| Title | A multi-isotope (O, H, B, Sr) approach for identifying salinity contamination along the coastal sector of Murgia aquifer (Apulia, Southern Italy) |
| Abstract | The analysis of pressures and impacts on the Apulian aquifers, as required by the EU WFD, has evidenced
physical and chemical parameters related to groundwater salinization, particularly along the coastal strip.
Predisposing factors such as lithology, tectonic evolution, aquifer over-exploitation (Passarella et al., 2017),
and the ongoing climate change are various. Therefore, distinguishing natural from anthropogenic sources
of salinization becomes a fundamental issue for assessing the aquifer's chemical status. In this framework,
isotopic measures of O, H, B, and Sr, suitably support distinguishing different sources of salinity, water-rock
interaction processes, and the origin of the water molecules (Pennisi et al., 2006). This study focuses on the
coastal sector of the Murgia aquifer located on the Adriatic side of the Apulia region (south Italy). It is made
up of several hundred-meter-thick Mesozoic calcareous and calcareous-dolomite rocks affected by fracturing
and karst phenomena. The aquifer is confined and characterized by irregular geometry. Groundwater flows to
the sea where it rises in numerous coastal springs. Paleo-seawater as an additional source of salinity has been
suggested by previous studies.
87 Sr/86Sr, 11B/10B, (expressed as ?11B permil), ?18O, ?2H determined with overall chemistry in about
50 samples collected in autumn 2019 in the study area, range from 0.70768 to 0.70884, from +15.3? to
+43.0?, from -7.78? to -3.40? and from -49.50? to -23.30?, respectively. The coupled chemical and
isotopic approach evidenced that different mixing processes concur in the water, highlighting hydrogeologic
zoning and complex groundwater circulation patterns. Some samples reveal Sr and B isotopic compositions
typical of the local Cretaceous carbonate rocks implying a prolonged water-rock interaction. Chemistry and
isotopes in 6 samples, where chlorine ranges from 3162 to 9684 mg/L indicate a significant contribution from
modern seawater. Water>s intermediate compositions are explained by a different mixing degree of known
endmembers, such as meteoric, marine, and rock-interacting water. ?11B values, 87 Sr/86Sr ratios, and Cl, B, and
Sr contents seem to exclude the contribution of fossil seawater to the studied groundwater. Further studies on
high conductivity samples are ongoing to better detail the zoning based on the isotopic and hydrogeological
characteristics and to confirm or deny the occurrence of fossil marine waters. |
| Source | GEOLOGY WITHOUT BORDERS - 90° Congresso della Società Geologica Italiana, Trieste, 14-16 settembre 2021 |
| Keywords | salinizationboron isotopescoastal aquiferstrontium isotopesMurgiapaleo-seawaterwater-rock interaction. |
| Year | 2021 |
| Type | Abstract in atti di convegno |
| Authors | Salvadori Matteo, Frollini Eleonora, Ghergo Stefano, Masciale Rita, Parrone Daniele, Passarella Giuseppe, Preziosi Elisabetta, Pennisi Maddalena. |
| Text | 483666 2021 salinization boron isotopes coastal aquifer strontium isotopes Murgia paleo seawater water rock interaction. A multi isotope O, H, B, Sr approach for identifying salinity contamination along the coastal sector of Murgia aquifer Apulia, Southern Italy Salvadori Matteo, Frollini Eleonora, Ghergo Stefano, Masciale Rita, Parrone Daniele, Passarella Giuseppe, Preziosi Elisabetta, Pennisi Maddalena. National Research Council, Water Research Institute IRSA Bari BA , Italy National Research Council, Water Research Institute IRSA Montelibretti RM , Italy National Research Council, Geosciences and Earth Resources Institute IGG Pisa PI , Italy Published version https //doi.org/10.3301/ABSGI.2021.03 GEOLOGY WITHOUT BORDERS 90° Congresso della Societa Geologica Italiana Trieste 14 16 settembre 2021 Internazionale Contributo The analysis of pressures and impacts on the Apulian aquifers, as required by the EU WFD, has evidenced physical and chemical parameters related to groundwater salinization, particularly along the coastal strip. Predisposing factors such as lithology, tectonic evolution, aquifer over exploitation Passarella et al., 2017 , and the ongoing climate change are various. Therefore, distinguishing natural from anthropogenic sources of salinization becomes a fundamental issue for assessing the aquifer s chemical status. In this framework, isotopic measures of O, H, B, and Sr, suitably support distinguishing different sources of salinity, water rock interaction processes, and the origin of the water molecules Pennisi et al., 2006 . This study focuses on the coastal sector of the Murgia aquifer located on the Adriatic side of the Apulia region south Italy . It is made up of several hundred meter thick Mesozoic calcareous and calcareous dolomite rocks affected by fracturing and karst phenomena. The aquifer is confined and characterized by irregular geometry. Groundwater flows to the sea where it rises in numerous coastal springs. Paleo seawater as an additional source of salinity has been suggested by previous studies. 87 Sr/86Sr, 11B/10B, expressed as 11B permil , 18O, 2H determined with overall chemistry in about 50 samples collected in autumn 2019 in the study area, range from 0.70768 to 0.70884, from 15.3 to 43.0 , from 7.78 to 3.40 and from 49.50 to 23.30 , respectively. The coupled chemical and isotopic approach evidenced that different mixing processes concur in the water, highlighting hydrogeologic zoning and complex groundwater circulation patterns. Some samples reveal Sr and B isotopic compositions typical of the local Cretaceous carbonate rocks implying a prolonged water rock interaction. Chemistry and isotopes in 6 samples, where chlorine ranges from 3162 to 9684 mg/L indicate a significant contribution from modern seawater. Water>s intermediate compositions are explained by a different mixing degree of known endmembers, such as meteoric, marine, and rock interacting water. 11B values, 87 Sr/86Sr ratios, and Cl, B, and Sr contents seem to exclude the contribution of fossil seawater to the studied groundwater. Further studies on high conductivity samples are ongoing to better detail the zoning based on the isotopic and hydrogeological characteristics and to confirm or deny the occurrence of fossil marine waters. Abstract in atti di convegno danieleparrone PARRONE DANIELE eleonorafrollini FROLLINI ELEONORA matteosalvadori SALVADORI MATTEO stefano.ghergo GHERGO STEFANO giuseppe.passarella PASSARELLA GIUSEPPE elisabetta.preziosi PREZIOSI ELISABETTA rita.masciale MASCIALE RITA maddalena.pennisi PENNISI MADDALENA TA.P04.005.008 Integrazione di metodologie per il monitoraggio e la modellizzazione per la gestione delle risorse idriche |
