Influence of the Po River runoff on the bacterioplankton community along trophic and salinity gradients in the Northern Adriatic Sea

The Po River runoff strongly affects the oceanographic and ecological characteristics of the Northern Adriatic Sea. Catalysed reported deposition ‐ fluorescence in situ hybridization (CARD‐FISH) analysis was employed to assess how the composition of the coastal bacterioplankton community is influenced by the river runoff in two different seasons (spring and autumn). Samples were collected from the water column along a coastal–offshore transect in the Northern Adriatic Sea at different depths. Four clone libraries were then constructed from coastal (0 m) and offshore waters (?65 m). Higher abundances of bacteria were recorded in coastal waters as compared with the offshore samples. This result was mainly due to the trophic state of the water column, and it was related to salinity. Particularly, Actinobacteria and Gammaproteobacteria were affected by the riverine inputs, whereas Bacteroidetes and Alphaproteobacteria showed only minor responses. This was particularly clear in the autumn sample, in which a clear difference between the coastal and the offshore samples was found due to a strong influence of the less saline river water with high nutrient concentrations. Analysis of 205 partial length 16S rRNA gene sequences indicated a high diversity with the dominance of Alphaproteobacteria, Bacteroidetes and Gammaproteobacteria mainly affiliated to coastal and marine bacterioplankton clades. Actinobacteria were also detected and, together with Gammaproteobacteria, strongly follow the freshwater intrusion. Overall, our results indicate that the seasonal difference in the Po River discharge greatly affects the bacterioplankton community. In spring we observed a smooth transition from coastal to open‐sea conditions owing to the more superficial freshwater plume. In autumn the deeper freshwater intrusion in the coastal site and thermal stratification offshore resulted in a marked difference between the coastal and offshore microbial communities.     

A unified assessment of marine Mediterranean assemblages: a lesson from benthic hydroids

Hydroids are important components of the communities of rocky bottom shallow coastal areas. The hydrozoan fauna of the Mediterranean Sea is probably one of most investigated in the world, with lots of faunistic and biogeographical studies. However, quantitative studies using the same sampling methodology and controlled sampling effort have been restricted to areas in the Western and Central Mediterranean. We compared hydroid assemblages in four areas of the Mediterranean Sea, from the Gulf of Cádiz to the South Adriatic Sea, following the same sampling and quantification methodology. Our analysis showed the dominant Atlantic character of the assemblages of the Gulf of Cádiz and the South Alboran Sea because of the influence of the inflowing Atlantic waters. Conversely, the hydroid assemblages of the North Alboran Sea were more similar to the assemblages in the Ligurian and in the South Adriatic, and with a number of species ranking between the observed in these two Mediterranean zones. Fourteen species were identified as making the most significant contributions to characterizing the Mediterranean hydroid species pool from a quantitative point of view. These taxa include species previously named as typical components of the Mediterranean hydroid fauna as well as those only recently recorded in the region (Eudendrium moulouyensis) and invaders such as Clytia hummelincki.     

Shallow-landslide susceptibility in the Costa Viola mountain ridge (southern Calabria,Italy) with considerations on the role of causal factors

The “Costa Viola” mountain ridge (southern Calabria), in the sector between Bagnara Calabra and Scilla, is particularly exposed to geo-hydrological risk conditions. The study area has repeatedly been affected by slope instability events in the last decades, mainly related to debris slides, rock falls and debris flows. These types of slope movements are among the most destructive and dangerous for people and infrastructures, and are characterized by abrupt onset and extremely rapid movements. Susceptibility evaluations to shallow landslides have been performed by only focusing on source activation. A logistic regression approach has been applied to estimating the presence/absence of sources in terms of probability, on the basis of linear statistical relationships with a set of territorial variables. An inventory map of 181 sources, obtained from interpretation of air photographs taken in 1954–1955, has been used as training set, and another map of 81 sources, extracted from 1990 to 1991 photographs, has been adopted for validation purposes. An initial set of 12 territorial variables (i.e. lithology, land use, soil sand percentage, elevation, slope angle, aspect, across-slope and down-slope curvatures, topographic wetness index, distance to road, distance to fault and index of daily rainfall) has been considered. The adopted regression procedure consists of the following steps: (1) parameterization of the independent variables, (2) sampling, (3) calibration, (4) application and (5) evaluation of the forecasting capability. The “best set” of variables could be identified by iteratively excluding one variable at a time, and comparing the ROC results. Through a sensitivity analysis, the role of the considered factors in predisposing shallow slope failures in the study area has been evaluated. The results obtained for the Costa Viola mountain ridge can be considered acceptable, as 98.1 % of the cells are correctly classified. According to the susceptibility map, the village of Scilla and its surroundings fall in the highest susceptibility class.     

