whereas the fluoride content remained above the threshold value when the Pc sample was treated using the SPR 10113 membrane. The obtained permeates were characterized by a low ionic load and were not suitable for long-term consumption as drinking water. However, all of the produced waters did not need any further re-mineralizing processes for agricultural irrigation or other purposes