Seasonal variations of exposure biomarkers, oxidative stress responses and cell damage in the clams, Tapes philippinarum, and mussels, Mytilus galloprovincialis, from Adriatic sea

This work investigated the natural variability of several biomarkers in Tapes philippinarum and Mytilus galloprovincialis, sampled from Northern Adriatic where these organisms are important sentinel species for future environmental impact assessment. Levels of metallothioneins, peroxisomal enzymes and acetylcholinesterase, showed a significant seasonality and marked differences between clams and mussels. Among antioxidant enzymes, catalase and GST decreased during the warmer period, the latter enzyme activity resulting particularly high in clams. The total oxyradical scavenging capacity toward peroxyl radicals decreased in mussels from winter to summer, indicating a prooxidant challenge due to higher seawater temperature and intensity of light irradiance. Lysosomal membrane stability did not exhibit significant seasonal variations, while some variations were observed for DNA damages. Overall results indicated a significant influence of seasonal variability on several biomarkers and species-specific differences which should be considered to discriminate the appearance of anthropogenic disturbance.     

Diel microbial variations at a coastal Northern Adriatic station affected by Po River outflows

Diel sampling was performed during an early spring survey in the Northern Adriatic Sea at a coastal station off the Po River delta. Samples were taken every 6 h at spring tide maxima and minima in the sub-superficial layer, at the maximum fluorescence depth (∼3 m). Variations in microbial community structure and its processes were assessed by considering heterotrophic bacteria, picocyanobacteria, viruses, exoenzymatic activities, microphytoplankton, nanoplankton and bacterial/cyanobacterial Denaturing Gradient Gel Electrophoresis (DGGE) profiles. A considerable diatom bloom, mostly supported by Skeletonema marinoi was detected. All microbial parameters except viruses, showed a sinusoidal trend with a 12 h period; only picocyanobacteria expressed relative maxima during high tide, showing a phase in opposition to the other parameters. No substantial changes in DGGE band patterns were detected. Even though the results showed bacterial activities to be influenced by the phytoplankton bloom, all microbial parameters' diel trends (except viruses) preferentially followed the tidal fluctuation rather than the light:dark cycle.     

Stellar Velocity Field in the Central Region of NGC 1068

We present the velocity field of the stars in the central 25″ × 22″ of NGC 1068 derived from 2-D spectroscopy of the Ca II triplet. A preliminary analysis provides evidence for two distinct stellar systems in the centre of NGC 1068. In the outer regions (say r > 10″), the mean stellar velocity field seems coupled to those of the ionized and molecular gas, indicating aproximately regular rotation with the kinematic minor axis at PA ~ 0°. However, in the inner region, the stars are rotating, whereas the ionized gas is outflowing in the NE-SW direction probably due to the effects of the nuclear activity, and the molecular gas is responding to the bar potential. This revised version was published online in July 2006 with corrections to the Cover Date.     

Simulations of Superrotation on Slowly Rotating Planets: Sensitivity to Rotation and Initial Condition

We use a simplified terrestrial general circulation model as a nonlinear process model to investigate factors that influence the extent of equatorial superrotation in statically stable atmospheres on slowly rotating planets such as Titan and Venus. The possibility of multiple equilibria is tested by running the same model to equilibrium from vastly different initial conditions. The final state is effectively independent of initial state, reinforcing the impression that equatorial superrotation is inevitable on slowly rotating planets with stable radiative equilibrium structures. Of particular interest is the fact that at Titan rotation, the model equilibrates with strong prograde winds even when initialized with strong retrograde winds. This suggests that reliable remote sensing inferences of latitudinal temperature gradients on Titan can unambiguously be interpreted as evidence for superrotation. We also demonstrate for the first time that significant equatorial superrotation can be produced at Venus' rotation rate in such models, given sufficient numerical precision. The strength of superrotating zonal winds increases with rotation rate in the slowly rotating regime when other parameters are held fixed. However, the efficiency of superrotation relative to the angular momentum of an atmosphere corotating with the solid planet increases with decreasing rotation rate instead, because the Hadley cell strengthens and expands poleward. This allows for the formation of stronger high latitude jets, which ultimately serve as the source for equatorial superrotation via barotropic instability. Estimates of relevant parameter settings for Triton and Pluto tentatively imply that their atmospheres may marginally be in the superrotating regime, but only if temperature decreases with height near the surface.     

