Si comunica a tutti i soci ed ai nostri lettori del WEB che la Commissione grotte E.Boegan pubblica in anteprima i lavori del n. 53 della rivista Atti e Memorie.
01 – La fonte Pliniana (Como) – Ricerche storiche e nuove esplorazioni
The Fonte Pliniana (Pliny’s Spring) is a periodic variable spring, located on Lake Como shore (Lombardy, Northern Italy). Its rhythmic behaviour was mentioned by both Pliny the Elder and Pliny the Younger. The spring attracted interest in a large number of scholars from Renaissance to the modern age, first of all Leonardo da Vinci; some of them collected discharge data over time and tried to figure out the reason behind such an odd behaviour. Usually, the siphon model was involved, but also relations with local winds and rain were considered, and even an unlikely underground oscillating stone model was suggested. However, collected data were often deceptive and misleading. Finally, in 2010 the late physicist and caver Giovanni Badino succeeded in collecting a long-period flow rate data set. It shows clearly that the spring discharge is periodical when the flow rate is below a critical level. Over such a level, the periodicity becomes erratic and then disappears at all. Recently, preliminary inspections were performed in the spring, both swimming and with an ROV, in order to ascertain the basin morphology and the prosecution chances.
02 – Nuova grotta scoperchiata presso Roditti (SLO)
The degradation processes of carbonate rock give rise to the phenomenon of denudation, which is responsible for the continuous lowering of the topographic surface in a karst area. When the topographic surface intersects a cavity and removes its roof, a so-called unroofed cave (known as “brezstropna jama” in Slovene) is created. Despite being partially or almost completely transformed by degradation processes, or even completely filled with sediment deposits and debris, these caves serve as important evidence of the karst evolution in the area where they are found. Sometimes, these morphologies retain the original shape of the cave and can be identified both through field observation and by analyzing LIDAR images of the topographic surface. Through these investigative methods, in the transition zone between Matarsko Podolje to the south and Divaški Kras to the north, a torrential groove originating from the western foothills of the Brkini Mountains has been examined. It is completely developed in limestone and likely represents a relic of an ancient cavity, as evidenced by a substantial deposit of calcite with clear hypogean origin.
03 – Il magnesio nel complesso dolomitico del carso Triestino. Una rivisitazione.
The article describes the chemical characteristics of the waters that pass through the geological formation known as the “dolomite member” of the Karst near Trieste.
04 – Hydrogeological relations between the karst aquifer of Gradisca city and the phreatic aquifer of Isonzo/Soča river (ITALY)
As known, north-western part of the Classical Karst hydrostructure recharge comes mainly from losses of the Isonzo/Soča river and from autogenic recharge due to the diffuse infiltration on the Karst plateau. In the High Plain of Isonzo, in right-bank of the Isonzo river, there is the isolated limestone spur of the city of Gradisca with some karst cavities intercepting the water table. Gradisca is located in a geological framework given by the contiguity of phreatic aquifers, karst aquifers and aquitards. To get more information a CTD-Diver coupled to a Baro-Diver probe have been installed in the Pozzo dei Frari in Gradisca (Italy). To evaluate aquifer recharge variations, groundwater levels have been compared with Isonzo and Vipacco river discharge and with meteorological data. Mean EC values (electrical conductivity) compared with the rapports of bibliographic data indicate that the average contribute of Isonzo river to the recharge of this area of the aquifer is about 75%. The observed inverted groundwater temperature trend (with maximum values reached in November/December and minimum values in June/July) respect air temperature and Isonzo river temperature could be due to the recharge from Isonzo river (characterized by cold waters) that prevails in low level conditions. Analyzing the trend of EC over time, usually after a relevant level increase EC initially decreases and then rises indicating a piston flow effect, index of mobilization of more mineralized waters. The comparison with the main chemical parameters of the groundwater of the Pozzo dei Frari and the phreatic waters in the wells of the High Isonzo Plain confirms this relationship. In this hydrogeological framework it is therefore justified to consider that the karst aquifer of the High Plain of Isonzo area, including Gradisca with its karst cavities, is mostly affected by waters of Isonzo origin.
05 – Metodo multidisciplinare per riconoscere le grotte ipogeniche sulfuree
In the last two decades sulfuric acid caves have been reported in several areas of the world including North America, Central America, South America, South Africa, Europe, Asia, and Papua New Guinea. Italy hosts ~ 25% of the worldwide active and inactive sulfuric acid caves, thanks to its variegated geological terrain dominated by soluble rock. Here we report on the multidisciplinary method based on geomorphological observation, mineralogical association, geochemical and microbiological characterization useful to discriminate this peculiar hypogene speleogenesis. We think the article can be helpful for all italian cavers who want to search for new sulfuric acid caves.
06 – Congeria in the Dinaric karst: conservation and scientific study of a unique cave-dwelling bivalve genus
Congeria, one of the few extant genera of cave-dwelling bivalve mollusks, is endemic to the Dinaric Karst and currently comprises three distinct species with highly fragmented distributions, facing serious threats of extinction. Here we highlight the unique life history traits exhibited by Congeria and discuss the potential of ongoing and future scientific research in addressing the critical challenges associated with its conservation. The subterranean waters of the Karst represent a highly stable yet vulnerable ecosystem that has been significantly impacted by human activities over the past few decades. Hydrotechnical projects have notably reduced water flow to underground habitats that are essential for the reproduction and survival of Congeria, leading to habitat loss and severe population declines in several areas. These challenges, together with water pollution, intensive agriculture and tourism, are projected to cause further population decreases in the coming decades, exacerbated by inadequate regulatory measures and our limited understanding of the biology of these bivalves. Scientific advancements, which include the recently completed sequencing of the genome of C. kusceri, have the potential to provide critical insights into previously unexplored aspects of Congeria biology, unveiling the molecular mechanisms underlying its adaptive success in this challenging environment. Such research may offer a platform for an improved understanding of the factors underpinning the adaptation of Congeria to the subterranean environments and a comprehensive assessment of the genetic health, demographic history and resilience of the three extant species in the face of habitat alterations. .