Papers by Giordano Montegrossi
Applied Geochemistry, 2009
A geochemical survey of thermal waters collected from submarine vents at Panarea Island (Aeolian ... more A geochemical survey of thermal waters collected from submarine vents at Panarea Island (Aeolian Islands, southern Italy) was carried out from December 2002 to March 2007, in order to investigate i) the geochemical processes controlling the chemical composition of the hydrothermal fluids and ii) the possible relations between the chemical features of the hydrothermal reservoir and the activity of the magmatic system. Compositional data of the thermal water samples were integrated in a hydrological conceptual model, which describes the formation of the vent fluid by mixing of seawater, seawater concentrated by boiling, and a deep, highly-saline end-member, whose composition is regulated by water-rock interactions at relatively high temperature and shows clear clues of magmatic-related inputs. The chemical composition of concentrated seawater was assumed to be represented by that of the water sample having the highest Mg content. The composition of the deep end-member was instead calculated by extrapolation assuming a zero-Mg end-member. The Na-K-Ca geothermometer, when applied to the thermal end-member composition, indicated an equilibrium temperature of approximately 300 °C, a temperature in agreement with the results obtained by gasgeothermometry.
Physico-chemical properties of quartz from industrial manufacturing and its cytotoxic effects on alveolar macrophages: the case of green sand mould casting for iron production
Journal of Hazardous Materials, 2016
Industrial processing of materials containing quartz induces physico-chemical modifications that ... more Industrial processing of materials containing quartz induces physico-chemical modifications that contribute to the variability of quartz hazard in different plants. Here, modifications affecting a quartz-rich sand during cast iron production, have been investigated. Composition, morphology, presence of radicals associated to quartz and reactivity in free radical generation were studied on a raw sand and on a dust recovered after mould dismantling. Additionally, cytotoxicity of the processed dust and ROS and NO generation were evaluated on MH-S macrophages. Particle morphology and size were marginally affected by casting processing, which caused only a slight increase of the amount of respirable fraction. The raw sand was able to catalyze OH and CO2(-) generation in cell-free test, even if in a lesser extent than the reference quartz (Min-U-Sil), and shows hAl radicals, conventionally found in any quartz-bearing raw materials. Enrichment in iron and extensive coverage with amorphous carbon were observed during processing. They likely contributed, respectively, to increasing the ability of processed dust to release CO2- and to suppressing OH generation respect to the raw sand. Carbon coverage and repeated thermal treatments during industrial processing also caused annealing of radiogenic hAl defects. Finally, no cellular responses were observed with the respirable fraction of the processed powder.
Reservoir modelling of deep geothermal systems: the examples of Guardia Lombardi
ABSTRACT In the framework of the VIGOR project, a characterization of medium enthalpy geothermal ... more ABSTRACT In the framework of the VIGOR project, a characterization of medium enthalpy geothermal resources was carried out in the Campania region (southern Italy), with a focus on the "Guardia dei Lombardi" area (Avellino). The VIGOR project started on the basis of an agreement between the Ministry of Economic Development and the Italian National Research Council, and it deals with the exploitation of innovative uses of geothermal energy in the so-called "regions of convergence" (Campania, Calabria, Puglia and Sicily). One of the main results of this research is the development of an integrated 3D geological model, which provides the base for a detailed assessment of possible geothermal exploitation of the carbonate reservoir. The preliminary results of our study suggest that "Guardia dei Lombardi" can be indicated as an interesting area for medium enthalpy geothermal exploitation, although the presence of a CO2 gas cap and the scaling capability of the deep fluids need to be carefully evaluated. The aim of this work is to give an estimation of a geothermal well productivity, in the case of a geothermal exploitation. The geothermal well that is thought to be more suitable in the Guardia dei Lombardi Area is named Bonito 1 Dir, a well with a measured temperature of 118 °C at 3,107m depth, which gives a corrected temperature of 138 °C with an error of 8 °C. The pressure was found to be nearly hydrostatic, with 266.9 bar at 2992.4 m depth, and the potential reservoir is hosted in the Mesozoic carbonate formation. According to hydraulic tests, we found that the permeability porosity product gives nearly 100 mD for the carbonatic formation. Since the matrix porosity is nearly 1% with 0.65 mD from core drilled tests, the result of the hydraulic test is to be related to a fractured system; in this case, there is no a clear relation among porosity and permeability, thus we had a sensitivity check on the possible porosity-permeability values of the system, keeping as a constrain the value obtained from the hydraulic test. From the 3D geological model we obtained the boundary of the carbonate formation hosting the geothermal reservoir, and we modelled the cases of both a single producing well and a geothermal doublet in order to give an estimation of the geothermal potential. Deposition of calcite in a formation may significantly reduce the inflow performance of geothermal wells producing brine with CO2-rich content. The key operational and reservoir parameters influencing the magnitude of impairment by calcite deposition were identified through the numerical modelling of the rate of calcite deposition and its effect on flow rate assuming idealized flow conditions. This is an important constrain for a well lifetime, especially in the case of a 138 °C well, because the power production requires a large fluid flow, and an encrustating fluid may severely affect the geothermal well performance. The results of the model, in terms of fluid flow at wellhead and scaling potential, will be available for an economic evaluation of the feasibility of geothermal exploitation of the Bonito 1 Dir well, in the Guardia dei Lombardi area.
