Southeastern Italy Research Articles

Long-term characterisation of African dust advection in south-eastern Italy: Influence on fine and coarse particle concentrations, size distributions, and carbon content

Abstract Saharan dust (SD) is a relevant source of mineral particles (PM) for the Mediterranean region with potential impacts on air quality and climate. In this work, a long-term analysis of 56 SD events recorded between 2013 and 2018 at the Environmental-Climate Observatory of Lecce (SE Italy) was performed to investigate the effects and the seasonality of dust advection on PM2.5 and PM10, on carbon content, and on number and mass size distributions. The average duration of events was 2.6 days (10% of days) with a pronounced seasonality, 12.5% during warm seasons and 7.5% during cold seasons. The average contribution to PM10 was 1.5 μg/m3, between 1.4 μg/m3 (cold seasons) and 1.8 μg/m3 (warm seasons). Contribution to PM2.5 was significantly lower and not negligible during warm seasons (0.5 μg/m3). The impact of SD in south-eastern Italy is comparable with that in central Italy rather than to that observed in south-western Italy. Looking at PM10, 70 days exceeding legislation threshold were observed (4.8% of days), 22.9% of these exceedances were during SD. Extreme SD events (contributions > 100 μg/m3) cover 2% of the cases. Comparison of carbon content between SD and non-SD days shows that SD does not influence EC and eBC concentrations; however, SD contributes to secondary organic aerosol in the coarse fraction (PM10-2.5). Size distributions (in number and mass) measured during SD and non-SD days show that SD increases the particle number concentrations for diameters (Dp) larger than about 0.9–1 μm. Maximum increase was for Dp 2.5–3 μm.

Reappraisal of some species of the giant galericine Deinogalerix (Mammalia, Eulipotyphla, Erinaceomorpha, Erinaceidae) from the Miocene of south-eastern Italy, with a review of the genus

A revision of the remains of Deinogalerix from the Terre Rosse of Gargano, stored at the Department of Earth Sciences of Florence, improved our knowledge of the genus. The goals of this study are to clear the taxonomic status of the specimens and to tackle several issues connected with the evolutionary relationships of the different species. The sample of dental remains of Deinogalerix freudenthali provides new information, which confirms that this species belongs to the most primitive members of the genus, alongside D. masinii. It is now clear that D. freudenthali is very close to the hypothetical ancestor of all other Gargano species, except D. masinii. Nonetheless, the oldest fissures of the Gargano Terre Rosse contain also primitive species of unsettled taxonomic and phylogenetic position. The present analysis shows the systematic validity of D. minor and D. intermedius, whose status was debated. Moreover, the study verifies the consistency of the two phyletic lineages Deinogalerix minor–D. brevirostris and Deinogalerix intermedius–D. koenigswaldi, as well as the co-occurrence of members of the two lines at least in the most recent Terre Rosse fissures. The enhanced information contributes to our understanding of the genus Deinogalerix and especially of the most ancient phases of colonisation of the Apulia Platform. Nonetheless, the fossil record of the genus remains imperfect, with many gaps blurring the origins of its various evolutionary lines.

Lactic Acid Fermentation of Pomegranate Juice as a Tool to Improve Antioxidant Activity.

An increasing consumer demand for pomegranate has been globally observed, mainly thanks to the scientific evidence related to its functional and health-promoting features. Pomegranate fruits from twenty accessions identified in Southeastern Italy were characterized according to morphological and chemical features. Juices extracted from pomegranate fruits were fermented with selected Lactobacillus plantarum PU1 and the antioxidant activity investigated. Whey was added to juices to promote the microbial growth. Fermentation led to the increase of the radical scavenging activity (up to 40%) and significant inhibition of the linoleic acid peroxidation. The three fermented juices showing the highest antioxidant activity, and the corresponding unfermented controls, were further characterized. In detail, the cytotoxicity and the protective role toward artificially induced oxidative stress were determined on murine fibroblasts Balb 3T3 through the determination of the viability and the intracellular ROS (reactive oxygen species) scavenging activity (RSA). RSA reached values of ca. 70% in fermented juices, being ca. 40% higher than the unfermented and control samples. Phenols compounds of the pomegranate juices obtained from accessions “Bitonto Piscina,” “Sanrà nero,” and “Wonderful (reference cultivar) were analyzed through ultrahigh pressure liquid chromatography coupled with mass spectrometry, showing that a marked increase (up to 60%) of the ellagitannins derivatives occurred during fermentation. Sensory analysis showed suitability of the fermented juices to be used as beverage and food ingredient.

