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Fluid Geochemistry Laboratory

The Fluid Geochemistry Laboratory uses various analytical instruments to determine the concentrations of major, minor, and trace chemical constituents in water and gas samples (as well as in solid samples), in order to study their content and distribution in natural systems.

The Laboratory

The Fluid Geochemistry Laboratory uses various analytical tools to determine the concentrations of major, minor, and trace chemical constituents in water and gas samples, in order to study their content and distribution in natural systems. Geochemical data are therefore an essential tool for identifying the origin of fluids (water and gas), investigating their evolution in the Earth's crust/surface (e.g., physical-chemical processes such as water-rock interaction, liquid-vapor separation, precipitation of mineral phases, mixing between different types of water), and identifying the origin and fate of contaminants.

The laboratory is primarily dedicated to determinations of natural waters (surface water, groundwater, or transitional-marine waters), fluids from natural occurrences in volcanic and/or geothermal systems, as well as geothermal brines and fluids produced by producing geothermal wells. Depending on the type and chemical composition of the samples to be analyzed, the most appropriate analytical methods are chosen to avoid interferences that may occur during the analyses (for example due to matrix effects), particularly for samples characterized by high TDS values.

Instruments

The laboratory is equipped with the following tools:

  • Perkin Elmer Optima 2000 DV Inductively Coupled Plasma Atomic Emission Spectrometer
  • Agilent 7800 Inductively Coupled Plasma Mass Spectrometer
  • Cromatografo ionico Metrohm 883 Basic IC Plus
  • Metrohm 905 Titrando Automatic Titrator
  • Jasco V-530 Spectrophotometer
  • Gascromatografi Agilent 7890A, Perkin Elmer Clarus 580, Varian 3900 (Detectors: TCD, FID, RGD)
  • Conducimetro da banco Radiometer Analytica CDM210
  • PH-metro da banco Eutech Instrument Ion 2700
  • Transfer line per accoppiamento GC-ICP-MS
ICP-OES Perkin Elmer Optima 2000DV
ICP-MS Agilent 7800
Metrohm 883 Basic IC Plus Ion Chromatograph
Metrohm 905 Titrando Automatic Titrator
Field equipment for water sampling
Jasco V-530 Spectrophotometer
(a) Perkin Elmer Clarus 580 coupled to the Perkin Elmer Autosystem XL GC; (b) Agilent 7890A
Agilent 7890A gas chromatograph interfaced with Agilent 7800 mass spectrometer

Staff and Contacts

The Fluid Geochemistry Laboratory is made up of a dedicated team of experts:

  • Dr. Matteo Lelli (CNR Researcher – Laboratory Manager)
  • Dr.ssa Brunella Raco (Prima Ricercatrice CNR)
  • Ilaria Baneschi (Prima Tecnologa CNR)
  • Evelina Dallara (Borsista di Ricerca CNR)

Contacts:
Phone: +39 050 6212321 (Dr. Matteo Lelli)
Email: matteo.lelli@igg.cnr.it 

Methods and Applications

Field activities
Field activities represent one of the most important steps in any study of natural systems since they are necessary to: a) measure parameters subject to change after sampling; b) appropriately treat the collected samples, stabilizing the dissolved ions or compounds for subsequent laboratory analyses.

Waters

Presso il laboratorio sono disponibili gli strumenti portatili essenziali per le attività di terreno: misurazione della temperatura, livello piezometrico, pH, conducibilità elettrica, potenziale redox e O2 disciolto. L’alcalinità totale viene sistematicamente determinata direttamente sul campo mediante titolazione acido-base, utilizzando un microdosimetro (quantità minima dosabile 1 µL) contenente HCl (a seconda del tipo di studio, altri parametri vengono determinati come ad esempio i solfuri). Esistono anche sonde specifiche (CTD) per il monitoraggio in continuo del livello dell’acqua in pozzi o piezometri, temperatura e conducibilità elettrica.

