QMorphoStream: processing tools in QGIS environment for the quantitative geomorphic analysis of watersheds and river networks

The quantitative geomorphic analysis is a powerful tool for the study of geomorphology and landforms, as it provides objective methods to describe the main properties of drainage basins by means of an appropriate set of parameters. Over the last decades, GIS techniques and processing tools have been widely applied to the geomorphic analysis, and specific applications were developed, essentially using commercial software. In the present paper, the first experimental version of QMorphoStream, an originally developed set of processing tools for quantitative geomorphic analysis in QGIS environment, is presented. Besides the obvious advantage in terms of cost reduction, the choice of an open source development environment allowed us to integrate original algorithms with both QGIS built-in functions and processing tools available in the developers’ community.     

Resilience and seismic risk perception at school: a geoethical experiment in Aiello Calabro,southern Italy

The last few years have seen the debate on the geoethics of environmental and climatic protection growing to include resilience as a central idea within this new discipline, which holds many similarities with geography. Resilience analysis often looks at the capacity to re-establish conditions of equilibrium within a system which has been hit by a serious shock, e.g. a natural or man-made disaster. Geoethics works, in tandem with geological analyses and the geography of risk, to inform a population and develop integrated risk management in such a way as to strengthen a community’s resilience. The aim of this work is to study some people’s capacity to overcome what was potentially a disastrous event and, through a process of reconstruction, turn it into an occasion for growth. The experiment, carried out in the primary and middle schools in Aiello Calabro (Calabria, southern Italy), was conducted on the basis of the belief that there is a close relationship between a population’s having a realistic understanding of the risk of such an event, e.g. an earthquake, and high levels of resilience. We also tried to gain an insight into the relationship that may exist between resilience in primary and secondary school children and methods of coping which give an appropriate management of seismic risk. To be more precise, we try to discover whether there is a link between good/appropriate resilience and good/appropriate risk management.     

Occupation surfaces sealed by the Avellino eruption of Vesuvius at the Early Bronze Age village of Afragola in southern Italy: A micromorphological analysis

This paper reconstructs the use of space and defines activity areas within a single hut (Hut 8) at the Early Bronze Age village of Afragola (southern Italy). The village, consisting of a number of huts and other structures, was covered by approximately 1m of volcanic ash during the eruption of Vesuvius in 3550 ± 20BP. Thirteen samples were collected from inside the hut to analyze the spatial variability in sedimentary characteristics among three areas of Hut 8—the apsidal, central, and entrance areas. The micromorphological analysis revealed details about the occupation surface and its relationship to features and material remains in the hut not apparent in the field. The apsidal area was probably used for storage but not of solids, as no significant quantities of organic material were found. The central area contains a small oven, calcareous ash from fires, and organic material composed of charred remains and bone fragments and was likely used for small‐scale household tasks. A possible connection exists between the lithics and the microstratigraphic sequencing in the area west of the oven, suggesting that people congregated there to perform specific tasks. The entrance area contains highly compacted and heterogeneous sediments that were brought in from outside. Notable is the paucity of anthropogenic materials found inside the hut, especially given the remarkable preservation offered by the thick cover of volcanic ash. We hypothesize that Hut 8 was not occupied long enough to produce a large amount of debris or that it had limited indoor activities and was thoroughly cleaned. © 2010 Wiley Periodicals, Inc.     

Bearing Capacity of Strip Footings Near Slopes

In the last decades a great attention was given by many authors to the evaluation of the static and seismic bearing capacity of footings near slopes. In this paper a model has been developed based on the limit equilibrium method, considering a circular surface propagates towards the slope until the sloping ground is reached. The bearing capacity is investigated considering either the distance of the footing from the edge of the slope and/or the effect of the footing embedment. A validation of the proposed model was made by a comparison with solutions taken from literature regarding the evaluation of the bearing capacity for a footing adjacent to a slope and for an inclined load. The loading conditions consist in vertical and horizontal stress on the footing and on the soil below the footing. Both the inertial and kinematic effects of the seismic loading have been analyzed, and a simple equation has been derived for the evaluation of the seismic bearing capacity. The static and seismic bearing capacity has been investigated as a function of the soil friction angle, of the seismic coefficient, of the sloping ground. Finally, the influence of the distance of the footing from the edge of the slope was taken into consideration in the evaluation of the bearing capacity, and a threshold distance at which the reduction of the bearing capacity due to the sloping ground vanishes has been defined.     