Budget impact analysis of PCSK9 inhibitors costs from a community payers’ perspective in Apulia, Italy

IntroductionDespite established clinical efficacy of PCSK9 inhibitors (PCSK9i) in reducing cardiovascular events, their cost still represents a big matter of debate. We therefore sought to estimate possible impact of PCSK9i...

Wild vegetables do not lie: Comparative gastronomic ethnobotany and ethnolinguistics on the Greek traces of the Mediterranean Diet of southeastern Italy

ABSTRACT Bio-cultural and historical aspects of the “wild plant” portion of the Mediterranean Diet are still very much understudied despite the large number of bio-medical studies on the topic. The current gastronomic ethnobotanical and ethnolinguistic field study focused on the wild leafy vegetables used among Greek populations in SE Italy and NE Greece. A total of 52 folk taxa, corresponding to 58 wild botanical species, were recorded. The frequency of consumption of these wild ingredients was higher in NE Greece than in SE Italy, although approximately one-third of the recorded wild taxa overlapped in the two study sites. Most of these common species were designated by cognates, having in most cases a clear Greek origin, while one-third of the recorded wild vegetables in SE Italy were also used by another Greek diaspora living in SW Italy. The majority of the original Greek wild vegetables are synanthropic weeds. It is likely that the culinary uses of these species originated in the Near East during the post-Neolithic period before they migrated west to Italy and the Mediterranean Basin via Greece and Greek diasporas.

A Modelling Approach for Assessing the Hydrogeological Equilibrium of the Karst, Coastal Aquifer of the Salento Peninsula (Southeastern Italy): Evaluating the Effects of a MAR Facility for Wastewater Reuse

The Salento Peninsula is characterized by poor surface water resources, due to the karstic nature of its territory. On the other hand, important groundwater resources are located in the deep, karst, coastal aquifer, which is of strategic importance for the economic and social development of the area. The increasing water demand, however, if not properly managed may pose serious problems to the hydrogeological equilibrium of this aquifer, which is highly susceptible to natural and anthropogenic changes and to saltwater intrusion. Taking steps from the previous works, the present paper focuses on the characterization of the deep aquifer of the Adriatic portion of the Salento Peninsula from a quantitative point of view by means of modelling tools for the simulation of groundwater dynamics. Conclusions about the extent of the saltwater intrusion phenomenon are consequently inferred. As a result of the implementation of a density-dependent flow model, the lateral extent of such phenomenon and the vertical depth of the transition zone between freshwater and saltwater were inferred, highlighting also the role of major faults which characterize the hydraulic behaviour of the karst system under exam. The model was also applied to design a Managed Aquifer Recharge facility for management and protection of the hydrogeological equilibrium of the deep aquifer. Its positive effects on the advancement of the saline front were highlighted. Model results also allowed identifying areas where the lack of data prevents a proper comprehension of the hydrogeological processes investigated, thus representing a supporting tool for planning further monitoring campaigns.

Size-resolved particle emission factors of vehicular traffic derived from urban eddy covariance measurements

Road traffic is one of the major sources of atmospheric particles in urban areas. Modelling the contribution of this source to urban pollution requires reliable estimates of emission factors possibly resolved in size. In this work, size-resolved particle emission factors (EFs) of the mixed vehicle fleet were measured in the urban area of Lecce (south-eastern Italy). The approach used is based on vertical fluxes measured with eddy-covariance, counting of vehicles, and estimation of footprints. Results show that the average EF in number (range 0.009–3 μm) was 2.2*1014 #/Veh km, being dominated by ultrafine particles (Dp < 0.25 μm) due to exhaust emissions. EF number size distribution decreases with particle size. A reduction of more than four orders of magnitude was observed at Dp ≅ 0.9 μm. EF mass size distribution reaches a maximum around Dp ≅ 0.3 μm then decreases until Dp ≅ 0.9 μm. For larger particles EF in mass increases for the influence of non-exhaust emissions. Average emission factor of PM1 was 56 mg/Veh Km and that of PM2.5 was 63 mg/Veh Km. A comparison of measurements taken in 2010 and 2015 in the same area shows a decreasing trend of the average total EF in number of about 56%, likely as a consequence of the increased use of new generation vehicles following more restrictive limits for particle emissions.