Field equipment for water sampling


Gas

Gas sampling from natural gas fields and/or geothermal wells is performed using the most suitable geochemical techniques. Field equipment allows for the collection of total fluid (using glass ampoules partially filled with 4.5N NaOH aqueous solution), condensed and separated vapor, and the non-condensable gas fraction (using the condenser—specifically for hydrogen and oxygen stable isotope analyses of the vapor fraction and for determining carbon monoxide and sulfur species, such as COS, in the non-condensable fraction). Dissolved gases are collected using glass ampoules equipped with a three-way high-vacuum stopcock. Field activities also include diffuse outgassing measurements (particularly for CO2 and CH4) using the accumulation chamber method. Flow measurements are performed in geothermal and volcanic areas (geothermal prospecting and volcanic activity monitoring), but also in areas characterized by the presence of faults/fractures that may represent preferential routes for the ascent of deep fluids.
Le attività sul campo includono anche misure di degassamento diffuso (in particolare per CO2 e CH4), utilizzando il metodo della camera di accumulo. Le misurazioni del flusso vengono eseguite in aree geotermiche e vulcaniche (prospezione geotermica e monitoraggio attività vulcanica), ma anche in aree caratterizzate dalla presenza di faglie/fratture che possono rappresentare vie preferenziale di risalita di fluidi profondi.

Laboratory analysis

The most well-known analytical techniques are used to determine the elemental/compound content of collected samples. However, depending on the nature and characteristics of the samples (particularly in terms of total dissolved solids content), different approaches can be used for sample preparation/treatment or instrument calibration that best suit the specific case. Typically, instruments are calibrated daily with single or multi-element external standards, which are analyzed for each batch of samples (typically 10 samples) to control instrument drift. For complex matrices, the addition method is preferable for at least some determinations.
The following chemical analyses are routinely performed on various types of liquid samples, such as freshwater (surface and groundwater), coastal and marine waters, thermal waters, geothermal/volcanic vapor condensates, and brines:

  • Na, K, Ca, Mg, Li, Sr, B, Fe, Mn, As, Al, Ba, Be, Cd, Cr, Cs, Cu, Co, Hg, Ni, Pb, Rb, Sb, Si, Sn and Zn, carried out with ICP-OES . ICP-MS.
  • F, Cl, NO3, NO2, Br, PO4 and SO4, carried out with IC.
  • F and NH3 at low concentrations, using Potentiometry-ISEWith the same instrumentation, chloride content (Argentometry), total and carbonate alkalinity (acid-base titrations) can also be determined.
  • Monomeric silica (SiO2), using UV-VIS Spectroscopy .

In gas samples, the following compounds are commonly determined in geothermal/volcanic fluids from natural occurrences and/or geothermal wells:
H2O, CO2, Ar, He, O2, N2, CH4, H2S, H2, CO (CH4, H2 and CO can also be determined at the ppm level), using Gas Chromatography.By coupling GC-ICP-MS, various trace sulfur species (such as H2S, COS, CH3-HS e CS2) present in gas samples can be determined .



Scientific Applications

The Fluid Geochemistry Laboratory's activities encompass various fields of application in Earth Sciences and environmental geochemistry. The main fields of application include geothermal exploration, geochemical activities aimed at mitigating volcanic risk, soil degassing, hydrogeochemistry and isotopic hydrology, environmental geochemistry, chemical speciation and the study of water-rock interactions, the identification of the source and fate of contaminants, and the development of instrumental prototypes for geochemical applications (e.g., development of a semi-continuous system for the determination of monomeric silica in geothermal brines, and a system for field measurements of total dissolved inorganic carbon (TDIC).

Scientific Projects and Interests

Main ongoing projects

  • Natural Hydrogen for Energy trAnsiTion (NHEAT, Prin PNRR)
  • Advancing the storage of anthropogenic CO2 emissions by understanding natural carbonation systems (STORECO2, Prin PNRR)
  • SuperHot geothermal – Integrated demonstration and Flow Testing (SHiFT, Horizon Europe).
  • GAS Emission in Pianosa islANd Project (GASEPIAN, IGG-CNR project)
  • New Geoindicators In Geothermal And Volcanic Sites Project (IGG-CNR Project)
  • The Fluid Geochemistry Laboratory has been selected for the European analytical network of the EPOS (European Plate Observing System) project.

