Organic pollutants (PAHs, PCBs) in sediments from the Mar Piccolo in Taranto (Ionian Sea, Southern Italy)

Polychlorinated biphenyls (PCBs) and 17 parent polycyclic aromatic hydrocarbons (PAHs) were determined in surface sediments from nine stations in the Mar Piccolo of Taranto (Ionian Sea, Southern Italy). Total PAH concentrations ranged from 380 to 12,750 microg/kg d.w., while total PCB levels ranged from 2 to 1684 microg/kg d.w.; this values were higher than those found in others marine coastal areas of the Mediterranean Sea. For PAHs, low molecular weight/high molecular weight, phenanthrene/anthracene and fluoranthene/pyrene ratio were used for discriminating between pyrolitic and petroleum origin. Results showed that PAHs were mainly of pyrolitic origin. PCB and PAH levels in sediments were compared with Sediments Quality Guidelines (ERM-ERL, TEL-PEL indexes) for evaluation probable toxic effects on marine organism. Finally, ERM and PEL quotients were used to evaluate the degree to which chemicals exceed guidelines. Results suggest an ecotoxicological risk for benthic organisms mainly in the first inlet, where high concentrations of PCBs were found in sediments influenced by harbour activities.     

Role of wall panel connections on the seismic performance of precast structures

Past seismic events, including the 2009 L’Aquila earthquake and the 2012 Emilia earthquake, clearly demonstrated the inadequacy of the current design approach for the connection system of the cladding wall panels of precast buildings. To clarify this problem the present paper investigates the seismic behaviour of a traditional precast structural frame for industrial buildings with a new type of connection system of cladding panels. This system consists of a statically determined pendulum arrangement of panels, each supported with two hinges to the structure, one at the top and one at the bottom, so to have under seismic action a pure frame behaviour where the wall panels are masses without stiffness. Adding mutual connections between the panels, the wall cladding panels become part of the resisting structure, leading to a dual frame/wall system or to a wall system depending on the stiffness of the connections. The seismic behaviour of this structural assembly is investigated for different degrees of interaction between frame and panels, as well as for an enhanced solution with dissipative connections. The results of nonlinear static (pushover) analyses and nonlinear dynamic analyses under recorded and artificial earthquakes highlight the role of the wall panel connections on the seismic behaviour of the structural assembly and show the effectiveness of the dual frame/wall system with dissipative connections between panels.     

Food preferences and rhythms of feeding activity of two co‐existing demersal fish,the longspine snipefish,Macroramphosus scolopax (Linnaeus, 1758), and the boarfish Capros aper (Linnaeus, 1758), on the Mediterranean deep shelf

The feeding behaviour of two potentially competing species, the longspine snipefish, Macroramphosus scolopax, and the boarfish Capros aper was examined. While both species are very abundant along the Mediterranean coast and are regularly caught by demersal trawlers, they are of no commercial value. The diets of boarfish and longspine snipefish were investigated from samples collected between January 2001 and May 2002. Variations in the diet with fish size and season, as well as diet overlap and diversity were explored. Mysid shrimps, amphipods and gastropods were the most important food items in the diet of longspine snipefish. During ontogenetic development, M. scolopax occupies different trophic levels: the diet shifts from being predominantly composed of mysids (Anchialina agilis, Lophogaster typicus, Erythrops sp., Leptomysis spp.) in the smaller longspine snipefish [<6.5 cm total length (TL)] towards decapods (Anapagurus laevis) and amphipods (Leucothoe incisa, Eusirus longipes, Hyperidea) in the larger individuals (>6.5 cm TL). Crustacean decapods and copepods were the most important prey in the stomachs of boarfish. Mysids (Lo. typicus), euphausiids and nematodes were present in the larger individuals (>8 cm TL). A more generalist diet, still containing copepods, crustacean decapods, gastropods (Limacina retroversa) and a large variety of amphipods (e.g. Phtysica marina, Stenotoe bosphorana) and mysids (e.g. A. agilis, Leptomysis spp., Erythrops sp.), dominated the diet of C. aper between 2 and 8 cm TL. Diet overlap between longspine snipefish and boarfish was very low and the differences in stomach species diversity were explained by season and fish size.     