Groundwater resources at salinisation risk: effects of climate and utilisation changes in the case of Apulian coastal aquifers (Southeastern Italy)

Seawater intrusion is the main cause of groundwater salinisation in Italy. The largest coastal aquifers, highly vulnerable to salinisation, are in Apulia. For these aquifers, main changes in terms of climate change and utilisation are discussed together with piezometric trends, as the latter are relevant triggering factors for upconing and lateral seawater intrusion. For this purpose, time series from 1921 to 2016 concerning climate (rainfall and temperature), from 1965 to 2016 concerning groundwater availability (piezometric values), and recent periodic data on potable utilisation are discussed. Climate and groundwater availability trends at 2016 are compared with trends previously assessed, using the same dataset (1921-2001 for rainfall and temperature). The negative characteristic of rainfall 1921-2001 trend improved in the next years up to disappear in the assessment of rainfall 1921-2016 trend. Notwithstanding the improving of rainfall trend and the reduction of groundwater utilisation, both observed at 2016, the improvement of piezometric trends at 2016 is not enough to remove a prevailing decreasing trend, previously observed. The increases of temperature and effective evapotranspiration should be considered a relevant explanation of groundwater availability reduction. The consequence of these results should be quickly considered in the management of groundwater resources.

Evolution of fluviokarst canyons in response to the Quaternary tectonic uplift of the Apulia Carbonate Platform (southern Italy): Insights from morphometric analysis of drainage basins

The evolution of fluviokarst landscapes results from the interplay of karst and fluvial processes, all driven by rock uplift or base level fall. The fluviokarst landscape of the Murge Plateau in the central Apulian Region (southeastern Italy) is characterized by narrow, steep-sided, V-shaped canyons, locally called ‘Gravine’, and deeply incised into the Plio-Pleistocene deposits of the Bradanic Trough and the underlying Apulian limestone bedrock. Previous studies propose alternative models of canyons development, however identifying a dominant morphogenetic process for the evolution of the ‘Gravine’ fluviokarst drainage basins remains an open question. The results of our regional morphometric analysis reveal a marked transition from the relict, low-relief landscape preserved in the Murge uplands to the steep channel reaches below prominent knickpoints showing evidence of a transient wave of river incision that is propagating inland. We observe anomalies of mean local relief and channel steepness, and the distribution of fluvial knickpoints consistent with a regional uplift affecting the Murge Plateau since Middle-Late Pleistocene. These findings demonstrate that the history of landscape evolution was dominated by fluvial processes. Using transformed river profile analysis we show that χ anomalies in the ‘Gravine’ trunk channels indicate drainage basin instability by drainage area capture. The convex-shape of the hypsometric curves and high hypsometric integrals confirm that the disequilibrium state of the 13 analyzed basins results from a combination of regional uplift and subsequent river network reorganization and plateau area captures. Based on our results, we propose a new model of landscape evolution for the ‘Gravine’ fluviokarst drainage basins.