Main Completed Projects

  • Geco– Geothermal Emission Control – (EU Horizon 2020)
  • Gemex – Cooperation in Geothermal energy research Europe-Mexico for development of hot enhanced (hot-EGS) and super-hot geothermal (SGHS) systems – (EU Horizon 2020);
  • Descramble “Drilling in dEep, Super-CRitical AMBients of continentaL Europe”” (EU Horizon 2020)
  • CNR’s Researches in Arctic: ISMOGLAC (ISotopic and physical-chemical MOnitoring of GLACial drainages and sea water in the Ny-Alesund area, Svalbard islands – 2015), ARDISCO (Arctic DISsolved CO2, Svalbard islands, 2018) and Arctic Earth Critical Zone, Svalbard islands – 2018);
  • Società Metropolitana Acque Torino (SMAT) Project – “Study of the impacts of climate change on underground water bodies for drinking purposes in the Turin area” (2016-2018);
  • Tuscany Region projects: “Implementation of an integrated multidisciplinary geological-environmental study in the Baccatoio stream basin” regarding the contamination of tap water with thallium; 2) “The Water Paths of Pianosa Island” (2015-2016); 3) “Origin of hexavalent chromium in Val di Cecina, Tuscany Region (Italy) (2008-2010);
  • Geothermal exploration in high enthalpy systems in Tanzania (Africa, 2016), Central and South America (2006-2013) and in Italian hydrothermal systems (2012-2016);
  • MINeral SCale Program – European FP7 Marie Curie Initial Training Network (2012-2015);
  • National project PRIN 2009 – “Study of the geochemical behavior of antimony: speciation in the aqueous solution and dispersion in abandoned mining areas”;
  • Programma quadro INGV-DPC 2005-2006: a) Progetto V3 “Research of active volcanoes, precursors, scenarios, hazard and risk”, Sub Project V3_1 Colli Albani; b) Project V5 “Diffuse degassing in Italy”;
  • INGV-DPC Framework Program 2005-2006: a) Project V3 “Research of active volcanoes, precursors, scenarios, hazard and risk”, Sub Project V3_1 Colli Albani; b) Project V5 “Diffuse degassing in Italy”;

Scientific Interests:

  • Geochemical exploration aimed at estimating geothermal potential and using geothermal/hydrothermal resources.
  • Monitoring of active and/or quiescent volcanic systems.
  • Sustainable management of water resources and assessment of their quality, study and identification of the sources and fate of contaminants.
  • Monitoring of the diffuse flux of gas from the soil to identify degassing structures (faults/fractures) and characterize (total emission and chemical and isotopic composition) of the emitted gases.
  • Effects of climate change on waters in Polar Regions.
  • Environmental monitoring at non-hazardous waste disposal sites.
  • Study of the thermodynamic properties of specific complex ions present in aqueous solution

