Riviste Online SApienza - R.O.SA - 2 (Sapienza University of Rome)
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Integrity of fine-grained layers to DNAPL migration in multilayered aquifers: assessment in a pce-contaminated alluvial system, using high-precision simulations
No full textChlorinated organic compounds widely contaminate aquifer systems worldwide (Doherty, 2000). They belong to the so-called DNAPLs (dense non-aqueous phase liquids), are denser than water, and have very low water solubility. Thus, they can migrate under pressure and gravity forces through the unsaturated and saturated porous medium until they reach a bottom aquiclude (Mercer & Cohen, 1990). They are usually detected in industrial and urban areas, persist in the environment, and are linked to toxic effects. The behavior of chlorinated organic compounds in the subsurface has been studied since the early 1980s, e.g., (Parker et alii, 1987; Kueper et alii, 1989). Some numerical models, including migration and remediation of alluvial aquifers (Guadano et alii, 2022), using the MT3DMS numerical code (Zhou et alii, 2023; Zheng & Wang, 1999), have been written to simulate their migration in aquifer systems. The dynamics of a spilled DNAPL migration in a variably saturated zone can be described using numerical simulations for the governing equations of immiscible phase fluid flow in a porous medium. These are coupled with conserved partial differential equations for each fluid flow, based on the Darcy equation, together with the conservation of mass and an equation of state. They are written as a function of each fluid flow’s saturation, capillary pressure, density, viscosity, permeability, and porosity. Since each phase’s capillary pressure and permeability are a function of the saturation, these equations are non-linear, with a dominant hyperbolic advection term proportional to gravity and the pressure gradient. It is responsible for forming sharp (shocks) front and rarefaction, which can create significant errors in the output results if not treated with conservative numerical solutions methods. The present study deals with the three-dimensional (3D) numerical model implemented to analyze the expected impact of perchloroethylene (PCE) releases in multilayered aquifer systems characterized by the juxtaposition of more permeable layers (gravel and sand) with low-permeability layers (silt and clay). A 3D numerical model is developed using the numerical code CactusHydro, introduced in (Feo & Celico, 2021; Feo & Celico, 2022). It is based on the high-resolution shock-capturing flux (HRSC) conservative method to follow sharp discontinuities accurately and temporal dynamics of a three-phase immiscible fluid flow in a porous medium. CactusHydro resolves the governing equations that describe the migration of an immiscible phase fluid flow in a porous medium composed of non-aqueous (n), water (w), and air (a), and a variably saturated zone. The migration of the spilled DNAPL is considered immiscible, and the effects of the volatilization, biodegradation, or dissolution are not considered. CactusHydro treats the vertical and horizontal movement of the contaminant in the variably saturated zone as a whole and is numerically resolved as a unique zone (not separating the vertical movement from the horizontal one since the flow equation includes both zones). The model presented here simulates the DNAPL migration with the aim of predicting (i) the free-product distribution in multilayered aquifers (up to several hundred meters thick) and then (ii) the distribution of possible long-term pollution sources for shallow and deep groundwaters. A first scenario was simulated in detail, with the scope of understanding whether the interposition of a low-permeability layer between two higher permeability horizons can influence the vertical migration of DNAPLs. The test site is the alluvial aquifer of Parma Plain (Northern Italy), where perchloroethylene (PCE) was recently detected in groundwater (Zanini et alii, 2019; Zanini et alii, 2021), therefore suggesting the existence of DNAPLs sources. The results demonstrated that the PCE can migrate downward through low-permeability layers, even though a very low velocity was estimated
First record of Formica pratensis in a reedbed along the Nestos River near Xanthi, Greece (Hymenoptera: Formicidae)
Full text linkThe ant Formica pratensis Retzius, 1783 (Hymenoptera, Formicidae) is reported from a locality in Dasochori (Xanthi, Greece). Foraging workers were manually collected from the top of the mounds. This new observation represents the lowest altitude record in Greece and the first in a reedbed. Additionally, the mutualism with the aphid Aphis urticata Gmelin, 1790 has been observed
New distributional records of the genus Tetragonoderus Dejean, 1829 from the United States of America, including an updated key to species (Coleoptera: Carabidae)
