Total content and chemical speciation of arsenic in the polychaete Sabella spallanzanii

An unusual feature has been observed in polychaetes regarding their capacity to accumulate high levels of relatively toxic forms of arsenic in specific tissues. Basal levels of arsenic and distribution of its compounds were investigated in tissues of the Mediterranean polychaete Sabella spallanzanii. Particularly high concentrations were measured in the branchial crown (1036+/-136 microg/g d.w.) and chemical speciation revealed that the predominant form was the relatively toxic dimethylarsinate (DMA). These data suggest a potential role of As as anti-predatory strategy in polychaetes.     

Seabed Morphology and Pollution Along the Bagnoli Coast (Naples, Italy): a Hypothesis for Environmental Restoration

Abstract. The interaction of coastal and submarine morphology with the hydrodynamic regimes exerts a control on coastal dynamic processes, conditioning the dispersion of sediments and potential pollutants existing in the area. Thus, the study of such parameters is useful in order to define environmental threats. Within the submerged sector of the Bagnoli coast and particularly in the southern part of the investigated area, there are sediment groups composed of very fine sands located in low-energy zones due to wave refraction and diffraction; they can also be found on the sea bottom and on the man-made structures typical of this zone. These areas show high pollutant levels of N, P, Cu, Fe, Mn, Ni, Pb, Zn, Cd, polyaromatic hydrocarbons (PAHs) and polychlorinated bi-phenyls (PCBs). The northern area, a place of high-energy hydrodynamic processes, also shows high concentration levels of pollutants due to the presence of secondary cell circulation.
Morphological research and analysis of textural characteristics of bottom sediments along the Bagnoli coast allowed the actual processes and their evolution in space and time to be defined. It has also been possible to correlate such processes to the seabed morphology system, the wave formations which affect the coast, the complex system of sediment transport, as well as to the man-made interventions in the area. The results of recent chemical analyses of beach sediments and bottom sediments off the Bagnoli coast were also incorporated. They prove the presence of heavy metals, PAHs and PCBs in high and sometimes very high concentrations. Finally, based on the results of research and analyses, a hypothesis for an intervention for environmental restoration has been formulated in order to renaturalise the coast through dredging and treatment of the sand, both on the seabed and on the emerged beach.     

Hamiltonian perturbation theory on a manifold

This paper deals with Hamiltonian perturbation theory for systems which, like Euler-Poinsot (the rigid body with a fixed point and no torques), are degenerate and do not possess a global system of action-angle coordinates. It turns out that the usual methods of perturbation theory, which are essentially local being based on the construction of normal forms within the domain of a local coordinate system, are not immediately usable to study perturbations of these systems, since degeneracy makes impossible to control that the system does not fall into a singularity of the coordinates. To overcome this difficulty, we develop a global formulation of Hamiltonian perturbation theory, in which the normal forms are globally defined on the phase space manifold. The key for this study lies in the geometry of the fibration by the invariant tori of an integrable degenerate Hamiltonian system, which is described by some generalizations of the Liouville-Arnol'd theorem and is reviewed in the paper. As an application, we provide a global formulation of Nekhoroshev's theorem on the stability for exponentially long times.     

Far-infrared observations of main sequence stars surrounded by dust shells

We present 50 and 100µm photometry and size information for several main sequence stars surrounded by dust shells. The observations from NASA's Kuiper Airborne Observatory include the Vega-like stars, Beta Pic, Fomalhaut, as well as four stars suggested by Walker and Wolstencroft to belong possibly to the same class. The results of our observations are best interpreted as upper limits to the far-infrared sizes of the dust clouds around all of the stars except Fomalhaut and Beta Pic. We have also fit simple, optically thin models to the Beta Pic data to explore the range of shell parameters consistent with our limits and with previous observations.     

On Szebehely's problem for holonomic systems involving generalized potential functions

We consider the problem of finding the generalized potential function V = U _i(q ¹, q ²,..., q ⁿ)q ⁱ + U(q ¹, q ²,...;q ⁿ) compatible with prescribed dynamical trajectories of a holonomic system. We obtain conditions necessary for the existence of solutions to the problem: these can be cast into a system of n – 1 first order nonlinear partial differential equations in the unknown functions U ₁, U ₂,...;, U _n, U. In particular we study dynamical systems with two degrees of freedom. Using adapted coordinates on the configuration manifold M ₂ we obtain, for potential function U(q ¹, q ²), a classic first kind of Abel ordinary differential equation. Moreover, we show that, in special cases of dynamical interest, such an equation can be solved by quadrature. In particular we establish, for ordinary potential functions, a classical formula obtained in different way by Joukowsky for a particle moving on a surface.Work performed with the support of the Gruppo Nazionale di Fisica Matematica (G.N.F.M.) of the Italian National Research Council.     