The Menengai caldera is an elliptical depression with minor and major axes measuring about 8 and ... more The Menengai caldera is an elliptical depression with minor and major axes measuring about 8 and 12 km respectively, located near Nakuru, Kenya's Rift Valley. Geophysical investigations (micro-seismic monitoring, gravity and MT surveys), geological surveys, geochemical surveys (fumaroles sampling, soil gas surveys) and a soil temperature survey allowed Geothermal Development Company (GDC) to locate the first exploratory well MW-01 which intercepted a deep reservoir with temperatures exceeding 300°C, found beneath a shallower liquid-dominated reservoir at a temperature in the range 190-200°C. The exploratory and development drilling campaign, which is undergoing, provided the drilling of some 20 deep wells by December 2013 aimed at characterizing the deep reservoir properties, delineate the field extension and provide additional steam for power development. The geochemical data acquired with production well testing allowed not only to characterize the chemistry of the shallow aquifer and of the deep steam-dominated reservoir, but indicates also an 'intermediate temperature zone' that could be interpreted as a 'rim' of the deep reservoir. Surface exploration surveys and the findings derived from drilling, logging and testing of geothermal wells were used to build a 3D numerical model of the geothermal system natural state by means of the TOUGH2 reservoir simulator, supported by Petrasim 5.3 graphical interface. The numerical model was intended to check the consistency of the conceptual model, give a better picture of the reservoir thermodynamic conditions, and constrain the mass and heat flows through the system. Making in numbers the idea arisen in the conceptual model, the 3D natural state has been reconstructed by simulating the heating up due to a hot intrusion in a complex system. The complexity of the system arises in a particular structure consisting in a deep vapordominated high temperature reservoir just on top of the hot intrusion at temperatures higher than 300°C, separated from the shallower liquid-dominated reservoir (with temperatures ranging from 130 up to 210°C) by a relatively thin impermeable layer. The model was run to steady-state conditions, and calibrated against data obtained from geochemical investigations, well pressure and temperature profiles recorded under warm-up and flowing conditions, as well as available production test results. The details about the 3D model construction within TOUGH2 and Petrasim and the results of the simulated natural state are presented and discussed.
A geochemical atlas of the ground- and running waters of Arezzo (Tuscany, Italy)
Since 2000 a joint project between the Department of Earth Science of Florence and the Unit of En... more Since 2000 a joint project between the Department of Earth Science of Florence and the Unit of Environment and Health of the Municipality of Arezzo has allowed to geochemically characterise the superficial and ground waters of the municipal territory of Arezzo in order to establish the water quality and to investigate the main natural and anthropic processes responsible of their composition. The available geochemical data-base consists of more than 500 samples sites (90% of which are private wells and 7 and 3% are springs and ...
