| Title | Multi-isotope tool (O, H, B, Sr) to distinguish salinity sources in a Mediterranean karstic aquifer (Murgia, Apulia, Southern Italy) |
| Abstract | Scientific literature widely reports the presence of saline and brackish water in sedimentary formations along the Mediterranean coastal area (Gilli, 2015). In Italy, examples are the Apennine foreland basin and the Apulian carbonate platform (Boschetti et al., 2011; Fidelibus et al., 2011). Marine water of Miocene or Plio-Pleistocene ages, trapped during regression/transgression events, underwent interactions with sediments and redox processes, during early- and late-state diagenesis, and mixe with the groundwater of meteoric origin to varying degrees.
In this study, 50 wells have been sampled from 2019 to 2021 (Frollini et al., 2022). A combined approach based on multi-isotopic (H, O, Sr, B) and chloride measures have been used to distinguish the sources of salinization in the Murgia coastal karst aquifer, located in Apulia, South-Eastern Italy. Measures of d18O and Cl and mixing calculations have been used to infer the saline contribution to the freshwater is of the order of 4-10%. The good alignments of the samples along the meteoric line in the of dD vs. d18O allowed us to distinguish two recharge areas. The crossed evaluation of 87Sr/86Sr and d11B, supported by geomorphological, hydrogeological, and lithological knowledge, allowed us to infer some important characteristics of the study aquifer such as different underground pathways, water/rocks interactions, and groundwater salinity sources. First, several samples, all collected within the NW sector, characterized by 87Sr/86Sr and d11B values around 0.7076 and +20? respectively, indicate extensive water/rock interactions which cause water to acquire the above isotopic composition of the local Mesozoic carbonate rocks. On the contrary, all the remaining samples indicate seawater modified to different degrees of water/rock interaction, in agreement with the end members reported by Fidelibus et al. (2011). The extensive multi-isotopic survey confirms that modern seawater is not the main source of salinity in the coastal Murgia aquifer, while a widespread presence of modified seawater characterizes the system. This work shows that a 4-5% proportion of modified seawater can be detected in fresh groundwater using isotopes and chloride and that B and Sr isotopes can support in assessing hydrological pathways and characterizing peculiar geochemistry of groundwater. Understanding salinization sources in coastal karstic aquifers is crucial for sustainable water resource management, given the increasing demand for good quality freshwater.
This research has been carried out within the frame of the VIOLA project developed by the IRSA-CNR. Isotopic analyses have been carried out at the lab Neptune Plus, Stable Isotopes, and Clean Room of the IGGCNR, Pisa. |
| Source | The Geoscience paradigm: Resources, Risks and future perspectives, Potenza, 19-21/09/2023 |
| Keywords | stable and radiogenic isotopescoastal aquiferssalinization |
| Year | 2023 |
| Type | Abstract in atti di convegno |
| Authors | Matteo Salvadori, Maddalena Pennisi, Rita Masciale, Eleonora Frollini, Stefano Ghergo, Daniele Parrone, Elisabetta Preziosi, Giuseppe Passarella |
| Text | 486713 2023 stable and radiogenic isotopes coastal aquifers salinization Multi isotope tool O, H, B, Sr to distinguish salinity sources in a Mediterranean karstic aquifer Murgia, Apulia, Southern Italy Matteo Salvadori, Maddalena Pennisi, Rita Masciale, Eleonora Frollini, Stefano Ghergo, Daniele Parrone, Elisabetta Preziosi, Giuseppe Passarella Geosciences and Earth Resources Institute, National Research Council IGG CNR , Pisa, Italy. Water Research Institute, National Research Council IRSA CNR , Bari, Italy. Water Research Institute, National Research Council IRSA CNR , Rome, Italy. Published version Congresso congiunto SIMP, SGI, SOGEI, AIV The Geoscience paradigm Resources, Risks and future perspectives Potenza 19 21/09/2023 Internazionale Contributo Scientific literature widely reports the presence of saline and brackish water in sedimentary formations along the Mediterranean coastal area Gilli, 2015 . In Italy, examples are the Apennine foreland basin and the Apulian carbonate platform Boschetti et al., 2011; Fidelibus et al., 2011 . Marine water of Miocene or Plio Pleistocene ages, trapped during regression/transgression events, underwent interactions with sediments and redox processes, during early and late state diagenesis, and mixe with the groundwater of meteoric origin to varying degrees. In this study, 50 wells have been sampled from 2019 to 2021 Frollini et al., 2022 . A combined approach based on multi isotopic H, O, Sr, B and chloride measures have been used to distinguish the sources of salinization in the Murgia coastal karst aquifer, located in Apulia, South Eastern Italy. Measures of d18O and Cl and mixing calculations have been used to infer the saline contribution to the freshwater is of the order of 4 10%. The good alignments of the samples along the meteoric line in the of dD vs. d18O allowed us to distinguish two recharge areas. The crossed evaluation of 87Sr/86Sr and d11B, supported by geomorphological, hydrogeological, and lithological knowledge, allowed us to infer some important characteristics of the study aquifer such as different underground pathways, water/rocks interactions, and groundwater salinity sources. First, several samples, all collected within the NW sector, characterized by 87Sr/86Sr and d11B values around 0.7076 and 20 respectively, indicate extensive water/rock interactions which cause water to acquire the above isotopic composition of the local Mesozoic carbonate rocks. On the contrary, all the remaining samples indicate seawater modified to different degrees of water/rock interaction, in agreement with the end members reported by Fidelibus et al. 2011 . The extensive multi isotopic survey confirms that modern seawater is not the main source of salinity in the coastal Murgia aquifer, while a widespread presence of modified seawater characterizes the system. This work shows that a 4 5% proportion of modified seawater can be detected in fresh groundwater using isotopes and chloride and that B and Sr isotopes can support in assessing hydrological pathways and characterizing peculiar geochemistry of groundwater. Understanding salinization sources in coastal karstic aquifers is crucial for sustainable water resource management, given the increasing demand for good quality freshwater. This research has been carried out within the frame of the VIOLA project developed by the IRSA CNR. Isotopic analyses have been carried out at the lab Neptune Plus, Stable Isotopes, and Clean Room of the IGGCNR, Pisa. Salvadori_et_al_Abstract Congresso SGI SIMP_POTENZA_2023 Estratto dal Book degli abstract Salvadori_et_al_Abstract Congresso SGI SIMP_POTENZA_2023.pdf Abstract in atti di convegno danieleparrone PARRONE DANIELE matteosalvadori SALVADORI MATTEO stefano.ghergo GHERGO STEFANO giuseppe.passarella PASSARELLA GIUSEPPE elisabetta.preziosi PREZIOSI ELISABETTA rita.masciale MASCIALE RITA maddalena.pennisi PENNISI MADDALENA |
