Microplastic pollution in karst areas: a threat to caves, groundwater and protected species and habitats

Microplastics (MPs) are a global problem, contaminating also remote areas, being them extremely mobile. However, MP pollution is poorly known in karst areas, especially in subterranean environment. Groundwater in karst aquifers constitutes about 25% of the global drinking water sources and karst caves are one of the most important and well-known geological features in the world, fragile sites with an exceptional scientific value, rich in endemic fauna, an environmental and cultural heritages, as well as an important economic resource. MPs can endanger the fragile subterranean ecosystems, be ingested by animals, irreversibly damage speleothems and paleontological/archaeological findings depositing on them and pollute karst aquifers. Extending the research started for the Italian project PRIN SHOWCAVE [1], the aim of this study is to investigate and monitor MP pollution in karst superficial and subterranean environments from a geological, biological and environmental point of view, in order to define strategies for protection and conservation purposes. A new detection technique has been developed to study cave sediments [2], subsequently adapted to the different studied matrices. Samples from different karst areas of Italy were collected and investigated. The sediments of three show caves were analyzed, highlighting the presence of MPs and the damaging of speleothems and paleontological remains. Superficial and underground water samples of the Bossea karst system (Piedmont) were analyzed, showing MP pollution in all examined waters, underlining the importance of the entire aquifer karst systems monitoring, even susceptible to contamination by surface pollutants. Different water environment samples of springs and caves in Carso system (Friuli-Venezia Giulia) were collected and will be analyzed to verify the MP pollution in different habitats, hosting particularly protected species such as Proteus anguinus. Sediment samples in a not jet explored caves will be collected to verify the MPs pollution even in underground environments not directly affected by human presence

COVID-19 pandemic: an opportunity to monitor the naturalness of show caves

The CO2 air concentration variations in show caves can be linked to natural and/or anthropogenic factors. The CO2 increase, linked to climate change or anthropogenic impact, can alter the rock-atmosphere interface and damaging speleothems and ecosystems, therefore, knowing the natural dynamics in the underground environment is fundamental. Today, before the opening of new tourist caves, a year monitoring of the main environmental parameters is recommended. Instead, the show caves opened in the past hardly have previous data relative to the natural environmental parameter variations. Thanks to the closure of the caves for Covid-19 pandemic restrictions, it was possible to make assessments in the absence of tourists, highlighting the natural CO2 air concentration variations. To understand the environmental parameters dynamics in three NW Italian show caves, a continuous monitoring of the main parameters (temperature, air circulation, CO2, etc.) was carried out for a year. To monitor the CO2 air concentration, VAISALA systems with INDIGO 520 sensors were installed in different cave areas, with two GMP 252 probes (maximum error 2%) each. The data was continuously recorded with intervals of 10 minutes. From the reopening after the COVID-19 restrictions, daily variations of CO2 air concentrations related to the tourist flow were observed in Toirano caves, Liguria, with an increase of even 1000 ppm. In Borgio Verezzi cave, Liguria, during the winter and spring closure period due to restrictions from COVID-19, CO2 values between 500 and 650 ppm were measured. Since the reopening of the cave, marked decrease of CO2 of about 1000 ppm in the weeks and of about 2000 ppm in the weekends were monitored; these decreases seem to be linked to the opening of the main door, resulting in significant air exchange and reduction of the concentration of the CO2 air concentration. In Bossea cave, Piedmont, during the closing period, natural variations of CO2 air concentration between 750 and 1000 ppm were recorded in winter and spring. In the summer, a further increase, partly natural and partly linked to the anthropic impact was recorded. The anthropogenic increase occurred of about 50 ppm in the week and doubled during weekends and holidays