An Inticetus-like (Cetacea: Odontoceti) postcanine tooth from the Pietra leccese (Miocene, southeastern Italy) and its palaeobiogeographical implications

An Inticetus-like (Cetacea: Odontoceti) postcanine tooth from the Pietra leccese (Miocene, southeastern Italy) and its palaeobiogeographical implications

Optical properties of PM2.5 particles: Results from a monitoring campaign in southeastern Italy

The performance of aerosol classification schemes based on intensive optical parameters and applied to mixed particle populations monitored at the surface has been investigated to test the ability of optical parameters to identify different types of particles/particle mixtures and explore their complex features. The results show that the combination of two intensive optical parameters does not allow for the unique identification of different particle types. The classification scheme based on the Absorption Ångström Exponent (AAE) as a function of the Scattering Ångström Exponent (SAE) and color-coded by the Single Scattering Albedo difference (dSSA) is a good graphical framework to discriminate between different types of particle/particle mixtures. This aerosol classification scheme has been applied to study the optical properties of heterogeneous PM2.5 particles that were monitored at a coastal site of the Central Mediterranean and were significantly affected by both natural and anthropogenic sources also because of long-range transport from surrounding countries. The calculated AAE, SAE, and dSSA hourly means smoothly and continuously vary within their respective range (0.6–3.4, −0.7–3.0, and −0.33–0.52, respectively) because of the different mixing degree of different types of particles. Consequently, the main features of the particle populations depend on the range of the AAE, SAE, and dSSA values. Eight different clusters have been selected within the used graphical framework to identify four key particle populations (dust, marine, OC-dominated, and BC-dominated particles) and four particle mixtures dominated by key aerosol populations. In addition, their main features have been characterized. Particle mixtures consisting of large and low-absorbing particles (LLAP), small and high-absorbing particles (SHAP), dominated by dust, and large organic particles have been characterized. Marine, LLAP, and mixed dust clusters with a SAE value below 1 are responsible for aerosol scattering coefficients (σs; at 470 nm) below 100 Mm−1. Conversely, SHAP, BC-dominated, and OC-based mixtures are responsible for the highest σs values and represent dominant particles species.

Il sito medievale di Montecorvino (FG) e il suo territorio. Analisi spaziali in ambiente GIS Open Source

Since 2016, the Montecorvino project has studied the topics of intervisibility and of the movement of humans and goods in the area of Monti Dauni (Foggia, South-Eastern Italy) in the late Middle Ages. This has been accomplished through the use of spatial analysis in an Open Source GIS. The use of Digital Terrain Models in a hilly area has been crucial in analyzing the influence of geo-morphological contexts on the genesis and development of settlements. Single and cumulative viewshed analyses have been applied to figure out if and to what extent these settlements could keep sight of each other, their surroundings and the communication routes. By means of a cost surface analysis, some site catchment areas have been defined and the potential and easiest (least costly) paths between some of these settlements have been generated. The results have then been integrated into a much wider research-field, which features archaeological, historical and bibliographical sources of information, to produce a comprehensive and integrated study of the ancient landscapes.

Le sommet de l’iceberg ? Colonisation pionnière et néolithisation de la France méditerranéenne

