Hydrogeochemistry and Isotopic Composition of Waters in the Renella Cave (Central Italy): New Insights into Groundwater Dynamics

This article presents data from monthly monitoring carried out on cave and stream watersbelonging to the Renella Cave karst system from September 2020 to April 2022. Additionally, olddata pertaining to cave waters from previous published work are discussed. The aim is to develop adataset for future climatic and hydrological studies on the Renella Cave and its surface recharges.Water samples were collected and analyzed for major ions, ?18O and ?2H, on water molecules. Thecave sump water level, water temperature, and electrical conductivity were continuously measuredand compared to the precipitation data. Additionally, air temperature and pressure inside and outsidethe cave were also monitored. The classification based on the Piper-Hill diagram indicated that bothstream and cave waters belong to the bicarbonate-alkaline earth hydrochemical facies, indicating thattheir chemism is essentially determined by the dissolution of the Grezzoni Fm. Isotopic data suggestthat both stream and cave waters have a meteoric origin, and their variability mainly depends onunderground homogenization. Hydrogeochemistry, isotopic composition, and the monitoring dataallowed a deeper understanding of the cave karst system, and identified an underground circulationnetwork that is fragmented into independent parts.