Rhagidiidae mites of the Western Italian Alps

In the pre-alpine areas of the Mediterranean basin fragmented underground environments have differentiated, probably almost unchanged since the Miocene (over 5 million years ago). These environments enabled long periods of colonization and geographical isolation for organisms, allowing the Rhagidiidae mites an evolutionary process of millions of years. Their evident morphological adaptations to the underground environment depended on the rigid climate conditions, the environmental parameters variations, the glaciations and the time of stay in these peculiar environments. The lengthening of the appendages and bristles, and the progressive sensory organs development, called solenidia, on the tarsi and tibiae of the first two pairs of paws, provide an indication of the underground environment adaptation degree. In the Western Alps, strongly affected by the Quaternary glaciations, underground arthropods studies have neglected Rhagidiidae (Acari, Trombidiformes) for a long time, which do not appear in the faunal lists until recent times. This study has been carried out since 1990s, investigating the underground cavities of Piedmont and Aosta Valley regions to deepen the knowledge on the Alps underground fauna and create the basis for future and more in-depth research. In 1995, a species belonging to this systematic group was finally found at a depth of about 250 meters in Abisso Bacardi cave (PI873, Frabosa Soprana); subsequently, different cave-adapted mites were found in Bossea cave in 1998 (PI108, Frabosa Soprana) and in Barôn Litrôn cave in 2003 (PI1214, Valdieri). In 2009, collected mites were analyzed by the specialist Miloslav Zacharda of Prague, establishing all the collected specimens belonged to a new species for science, described it in 2011 as Troglocheles lanai. Hundreds of Rhagidiidae specimens were found in over 90 underground stations and cavities since 2014, including other new species for science of the genus Troglocheles, Traegaardhia and Robustocheles. At the moment, dozens of other samples have been collected in the Alps, waiting to be analyzed. The increasingly marked shortage of specialists has led to the slowdown of much field of research. However, underground environments still offer several research possibilities and many species are still unknown to science, needing in-depth studies and descriptions. With this summary we sincerely hope to stimulate researchers to deal in the near future with this very interesting group of arachnids, really significant for the biogeography of the underground environment of the Alpine chains

Parabathyscia dematteisi Ronchetti & Pavan, 1953: a silent invader

In the 1950s, the speleologist Giuseppe Dematteis discovered a small “cave” insect exploring the Fornaci di Rossana (FDR) cave, Piedmont, Italy, subsequently described as Parabathyscia dematteisi (PD) Ronchetti & Pavan, 1953 (Coleoptera, Leptodirini). The FDR cave develops under a quarry of lime stone which was feared would destroy the cavity. In the 1960s, cave fauna was deemed endemic to individual cavities, therefore, a cave destruction could have led to the extinction of the species living there. Different people started a campaign to "save" PD from the quarry activities, transferring many insects from FDR cave to improvised laboratories in Dossi (PI106) and Bossea (PI108) show caves, located about 50 km from it. Soon, the PD case was forgotten, as well as the specimens transferred into the two caves, which escaped from the artisanal terrariums, invading the guest cavities. During our research on subterranean Piedmontese fauna, Leptodirini specimens were found in Bossea (1992) and Dossi (1995) caves, subsequently identified by the specialists as PD. In the Underground Karst Laboratory of Bossea cave, the reproduction and development stages of this species were documented thanks to direct observations and macro photography. Moreover, these insects were found in different areas of the two cavities, evidencing an extensive invasion of the species. In FDR cave, PD coexists with Doderotrechus casalei Vigna Taglianti, 1969, a hypogeal Carabidae Trechinae which prey PD larvae and juveniles. In Bossea and Dossi caves, Trechinae predators have never been reported, probably favoring the PD diffusion. In the last 30 years, observation on this allochthonous species in Bossea and Dossi caves were taken, and new native underground stations of PD were found in the Maira and Varaita valleys caves, confirming its not uniqueness for the FDR cave. Alien species are accidentally or intentionally introduced by human to a place outside its origin area. Many of these species fail to reproduce and they disappear, however, other one successfully settle in the new area, becoming invasive and a serious threat to biodiversity, altering the ecological balance, and bringing some autochthonous species to extinction. The false beliefs about the "cave" fauna could have had serious consequences for the ecology and biology of two important show caves of the Italian Alps, still to be evaluated. With our direct long-term observations on subterranean fauna we hope to contribute actively to the conservation of underground ecosystems and to provide useful information for future studies

Segmentation and classification of gait cycles

Gait abnormalities can be studied by means of instrumented gait analysis. Foot-switches are useful to study the foot-floor contact and for timing the gait phases in many gait disorders, provided that a reliable foot-switch signal may be collected. Considering long walks allows reducing the intra-subject variability, but requires automatic and user-independent methods to analyze a large number of gait cycles. The aim of this work is to describe and validate an algorithm for the segmentation of the foot-switch signal and the classification of the gait cycles. The performance of the algorithm was assessed comparing its results against the manual segmentation and classification performed by a gait analysis expert on the same signal. The performance was found to be equal to 100% for healthy subjects and over 98% for pathological subjects. The algorithm allows determining the atypical cycles (cycles that do not match the standard sequence of gait phases) for many different kinds of pathological gait, since it is not based on pathology-specific template

Study of the Trends of Chemical–Physical Parameters in Different Karst Aquifers: Some Examples from Italian Alps

