Publication Date:
2021-01-07
Description:
The elemental fluxes and heat flow associated with large aquifer systems can be significant both at local and at
regional scales. In fact, large amounts of heat transported by regional groundwater flow can affect the subsurface
thermal regime, and the amount of matter discharged towards the surface by large spring systems can be significant
relative to the elemental fluxes of surface waters. The Narni-Amelia regional aquifer system (Central Italy)
discharges more than 13 m3 sec)1 of groundwater characterised by a slight thermal anomaly, high salinity and
high pCO2. During circulation in the regional aquifer, groundwater reacts with the host rocks (dolostones, limestones
and evaporites) and mixes with deep CO2-rich fluids of mantle origin. These processes transfer large
amounts of dissolved substances, in particular carbon dioxide, and a considerable amount of heat towards the
surface. Because practically all the water circulating in the Narni-Amelia system is discharged by few large springs
(Stifone-Montoro), the mass and energy balance of these springs can give a good estimation of the mass and
heat transported from the entire system towards the surface. By means of a detailed mass and balance of the
aquifer and considering the soil CO2 fluxes measured from the main gas emission of the region, we computed a
total CO2 discharge of about 7.8 · 109 mol a)1 for the whole Narni-Amelia system. Finally, considering the
enthalpy difference between infiltrating water and water discharged by the springs, we computed an advective
heat transfer related to groundwater flow of 410 ± 50 MW.
Description:
Published
Description:
182-196
Description:
2.4. TTC - Laboratori di geochimica dei fluidi
Description:
4.5. Studi sul degassamento naturale e sui gas petroliferi
Description:
JCR Journal
Description:
reserved
Keywords:
carbon dioxide degassing
;
heat flow
;
regional aquifer
;
04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration
;
04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
;
04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