Asymmetric copula in multivariate flood frequency analysis

The univariate flood frequency analysis is widely used in hydrological studies. Often only flood peak or flood volume is statistically analyzed. For a more complete analysis the three main characteristics of a flood event i.e. peak, volume and duration are required. To fully understand these variables and their relationships, a multivariate statistical approach is necessary. The main aim of this paper is to define the trivariate probability density and cumulative distribution functions. When the joint distribution is known, it is possible to define the bivariate distribution of volume and duration conditioned on the peak discharge. Consequently volume–duration pairs, statistically linked to peak values, become available. The authors build trivariate joint distribution of flood event variables using the fully nested or asymmetric Archimedean copula functions. They describe properties of this copula class and perform extensive simulations to highlight differences with the well-known symmetric Archimedean copulas. They apply asymmetric distributions to observed flood data and compare the results those obtained using distributions built with symmetric copula and the standard Gumbel Logistic model.     

The carbonate fraction in carbonatitic Italian lamprophyres

Alkaline and ultramafic lamprophyres represent the majority of pre-Pleistocene alkaline mafic magmatic activity in Italy and have been described from several localities. The age of magmatism ranges from Triassic to Lower Oligocene. Some contain appreciable amounts of carbonate. The primary carbonate of the Italian carbonatitic lamprophyres is mainly Sr- or Mn-rich calcite that occurs mostly as immiscible ocelli or as groundmass. Its textural occurrence, composition, and relationship with co-precipitating silicate phases is taken as evidence of an igneous origin. Low BaO and REE contents in the carbonate are explained by early crystallization of essential mica and subordinate apatite. Whole rock analyses and isotopic data (Rukhlov, A.S., Bell, K., Vichi, G., Stoppa, F., submitted for publication. The heterogeneous deep mantle: the Sr, Pb and Nd isotopic evidence from Early Cretaceous alkaline lamprophyres of Southern Tuscany, Italy. Lithos.) suggest a mantle origin for these rocks and rule out contamination in either high or low pressure regimes. The bulk compositions of the carbonatitic lamprophyres have high HFSE / LILE and LREE / HREE ratios and although the abundances of these elements are generally lower than for carbonatites s.s., they are comparable with the abundances in other ‘carbonate-free’ Italian lamprophyres and Italian carbonatites, suggesting similar mantle sources. Moreover, the age of the Italian lamprophyres, ranging from Middle Triassic to Lower Oligocene, is much greater than the Pleistocene age of Italian carbonatites and indicates that the source remained similar over a long time span.     

Melilitite at Fort Portal, Uganda: Another dimension to the carbonate volcanism

Because the calciocarbonatite lavas at Fort Portal were the first ever described they have received great attention, with the pyroclastic rocks being relatively neglected. Volumetrically the lavas are minute, and the major deposit is a 2 m thick blanket of “flaggy” tuffs, long regarded as carbonatite tuff with crustal debris. Fresh examination shows these tuffs to contain melilitite previously unreported from Fort Portal. The rock is a mix of crust and mantle debris with near-isotropic lapilli, set in a matrix composed predominantly of carbonate. The low birefringence parts of the lapilli are devitrified melilitite glass. Compound lapilli are abundant, containing aggregates of globules, together with xenolithic/crystic fragments. In some, there are concentric zones of more carbonate rich material alternating with melilitite: tangential phlogopite flakes mark the outer zones, in marked contrast to their planar distribution through the enclosing rock matrix. Euhedral titano-magnetite (10–15%) is the most obvious cognate mineral. Devitrified melilitite contains abundant small crystals and microlites of melilite, apatite, magnetite, and carbonates, mostly formed during disequilibrium quench crystallisation. Because of this, and widespread fine grained accidental debris, a precise bulk melt composition is hard to obtain, but the average is close to melilitite with high P₂O₅. Mantle debris is largely disaggregated magnetite–phlogopite clinopyroxenite, which could give a bulk composition close to the melt. Low Mg and high Mg calcite are present in the melilitite lapilli, and in the enclosing carbonate rich matrix. Previously, high Mg calcite was reported only as cement in lapilli tuffs, while the lavas contain only low Mg calcite in the assemblage calcite–periclase (consistent with low pressure carbonate melt crystallisation). Carbonatite–melilitite magma left the mantle carrying restite debris. Melt fragmentation took place in the deep crust, with rapidly quenched droplets enclosing crust debris. Chemical covariations within the flaggy tuffs are uniform and explicable as carbonatite–melilitite plus a thoroughly mixed combination of crust and mantle debris. New links are indicated with the alkaline ultramafic-carbonate volcanism to the south, in Uganda, and parallels with that in Italy.     