A low plain between arcadia and agronomy: Ippolito Nievo and the Friulan landscape

An analysis of the historical and cultural context of a large number of literary works illuminates the concept of landscape, a recurrent theme in contemporary humanistic geography. In this context, the works of Ippolito Nievo present an opportunity to look closer at the socio-economic circumstances of his time while also offering suggestive interpretative elements about the attitudes held concerning the wetlands of the lower Friulan plain.     

Rainfall induced debris flows in pyroclastic deposits, Campania (southern Italy)

A combination of empirical and physically based hydrological models has been used to analyze historical data on rainfall and debris-flow occurrence in western Campania, to examine the correlation between rainfall and debris-flow events.

Rainfall data from major storms recorded in recent decades in western Campania were compiled, including daily series from several rain gauges located inside landslide areas, supplemented by hourly rainfall data from some of the principal storms.

A two-phase approach is proposed. During phase 1, soil moisture levels have been modelled as the hydrological balance between precipitation and evapotranspiration, on a daily scale, using the method of Thornthwaite [Geograph. Rev. 38 (1948) 55].

Phase 2 is related to the accumulation of surplus moisture from intense rainfall, leading to the development of positive pore pressures. These interactions take place on an hourly time scale by the “leaky barrel” (LB) model described by Wilson and Wiezoreck [Env. Eng. Geoscience, 1 (1995) 11]. In combination with hourly rainfall records, the LB model has been used to compare hydrological effects of different storms. The critical level of retained rain water has been fixed by the timing of debris-flow activity, related to recorded storm events.

New rainfall intensity–duration thresholds for debris-flow initiation in western Campania are proposed. These thresholds are related to individual rain gauge and assume a previously satisfied field capacity condition. The new thresholds are somewhat higher than those plotted by previous authors, but are thought to be more accurate and thus need less conservatism.     

Thermal decay of carbonate dimension stones: fabric,physical and mechanical changes

This paper deals with the effects of thermal stresses on selected carbonate rocks used as dimension stones. They are Mesozoic calcareous and dolomitic rocks cropping out in Apulia (southern Italy) that, for their physico-mechanical and aesthetic properties, have always been finding a large application both as ornamental stones and as simple construction materials; their use is attested not only in Italy, in works of archaeological, historical and artistic interest too. The cause–effect relationships of thermal degradation were studied by means of an artificial accelerated ageing test, in order to provide a perspective about the decay of carbonate stones due to diurnal and seasonal temperature fluctuations, as well as thermal shocks during events of fire development. The stone samples were subjected to thermal cycles in a muffle furnace, ranging from 100 to 700 °C; after each cycle, several non-destructive and semi-destructive tests were carried out: mass and volume measurements, mercury intrusion porosimetry, sclerometer tests, ultrasonic tests, thin-section observations and determination of chromatic alterations through image analysis and Munsell charts method. In this way, the qualitative and quantitative modifications induced in fabric, physical and mechanical properties were discussed. The results highlight the fundamental role of depositional and diagenetic fabric that, together with mineralogical composition, represents the most significant discriminating factor in the response of the stone to thermal stresses.     

Impacts of extreme weather on wheat and maize in France: evaluating regional crop simulations against observed data

Extreme weather conditions can strongly affect agricultural production, with negative impacts that can at times be detected at regional scales. In France, crop yields were greatly influenced by drought and heat stress in 2003 and by extremely wet conditions in 2007. Reported regional maize and wheat yields where historically low in 2003; in 2007 wheat yields were lower and maize yields higher than long-term averages. An analysis with a spatial version (10?×?10?km) of the EPIC crop model was tested with regards to regional crop yield anomalies of wheat and maize resulting from extreme weather events in France in 2003 and 2007, by comparing simulated results against reported regional crops statistics, as well as using remotely sensed soil moisture data. Causal relations between soil moisture and crop yields were specifically analyzed. Remotely sensed (AMSR-E) JJA soil moisture correlated significantly with reported regional crop yield for 2002–2007. The spatial correlation between JJA soil moisture and wheat yield anomalies was positive in dry 2003 and negative in wet 2007. Biweekly soil moisture data correlated positively with wheat yield anomalies from the first half of June until the second half of July in 2003. In 2007, the relation was negative the first half of June until the second half of August. EPIC reproduced observed soil dynamics well, and it reproduced the negative wheat and maize yield anomalies of the 2003 heat wave and drought, as well as the positive maize yield anomalies in wet 2007. However, it did not reproduce the negative wheat yield anomalies due to excessive rains and wetness in 2007. Results indicated that EPIC, in line with other crop models widely used at regional level in climate change studies, is capable of capturing the negative impacts of droughts on crop yields, while it fails to reproduce negative impacts of heavy rain and excessively wet conditions on wheat yield, due to poor representations of critical factors affecting plant growth and management. Given that extreme weather events are expected to increase in frequency and perhaps severity in coming decades, improved model representation of crop damage due to extreme events is warranted in order to better quantify future climate change impacts and inform appropriate adaptation responses.