The present work aims to assess the hazard for human health related to CO 2 anomalous concentrati... more The present work aims to assess the hazard for human health related to CO 2 anomalous concentrations in air emitted from dry gas vents located in the NE area of Mt. Amiata volcano (Tuscany, central Italy). A geochemical multi-methodological approach is adopted to determine the composition and the flux rate of the gas discharges in order to establish (1) the origin of the gas vents and (2) the behaviour of the discharged gases in the areas surrounding the emission sites. The gas vents are hosted within subcircular morphological depressions (∅∼10-30 m), which likely originated by the collapse of cavities formed at shallow depth in the ground by dissolution of Triassic anhydrite formations and recent travertine deposits. CaCO 3 and CaSO 4 dissolution is mainly related to the underground circulation of CO 2 -rich fluids whose hydrological pattern is regulated by local and regional tectonics. The CO 2 -rich (up to 996,070 μmol/mol) gases tend to accumulate within the topographic lows, thus creating a sort of CO 2 ponds, and the knowledge of their evolution in time and space is important to evaluate the related hazard. Consequently, a conceptual model of CO 2 diffusion in air is developed to understand the dynamic of the CO 2 accumulation/dispersion process based on (1) a 24-h continuous measurement of the CO 2 flux from one of the main emission sites and (2) the recording of the main meteoric parameters, i.e. air temperature, wind direction and speed to check their influence. The results indicate that the threshold of CO 2 concentrations considered dangerous for the human health is frequently overcome. Moreover, when meteoric conditions, i.e. low wind and cloudy weather, did not allow a rapid dispersion of the gas phase emitted from the dry vents, CO 2 -rich clouds periodically overflowed the morphological depressions for several tens of meters without any significant mixing with air. On the basis of these considerations, the monitoring of the output rate from the main gas emissions, combined with the continuous control of the local meteorological parameters, may be considered an efficient procedure to mitigate the CO 2 hazard deriving from dry gas vents. An improvement of the protocol can be achieved in case of installations of CO 2 sensors located in the most sensitive areas and Water Air Soil Pollut: Focus (connected to a telemetry system able to transmit the data in real time to the closest Civil Defence centre. The CO 2 degassing sites can also represent a tourist attraction after the installation of suitable metallic fences and a proper campaign of information about these natural phenomena.
Modelling of mineral alteration in a natural CO2 res ervoir
The investigation of natural reservoirs as analogue of Carbon Capture and Sequestration (CCS) sit... more The investigation of natural reservoirs as analogue of Carbon Capture and Sequestration (CCS) site has a considerable impact in the reaction path modeling. It is indeed the main information able to predict the mineral evolution during and after CO2 injection in feasible CCS site. In the 80's, during oil exploration in central Italy, a high pressure CO2 reservoir was found while drilling the PSS1 well, located in the San Cassiano basin, Tuscany, Central Italy [1]. The CO2 reservoir has pressure higher than 600 bar and a temperature of about 115°C. The reservoir rocks at depth of about 3,700 m consist of altered volcanic rocks. According to ENI report (1983) the original rocks had an andesitic composition. The aim of this work is to assess a reaction path able to predict the reservoir rocks evolution from the pristine mineralogical composition to the present one. The mineralogical and mineral chemistry investigation was carried out on 6 drill core samples from the CO2 reservoirs h...
A geochemical survey of thermal waters collected from submarine vents at Panarea Island (Aeolian ... more A geochemical survey of thermal waters collected from submarine vents at Panarea Island (Aeolian Islands, southern Italy) was carried out from December 2002 to March 2007, in order to investigate (i) the geochemical processes controlling the chemical composition of the hydrothermal fluids and (ii) the possible relations between the chemical features of the hydrothermal reservoir and the activity of the magmatic system. Compositional data of the thermal water samples were integrated in a hydrological conceptual model, which describes the formation of the vent fluid by mixing of seawater, seawater concentrated by boiling, and a deep, highly-saline end-member, whose composition is regulated by waterrock interactions at relatively high temperature and shows clear clues of magmatic-related inputs. The chemical composition of concentrated seawater was assumed to be represented by that of the water sample having the highest Mg content. The composition of the deep end-member was instead calculated by extrapolation assuming a zero-Mg end-member. The Na-K-Ca geothermometer, when applied to the thermal end-member composition, indicated an equilibrium temperature of approximately 300°C, a temperature in agreement with the results obtained by gas-geothermometry.