Site response study in Abruzzo (Central Italy): underground array versus surface stations

In this site response study we examined local earthquakes recorded at surface stations of a local seismic network and at a temporary underground seismic array installed in a tunnel underneath the Gran Sasso Massif in Abruzzo (central Italy). This allowed us to compare the seismic site response beneath the mountain and on the surface in similar geological environment (soft rock sites). We applied spectral ratios method on different segments of the seismograms and used different reference spectra in the 1–20 Hz frequency band. We found little or no amplification effects at most of the surface stations whereas site transfer functions evaluated with respect to underground sites show an amplification factor up to 6 in the 1–8 Hz frequency range. Coda spectral ratios estimated at soft rock sites are confirmed as good estimates of shear wave transfer function.     

Magnetic history of a dyke on Mount Etna (Sicily)

During the 1989 eruption of Mount Etna, two fracture systems, trending c. N45°E and N150°E, opened at the foot of its 3000 m high SE Crater and propagated quickly downslope to distances of ≈3 and 7 km, respectively. The northeastern fracture fed a flank eruption, whereas the southeastern fracture remained dry and offered contrasting volcanological and geophysical evidence of the presence of magma at a shallow depth. During the opening of this non-eruptive fracture system, a differential magnetic network was set up on a short profile across its distant extremity. Initially, the magnetic field did not display any change along the profile between frequent surveys. However, repeated measurements at intervals of about 3 months for two years revealed the slow build-up of a 130 nT anomaly. The anomaly vanishes laterally within 0.2 km of the surface expression of the fracture system. This exceptional set of observations constrains the location and time of cooling of a shallow dyke. The increase in magnetization of the dyke inferred by the rate of growth of the anomaly leads to the interpretation that the dyke was emplaced near the end of the eruption.     

Precise determination of uranium in rocks and minerals by neutron activation analysis using 133I fission product

A radiochemical neutron activation technique for uranium determination in rock and mineral samples is presented. The method is based on an alkaline fusion, a selective oxidation of iodine by a sodium-nitrite solution, followed by an iodine distillation technique for the isolation of the ¹³³I produced in fission. The outlined scheme is rapid, sensitive and reliable. Determination of uranium in U.S. Geological Survey standard rocks (G-1, W-1, G-2, BCR-1, AGV-1, GSP-1), C.R.P.G. Nancy geochemical standards (GA, GH, BR, Mica-Fe, Mica-Mg), C.A.A.S. reference syenite rocks (SY-1, SY-2, SY-3) and other analysed rock samples are reported. These results are compared with those obtained by other methods.     

Tectonic evolution of the internal sector of the Central Apennines, Italy

A wide sector of the internal portion of the Central Apennines, which comprises the southern Lepini Mtns up to the northern Simbruini Mtns has been investigated through detailed field mapping and integrated with structural analyses. A few small productive oil fields and a large number of hydrocarbon seeps and oil impregnations are located in this sector. This area offers good opportunities for testing the use of structural fieldwork methodologies in order to highlight oil migrating paths, from Triassic source rocks, and prospecting chances for oil field exploitation.The main stages of the structural evolution of the area took place after deposition of the foredeep sediments (Frosinone Fm.), i.e. after Late Tortonian, under a stress field characterised by a NE–SW trending σ₁, which was responsible for the early emplacement of major thrust faults present in the area. The Messinian-Early Pliocene thrust-top basin deposits allowed the reconstruction of an in-sequence evolution of the thrust system. The development of out-of-sequence thrusting post-dates these structures leading to a further strong shortening phase in the area during the Pliocene. This phase is characterised by a roughly NNE–SSW trending σ₁. Some peculiar tectonic features evidenced by thrust faults with younger-over-older relationships and an inversion of the original stacking of thrust sheets developed during this phase.Successively, a block-faulting tectonic, mainly with NE–SW extension stress field, occurred and dismembered the compressive tectonic edifice.Later on up to the Middle Pleistocene, N–S to NNE–SSW trending dextral strike-slip faults also acted in the area. Associated to the strike-slip tectonics are local volcanic centres as well as necks, whose compositions show a mantle origin, thus indicating deep seating and a possible lithospheric significance of these structures.In the light of this study, the reduced extension of the productive oil area as well as the spotting of oil seeps, may indicate that the migration conditions are not tied to well defined structures but that likely the cross-cutting points among structures facilitate the conditions for an upwards rising of oil. These conditions in particular are achieved at least in two cases: (1) where the Late Triassic source rocks do not have great depth due to normal or reverse faults, or (2) at a major depth when encountered by transcurrent-oblique roughly N–S trending faults—in both cases oil can easily migrate along the damage zone associated to the fault plane.