Hydrological Regime and Renewal Capacity of the Micro-tidal Lesina Lagoon,Italy

A multidisciplinary approach that combines field measurements, artificial neural networks, water balance analyses and hydrodynamic modelling was developed to investigate the water budget and renewal capacity of semi-closed coastal systems. The method was applied to the Lesina Lagoon, a micro-tidal lagoon in the southern Adriatic Sea (Italy). Surface water flux between the lagoon and the sea was determined by neural network prediction and used as input in the analysis. Strong seasonal variations in the water budget equation were predicted. Fresh water inputs estimated by the water balance analysis were used as forcing by a calibrated finite element model to describe the water circulation and transport time scale of the lagoon’s surface waters. The model highlighted the spatial heterogeneity of the renewal behaviour of the system, with a strong east–west water renewal time gradient. Knowledge of spatial distribution of water renewal times is crucial for understanding the lagoon’s renewal capacity and explaining the high spatial variability of the biogeochemistry of the Lesina Lagoon.     

Relationships between seep-carbonates,mud volcanism and basin geometry in the Late Miocene of the northern Apennines of Italy: the Montardone mélange

The Montardone mélange (Mm) is a chaotic, block-in-matrix unit outcropping in the Montebaranzone syncline in the northern Apennines. The Mm occurs in the uppermost part of the Termina Fm, the Middle–Late Miocene interval of a succession deposited in a wedge-top slope basin (Epiligurian succession). The Mm is closely associated with bodies of authigenic carbonates, characterized by negative values of δ¹³C (from ?18.22 to ?39.05 ‰ PDB) and chemosynthetic benthic fauna (lucinid and vesicomyid bivalves). In this paper, we propose that the Mm is a mud volcano originated by the post-depositional reactivation and rising of a stratigraphically lower mud-rich mass transport body (Canossa–Val Tiepido sedimentary mélange or olistostrome) triggered by fluid overpressure. We base our conclusion on (1) the Mm pierces the entire Termina Fm and older Epiligurian units and represents the direct continuation of the underlying Canossa–Val Tiepido mélange; (2) the geometry and facies distribution of the Montebaranzone sandstone body, which are compatible with a confined basin controlled by the rising of the Mm; (3) the systematic presence of large-scale (lateral extension 300–400 m) seep-carbonates associated with the mélange, suggesting a persistent gas-enriched fluid vent from the ascending overpressured mud; (4) blocks and clasts sourced from the Mm, hosted by the authigenic carbonates, conveyed by ascending mud and gas-enriched fluids. The Mm represents one of the few fossil examples of reactivation of a basin-scale sedimentary mélange (olistostrome); a three-stage model showing mechanisms of Mm raising is proposed.     

Terrestrial laser scanner and geomechanical surveys for the rapid evaluation of rock fall susceptibility scenarios

The primary objective of this paper is to present a semiautomatic procedure that, integrated with traditional methods, can be useful for a rapid definition of rock fall susceptibility scenarios with the purpose of civil protection. Due to its morphology (steep slopes and narrow valleys), regional seismicity, and rock mass characteristics, the Nera Valley (Valnerina, Umbria Region, Italy) is characterized by high rock fall risk. With the aim of covering a wide range of features and investigating the main advantages and drawbacks of the proposed approach, data collection (terrestrial laser scanning (TLS) and geomechanical surveys) was carried out at three different slopes. Detailed three-dimensional (3D) models were created to reconstruct the shape and volume of the most unstable blocks, to define the position of the main rock fall source areas, and to precisely distinguish the outcropping materials and the position of the elements at risk for reliable runout analyses. The proposed approach can be useful in supporting proper maintenance and land management programs both in ordinary and in emergency circumstances.     