Publications

  • Lelli M., Dallara E., Marini L., Bini G., (2026). Hydrothermal gas equilibria in the H2O-CO2-H2S-H2-CH4-CO-COS system. Geothermics, Vol.136, 130606, https://doi.org/10.1016/j.geothermics.2026.103606
  • Marini L., Principe C., Lelli M., (2025). Time changes during the last 40 years in the Solfatara magmatic–hydrothermal system (Campi Flegrei, Italy): new conceptual model and future scenarios. Solid Earth, 16, 551–578, https://doi.org/10.5194/se-16-551-2025.
  • Marini L., Vespasiano G., De Rosa R., Viccaro M., Principe C., Bloise A., Fuoco I., Lelli M., La Russa M., Caruso C.G., Gattuso A., Lazzaro G., Longo M., Guido A., Muto F., Russo L., Ciniglia F., Tsegaye A.A., Apollaro C., (2025). The geothermal resources of Vulcano Island (Aeolian Archipelago, Italy). Renewable Energy (in press.). https://doi.org/10.1016/j.renene.2025.123622
  • Marini L., Principe C., Lelli M., (2025). Closed-System Magma Degassing and Disproportionation of SO2 Revealed by Changes in the Concentration and δ34S Value of H2S(g) in the Solfatara Fluids (Campi Flegrei, Italy). Geosciences, Vol.15(5). DOI: 10.3390/geosciences15050162
  • Bini G., Lelli M., Caliro S., Ricci T., Mortensen A.K., Sigurðardóttir A.K., Santi A., Costa A., (2025). Gas equilibrium in the H2O-H2-CO2-CO-CH4 system for wet-steam geothermal-well fluids and their sources: A case study from Krafla, Iceland. Geothermics, Vol.130, 103322
  • Llano J., Vigni L.L., Agusto M., Brusca L., Caselli A., Chiodini G., D’Alessandro W., Lelli M., Tassi F., Vaselli O., Calabrese S., (2025). Hydrogeochemical processes governing the origin, mobility and transport of trace elements in the Domuyo Volcanic complex Geothermal system (Patagonia, Argentina). J. of Volcanol. Geoth. Res., Vol.462, 108322
  • Stefánsson A., Ricci A., Garnett M., Gunnarson-Robin J., Kleine-Marshall B.I., Scott S., Lelli M., Cardoso C.D., Pik R., Santinelli C., Ono S., Barry P.H., (2024). Isotopic and kinetic constraints on methane origins in Icelandic hydrothermal fluids. Geoch. Cosmochi. Acta, Vol.373, pp. 84-97
  • Massiot C., Adam L., Boyd E., Cary S.C., Colman D.R., Cox A., Hughes E., Kilgour G., Lelli M., Liotta D., Lloyd K., Marr T. (2024). CALDERA: a scientific drilling concept to unravel Connections Among Life, geo-Dynamics and Eruptions in a Rifting Arc caldera, Okataina Volcanic Centre, Aotearoa New Zealand. Scientific Drilling, Vol.33 (1), pp. 67-88
  • Granieri D., Mazzarini F., Cerminara M., Calusi B., Scozzari A., Menichini M., Lelli M. (2023). Shallow portion of an active geothermal system revealed by multidisciplinary studies: The case of Le Biancane (Larderello, Italy). Geothermics, Vol.108: 102616
  • Marini L., Principe C., Lelli M., (2022). The Solfatara Magmatic-Hydrothermal System – Geochemistry, Geothermometry and Geobarometry of Fumarolic Fluids. Advances in Volcanology, Springer Nature eds. ISBN 978-3-030-98470-0
  • Rizzello D., Armadillo E., Pasqua C., Pisani P., Principe C, Lelli M., Didas M., Giordan V., Mnjokava T., Kabaka K., Tumbu L., Marini L. (2022). Assessment of the Kiejo-Mbaka geothermal field by three-dimensional geophysical modelling. Geomechanical and Geophysical for Geo-Energy and Geo-Resources, Vol.8 (5): 143.
  • Lelli M., Agostini L., Monegato G., Cavazzini G., Fasson A., Giaretta A., Galgaro A., Doveri M. (2022). Fluid geochemistry of Lessini Mountain’s thermal area: New data from Caldiero, S. Ambrogio-Colà di Lazise and Sirmione hydrothermal districts (Verona-Brescia Provinces, Italy). Geothermics, 101, 102377
  • Lelli M., Kretzschmar T., Cabassi J., Doveri M., Sanchez-Avila J.I., Gherardi F., Magro G., Norelli F. (2021). Fluid geochemistry of the Los Humeros geothermal field (LHGF – Puebla, Mexico): New constraints for the conceptual model. Geothermics, vol.90 – 101983.
  • Barcelona H., Lelli M., Norelli F., Peri G., Winocur D. (2019). Hydrochemical and geological model of the Bañitos-Gollete geothermal system in Valle del Cura, main Andes Cordillera of San Juan, Argentina. Journal of South American Earth Sciences, Vol.96, 102378.
  • Ghezzi L., D’Orazio M., Doveri M., Lelli M., Petrini R., Giannecchini R. (2019). Groundwater and potentially toxic elements in a dismissed mining area: thallium contamination of drinking spring water in the Apuan Alps (Tuscany, Italy). Journal of Geochemical Exploration 197, 84-92.
  • Lelli M. and Raco B. (2017). A reliable and effective methodology to monitor CO2 flux from soil: The case of Lipari Island (Sicily, Italy). Applied Geochemistry 85, 73-85.
  • Cardellini C., Chiodini G., Frondini F., Avino R., Bagnato E., Caliro S., Lelli M., Rosiello A. (2017). Monitoring diffuse volcanic degassing during volcanic unrests: the case of Campi Flegrei (Italy). Scientific reports 7 (1), 1-15.
  • Ranaldi M., Lelli M., Tarchini L., Carapezza M.L., Patera A. (2016). Estimation of the geothermal potential of the Caldara di Manziana site in the Sabatini Volcanic District (central Italy) by integrating geochemical data and 3D-GIS modelling. Geothermics 62, 115-130.
  • Lelli, M., Grassi, S., Amadori, M., Franceschini, F. (2013). Natural Cr(VI) contamination of groundwater in the Cecina coastal area and its inner sectors (Tuscany, Italy). Environmental Earth Science, DOI: 10.1007/s12665-013-2776-2.
  • Barberi F., Carapezza M.L., Cioni R., Lelli M., Menichini M., Ranaldi M., Ricci T., Tarchini L. (2013). New geochemical investigations in Platanares and Azacualpa geothermal sites (Honduras). J. Volcanol. Geotherm. Res., vol. 257, pp. 113-134.
  • Naharro Rodrigo J., Nisi B., Vaselli O., Lelli M., Saldana R.,Clemente-Jul C., Perez del Villar L. (2013). Diffuse soil CO2 flux to assess the reliability of CO2 storage in the Mazarron-Ganuelas Tertiary Basin (Spain). Fuel, 114, 162-171.