Ecotoxicological and human health risk in a petrochemical district of southern Italy

An ecotoxicological investigation has been carried in the petrochemical district of Priolo (Sicily, Italy), one of the largest in Europe. Results indicated a severe mercury contamination in sediments sampled near a chloro-alkali plant. A clear bioavailability of this element was demonstrated in mussels Mytilus galloprovincialis (both native and translocated) and the benthic fish Mullus barbatus, which also exhibited marked genotoxic damages. The elevated mercury concentrations in marine organisms are a serious concern for human health; according to the national average fish consumption, the provisional tolerable weekly intake (PTWI) of Hg would be easily exceeded by at least 4 to 12 fold. Such toxicological risk is of particular importance for pregnant women, being possibly involved in the elevated frequency of neonatal malformations.     

Origin and timing of the post-Variscan gabbro–granite complex of Porto (Western Corsica)

The post-Variscan complex of Porto consists of metaluminous to slightly peraluminous A-type biotite granites mingled with gabbro-dioritic rocks, and late dykes with basaltic to trachyandesitic composition. U-Pb zircon dating by LA-ICP-MS on two mafic intrusive samples constrains the time of the gabbro–granite crystallisation at 281 ± 3 Ma and 283 ± 2 Ma. Hornblende ⁴⁰Ar-³⁹Ar ages from a late trachyandesite dyke date the dyking event at 280 ± 2 Ma, which is within error the U-Pb zircon ages of the intrusives. Biotite granites show variable major and trace element compositions and similar initial ε_Nd (−0.3 to +0.9). Whole rock chemistry variations and trace element compositions of plagioclase and allanite indicate that the granites are genetically linked, essentially through fractional crystallisation of feldspars and minor allanite. On the basis of whole-rock chemistry e.g. initial ε_Nd +4.9 to +1.7 and trace element clinopyroxene compositions, we have ascertained that the mafic intrusives and basic dykes formed from isotopically depleted mantle source-derived melts with similar trace element signature. These basic melts experienced slightly different evolutionary histories, controlled by fractional crystallisation and crustal contamination, mainly by the acid magma that gave rise to the associated biotite granites, but also by the enclosing older Variscan granitoids. U-Pb zircon data suggest that the Porto complex was affected by hydrothermal fluid circulation at 259 ± 9 Ma.     

Comparing Beerkan infiltration tests with rainfall simulation experiments for hydraulic characterization of a sandy‐loam soil

Saturated soil hydraulic conductivity, K _s , data collected by ponding infiltrometer methods and usual experimental procedures could be unusable for interpreting field hydrological processes and particularly rainfall infiltration. The K _s values determined by an infiltrometer experiment carried out by applying water at a relatively large distance from the soil surface could however be more appropriate to explain surface runoff generation phenomena during intense rainfall events. In this study, a link between rainfall simulation and ponding infiltrometer experiments was established for a sandy‐loam soil. The height of water pouring for the infiltrometer run was chosen, establishing a similarity between the gravitational potential energy of the applied water, E _p , and the rainfall kinetic energy, E _k . To test the soundness of this procedure, the soil was sampled with the Beerkan estimation of soil transfer parameters procedure of soil hydraulic characterization and two heights of water pouring (0.03 m, i.e., usual procedure, and 0.34 m, yielding E _p  = E _k ). Then, a comparison between experimental steady‐state infiltration rates, i _sR , measured with rainfall simulation experiments determining runoff production and K _s values for the two water pouring heights was carried out in order to discriminate between theoretically possible (i _sR  ≥ K _s ) and impossible (i _sR  < K _s ) situations. Physically possible K _s values were only obtained by applying water at a relatively large distance from the soil surface, because i _sR was equal to 20.0 mm h^?1 and K _s values were 146.2–163.9 and 15.2–18.7 mm h^?1 for a height of water pouring of 0.03 and 0.34 m, respectively. This result suggested the consistency between Beerkan runs with a high height of water pouring and rainfall simulator experiments. Soil compaction and mechanical aggregate breakdown were the most plausible physical mechanisms determining reduction of K _s with height. This study demonstrated that the height from which water is poured onto the soil surface is a key parameter in infiltrometer experiments and can be adapted to mimic the effect of high intensity rain on soil hydraulic properties.     

