Sardinia (Italy) represents a complex Mediterranean laboratory characterized by extreme geological heterogeneity. Despite an estimated availability of about1,500 Mm3 per year,, groundwater is still an underutilized resource, primarily due to a historical reliance on surface reservoirs. However, the escalating impacts of climate change, increasing water scarcity, and diverse anthropogenic pressures now necessitate a strategic shift toward a comprehensive knowledge-based management of these aquifers. Over the last decade, multi-isotopic tracers have been used to complement monitoring by constraining processes --recharge areas, flowpaths, mixing-- and identifying sources of salinity and contamination, thereby reducing conceptual uncertainty in aquifer models. This integrated methodology is effectively demonstrated through three critical case studies across the island. In the Muravera coastal plain, an extensive isotopic suite including Strontium (87Sr/86Sr), Boron (δ11B), Sulfate (δ34S-SO4, δ 18O-SO4), Tritium, and Helium was deployed to study seawater intrusion dynamics, successfully identifying flowpaths, and the origin of groundwater. In the Arborea Nitrate Vulnerable Zone (NVZ), the island’s primary agricultural district, the application of nitrate isotopes (δ15N-NO3, δ18O–NO3) coupled with stable water isotopes allowed for the precise fingerprinting of contamination within the Quaternary deposits. Finally, in the Portoscuso industrial district, one of the most polluted areas of Sardinia, characterized by high sulfate concentrations, δ34SSO4 and δ18OSO4 and water isotopes were utilized to discriminate between geogenic sulfate dissolution, legacy mining impacts, and active industrial contributions. These applications show that geochemical and isotopic analyses add process-based constraints that inform monitoring design and support management choices. They can help value groundwater and, considering quality and availability, guide allocation to appropriate uses (e.g., potable supply versus irrigation). They also support zoning of protection areas, vulnerability assessment, and prioritization of actions, including well protection, nitrate mitigation, and control of industrial discharges. This study was funded by Agreement POA FSC 2014–2020 - 16.12.2019 among the ex MATTM- DGSTA and River Basin Authority (AdB) of Sardinia - Service for the protection and management of water resources, water services and drought management - Regional Agency of the River basin district of Sardinia, Action 2.3.1 “Interventions to improve the quality of water bodies”. CUP F72G16000000001
Advancing knowledge for sustainable groundwater management in Sardinia: An integrated multi-isotopic approach
Stefania Da Pelo;Riccardo Biddau;Maria Chiara Porru
;Francesca Lobina;Fabrizio Antonio Piscedda;Vittorio Fancello;Antonio Maria Sessini;Claudio Arras;Mara Calia
2026-01-01
Abstract
Sardinia (Italy) represents a complex Mediterranean laboratory characterized by extreme geological heterogeneity. Despite an estimated availability of about1,500 Mm3 per year,, groundwater is still an underutilized resource, primarily due to a historical reliance on surface reservoirs. However, the escalating impacts of climate change, increasing water scarcity, and diverse anthropogenic pressures now necessitate a strategic shift toward a comprehensive knowledge-based management of these aquifers. Over the last decade, multi-isotopic tracers have been used to complement monitoring by constraining processes --recharge areas, flowpaths, mixing-- and identifying sources of salinity and contamination, thereby reducing conceptual uncertainty in aquifer models. This integrated methodology is effectively demonstrated through three critical case studies across the island. In the Muravera coastal plain, an extensive isotopic suite including Strontium (87Sr/86Sr), Boron (δ11B), Sulfate (δ34S-SO4, δ 18O-SO4), Tritium, and Helium was deployed to study seawater intrusion dynamics, successfully identifying flowpaths, and the origin of groundwater. In the Arborea Nitrate Vulnerable Zone (NVZ), the island’s primary agricultural district, the application of nitrate isotopes (δ15N-NO3, δ18O–NO3) coupled with stable water isotopes allowed for the precise fingerprinting of contamination within the Quaternary deposits. Finally, in the Portoscuso industrial district, one of the most polluted areas of Sardinia, characterized by high sulfate concentrations, δ34SSO4 and δ18OSO4 and water isotopes were utilized to discriminate between geogenic sulfate dissolution, legacy mining impacts, and active industrial contributions. These applications show that geochemical and isotopic analyses add process-based constraints that inform monitoring design and support management choices. They can help value groundwater and, considering quality and availability, guide allocation to appropriate uses (e.g., potable supply versus irrigation). They also support zoning of protection areas, vulnerability assessment, and prioritization of actions, including well protection, nitrate mitigation, and control of industrial discharges. This study was funded by Agreement POA FSC 2014–2020 - 16.12.2019 among the ex MATTM- DGSTA and River Basin Authority (AdB) of Sardinia - Service for the protection and management of water resources, water services and drought management - Regional Agency of the River basin district of Sardinia, Action 2.3.1 “Interventions to improve the quality of water bodies”. CUP F72G16000000001
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