The use of oxygen-18 and deuterium in the water dynamics assessment in the Quaternary volcanic structure of Mount Vulture, Southern Italy

The Quaternary caldera of Mount Vulture, Southern Italy, hosts two small lakes, Lago Piccolo (0.16 km2, 38 m deep) and Lago Grande, which are interconnected by a narrow channel and have a permanent emissary. Several springs gush out along the slopes and inside the caldera. Our objective is to assess the major flow paths of groundwater in the Quaternary volcanic structure by means of the isotopic composition and the main physical-chemical parameters (pH, temperature and electrical conductivity) of water. This investigation is a follow-up of a previous study, whose conclusions are revisited and updated by sampling a larger number of sites. The lakes were sampled at different depths to study the unusual water stratification, particularly evident in Lago Piccolo, resulting from recharge by bottom springs and surface heavy isotope enrichment by evaporation. Twenty-eight spring samples, with different chemical characteristics, allow establishing the isotopic gradient and recharging altitude. (author)