We describe and discuss the origin of short-term (hours) variations in the concentration of sulfu... more We describe and discuss the origin of short-term (hours) variations in the concentration of sulfur species (SO 2 , H 2 S, and S 8 0 ) of crater fumaroles discharging at different temperatures (up to 410 • C) from five volcanic systems. Sulfur species can be investigated as an independent subsystem within the whole composition characterizing the fumarolic fluids, their chemical behavior being governed by similar laws in volcanic systems. The measured data are time dependent and show regular oscillations whose amplitude is by far larger than the analytical error. The agreement between the theoretical and the measured concentrations of SO 2 , H 2 S, and S 8 0 suggests that the formation of dissipative structures can explain the observed oscillations. Accordingly, the periodicity and the amplitude of the compositional oscillations were found to be in strong relation with the entropy excess of the non-equilibrium systems under investigation. The results of our study suggest that the amplitude and magnitude of short-term natural (self-induced) fluctuations of the sulfur species caused by the presence of the dissipative structures, and their comparison with the compositional variations of other subsystems, should be taken into serious account for geochemical monitoring purposes.
A new analytical method for the determination of the sulfur species (SO 2 , H 2 S, S 8 0 ) in vol... more A new analytical method for the determination of the sulfur species (SO 2 , H 2 S, S 8 0 ) in volcanic gases is proposed by revising, updating, and improving previous methods. The most significant advantages of the proposed procedure can briefly be summarized, as follows: (i) the reaction among sulfur species stops during the gas sampling by using preevacuated thorion-tapped vials with purified 0.15M Cd(OH) 2 in 4 M NaOH to favor the precipitation of H 2 S as CdS; (ii) all the sulfur species (SO 2 , H 2 S, S 8 0 ) are analyzed by ion chromatography, after conversion to SO 4 , which allows the detection limit to be lowered significantly with respect to the previous studies; (iii) appropriate aliquots from intermediate steps may be used to determine other species commonly present in volcanic gases such as CO 2 , HCl, HF, HBr, HI, and so forth; (iv) determination of all the other gas species is not jeopardized by the proposed method, i.e., one single vial can be used for analyzing the full chemical composition of a volcanic gas with the exception of NH 3 . Statistical parameters calculated from gas sampling data at the F5 crater fumarole in Vulcano Island (Aeolian Islands, southern Italy), suggest that the standard error of mean (s/ n) is higher for S (0.10), followed by SO 2 , H 2 S, and CO 2 (0.04, 0.038, and 0.028, respectively). SO 2 shows the higher variation coefficient (12.1%) followed by H 2 S, S, and CO 2 (5.7, 1.5, and 0.8%, respectively). Furthermore, if the time dependence of sampling is taken into account, the measured values, instead of fluctuating in a random manner, tend to follow systematic patterns, out of statistical control, possibly suggesting a sort of natural fluctuation of the volcanic system. Other crater fumaroles from volcanic systems located in different geodynamical areas (Hawaii, USA, El Chichon, Mexico, Poas, Costa Rica) have been analyzed as well.
The Tendaho geothermal system is characterized by the presence of a 50 km wide graben trending NW... more The Tendaho geothermal system is characterized by the presence of a 50 km wide graben trending NW-SE, dissected on its turn by a series of normal faults which form a sequence of secondary horst and graben. The graben basement is composed of fissural basalts with minor rhyolite of the Afar Stratoid Series, overlain by a 1,200-1,400 m thick sedimentary sequence, consisting of clastic products (mostly siltstone with some sandstone) and intercalated basalt lenses. The occurrence within the graben of continental crust thinning and opening phenomena, accompanied by upward mass and heat transfer, represents a favourable element for the development of important thermal anomalies. According to surface exploration surveys performed during the 1970s and early 1980s, exploration drilling was carried out in the Tendaho Rift, in Central Afar (Ethiopia), from October 1993 to June 1995. Three deep and three shallow wells were drilled in the central part of the Northern Tendaho Rift to prove the exi...
After a brief overview of the previous sampling and analytical techniques used for fumarolic volc... more After a brief overview of the previous sampling and analytical techniques used for fumarolic volcanic gases, highlighting advantages and drawbacks in both the field and the laboratory, this paper presents an alternative approach that encompasses a sampling equipment characterized by cheap, light, versatile and resistant materials and an analytical methodology to determine main, minor, trace and ultra-trace gas compounds.