Full text linkNew distributional records are presented for the genus Tetragonoderus Dejean, 1829 from the United States of America. Tetragonoderus fasciatus (Haldeman, 1843) is a new state record for South Dakota, Tetragonoderus intersectus (Germar, 1824) is a new state record for Oklahoma, Tetragonoderus latipennis LeConte, 1874 is a new state record for Florida, Georgia, and Okhlaoma, and Tetragonoderus pallidus Horn, 1869 is a new state record for New Mexico and Utah. New county records for the introduced species Tetragonoderus laevigatus Chaudoir, 1876 in Florida and new state records for Georgia, Louisiana, and Mississippi signify a range extension. A new record of this species from Miami-Dade County from 2004 temporally precedes the known date of introduction. New observational records from citizen science platforms for the reported species are also noted. An updated key and distributional maps to the known species in the USA are also provided
An inventory of the spider species of “La Mandria” Regional Natural Park (NW Italy) (Arachnida: Araneae)
Full text linkWe present an inventory of the spider species of the “La Mandria” Regional Natural Park (Province of Turin, Piedmont, Italy), mostly based on original data collected between 2022 and 2023. Spiders were sampled by means of pitfall traps and beating trays in the most representative habitats of the Park. Few additional species were included to the inventory from iNaturalist observations and from available literature data. We reported a total of 149 species, representing 100 genera and 28 families. Thirty-seven species are recorded for the first time in the Province of Turin and 12 are new for Piedmont. The most represented families were Lycosidae and Linyphiidae, followed by Gnaphosidae and Thomisidae. The highest number of species (60) was recorded in woodland edges, followed by mown meadows (57) and mixed broadleaved woods (50). The composition of the spider assemblages aligns with those found in similar habitats in the frame of other studies conducted in the Po Valley. Most of the species have a Palaeartic distribution, followed by Turanic-European-Mediterranean and European elements. Noteworthy, we recorded two endemic species (Nemesia pedemontana and Dysdera lantosquensis) and three alien species (Mermessus trilobatus, Erigone autumnalis and Theridula gonygaster). We also provide new taxonomic illustrations of two riparian Gnaphosidae (Gnaphosa dolosa and G. rhenana). Besides the faunistic contribution, this inventory aims at providing a basis for further studies on the conservation ecology of spiders in NW Italy
Cold case: Ludwig Ganglbauer (1856–1912) and his 1908–1909 manuscript on the genus Podistra (Coleoptera: Cantharidae)
Full text linkThe circumstances around the publication of Ganglbauer’s manuscript of 1908–1909 on the genus Podistra (Coleoptera, Cantharidae) are studied in detail. Considerable evidence demonstrates that the work was actually published in 1914; therefore, the 1922 date reported by the scientific community is incorrect. The taxonomic records present in this paper are the subgenus Hemipodistra Ganglbauer, [1914] and the species Podistra (Absidia) pentheri Ganglbauer, [1914], Podistra (Absidia) caucasica Ganglbauer, [1914] and Podistra (Podistra) starcki Ganglbauer, [1914]. The relevant description pages are also carefully reported. Absidia ussuriensis Horn, 1921 is considered in the present document as nomen nudum
Gli scritti di Paolo Mini e l’ideologia del “Principe repubblicano”: tra approssimazioni successive e necessitate ricomposizioni
Full text linkThe essay analyses how the Florentine Paolo Mini elaborated the model of the “Principe repubblicano” (republican principality) in his writings such as the Difesa della città di Firenze e dei fiorentini (Lyon 1577). On the one hand, Mini – linked to the context of the anti-Medicean Florentine diaspora in France – proposed an idea of the “republican principality” based on the continuity between the Florentine republican experience and the grand duchy of Cosimo I de’ Medici. On the other hand, Mini interpreted the foundation of the principality promoted by Cosimo as a “providential” turning point. Furthermore, a copy of the Difesa was in Gian Vincenzo Pinelli’s library and it might suggest some influence on the later unfinished treatise Della Potestà de’ prencipi (Potestà) drafted by Paolo Sarpi between 1610 and 1611
L’europeismo di Nilde Iotti negli anni della presidenza della Camera (1979-92)
Full text linkThe essay examines Nilde Iotti’s contribution to the process of European integrationduring her presidency of the Italian Chamber of Deputies (1979-92),focusing on two areas of political-institutional activity: public discourse and interparliamentarywork. The analysis of the themes present in her public discoursemakes it possible to extrapolate the contents, the connections and, ultimately, themeaning (also civil and pedagogical) of the Europeanism conveyed by the thirdOffice of the Italian State. The focus on interparliamentary work highlights thecommitment to the creation of a stable network among the national parliamentsof the EEC member states and between them and the European Parliament: anarea in which Iotti was active, moved by the conviction that the exchange ofexperiences and, above all, the difficult but necessary search for common initiativesand priorities were decisive factors for the democratic strengthening of theprocess of European construction
