Understanding how environmental and anthropogenic factors influence group living is particularly valuable from an ecological and management point of view, since social systems influence individual ...feeding, breeding and health, which in turn affect the population size. Foraging strategies, presence of calves and avoidance of predators are known factors influencing group size in bottlenose dolphins, but little research has been done to investigate the concomitant effect of environmental, social and anthropogenic factors. Thus, here we tested the relationship between the group size of a common bottlenose dolphin population in Sardinia (Mediterranean Sea) and some proxies of prey availability (sea surface temperature, seabed depth and habitat type), social context (presence of calves and sex ratio) and sea ambient noise levels, as noise may impair communication and elicit predator avoidance-like response. Group size, both at intra-population (PGS) and individual levels (IGS), was mainly influenced by water temperature, noise, and the social factors. PGS changed with seasons and both PGS and IGS decreased with increasing sea surface temperature, likely suggesting a relationship between group size and the availability of demersal species assemblages, since the latter are known to be strongly affected by temperature. Further, the increase in noise levels led to a reduction in PGS (in presence of calves) and in IGS (in females with calves only). In degraded acoustic environments, the communication between group members may be further impaired by the density of individuals, thus mother-calf pairs may try to reduce the effect of boat noise by staying in a smaller group, where the masking of one’s signals by those from conspecifics decrease.
Significance statement
The study highlighted the relationship between SST (sea surface temperature) and clustering pattern of a Mediterranean common bottlenose dolphin population, which in turn may derive from the influence of water temperature on prey abundance and distribution. Further, the effect of noise and boat presence on the grouping of the most vulnerable portion of the population (mothers with calves) was described for the first time. These results support the need for further investigations with the aim of better understanding the effects of warming and noise on coastal dolphins and provide information potentially useful in a management context.
An intense positron sources is a demanding element in the design of future lepton colliders. A crystal-based hybrid positron source could be an alternative to a more conventional scheme based on the ...electron conversion into positron in a thick amorphous target. The conceptual idea of the hybrid source is to have two separate objects, a photon radiator and a photon-to-positron converter target. In such a scheme an electron beam crosses a thin axially oriented crystal with the emission of a channeling radiation, characterized by a considerably larger amount of photons if compared to Bremsstrahlung. The net result is an increase in the number of produced positrons at the converter target. In this paper we present the results of a beam test conducted at the DESY TB 21 with 5.6 GeV electron beam and a crystalline tungsten radiator. Experimental data clearly highlight an increased production of photons and they are critically compared with the outcomes of novel method to simulate the number of radiated photons, showing a very good agreement. Strong of this, the developed simulation tool has been exploited to design a simple scheme for a positron source based on oriented crystal, demonstrating the advantages in terms of reduction of both deposited energy and the peak energy deposition density if compared to conventional sources. The presented work opens the way for a realistic and detailed design of a hybrid crystal-based positron source for future lepton colliders.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We report the direct observation of muon neutrino interactions with the SND@LHC detector at the Large Hadron Collider. A dataset of proton-proton collisions at sqrts=13.6 TeV collected by SND@LHC in ...2022 is used, corresponding to an integrated luminosity of 36.8 fb^{-1}. The search is based on information from the active electronic components of the SND@LHC detector, which covers the pseudorapidity region of 7.2<η<8.4, inaccessible to the other experiments at the collider. Muon neutrino candidates are identified through their charged-current interaction topology, with a track propagating through the entire length of the muon detector. After selection cuts, 8 ν_{μ} interaction candidate events remain with an estimated background of 0.086 events, yielding a significance of about 7 standard deviations for the observed ν_{μ} signal.
The Poiano karst spring is located in the North Apennines (Italy) and it drains Triassic evaporite rocks with a mean discharge of hundreds of liters/second. Two hydrogeological conceptual models have ...been proposed (and published) for the spring based on tracer tests. Both models highlighted the contribution of the local streams to recharge of the karst aquifer system, through sinking-stream processes, as well as recharge through rainfall; however, those studies differed in the water courses selected to monitor the recharge processes. The aim of the present research is to increase knowledge about the groundwater recharge processes of the Poiano karst spring with new surveys and analyses, resulting in a large dataset of temporal water stable isotope analyses (δ
18
O, δ
2
H), temporal stream discharge measurements, and temporal water tritium isotope data (T). A new hydrogeological conceptual model for the Poiano karst spring is proposed, within which a new list of streams becomes involved in the recharge-processes model based on different sources of water. In addition, the research identifies and confirms the occurrence of groundwater flow processes inside the karst system, such as the piston effect.