Influence of different mechanical column-foundation connection devices on the seismic behaviour of precast structures

Dry-assembled precast concrete frame structures are typically made with dowel beam-to-column connections, which allow relative rotation along the beam direction. In the orthogonal direction the rotation of the beam is prevented but again the connections of the superimposed floor elements allow for relative rotation. All the ductility and energy dissipation demand in case of seismic action is therefore concentrated at the base of cantilever columns. Hence, the column-to-foundation connection plays a key role on the seismic performance of such structures. Mechanical connection devices, even if correctly designed for what concerns resistance, may affect the behaviour of the whole joint modifying the ductility capacity of the columns and their energy dissipation properties. An experimental campaign on different mechanical connection devices has been performed at Politecnico di Milano within the Safecast project (European programme FP7-SME-2007-2, Grant agreement No. 218417, 2009). The results of cyclic tests on full scale structural sub-assembly specimens are presented. Design rules are suggested for each of the tested connections on the basis of the experimental observations, and numerical analyses have been performed with hysteretic parameters calibrated on the experimental loops. The seismic performance of structures provided with those connections is investigated through a case study on a multi-storey precast building prototype, which has also been subject to full-scale pseudo-dynamic testing within the same research project at the European Laboratory of Structural Assessment of the Joint Research Centre of the European Commission. The comparison of the results from the structure provided with the different studied connections clearly highlights how some solutions may lead to both reduction of ductility capacity and dissipation of energy, increasing the expected structural damage and the seismic risk.     

Settlement and colonization of epi‐endobenthic communities on calcareous substrata in an underwater archaeological site

Underwater archaeological sites represent assets of great value that are subjected to physical and biological stresses. The study of biological settlement on calcareous substrata is the first step to understanding the biodeterioration processes that take place on man‐made structures (marble, statues, columns and other architectonic elements) in marine environments. To accomplish this objective, calcareous panels (30 × 30 × 2 cm) were immersed for 3, 6, 9 and 12 months along a north?south transect in marine protected areas of Baia (Naples). Both epilithic and endolithic assemblages were analysed: the latter was observed by scanning electron microscope after the cast‐embedding technique had been used. After 1 year the epilithic community was still changing, with algae and pioneer species overgrown by encrusting organisms, and the endolithic assemblage dominated by cyanobacteria/chlorophyte traces. Changes of epilithics lead changes on endolithics. The initial phototrophic borers were replaced by more sciophilous and competitive species; moreover, the first macroboring organisms arrived after the settlement of grazers. After 12 months of immersion, the rate of bioerosion was high, the material was deeply bored and all of the limestone surface was heavily covered.     

Conceptual design and full‐scale experimentation of cladding panel connection systems of precast buildings

Despite the long series of European research projects that has led to the setting of fully reliable seismic design criteria for precast structures, recent earthquakes have shown that a weak point still exists in the proportioning of the connection systems of cladding wall panels. Following this finding, this paper outlines an organic setting of the design problem of precast concrete structures including cladding–structure interaction and describes three possible solutions, namely, the isostatic, integrated, and dissipative systems. The related fastening arrangements, with the use of existing and innovative connection devices, are also described. This paper comments on the results of the pseudo‐dynamic and cyclic tests performed at ELSA Laboratory of the European Joint Research Centre of Ispra (Italy) on a full‐scale prototype of precast structure. The conception and the experimental performance of the structure with nine different configurations of either vertical or horizontal wall panel claddings are presented. The analysis of the results highlights the effectiveness of the different solutions in a comparative way. Copyright © 2017 John Wiley & Sons, Ltd.