Late Quaternary palaeohydrology of Lake Pergusa (Sicily,southern Italy) as inferred by stable isotopes of lacustrine carbonates

Ten meters of lacustrine deposits retrieved from Lake Pergusa (Sicily, southern Italy) were investigated through stable isotope composition (carbon and oxygen) of authigenic carbonate (calcareous muds) and freshwater shells. The core chronology was established through three AMS dates, and by correlation with a previously dated nearby core. Stable isotope data show that the lake water evolution was mainly dominated by evaporation. Between ca. 20 and 28 ka the recovered sediments have very high δ¹⁸O values, likely corresponding to very dry climatic conditions. The observed rapid oscillations in the δ¹⁸O of the recovered sediments during this period also suggest important climatic fluctuations. More humid conditions dominated during the Holocene period, with the wettest interval occurring between ca. 9000 and 3000 years BP. Late Holocene sediments represent a substantial return to drier conditions. The available pollen data from a nearby core substantially confirm this general climatic trend during the Holocene. The positive correlation between δ¹³C of the calcareous muds and carbonate content suggests that biological activity played a key role in the carbon isotope evolution of dissolved inorganic carbon. However, a clear climatic signal is not evident from the δ¹³C record.     

Application of biomarkers for assessing the biological impact of dredged materials in the Mediterranean: the relationship between antioxidant responses and susceptibility to oxidative stress in the red mullet (Mullus barbatus)

In the period 1997-2000, approximately 1,800,000 m3 of material dredged from the Port of Leghorn was discharged into a sea dumping site located 14 miles from the coast. The red mullet (Mullus barbatus) was used as a bioindicator species for monitoring the biological impact of these discharges on a geographical and temporal scale. Organisms were sampled over three years (1998-2000) at different stations and several biomarkers, both of exposure and effect, were analyzed. Bioavailability of specific classes of pollutants was evaluated by analyzing levels of metallothioneins, the activity of cytochrome P450 1A (CYPIA) and of glutathione S-transferases. Among biomarkers of effect, special attention was paid to the balance between prooxidant challenge and antioxidant defenses, and to the appearance of damage caused by oxidative stress. The analyses of the main components of the antioxidant system included superoxide dismutase, catalase, glutathione peroxidases, glutathione reductase, glyoxalase I and II, and total glutathione. These data were integrated with the measurement of total oxyradical scavenging capacity (TOSC) as an indication of the overall biological resistance to toxicity of different forms of oxyradicals (peroxyl radicals, hydroxyl radicals and peroxynitrite). Results indicated a biological impact in organisms sampled near the disposal site; the impact was particularly evident during 1999 and mainly related to organic chemicals such as PAH. Exposure to these pollutants also caused variations in the levels and activity of several antioxidants. The analysis of TOSC, however, revealed that the overall capacity of specific tissues of organisms to absorb various oxidants was not seriously compromised when challenged with increased prooxidant pressures. Variations of single antioxidants were useful in revealing early warning "biological responses", while integration with TOSC analyses indicated if such changes also reflect a more integrated and functional "biological effect" with possible consequences at the organisms level. The red mullet appears to be a useful sentinel species for a biomarker approach to monitoring impact caused by dredged materials.