Search

The Mucille karst depression is one of the few examples of polje on the Italian side of the Classical Karst Region, a shared area between Italy and Slovenia. The polje is subject to frequent flooding, becoming more problematic since 2000, as swallow holes more frequently have affected housing and recreational areas, leading the population to believe that their ability in draining the area had stopped functioning. Climate changes play an important role as there has been an intensification in extreme events (30-day cumulative precipitation of more than 350 mm) within the considered time-period 1919–2020. The necessity to provide answers to the inhabitants required in-depth studies such as hydrogeological investigations, discharge measurements and Electrical Resistivity Tomography (ERT) acquisitions. Over the 3 years of monitoring (2017–2020), two flood events reached the Selz settlement. In total, four events have been analysed to build a hydrogeological model of the area in order to properly estimate its recharge and regression curve, and to define the functionalities of the swallow holes. The defined model allowed a better knowledge and a greater awareness in proposing the proper mitigation measures able to increase the drainage capacity of the area avoiding always more frequent future floodings.

vengono riportati i primi risultati di un tracciamento all'interno della grotta Tirfor, finalizzato ad una migliore comprensione dell'andamento delle acque sotterranee nel massiccio delle Bernadia. L'esperimento si svolge nell'ambito di un progetto di ricerca tra Servizo Geologico FVG, DMG dell'Università di Trieste, con la collaborazione dei Gruppi speleologici regionali

In a mantled evaporite karst system, sinkholes are not always easily identifiable. These phenomena are not deeply studied in the Italian peninsula, because they do not cause so frequent and severe damages as for example in other countries like the United States and Spain. However, they are quite frequent in specific areas where gypsum is exposed or mantled, especially in some alpine valleys where evaporites acted as a tectonic lubricant during the main alpine orogenetic compression phases. This is the case of some portions of the north-eastern corner of Italy where, along the high Tagliamento valley, there are several villages built in areas where the alluvial deposits of the Tagliamento River created thick terraces over a buried evaporitic bedrock. In the past, within this area, several sinkhole events were recorded, few of them occurred below or close to the built houses and the farmers usually refilled the voids in order to continue to exploit the land, while ignoring the actual cause of those sudden events. This is the case of Quinis village, a hamlet of Enemonzo, where the farming activities masked for a period the precursor signs of the sinkhole occurrences. The outline of the sinkhole events appear to be particularly difficult in an urbanized environment where the geomorphological surveys do not guarantee a recognition of their characteristic shapes, while trenching activities are not always possible and are of high impact. For these reasons, geophysical techniques are a valid approach in the study of these phenomena. In an area under cultivation, just outside from the inhabited zone, an integrated geophysical investigations (2D, 3D electrical resistivity tomography, and gravimetric measurements) have been performed in order to image the subsurface below a smoothed surface depression which represents a possible hint of a mantled sinkhole. In the 3D acquisition we used a “horseshoe” electrodic geometry, with 72 electrodes having a constant spacing equal to 2m and located all around the resistivity anomaly previously recognized along a 2D resistivity profile crossing the surface depression. A gravimetric profile with 10m-spaced data was at first realised along the 2D resistivity profile. Later 74 additional measurements were collected within a 5m grid centred in correspondence of the depressed area. The geophysical investigations permit to locate an approximately 15 m wide zone vertically extending for tens of meters. The evaporitic bedrock in the sinkhole area lies at a depth exceeding 100 m and is masked in the electrical data by an aquifer reaching a depth of about 45 m below the surface. The experience realised in the area permitted to identify the best approach to investigate these type of buried phenomena, highlighting that the 3D electrical tomography is a useful tool to image the lateral extension, the depth and the shape of the sinkhole.

This work aims at evaluating mercury (Hg) occurrence, spatial distribution and speciation in groundwater of the Isonzo/Soca River upper alluvial plain downstream from the Idrija Hg mine (Western Slovenia). Several wells and piezometers were sampled both in static and dynamic mode. Total (THg) and filtered (FHg) concentrations were generally higher in static (THg, 1.87–855 ng L−1; FHg, 0.20–13.61 ng L−1) than in dynamic mode (THg, 0.08–78.77 ng L−1; FHg, 0.28–6.65 ng L−1). The estimated background value accounts for 2–3 ng L−1. On the basis of hydrochemistry and isotopic composition, the main sources of groundwater were established. Hg concentrations in the Slovenian sector, supplied by local rainfall, are comparable to values measured close to the Isonzo River. Possible further Hg local sources have been suggested. Stability field analysis for the aqueous Hg species revealed that in the presence of chloride Hg solubility may be increased by the formation of chlorocomplexes. Mercury that rarely enters reduced surrounding conditions can be bound to sulphur to form polysulphide species depending on the pH of water. Since Hg-contaminated alluvial sediments of the Isonzo River may act as a secondary Hg source in groundwater, a borehole was dug down to the water table. Mercury content and speciation revealed that cinnabar (HgS) is the prevalent form followed by the matrix-bound Hg (Hgbound). Variations of the physico-chemical boundary conditions, as well as the raising/lowering of the water table, may be locally responsible for the slight variability of Hg concentrations in the aquifer.

In 2012, an extreme summer drought induced species-specific die-back in woody species in Northeastern Italy. Quercus pubescens and Ostrya carpinifolia were heavily impacted, while Prunus mahaleb was largely unaffected. By comparing seasonal changes in isotopic composition of xylem sap, rainfall and deep soil samples, we show that P. mahaleb has a deeper root system than the other two species. This morphological trait allowed P mahaleb to maintain higher water potential (Ψ), gas exchange rates and non-structural carbohydrates content (NSC) throughout the summer, when compared with the other species. More favourable water and carbon states allowed relatively stable maintenance of stem hydraulic conductivity (k) throughout the growing season. In contrast, in Quercus pubescens and Ostrya carpinifolia, decreasing Ψ and NSC were associated with significant hydraulic failure, with spring-to-summer k loss averaging 60%. Our data support the hypothesis that drought-induced tree decline is a complex phenomenon that cannot be modelled on the basis of single predictors of tree status like hydraulic efficiency, vulnerability and carbohydrate content. Our data highlight the role of rooting depth in seasonal progression of water status, gas exchange and NSC, with possible consequences for energy-demanding mechanisms involved in the maintenance of vascular integrity.