Numerical simulation on the groundwater contamination evolution in industrial settings
No full textThe hydrogeological numerical simulation represents a tool for the protection of aquifers and for modeling the groundwater flow and transport. This study aims to build numerical models of a porous aquifer located in the alluvial plain of Catania (eastern Sicily, Italy), to evaluate groundwater flow and hypothetical contamination plume trends, even in interaction with pumping activity. To implement the flow and transport simulations, geological and hydrogeological conceptual models were defined using borehole and well data. The studied aquifer is semi-confined, with the presence of alluvial sediments mixed with sandy clays and silts. Because of the presence of anthropic activities in the area, the accidental spill of a contaminant would represent a social problem in the frame of the environmental and health risk. In this regard, we carried out numerical simulations that consider the hydrodynamic parameters of the aquifer, the contaminant concentration, and the presence of pumping wells. The model shows that groundwater flow is directed towards east, and that the presence of wells locally affects it. The transport model shows that a hypothetical dissolved contamination plume mainly follows the groundwater flow path, and that the presence of pumping well accelerates its flow towards elements at risk
Hydraulic conductivity estimation through the use of tracers tests and geomechanical survey: preliminary outcomes from the Montagna dei Fiori carbonate aquifer (Central Italy)
No full textNowadays, groundwater is the most important resource on our planet. However, due to population growth, urbanisation, and climate change, this resource is often overexploited or contaminated. In this context, carbonate aquifers provide drinking water to approximately 25% of the global population. Due to aquifers heterogeneities and anisotropic fracture systems, they can be affected by potential contamination and their optimal exploitation represents a challenge aspect. In this particular scenario, carbonate mountain aquifers encompass valuable groundwater resources due to their high recharge rates and excellent water quality; therefore, the understanding of their hydrogeological characteristics are vital for aquifers protection and water management. A valid solution to explore water movement within such aquifers and to quantify the groundwater amount can be offered using artificial tracers. At the same time, the geomechanical surveys can deep the knowledge on fracture density and orientation, providing valuable insights about fracture connection and conductivity. This study combines the advantages of six artificial tracer tests performed in four deep wells (260-500 m b.g.l.) and a geomechanical survey used, among other, to estimate hydraulic conductivity of a mountainous carbonate aquifer located in Central Italy. The results obtained by different methods highlighted the presence of multiple layers with higher conductivity values, able to sustain the groundwater flow without significant piezometric level drawdown during water pumping operations. This approach provides an effective support to the water management company operating
Landslide impact on nature reserves: first results on the multisensor survey of unstable slopes in protected areas
No full textThis study is focused on the use of digital close-range remote surveying techniques for the identification and mapping of landslide phenomena along rock slopes in protected areas. This activity is part of a research project aimed at the digital analysis of slope models. The techniques compared herein are based on photographic and photogrammetric applications, carried out from both ground and aerial surveys, and on the use of infrared thermography in two test sites located within the Cinque Terre National Park (Liguria, Italy) and the “Timpa di Acireale” nature reserve (Sicily, Italy). The analysis of oblique aerial photographs allowed detecting key geomorphological indicators of past landslide movements and to carry out preliminary observations on unstable outcrops. The use of digital close-range sensors for the aerial photogrammetric survey allowed building a digital slope model to be analysed for the recognition and mapping of previous landslides. Moreover, key structural features, likely controlling the slope stability, were highlighted. Infrared thermography allowed detecting signs of landslides, providing the possibility of validating the photogrammetric data. In both protected areas, an almost zero level of environmental disturbance was guaranteed. Finally, both the potential and limitations of the techniques, used for the noninvasive morphological survey, are highlighted