The combined use of hydrogeological and hydrogeochemical methods can provide relevant information about the characteristics of aquifers in studies focused on groundwater protection and management. In ...the present study, spring discharge monitoring coupled with stable and unstable water isotopes was used to compare the behaviour of adjacent fractured and porous aquifers hosted in a 4.5 km
2
area along the same slope in the northern Apennines, Italy. Based on stable isotope analyses of four springs, a plausible local meteoric water line and a local vertical isotopic gradient were identified. Additionally, tritium contents revealed a recent meteoric origin for groundwater via infiltration in the area. The results of monthly stable isotope monitoring, hourly spring discharge monitoring, hourly rainfall monitoring, and statistical analyses (time series analysis) suggested that although the adjacent aquifers exhibited pronounced geological and hydrogeological differences, few discrepancies were observed regarding groundwater infiltration and release processes. Notably, they exhibited similar temporal delays associated with the response to precipitation events due to the roles of macro-fractures and macro-porosity. Groundwater circulation was characterized by piston and memory effects in both the fractured and porous aquifers, and these effects reflect the roles of micro-fractures/fissures and micro-porosity. The study highlights the relevant contributions of isotopes in studies that focus on spring vulnerability and aquifer processes. Moreover, results obtained in the Pietra di Bismantova site are useful to increase hydrological knowledge on the quite relevant aquifers hosted in Epi-ligurian rock slabs and the surrounding slope deposits in the northern Apennines of Italy.
A comprehensive understanding of bedrock lithology and groundwater circulation is necessary to identify areas prone to landslide initiation and reactivation. This necessity is particularly required ...in the case of outcroppings of weak rocks such as gypsum that, due to their high solubility and low mechanical strength, can promote slope deformation with the development of caves and collapses. In the Upper Secchia River Valley, where gypsum outcrops extensively and is covered by landslide deposits, an accurate identification of the gypsum outcrops and their distribution is needed to reduce the damage to urbanized slopes. In this paper, a hydrologic and geochemical approach is used in the Montecagno landslide to identify the origin, flow paths and transit time of groundwater circulating inside the landslide body and to identify gypsum deposits and their distribution in the bedrock. The results of groundwater-level monitoring, δ
18
O-δ
2
H and
3
H isotope analyses and FLOWPC modelling suggest a local and recent origin of the groundwater hosted in shallow flow paths inside the landslide. Chemical and isotope (
87
Sr/
86
Sr, δ
11
B) analyses offer evidence of the presence inside the landslide of small blocks of gypsum that, due to their dimensions, probably have a minor influence on landslide stability. This research demonstrates that the methodology used can provide satisfactory information about bedrock structures and their hydrological aspects.
At the European Level, SACs (Special Areas of Conservation) are considered among the most reliable tools for increasing the efficiency of protective actions and to identify species vulnerability ...hotspots across spatial scales. Nevertheless, SACs may fail in their scope when design and management are not dynamically adapted to meet ecological principles. Knowledge of the spatial distribution of relevant key species, such as common bottlenose dolphin (Tursiops truncatus), is crucial in order to achieve the objective of the Habitat Directive (92/43/EEC), and is a fundamental step in the process of Marine Spatial Planning. From this perspective, new data and analysis are required to produce forecasts at spatio-temporal scales relevant to individual organisms. Here, we propose a study based on a MaxEnt modelling exercise to define the spatial distributional patterns of bottlenose dolphin at different temporal scales (over periods of multiple months and years) to increase the ecological understanding of how the species use the eco-space, and to delimit boundaries of a SAC in the waters surrounding Lampedusa Island, a hotspot for cetaceans in the Southern Mediterranean Sea. We show that bottlenose dolphin prefer shallower feeding grounds that often host complex and rich food webs, but also that this preference is constrained by disturbance factors such as boat traffic. As sea-related tourism, including dolphin-watching, is one of the most important economic activities of the island, the study results can be used from a management perspective, in order to reach a solution regarding two apparently conflicting needs - species protection and economic development.
•MaxEnt was a sufficiently reliable tool in predicting the distribution of Tursiops truncatus.•Lampedusa dolphins were tightly associated to the most coastal part of the island.•The likelihood of dolphin occurrence in area nearest to the coast reduced in summer.•Chlorophyll-a was the second most important predictor of dolphin occurrence.•Our findings allow us to suggest a SAC for bottlenose dolphins of about 710 km2.