Oxidation processes on volatile organic compounds (VOCs) in the cover soil of Case Passerini solid waste landfill (Florence)
Guidelines/Templates for full paper REVIEW OF ISOTOPIC AND FLUID INCLUSION DATA AT TENDAHO PROSPECT-ETHIOPIA
The Menengai caldera is an elliptical depression with minor and major axes measuring about 8 and ... more The Menengai caldera is an elliptical depression with minor and major axes measuring about 8 and 12 km respectively, located near Nakuru, Kenya's Rift Valley. Geophysical investigations (micro-seismic monitoring, gravity and MT surveys), geological surveys, geochemical surveys (fumaroles sampling, soil gas surveys) and a soil temperature survey allowed Geothermal Development Company (GDC) to locate the first exploratory well MW-01 which intercepted a deep reservoir with temperatures exceeding 300°C, found beneath a shallower liquid-dominated reservoir at a temperature in the range 190-200°C. The exploratory and development drilling campaign, which is undergoing, provided the drilling of some 20 deep wells by December 2013 aimed at characterizing the deep reservoir properties, delineate the field extension and provide additional steam for power development. The geochemical data acquired with production well testing allowed not only to characterize the chemistry of the shallow aquifer and of the deep steam-dominated reservoir, but indicates also an 'intermediate temperature zone' that could be interpreted as a 'rim' of the deep reservoir. Surface exploration surveys and the findings derived from drilling, logging and testing of geothermal wells were used to build a 3D numerical model of the geothermal system natural state by means of the TOUGH2 reservoir simulator, supported by Petrasim 5.3 graphical interface. The numerical model was intended to check the consistency of the conceptual model, give a better picture of the reservoir thermodynamic conditions, and constrain the mass and heat flows through the system. Making in numbers the idea arisen in the conceptual model, the 3D natural state has been reconstructed by simulating the heating up due to a hot intrusion in a complex system. The complexity of the system arises in a particular structure consisting in a deep vapordominated high temperature reservoir just on top of the hot intrusion at temperatures higher than 300°C, separated from the shallower liquid-dominated reservoir (with temperatures ranging from 130 up to 210°C) by a relatively thin impermeable layer. The model was run to steady-state conditions, and calibrated against data obtained from geochemical investigations, well pressure and temperature profiles recorded under warm-up and flowing conditions, as well as available production test results. The details about the 3D model construction within TOUGH2 and Petrasim and the results of the simulated natural state are presented and discussed.
Transport of thermal water from well to thermal baths
ABSTRACT The main problem in building a thermal bath is having a hot spring or a thermal well loc... more ABSTRACT The main problem in building a thermal bath is having a hot spring or a thermal well located in an appropriate position for customer access; since Roman age, thermal baths were distributed in the whole empire and often road and cities were built all around afterwards. Nowadays, the perspectives are changed and occasionally the thermal resource is required to be transported with a pipeline system from the main source to the spa. Nevertheless, the geothermal fluid may show problems of corrosion and scaling during transport. In the Ambra valley, central Italy, a geothermal well has recently been drilled and it discharges a Ca(Mg)-SO4, CO2-rich water at the temperature of 41 °C, that could be used for supplying a new spa in the surrounding areas of the well itself. The main problem is that the producing well is located in a forest tree ca. 4 km far away from the nearest structure suitable to host the thermal bath. In this study, we illustrate the pipeline design from the producing well to the spa, constraining the physical and geochemical parameters to reduce scaling and corrosion phenomena. The starting point is the thermal well that has a flow rate ranging from 22 up to 25 L/sec. The thermal fluid is heavily precipitating calcite (50-100 ton/month) due to the calcite-CO2 equilibrium in the reservoir, where a partial pressure of 11 bar of CO2 is present. One of the most vexing problems in investigating scaling processed during the fluid transport in the pipeline is that there is not a proper software package for multiphase fluid flow in pipes characterized by such a complex chemistry. As a consequence, we used a modified TOUGHREACT with Pitzer database, arranged to use Darcy-Weisbach equation, and applying "fictitious" material properties in order to give the proper y- z- velocity profile in comparison to the analytical solution for laminar fluid flow in pipes. This investigation gave as a result the lowest CO2 partial pressure to be kept in the pipeline (nearly 2.5 bar) to avoid uncontrolled calcite precipitation, and accordingly the pipeline path was designed. Non-linear phenomena that may originate calcite precipitation, such as phase separation and pressure waves, were discussed. The pipeline and the thermal bath are planned to be built next year.