Recent research into the European Neolithisation process and the development of farming communities reveals a diverse and complex cultural landscape. In the Western Mediterranean, it is now well known that the first agro-pastoral economy appears around 6000 BCE in south-eastern Italy and that part of these sites, often grouped under the generic term “Impressed Ware”, represent the departure point for the diffusion of the Neolithic economy. In this context, its rapid dispersal towards northern Italy and southern France is now interpreted as part of a pioneering colonization based on the use of maritime routes and preceding of several centuries the expansion of the Cardial culture. In southern France, archaeological settlements that make it possible to characterize this early stage of the Neolithisation process are still rare and do not have an equal value. The new discovery of an Impressa implantation at the site of ZAC de la Farigoule 2 (Aubord), in the Mediterranean Languedoc, gives us the opportunity to consolidate our knowledge about this major historical phenomenon. Despite its limited size, this site provides a rich set of data : domestic structures, pottery production, flint and obsidian industries, ground stone tools… The technological and typological characteristics of the pottery and the flint industry can be clearly assigned to the Impressa facies (Arene Candide-Caucade-Peiro Signado style). La Farigoule 2 is therefore an undeniable testimony to the establishment of a group linked to the agro-pastoral communities of the Italian peninsula. It is not possible to discuss in length the nature of the occupation on the basis of the deposits provided by the excavation. Nevertheless, the indirect evidence of cereal farming (sickle blades), the diversity of craft activities, the domestic structures, the identification of potters' tools, all these data are consistent with the image of a permanent occupation. Local resources are exploited : siliceous raw materials, clay soils and hard rocks. However, the use of products acquired several hundred kilometres away reinforces the hypothesis of the pioneering displacement of human groups taking with them their technical, economic and cultural background. Discussed in the broader scale of southern France and western Mediterranean, these new data allow us to consider fundamental issues raised by this pioneering colonization process. Important spatial discontinuities are observed in the distribution of these settlements, although this phenomenon seems to concern the entire Western Mediterranean. Nevertheless, the discovery presented in this paper should encourage us to consider a perhaps higher density of sites. It should also lead us to question our ability to detect these settlements. Concerning the natural and cultural factors that determine the settlement patterns of these Impressa groups, they are still in discussion but the scarcity of the paleoenvironmental data (position of the shoreline, vegetal landscape) restricts argumentation. Another issue is the future of these pioneering groups and their impact on the overall Neolithisation process in the South of France and possibly in Mediterranean Spain. In a large part of Southern France, one can observe a real chronological hiatus between sites with Impressa facies and those from the Cardial. Without ruling out the possibility of a taphonomic bias, this situation could be related to the model of micro-breaks observed elsewhere in the Neolithic diffusion in the Mediterranean at different periods. Finally, the analysis of the material productions of these pioneering groups illustrates complex socio-cultural dynamics that we still need to unravel. While the temporal dynamics of the diffusion of the "Neolithic package" (farming economy, pottery,…) across the western Mediterranean seems to be well understood, the chronometric, social and cultural framework needs to be considerably refined. In this perspective, further works on this important stage of Neolithic history, particularly through the discovery of new sites, is a major challenge for future research.

‘The more South you go, the more frankly you can speak’: Metronormativity, critical regionality and the LGBT movement in Salento, South-Eastern Italy

In recent times, the region of Salento in South-Eastern Italy has become one of the most popular gay-friendly tourist spots in the country and several LGBT organisations have operated in this territory over the last few years. This article seeks to map the creation, development and challenges of the LGBT movement in this Italian sub-region by looking at forms of negotiation between ‘local’ and ‘queer’ identities and beyond narratives of ‘metronormativity’ of LGBT identities and from the perspective of ‘critical regionality’ and ‘meridian thought’. Through semi-structured interviews conducted with five local LGBT activists in 2016 and ethnographic observations carried out at Pride events in 2016 and 2017, the article looks at conflicting social processes whereby local activism is rooted in situated allegiances and interactions with the territory and its population, whilst being permeated by the globalising dynamics of LGBT identity politics.

Atmospheric response to the 20 March 2015 solar eclipse along the whole aerosol column by lidar measurements

Lidar measurements at 355, 532, and 1064 nm have been performed at Lecce (40.3°N, 18.1°E), in south-eastern Italy, to investigate for the first time the impact of the 20 March 2015 solar eclipse on both the planetary boundary layer (PBL) height and the aerosol optical and microphysical properties along the whole aerosol column. The partial solar eclipse lasted from 08:30 up to 10:47 UTC and reached the full phase at 09:37 UTC. The maximum percentage obscuration of the solar disk was 43.6%. The eclipse cooling effect was responsible at the full phase time (tF) for the downward solar irradiance decrease at the top of the atmosphere, at the surface, and within the atmosphere of 429.2 ± 0.6, 373 ± 25, and 56 ± 26 W m−2, respectively. The turbulent kinetic energy, the potential temperature flux, the sensible heat flux, the variance of air temperature, and the vertical wind speed at the surface revealed that the turbulence activity reached the maximum weakening at the time tF. The standard deviation (SD) technique has been applied to both the lidar range corrected signals (RCS) at 1064 nm and the linear volume depolarization ratio (δV) profiles at 355 nm to determine the time evolution of the shallow PBL height and the aloft aerosol layers. The SD technique applied to RCS and δV profiles revealed similar results within experimental uncertainties. The PBL height, which was equal to 380 ± 40 m above ground level (AGL) at the eclipse full phase (09:37 UTC), decreased up to 220 ± 20 m at 09:45 UTC because of the eclipse cooling effect and, then, increased up to 320 ± 30 m at 10:17 UTC. The determined PBL height time evolution was in good agreement with the ones of the main turbulence parameters at the surface after tF. The vertical profiles of the aerosol backscatter coefficient (ββ), the δV at 355 nm, and the extinction-related Ångström exponent (Å), calculated at the 355–1064 nm wavelength pair revealed a marked decrease of β, δV, and Å at the eclipse full phase within the aloft aerosol layers. The abrupt β, δV, and Å decrease due to the aerosol concentration and type changes has mainly been associated with the decrease of the fine-mode particle contribution.