具平缓电子能谱的伽玛射线暴的解析光变曲线

在标准的伽玛暴余辉模型中,电子通过费米一级加速后形成单幂律能谱分布dn/dγe∝γe-p(p≈2.3),但在某些伽玛暴事件中观测到了平缓的电子能谱分布(即p＜2).在单幂律谱和分段幂律谱两种情况下,分别给出了具有平缓电子能谱的伽玛暴余辉的解析光变曲线,并以GRB 060908为例进行了讨论.同时提出了伽玛暴低能谱危机的...     

Dissociation Constants of Protonated Oxidized Glutathione in Seawater Media at Different Salinities

Oxidized glutathione (GSSG), which has four carboxylic and two amino groups, interacts with metal ions and may affect the bioavailability and geochemistry of metals in natural waters. In the present paper, six stepwise protonation constants K^\textH_i K^{\text{H}}_{i} for GSSG were measured as a function of salinity, S = 5–35‰ at t = 25°C (and in NaCl/MgCl₂ mixtures at different ionic strengths), in order to provide thermodynamic data for their acid base properties, which are useful for studying the interaction with metals in these media. The protonation enthalpies (ΔH _i /kJ mol⁻¹) were also determined at t = 25°C. The results were interpreted using the SIT model and Pitzer equations. The seawater model with the interaction parameters accounts for the differences between the values in NaCl and seawater. The results suggest that it is important to consider all of the ionic interactions in natural waters in examining the proton dissociation of GSSG.     

Hydrogeochemistry of Roccamonfina volcano (Southern Italy)

This is the first hydro-geochemical investigation carried out on the Roccamonfina Volcanic Complex groundwaters. The chemistry of Roccamonfina waters is defined by water–rock and water–rock–gas interactions. In fact, interactions between rocks of the first eruptive high-K formations and circulating groundwaters are recognized by high K concentrations. On the other hand, inverse concentration of calcium versus alkali metals is related to two different rock interactions occurring in different areas of the volcano: (a) within the caldera where groundwaters flow within latite and pyroclastic formations releasing calcium, and (b) similarly at the base of the volcano where groundwaters flowing from surrounding carbonates got strongly enriched in Ca. These geochemical processes are also associated with K (SE of caldera) and Mg/Ca (in sites located at the NE base of the volcano) decrease. Completely different dynamics occurs at Riardo groundwaters (SE). Here waters are the result of a mix between the Roccamonfina deep aquifer and the carbonate aquifer of the Riardo plain. Rich-CO₂ emissions make these waters strongly mineralized. Minor elements show a similar geochemical behavior of major ions and are crucial defining interactions processes. The evolution of Roccamonfina groundwaters is also evident along the simultaneous enrichment of Ba, Sr, and Ca. Ba increase is the result of deep local carbonate alteration enhanced by CO₂ emissions and, the lower Sr/Ca ratio, from 10 to 2 (ppb/ppm), is also due to the same process. In the light of our results the Roccamonfina aquifer can be schematically divided into two main reservoirs: (a) a superficial aquifer which basically follows the volcanic structure morphology and tectonics and (b) a deeper reservoir, originating within the oldest Roccamonfina volcano ultra potassic lavas and then flowing into the carbonate aquifers of the neighboring plain. Eventually, the chemistry of the Roccamonfina aquifer does not show any specific and visible pollution, contrary to what happens in the volcano surrounding plains. In fact, only 14% of the samples we collected (206) show a NO₃ content >30 mg/l. These sites are all located at the base of the volcano, near the plain.