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una sintesi dei risultati ottenuti da due distinti traccimenti in tre cavità della zona del monte Bernadia

The Cansiglio-Cavallo plateau is a limestone massif shared between the Italian regions of Veneto and Friuli-Venezia Giulia (northeastern Italy). The area is characterized by a high density of dolines and groundwater circulation is known to occur through very deep karst conduits. Three main springs (Molinetto, Santissima and Gorgazzo) located along a 4 km front on the southeastern margin of the massif are the main outlets of this karst aquifer, discharging a global mean annual flow rate of 11 m3/s and giving origin to the Livenza river. These are the second most important springs of the Alps in terms of flow rate and represent a valuable and easily accessible resource for drinkable water and other economic activities (e.g. fish farming). The hydrogeology of this karst area is still poorly known, also due to the common lack of groundwater flow rates suitable for dye tracer injection inside the many cave systems of the area. A dye tracing experiment in 2008 showed a connection between one of the major cave systems named Abisso del Col de la Rizza with the springs Santissima and Molinetto. Instead, the tracer injection in the other major cave system (Bus della Genziana) did not give positive results in any of the springs. In order to enhance our knowledge on the recharging areas of the springs and their hydrogeological connections with the main local caves, a cave-to-spring multitracer test was carried out in late spring 2016, by using three different fluorescent tracers. This was preceded by preparatory geological, hydrodynamic and hydrochemical investigations carried out in the area since spring 2015, which allowed collecting useful information for the setup of the tracer test. One of the underground rivers in the Bus della Genziana cave, the Abisso del Col de la Rizza cave and Fessura della Tosca cave were used as tracer injection points. Prior to injection, charcoal detectors were emplaced in the main monitoring points (caves and springs), while the three main springs were equipped with GGUN-FL fluorimeters. The hydrogeological study gave the following results: 1) new detailed information was collected on the geological and tectonic structure of the plateau; 2) the discharge rates of the three main springs were monitored and reliable h/Q rating curves were reconstructed; 3) a water budget for the entire karst area was calculated based on all available hydrological data; 4) groundwater geochemistry and the trends of physico-chemical parameters allowed understanding the discharging behavior of the system with respect to different recharge conditions; 5) the multitracer test allowed to better define the recharge areas of the three springs and the effective groundwater flow velocities in different sectors of the massif.

Sono presentati e discussi alcuni dei principali risultati del progetto di ricerca nazionale (PRIN). Speleotemi di alcune grotte scelte dell’Italia settentrionale, centrale e meridionale sono stati studiati con diverse tecniche e datati in spettrometria di massa con il metodo U/Th. In generale, la velocità di accrescimento dopo aver raggiunto una massima velocità durante la prima parte dell’Olocene decresce sensibilmente. Si può notare come esista un’interrelazione tra temperatura media della grotta e velocità di accrescimento. I cambiamenti del δ13C mostrano un trend generalmente negativo, soprattutto durante il Tardiglaciale e la prima parte dell’Olocene. Soltanto durante gli ultimi 2 ka si nota un’inversione verso valori tendenzialmente positivi. I cambiamenti nel δ18O degli speleotemi delle grotte Savi (TS) e Frasassi (AN) mostrano un trend prevalentemente positivo durante l’Olocene (valori compresi tra -5 e -10 ‰); al contrario il trend della stalagmite delle Grotta di Carburangeli (PA) è negativo. La luminescenza eccitata da laser degli speleotemi della grotta Savi mostra i suoi massimi nella prima parte dell’Olocene, probabilmente in relazione con lo sviluppo di suoli forestali. I valori più bassi sono quelli degli ultimi 1,5 ka. Da uno sguardo d’insieme, i dati sono in accordo con le conoscenze sui cambiamenti climatici in Italia durante il Tardiglaciale e l’Olocene. Emergono tuttavia alcuni dati problematici che suggeriscono ulteriori ricerche. Some of the main result of a national research project (PRIN) are here presented and discussed. The speleothems of some selected caves of northern, central and southern Italy have been studied with different techniques and dated by U/Th mass spectrometry. In general, the growth rate shows a decrease during the middle and upper Holocene in all caves. A relationship between the annual growth rate and the cave mean annual temperatures seems evident. The δ13C changes show a generally negative trend, with a main slope during the Lateglacial and the fi rst part of Holocene. Only during the last 2 ka an inversion towards more positive values is occurring. The δ18O changes of the speleothems from Savi (TS) and Frasassi (AN) cave, show a mainly positive trend during the Holocene (range of values between -5 and -10‰); on the contrary the trend of Carburangeli cave (PA) stalagmite is negative. The laser induced luminescence of the spelothems of Savi cave shows the highest values during the fi rst part of the Holocene probably infl uenced by the soil and forest development. The lowest values are those of the last 1.5 ka. From an overall view, these data seem to fi t with the present day knowledge of the climatic and environmental changes of Italy. Nevertheless some problematic aspects arise suggesting further research work.