Changes in soil water content, groundwater flow and a rise in pore water pressure are well-known causal or triggering factors for hillslope instability. Rainfall and snowmelt are generally assumed as ...the main sources of groundwater recharge. This assumption neglects the role of deep water inflow in highly tectonized areas, a factor that can influence long-term pore-pressure regimes and play a role on local slope instability. This paper aims to assess the origin of groundwater in the Ca' Lita landslide (northern Italian Apennines) and to qualify and quantify the aliquot attributable to deep water inflow. The research is essentially based on in situ monitoring and hydrochemical analyses. It involved 5 yr of continuous monitoring of groundwater levels, electrical conductivity and temperature and with groundwater sampling followed by determination of major ions (Na+, K+, Mg2+, Ca2+, Cl−, HCO3−, SO42−), tracers (such as Btot and Sr2+), and isotopes (δ18O, δ2H and 3H). Leaching experiments on soil samples, hydrochemical modelling and water recharge estimation were also carried out. Results show that the groundwater balance in the Ca' Lita landslide must take into account an inflow of deep and highly mineralised Na-SO4 water (more than 9500 μS cm−1) with non-negligible amounts of Cl− (up to 800 mg l−1). The chemical and isotopic fingerprint of this water points to oilfield water hosted at large depths in the Apennine chain and that uprises through a regional fault line crossing the landslide area. It recharges the aquifer hosted in the bedrock underlying the sliding surface (at a rate of about 49 000–85 700 m3 yr−1) and it also partly recharges the landslide body. In both the aquifers, the hydrochemical imprint of deep water mixed with rainfall and snowmelt water was observed. This indicates a probable influence of deep water inflow on the mobility of the Ca' Lita landslide, a finding that could be applicable to other large landslides occurring in highly tectonized areas in the northern Apennines or in other mountain chains. The paper demonstrates that hydrochemistry should, therefore, be considered as a valuable investigation method to define hydrogeological limits and the groundwater sources in hillslope and to assess groundwater flow patterns in deep-seated landslides.
Deep-seated landslides are complex systems. In many cases, multidisciplinary studies are necessary to unravel the key hydrological features that can influence their evolution in space and time. The ...deep-seated Berceto landslide, in the northern Apennines of Italy, has been investigated in order to define the origin and geochemical evolution of groundwater (GW), to identify the slope system hydrological boundary, and to highlight the GW flow paths, transit time and transfer modalities inside the landslide body. This research is based on a multidisciplinary approach that involves monitoring GW levels, obtaining analyses of water chemistry and stable and unstable isotopes (δ
18
O-δ
2
H,
3
H,
87
Sr/
86
Sr), performing soil leaching tests, geochemical modelling (PHREEQC), and principal component analysis (PCA). The results of δ
18
O-δ
2
H and
87
Sr/
86
Sr analyses show that the source of GW recharge in the Berceto landslide is local rainwater, and external contributions from a local stream can be excluded. In the landslide body, two GW hydrotypes (Ca-HCO
3
and Na-HCO
3
) are identified, and the results of PHREEQC and PCA confirm that the chemical features of the GW depend on water–rock interaction processes occurring inside the landslide. The
3
H content suggests a recent origin for GW and appears to highlight mixing between shallow and deep GW aliquots. The
3
H content and GW levels data confirm that shallow GW is mainly controlled by a mass transfer mechanism. The
3
H analyses with GW levels also indicate that only deep GW is controlled by a pressure transfer mechanism, and this mechanism is likely the main influence on the landslide kinematics.
On March 28, 2016, the toe zone of the apparently dormant Pergalla earthslide-earthflow (Northern Apennines, Italy) had a paroxysmal reactivation. In the course of 2 days, displacements up to almost ...8 m severely damaged several houses and roads. At the bottom of the slope, the emersion of rotational sliding surfaces determined the uplift of almost 3 m of the Nure river streambed that was consequently partially dammed. The paper describes the landslide event on the basis of field surveys and analysis of post-event aerial photos, as well as data from geophysical surveys and pre- to post-failure displacement monitoring. It also discusses the possible concurrent causes of the event, including antecedent rainfall, the migration of active streambed channels of Nure river toward the landslide toe in the previous year, and the existence of long-term pre-failure slow movements. It is concluded that these factors, together with the presence of sliding surfaces extending beneath the valley floor, should be primarily considered if a preventive assessment of river damming potential due to streambed uplift should be made for other similar landslides in the Apennines.
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