Trace element distribution within olivine-bearing gabbros from the Northern Apennine ophiolites (Italy): evidence for post-cumulus crystallization in MOR-type gabbroic rocks

The trace element distribution in three selected olivine-bearing gabbros from the Northern Apennine ophiolites has been determined. These rocks consist of euhedral plagioclase and olivine, and subhedral to poikilitic clinopyroxene. Fe-Ti-oxides, titanian pargasite, orthopyroxene and apatite occur as interstitial accessory minerals. Plagioclase, clinopyroxene and accessory minerals were analysed for rare earth (REE) and selected trace elements by secondary ion mass spectrometry. Both plagioclase and clinopyroxene are compositionally zoned. The plagioclase rims have slightly lower anorthite component and higher light REE (LREE), Ba and K than the cores. Likewise, the clinopyroxene rims show a slight Mg and Cr decrease, and a marked increase in Zr, REE and Y relative to the core. The rims of plagioclase and clinopyroxene, Fe-Ti-oxides, apatite and titanian pargasite most likely formed through post-cumulus fractional crystallization of interstitial liquid. It is argued that such interstitial liquid had an exotic component, probably related to the infiltration of highly evolved, slightly LREE enriched liquid in the cumulate pile. On the basis of mass balance calculations, we show that Fe-Ti-oxides play an important role in the Ti budget of the whole rock, as does apatite for LREE. Received: 15 January 1998 / Accepted: 22 September 1998     

Stability of streambanks formed in partially saturated soils and effects of negative pore water pressures: the Sieve River (Italy)

Streambanks of alluvial channels are usually composed of loose materials, which are unsaturated in ambient conditions. Unsaturated soils are subject to negative pore water pressures, which cause an apparent cohesion. The latter is the main factor in allowing the stability of near-vertical banks. Even during moderate in-bank flow events, the apparent cohesion can be strongly reduced as the material approaches full saturation; therefore, during the drawdown phase, as the confining pressure of the water in the channel disappears, a bank failure is likely to occur. Channel bed-level lowering along the Sieve River, Central Italy, has caused widespread bank instability. A geomorphological reconnaissance of forms and processes was followed by in situ tests to determine the shear strength of the banks. Interpretation of the tests and a streambank stability analysis were based on concepts of soil mechanics for unsaturated soils, in order to obtain relations between bank angle and height in limit equilibrium conditions. A stability chart was obtained with curves for different apparent cohesion values, and a stability analysis was performed taking into account the effects of flow events. In order to investigate the pore pressure effects, a series of piezo-tensiometers were installed in a streambank of the Sieve River. Data from a 1 year monitoring period show variations in pore water pressure and matric suction as a consequence of rainfall, evapotranspiration, and water stage variations. A planar failure with a tension crack occurred in the upper cohesive part of the bank during December 1996. The safety factor has been expressed as a function of the geometry of the bank and of the shear strength of the material. Safety factor variations through time are therefore shown as a function of seasonal variations in matric suction.     

Turbulent behaviour within a coastal boundary layer,observations and modelling at the Isola del Giglio

The hydrodynamics of coastal areas is characterized by the interaction among phenomena occurring at different spatial and temporal scales, such as the interaction of a large-scale ocean current with the local bathymetry and coastline, and local forcing conditions. In order to take into account all relevant phenomena, the study of the hydrodynamics of coastal zones requires a high-spatial and temporal resolution for both observations and simulation of local currents. This resolution can be obtained by using X-band radar, which allows simultaneous measurement of waves and currents in a range of 1–3 miles from the coastline, as well as high-resolution numerical models implemented in the area and configured through multiple nesting techniques in order to reach resolutions comparable to such coastal observations. Such an integrated monitoring system was implemented at the Isola del Giglio in 2012, after the accident of the Costa Concordia ship. Results can be used as a cross-validation of data produced independently by radar observations and numerical models. In addition, results give some important insights on the dynamics of the coastal boundary layer, both for what concerns the attenuation in the profile of the depth-averaged velocities which typically occur in turbulent boundary layers, as well as for the production, detachment and evolution of vorticity produced by the interaction of large-scale ocean currents with the coastline and the subsequent time evolution of such boundary layer. This transition between large-scale regional currents and the coastal boundary layer is often neglected in regional forecasting systems, but it has an important role in the ocean turbulence processes.