Although the Cordillera de la Sal, close to San Pedro de Atacama (Chile), is one of the driest places on Earth, it contains extensive cave systems that have developed in halite. A detailed morphological study of these caves, combined with 16 AMS radiocarbon ages on wood and bone fragments recovered from cave ceilings and diamictons, have allowed us to define when these systems formed and when sediments were emplaced. The sometimes huge cave passages appear to have formed in less than 2000 years by a succession of short-lived flash floods, probably after single extreme rain events.

Interesting salt caves were recently discovered in one of the driest places on earth, the Atacama desert (Chile). The caves, sometimes over 1 km long, host important and widespread active halite speleothems among which peculiar macrocrystalline stalactites, which are here described for the first time. The macrocrystalline stalactites consist of a sequence of interpenetrated halite cubes, often with a hopper structure; the halite cubes are always oriented with the long diagonals coincident with the speleothem elongation axis. A few of these stalactites exhibit a perfectly vertical structure, while most of these speleothems are inclined (with a deviation from the verticality up to 30-40 degrees). Internal feeding tubes are completely absent. The evolution of these speleothems is induced only by condensation/evaporation processes. While the feeding of these speleothems is always related to condensation processes, their evolution is controlled by several interconnected factors: 1- air current distribution close to the speleothems; 2 - condensation and evaporation processes and 3- capillary, and/or gravitational movements of the solution along the speleothems. In many cases these factors allow for the development of exasperated hopper structures, giving rise to wide rectangular thin flat tabular crystals. Finally in a single location, peculiar bidimensional pyramidal structures of halite crystals have developed where the gravitational flow of the feeding solutions meets a strong upward air flow. Keywords: Halite, macro-crystalline speleothems, genetic mechanisms

Para proporcionar una evaluación precisa de la capacidad de generación de dispositivos foto voltaicos es necesario determinar de forma adecuada el recurso solar disponible. Diferentes autores afirman que celdas FV de referencia presentan menores desvíos, en relación a piranómetros térmicos, cuando se desea determinar la capacidad de generación FV. Teniendo en cuenta lo antes expuesto, este trabajo presenta el desarrollo y calibración de un medidor de radiación solar cuyo elemento sensor está constituido por celdas fotovoltaicas en un encapsulado convencional de dispositivo FV. El comportamiento del sistema fue estudiado, y los valores obtenidos son comparados con los valores medidos con un una celda patrón calibrada en el PV Evolution Labs (PVEL) en la ciudad de Berkeley, California. Se estudió el comportamiento del sistema, y los valores obtenidos se comparan con los medidos con una celda estándar. El análisis estadístico de las mediciones ha llevado a desarrollar una metodología para determinar los parámetros del modelo de análisis para medir el valor de la irradiancia. Una comparación entre los valores medidos resultó en valores de correlación mayores que 0,999 desarrollados entre la celda y la celda patrón, lo que confirma la linealidad y correspondencia del instrumento desarrollado con el patrón., To provide a precise capacity valuation of photovoltaic generation is necessary to determine the solar resource accurately. Several authors claim that reference cells have minor deviations that thermal pyranometers to determine the ability of PV generation. This work presents the development and calibration of a solar radiation meter sensor which consists of a conventional photovoltaic cells encapsulated device. The system behavior was studied, and the values obtained are compared with those measured with a standard cell. The statistical analysis of measurements has led to develop a methodology to determine the parameters of the analytical model to measure value of the irradiance. A comparison between measured values resulted in high correlation values (0.999) developed between the cell and the cell pattern, confirming the linear response of the instrument developed., Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES)

L'area del monte Covria è caratterizzata dalla presenza di differenti formazioni a grado di carsivicabilità differente. All'interno di alcune di esse sono presenti ampli sistemi carsici che alimentano acquedotti degli agglomerati urbani di fondovalle. L'area è stata studiata utilizzando il metodo SINTACS per realizzarene la carta di vulnerabilità intrinseca ed integrata.