Geochemical Modeling of Water-Rock Interaction Processes in the Pollino National Park

This work is aimed at reconstructing the water-rock interaction processes controlling the geochemical characteristics of the shallow or relatively shallow groundwaters of the Pollino National Park, based on the data acquired for 105 water samples from local springs. Reaction path modeling of rock dissolution was carried out in a purely stoichiometric mode for the main lithotypes cropping out in the study area, that is, limestone, Mg-limestone, dolomite, serpentinite, Al-silicate fraction of calcschist, and carbonate fraction of calcschist. Reaction path modeling was carried out in a purely stoichiometric mode, considering the rocks of interest as materials of known stoichiometry and unknown thermodynamic properties. Calculations were carried out assuming a closed system for secondary solid phases whereas an open system was assumed for gases, O2(g) and CO2(g). Comparison of the results of geochemical modeling and the analytical data acquired for the groundwaters of the Pollino National Park shows that concentrations of major solutes, SiO2, Li, Al, and Fe of the different chemical types of waters, are explained by the dissolution of pertinent lithotypes. Moreover, the detected concentrations of Al, Cl, F, NO3, and SO4 are within the threshold values recommended by WHO.

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Geochemical modeling of chromium oxidation and treatment of polluted waters by RO/NF membrane processes

10.5194/egusphere-egu2020-19709 ◽

2020 ◽

Author(s):

Ilaria Fuoco ◽

Alberto Figoli ◽

Alessandra Criscuoli ◽

Rosanna De Rosa ◽

Bartolo Gabriele ◽

...

Keyword(s):

Reaction Path ◽

Geochemical Modeling ◽

High Mobility ◽

Water Type ◽

Rock Interaction ◽

Serpentine Minerals ◽

Path Modelling ◽

Reaction Path Modelling ◽

Polluted Waters ◽

Water Rock Interaction

Geogenic Cr(VI) contamination is a worldwide environmental issue which mainly occurs in areas where ophiolitic rocks crop out. In these areas Cr (VI) can reach high concentrations into groundwaters becoming highly dangerous for human health. Indeed Cr(VI) is recognized as highly toxic element with high mobility and bioavailability [1]. Due to these features, starting from July 2017, Italian government has lowered the Cr(VI) limit value for drinking water to 10 &#181;g/L. To improve the living standards in contaminated areas, it is needed (i) to understand the release and fate of contaminant during the water-rock interaction and (ii) to develop efficient remediation systems for natural polluted waters. In this regard, a complementary study on genesis and treatment of a Cr-rich groundwater coming from Italian ophiolitic aquifers was conducted. Reaction path modelling is a proven geochemical tool to understand the release of Cr and its oxidation from Cr(III) to Cr(VI) during the water-rock interaction. The generally accepted hypothesis of scientific community is that geogenic Cr(III) oxidation&#160; is driven by the reduction of trivalent and tetravalent manganese (Mn(III); Mn (IV)) [2] whereas in this work the role of trivalent Fe hosted in serpentine minerals was re-evaluated. Unlike Mn, Fe is the main oxidant present in suitable amount in these rocks. Literature data confirmed the presence of Fe(III) into serpentine minerals hence reaction path modelling was performed varying the Fe (III)/Fe(tot) ratio ranging&#160; from 0.60 to 1.00. The theoretical paths, reproduce the analytical concentrations of relevant solutes, including Cr(VI), in the Mg-HCO3 water type hosted in the ophiolitic aquifers of Italy [3]. With increasing of Fe(III)/Fe(tot) ratio in serpentine minerals, high Cr(VI) concentration hold into solution until high alkalinity values. In addition, the spring with the highest Cr(VI) content (75 &#181;g/L) was treated to lower its concentration below the threshold values. &#160;In this work membrane technologies were used as&#160; innovative method considering their many benefits, like the improvement of product quality without using chemicals [4]. A laboratory-scale set-up was used to carry out both Nanofiltration (NF) and Reverse Osmosis (RO) experiments. The experiments were conducted on different commercial membranes: one NF membrane module named DK (polyamide) and two RO membrane modules named AD (polyamide) and CD (cellulose).Tests were performed varying the operating pressures, and high Cr(VI) rejections (around 95%) were reached for all tested membranes, leading to a water containing Cr(VI) in concentrations below the threshold limits. The high flux, obtained already at lower operating pressures (27 L/m2h-10bar), combined with high selectivity towards Cr(VI) makes NF a favorable remediation option. The results obtained in this work are in line with the few data available in the literature for natural contaminated waters and there are quite promising for future scientific developments and application.&#160;&#160;References[1]Marinho B. A. et al., 2019. Environ Sci Pollut Res,&#160;26(3), 2203-2227[2]Oze C. et al., 2007. Proc. Natl. Acad. Sci. 104, 6544&#8211;6549[3]Apollaro C. et al., 2019. Sci. Total Environ. 660, 1459-1471[4]Figoli &#160;A. & Criscuoli &#160;A., 2017. Springer (Singapore); ISBN:9789811056215

