Hydrogeology and geochemistry of the sulfur karst springs at Santa Cesarea Terme (Apulia, southern Italy)

Abstract

This work describes the geochemical and hydrogeological characteristics of Santa Cesarea Terme, an active sulfuric acid speleogenetic system located along the Adriatic coastline (Apulia, southern Italy). It represents a very peculiar site, where rising thermal and acidic waters mix with seawater creating undersaturated solutions with respect to CaCO3, able to dissolve and corrode limestone and create caves. The Santa Cesarea Terme system is composed of four caves: Fetida, Sulfurea, Gattulla, and Solfatara. Hypogene morphologies and abundant deposits of native sulfur (especially in Gattulla Cave) and sulfate minerals are present in these caves. Fetida and Gattulla caves were investigated primarily because they are easily accessible throughout the whole year through artificial entrances, the other caves being reachable only from the sea. Geochemical analysis of water, monitoring of cave atmosphere, and measurement of the stable isotopes of S, O, and H helped to identify the main processes occurring in this complex cave system. In particular, changes in Ba2+ and Sr2+ concentration allowed for the identification of two main domains of influence, characterized by marine and rising acidic waters.

Typology and hydrogeochemistry of karst springs in the southern coast of Albania

“…Many sites along the Adriatic and Ionian coasts are severely affected by seawater intrusion phenomena. This particularly occurs in low topography karst areas and in peninsulas, such as in Salento, southern Apulia (Tulipano 2003;Cotecchia 2014;Masciopinto and Liso 2016;D'Angeli et al 2021), in Slovenia and Croatia (Ravbar and Kovacic 2015), in Greece (Kalioras and Marinos 2015), and in Turkey (Bayari et al 2011;Günay et al 2015).…”

Karst Brackish Springs of Albania

“…This type of drainage is characteristic of high-permeability karst aquifers [12,60], in direct contact with the sea, and is also typical of other Mediterranean settings [61][62][63][64][65][66][67][68][69][70]. In particular, along the Adriatic Sea several springs and sinkhole features associated with mixing between freshwater and sea water characterize the Apulian coastlines [71][72][73][74][75][76]. This is also the case in most of the southern rocky coast of Albania where distributed drainage is spread in the three areas of Karaburun, Palasë-Qeparoi, and Ksamil-Gjuza (Figure 1) [28,77,78].…”

Dominance of Arcobacter in the white filaments from the thermal sulfidic spring of Fetida Cave (Apulia, southern Italy)

“…The microbial communities featuring Fetida Cave water are characterized by the presence of abundant floating white filaments. Their composition is related with the constant mixing between the thermal sulfidic fluids, rising from below, and seawater entering from outside that leads to variable contents of dissolved H 2 S along the cave (D'Angeli et al, 2021). The purpose of the present work is to extend the knowledge on the microbial communities composing white filaments in this unique SAS cave environment.…”

“…The present work is focused on the analysis of white filaments from Fetida Cave, a still active sulfuric acid cave opening at sea level and located in Santa Cesarea Terme, southeastern Salento (Apulia region, Southern Italy) (D'Angeli et al, 2019b(D'Angeli et al, , 2021 (Fig. 1).…”