The dissolution-corrosion (DC) is one of the most important key factors for the understanding of karst speleogenesis. Dissolution can be measured using tablets, balancing weight-loss/gain during the exposure in cave. In sulfuric acid environments, the oxidation of H2S is the most important process inducing speleogenesis (from here on, sulfuric acid speleogenesis is indicated as SAS). Here, the exposed surface of carbonate rocks is actively corroded by sulfuric acid (H2SO4). In aerate settings, CaCO3 can be easily replaced by CaSO4·2H2O, the most common SAS by-product, and produces an initial weight gain. The understanding of dissolution-corrosion (DC) rate in active SAS systems is a very important issue that can help in evaluating the speleogenetic stages of a cave, and in correlating them with landscape evolution, as demonstrated by previous studies carried out in the Grotta del Fiume at Frasassi, central Italy. Italy hosts 25 % of the known worldwide SAS caves, and some of them are still-active. In some of these, especially in those located in southern Italy, dissolution-corrosion rate studies started at the end of the 2015-beginning of 2016, and will continue until the beginning of 2021 (for a total of five whole years), to have a better distribution of weight loss/gain rates. The SAS systems under investigation are Ninfe Cave and Sibarite spa (in Calabria), Fetida Cave (Apulia), and Acqua Fitusa Cave (Sicily). Carbonate and gypsum tablets, 28 cm3, with a mean initial weight of 74 g, have been placed in the cave atmosphere, underwater, and at the interface zone. DC measurements showed interesting results, and demonstrated environmental parameters to be the essential controls in weight loss/gain rate. We observed that at the beginning of the experiment, DC was faster in underwater conditions, whereas during the last period of monitoring (after 582 days of permanence in cave) the dissolution at the interface zone increased, becoming even greater than the rate observed in subaqueous conditions.
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|Titolo:||Limestone and gypsum tablet weight loss in sulfuric acid speleogenetic caves of Southern Italy|
|Data di pubblicazione:||2019|
|Appare nelle tipologie:||4.2 Abstract in Atti di convegno|