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Genesis of Bonanza-style Ores in Uichang Area, Changwon City: Geochemical Interpretation by Reaction Path Modeling

Economic and Environmental Geology ◽

10.9719/eeg.2017.50.2.85 ◽

2017 ◽

Vol 50 (2) ◽

pp. 85-96

Author(s):

Seung-han Lee ◽

Sang-gun No ◽

Maeng-Eon Park

Keyword(s):

Reaction Path ◽

Path Modeling ◽

Reaction Path Modeling

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Geochemistry and reaction path modeling of the Beowawe hydrothermal system, Nevada: a barren end-member epithermal system

10.32469/10355/10551 ◽

2010 ◽

Author(s):

Mark Leatherman

Keyword(s):

Hydrothermal System ◽

Reaction Path ◽

Path Modeling ◽

Epithermal System ◽

Reaction Path Modeling

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Preliminary chemical characterization of groundwater in the Rome Municipality

Acque Sotterranee-Italian Journal of Groundwater ◽

10.7343/as-131-15-0158 ◽

2015 ◽

Author(s):

Luca Pizzino ◽

Daniele Cinti ◽

Monia Procesi ◽

Alessandra Sciarra

Keyword(s):

Chemical Elements ◽

Central Italy ◽

Chemical Characterization ◽

Mineral Waters ◽

Measured Temperature ◽

Large Variability ◽

Rock Interaction ◽

Interaction Processes ◽

Two Samples ◽

Water Rock Interaction

In summer 2015 a geochemical survey on groundwater was carried out at 31 sampling points (wells and piezometers) belonging to the new “Official monitoring groundwater network of Rome Municipality” (GMNR). The following parameters were measured: temperature, pH, electrical conductivity (i.e. salinity) and alkalinity; these data were used to compute partial pressure of CO2 (pCO2). Furthermore, samples were collected to characterise waters from a chemical point of view (major elements). To implement our data - base, chemical analyses of 6 CO2 - rich mineral waters of Rome were considered. Hydrochemical survey was mainly devoted to: i) classify waters in chemical facies; ii) investigate the main water-rock interaction processes governing the water’s chemical evolution, also affected by variable amounts of dissolved CO2 and iii) define the pCO2 level in groundwater in the frame of the knowledge so far acquired in the Tyrrhenian sector of central Italy.. Groundwater shows a dominant Ca-HCO3 chemistry; some samples belong to Na-HCO3, Na-Cl and CaCl2 hydrochemical facies. In the dominant facies waters show a large variability in the abundance of chemical elements, in their salinity (ranging between 0.46 e 3.83 g/l) and pH (in the interval 5.87-7.22); these features are mainly due to different water-rock interaction processes together with the presence of variable CO2 contents. Na-HCO3 waters show the lowest salinity values (TDS up to 0.32 g/l) and strongly alkaline pH; cation exchange processes with clays, causing Na enrichment and Ca and Mg removal from solution, can be invoked to justify the observed chemistry. Waters of the Castel Fusano Natural Reserve (CFNR) belong to the Na-Cl and Ca-Cl2 facies; the different chemistry reflects the geochemical processes going on in the considered coastal aquifers such as: i) mixing between freshwater and saline waters of marine origin (fossil waters, seawater intrusion) and ii) cationic exchanges with clays that make up the less permeable sediments of the area. Two samples of the CFNR group have Ca-HCO3 chemistry and represent aquifers not affected by salinization processes. Calculated pCO2 distribution is highly variable, from low (0.03 bar) to high values (0.72 bar), implying different CO2 input (and origin) in the studied aquifers. Highest levels of carbon dioxide are linked to the degassing processes going on in the Tyrrhenian sector of Central Italy.

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