Overview of the geochemical modelling on CO2 capture & storage feasibility studies in Italy
Deactivation of Palladium Electrocatalysts for Alcohols Oxidation in Basic Electrolytes
Electrochimica Acta, 2015
ABSTRACT Deactivation is one the main causes still preventing the full exploitation of palladium ... more ABSTRACT Deactivation is one the main causes still preventing the full exploitation of palladium electrocatalysts in alkaline direct alcohol fuel cells and the electrochemical reforming of alcohols. While often attributed to the adsorption of poisoning species generated in the alcohols oxidation, in the present work we demonstrate that deactivation is provoked by the formation of palladium oxides. A combined approach including i) fuel cell runs, ii) cyclic voltammetry and iii) near edge X-ray absorption spectroscopy has enabled us to draw the conclusions reported in the paper.
3D modeling of a fractured carbonate reservoir in the Southern Apennines (Campania, Italy): from geological data to resource assessment
Reservoir modelling of deep geothermal systems: the examples of Guardia Lombardi
ABSTRACT In the framework of the VIGOR project, a characterization of medium enthalpy geothermal ... more ABSTRACT In the framework of the VIGOR project, a characterization of medium enthalpy geothermal resources was carried out in the Campania region (southern Italy), with a focus on the "Guardia dei Lombardi" area (Avellino). The VIGOR project started on the basis of an agreement between the Ministry of Economic Development and the Italian National Research Council, and it deals with the exploitation of innovative uses of geothermal energy in the so-called "regions of convergence" (Campania, Calabria, Puglia and Sicily). One of the main results of this research is the development of an integrated 3D geological model, which provides the base for a detailed assessment of possible geothermal exploitation of the carbonate reservoir. The preliminary results of our study suggest that "Guardia dei Lombardi" can be indicated as an interesting area for medium enthalpy geothermal exploitation, although the presence of a CO2 gas cap and the scaling capability of the deep fluids need to be carefully evaluated. The aim of this work is to give an estimation of a geothermal well productivity, in the case of a geothermal exploitation. The geothermal well that is thought to be more suitable in the Guardia dei Lombardi Area is named Bonito 1 Dir, a well with a measured temperature of 118 °C at 3,107m depth, which gives a corrected temperature of 138 °C with an error of 8 °C. The pressure was found to be nearly hydrostatic, with 266.9 bar at 2992.4 m depth, and the potential reservoir is hosted in the Mesozoic carbonate formation. According to hydraulic tests, we found that the permeability porosity product gives nearly 100 mD for the carbonatic formation. Since the matrix porosity is nearly 1% with 0.65 mD from core drilled tests, the result of the hydraulic test is to be related to a fractured system; in this case, there is no a clear relation among porosity and permeability, thus we had a sensitivity check on the possible porosity-permeability values of the system, keeping as a constrain the value obtained from the hydraulic test. From the 3D geological model we obtained the boundary of the carbonate formation hosting the geothermal reservoir, and we modelled the cases of both a single producing well and a geothermal doublet in order to give an estimation of the geothermal potential. Deposition of calcite in a formation may significantly reduce the inflow performance of geothermal wells producing brine with CO2-rich content. The key operational and reservoir parameters influencing the magnitude of impairment by calcite deposition were identified through the numerical modelling of the rate of calcite deposition and its effect on flow rate assuming idealized flow conditions. This is an important constrain for a well lifetime, especially in the case of a 138 °C well, because the power production requires a large fluid flow, and an encrustating fluid may severely affect the geothermal well performance. The results of the model, in terms of fluid flow at wellhead and scaling potential, will be available for an economic evaluation of the feasibility of geothermal exploitation of the Bonito 1 Dir well, in the Guardia dei Lombardi area.
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Papers by Giordano Montegrossi