A statistical method based on the ensemble probability density function for the prediction of “Wind Days”

Numerical Weather Prediction (NWP) models are often used to predict meteorological events in a deterministic way. In recent years, operational Ensemble Prediction Systems are able to take into account some of the errors affecting the NWP models, and allow to estimate the probability of occurrence. In the traditional approach, this probability is given by the percentage of ensemble members predicting the event. In this study, we propose an alternative method to estimate the probability of occurrence, based on the ensemble probability density function (PDF), which takes into account only random errors unavoidably affecting the model. To estimate its reliability, we compare this method with classical categorical and probabilistic approaches by using different global models: ECMWF, GFS, and GEFS.In particular, we focus on wind speed forecasts in the area around the city of Taranto, located in Apulia region (southeastern Italy), to simulate the events called “Wind Days”, i.e. northwesterly wind above 7 m/s for 3 consecutive hours. Our analysis concerns 34 case studies covering 2016, opportunely chosen to have a balanced dataset of WD and no WD, the latter category mainly including cases that are very difficult to predict, at the border of the two categories. The results show that the probabilistic approaches have a better skill than the categorical ones. Among the probabilistic approaches, the best result (accuracy of 82%) is obtained using the method proposed here, with the control run of GEFS used to estimate the true value and the gamma distribution to model the error distribution.To reduce the systematic error, we test different thresholds and numbers of consecutive hours when the definition of WD is applied to model outputs. All the models show remarkably better performances after these parameters are changed. In particular, our method shows the best performance, with an accuracy of 94%. The analysis on test (leave-one-out strategy in 2016) and validation datasets (66 cases in 2017) confirms the previous outcomes. We test our procedures considering the forecast time intervals of 49–72 and 25–48 h, where similar performances are found. In conclusion, our analysis show that the proposed method presents better performances compared to the traditional approaches for different statistical performance indicators.

Influence of Wave State and Sea Spray on the Roughness Length: Feedback on Medicanes

Occasionally, storms that share many features with tropical cyclones, including the presence of a quasi-circular “eye” a warm core and strong winds, are observed in the Mediterranean. Generally, they are known as Medicanes, or tropical-like cyclones (TLC). Due to the intense wind forcings and the consequent development of high wind waves, a large number of sea spray droplets—both from bubble bursting and spume tearing processes—are likely to be produced at the sea surface. In order to take into account this process, we implemented an additional Sea Spray Source Function (SSSF) in WRF-Chem, model version 3.6.1, using the GOCART (Goddard Chemistry Aerosol Radiation and Transport) aerosol sectional module. Traditionally, air-sea momentum fluxes are computed through the classical Charnock relation that does not consider the wave-state and sea spray effects on the sea surface roughness explicitly. In order to take into account these forcing, we implemented a more recent parameterization of the sea surface aerodynamic roughness within the WRF surface layer model, which may be applicable to both moderate and high wind conditions. The implemented SSSF and sea surface roughness parameterization have been tested using an operative model sequence based on COAWST (Coupled Ocean Atmosphere Wave Sediment Transport) and WRF-Chem. The third-generation wave model SWAN (Simulating Waves Nearshore), two-way coupled with the WRF atmospheric model in the COAWST framework, provided wave field parameters. Numerical simulations have been integrated with the WRF-Chem chemistry package, with the aim of calculating the sea spray generated by the waves and to include its effect in the Charnock roughness parametrization together with the sea state effect. A single case study is performed, considering the Medicane that affected south-eastern Italy on 26 September 2006. Since this Medicane is one of the most deeply analysed in literature, its investigation can easily shed some light on the feedbacks between sea spray and drag coefficients.