The results of a series of continuous characterizations of physical parameters (flow, temperature, water conductivity) and chemical analyses in water springs fed by karst aquifers located in the Piedmont region (northwestern Italy) are presented in this work. Rock masses in carbonate rocks, characterized by very different hydrogeological situations, linked to a different degree of karstification, fracturing, and development of the saturated zone, were examined. A series of data-loggers were installed, operating for several years, and different water sampling missions and subsequent chemical analyses (main ions, metals, and rare earth elements) under different hydrodynamic conditions were carried out. The results show very different trends of chemical–physical water parameters, particularly following significant infiltrative events. Aquifers characterized by a high karstification and reduced saturated zone highlight water mineralization decreases, even within a few hours, as a result of significant flow rate increases (prevalent substitution). Aquifers with a well-developed saturated zone, during an entire flood event, highlight an increase in mineralization linked to the remobilization of water present in the less permeable sectors of the aquifer (piston flow phenomenon). Lastly, aquifers fed by very fractured rocky masses and reduced karstification have a water flow rate with mild annual variations and constant chemical–physical parameters over time (homogenization phenomenon)

Secondary minerals in minothems at Fragnè Mine (Turin, Italy)

The Fragnè mine, Chialamberto (TO), is located in the Lanzo valley. The study area is part of the structural complex historically indicated as "area of calcschists and greenstones" or "Piedmont area" formed by mesozoic ophiolitic units of the Piedmontese Ligurian Basin by the tectonic-metamorphic evolution related to the alpine orogenesis (Falletti et al., 2009). The mineralizations are characterized by massive pyrite and Cu-rich pyrite that occurs in greenschist (prasinite) and amphibolite schist. The underground works development is around 5 km, tunnels that branch off into different levels. In this work, we describe secondary minerals of minothems (Carbone et al., 2016) not yet described in the Fragnè mine and found usually inside natural caves characterized by different mineralogical associations. The results show that all samples are characterized by secondary Fe-rich minerals typical of acid mine drainage areas. Blisters are composed only by schwertmannite, war-clubs by schwertmannite and goethite with low crystallinity, and hair by epsomite and hexahydrite minerals. Jelly stalactites and jelly stalagmites are characterized by schwertmannite in association with bacterial masses, instead stalactites and stalagmites by jarosite and goethite. The results shows that a mineralogical transformation occurs from soft to hard minothems: schwertmannite tends to transform into goethite, probably due to ageing processes of schwertmannite or local pH variations, related to bacterial activity, since schwertmannite is a metastable phase which over time tends to turn into goethite (Jönsson et al., 2005)

Environmental parameters monitoring in show caves: some examples from NW Italian show caves

Natural cavities are characterized by particular environmental conditions such as no light and the remarkable stability of the air temperature. These distinctive environmental factors have been able to maintain and preserve speleothems, paleontological and archaeological remains, and particular habitats rich in specialized fauna over the centuries (Balestra et al., 2021). The development of a cave into a show cave requires different modification to create the necessary facilities for tourist use and the passage of several hundred visitors a day can irreversibly damage speleothems and ecosystems (Cigna, 2016; Cigna & Forti, 2013), therefore, it is necessary to pay special attentions and monitor environmental parameters over time. The data should be collected before the construction of the tourist facilities, followed by a constant monitoring of the parameters during the tourist use to examine and verify any possible impacts over time affecting the cavity. In general, there is a lack of data about the studies on cave environmental conditions before and during the tourist use, especially because there are no reference protocols regarding the main environmental parameters to monitor and how these monitoring must be carried out. In this work, the main environmental parameters of three different show caves in NW Italy (Bossea Cave, Piedmont, Toirano and Borgio Verezzi caves, Liguria) were monitored. These parameters are the main factors characterizing the delicate cave environment balance and they can be significantly modified by the lighting systems and the tourist passage. A series of instruments with high precision probes were installed in every cave, aiming at environmental monitoring, especially hydrogeology, hypogeal meteorology (temperature and air circulation) and air carbon dioxide concentrations. These instruments must be able to operate in particularly difficult conditions, such as high relative humidity (usually close to 100% in caves) and to detect even very small parameters variations, such as air velocity variations. The probes must be correctly located in different part of the cavities, especially considering the significant air stratifications that often occur in caves, with consequent vertical variations in air temperature and CO₂ content. The data recording time is a fundamental parameter too, allowing to examine with precision the possible impacts related to the tourist passages in some areas of the show cave