First records of Eyprepocnemis plorans plorans in southeastern Italy (Orthoptera: Acrididae)

New populations of Eyprepocnemis plorans plorans (Charpentier, 1825) are first reported for southeastern Italy. The species was found in the period 2013-2017 in different lowland habitats of Apulia and Basilicata. These data may document a most recent colonization of southeastern Italy, which is potentially due to a wide range shift or expansion of species distribution from adjacent regions or countries.

Biogeochemistry and sedimentology of Lago di Lesina (Italy)

The Lago di Lesina (Lesina Lake, southeastern Italy) is a coastal pond located on an alluvial plain to the north of Gargano Promontory. The aim of this work was to study the depositional and hydrological processes, the benthic environment and the heavy metal sediments pollution of Lesina Lake. The study was carried out by Redox potential, water content, grain-size, mineralogical and biogeochemical analyses in surface sediments collected from 100 sampling stations in the coastal pond bottom. The results showed a predominance of three types of bottom pelitic sediments of different origins and compositions: siliciclastic, carbonatic, and organic. Siliciclastic sediments, which were found especially in the western basin and in the northwestern sector of the central basin, are due to inputs from Acquarotta Canal, some intermittent western streams, and deflation by northerly winds of the sandy barrier that separates the lake from the sea. Carbonate sediments are carried by streams and canals draining the carbonate rocks of the Gargano Mountains and entering the lake from its eastern and southeastern border, these sediments are predominant in the eastern basin and in the southeastern sector of the central basin. Organic matter is abundant throughout the whole lake; it is due to the high productivity of the Lago di Lesina waters that are rich of nutrients for inputs of waters draining the surrounding intensively cultivated agricultural areas. The finer bottom sediments of the lake tend to be removed from the shallower bottoms between the central and eastern sub-basins and near the borders to be deposited in the central portion of the central and western sub-basins. Heavy metal sediment pollution due to anthropic inputs is limited and consists of As, Pb, Cu, and Ni in the western basin, Cu, Zn, and Ni in the eastern basin, and Pb along the northern border.

Relationship between the planetary boundary layer height and the particle scattering coefficient at the surface

The relationship between the Planetary Boundary Layer (PBL) height and the particle scattering coefficient (σp) at the surface has been investigated with the main goal of estimating the PBL height from the ground-level particle optical properties that are simpler to measure and are provided by instruments as nephelometers, which can run continuously. A lidar system and an integrating nephelometer operating within the European infrastructure ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure) have been used to simultaneously monitor the daily evolution of both the PBL height and σp. Measurements have been performed at a coastal site of south-eastern Italy, characterized by a shallow PBL (<1000 m), during a two-year period. The standard deviation technique has been applied to lidar signals to determine the daily evolution of the PBL height, being this technique independent on the lidar overlap function. The maximum value of the PBL height hourly mean was reached around midday and was equal to 470 ± 160 m in spring-summer (SS) and 580 ± 170 m in autumn-winter (AW). A statistically significant inverse correlation between the PBL height and σp was found both in AW and in SS, since σp decreased with the increase of the PBL height, because of the increase of the ground-level particles' vertical dispersion. The retrieved relationships between the PBL height and σp have been used to estimate the daily evolution of the PBL height from σp values both in SS and in AW. We found a satisfactory accordance, within experimental uncertainties, between estimated and experimentally determined PBL heights. Therefore, a new experimental methodology to estimate the PBL height from ground-based nephelometer measurements has been suggested in the paper. The analysis of the scattering Ångström exponent has revealed that in AW the mean size of the particles at the surface on average increased during the central hours of the day, since the PBL height increase likely favoured the vertical dispersion of fine particles more than the coarse ones. The comparison between the lidar-derived PBL heights and the corresponding ones calculated by the HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model has revealed that the HYSPLIT PBL height seasonal and daily trends were similar to the corresponding ones retrieved from lidar measurements. Nevertheless, the HYSPLIT model on average overestimated by 40% and underestimated by 20% the experimentally determined PBL height in autumn-winter and in spring-summer, respectively.