Biochemical alterations in juvenile carp (Cyprinus carpio) exposed to zinc: glutathione reductase as a target

The aim of this study was to investigate biochemical changes in juvenile carp (Cyprinus carpio) exposed to zinc chloride (10, 30 and 100 microM) for a period of 48 h. Zinc exposure caused a concentration-dependent reduction in glutathione reductase (GR) activity in gills, liver and brain. Gill glutathione S-transferase (GST) was reduced when animals were exposed to the highest concentration of 100 microM zinc. The phosphorylation of p38(MAPK) increased in the brain of fish exposed to zinc 100 microM, while phosphorylation of the extracellular signal-regulated protein kinase 1/2 (ERK1/2) and c-Jun N-terminal protein kinase 1/2 (JNK1/2) remained unchanged. Expression of proteins HSP60 and HSP70 were not affected by zinc exposure. Considering the significant concentration-dependent inhibition of GR in all tissues analyzed, this enzyme could be a potential biomarker of exposure to zinc, which has to be confirmed.     

Low-level decimetric (1.6 GHz) solar burst activity

Observations of solar bursts at 1.6 GHz were carried out in the month of July 1985 for about two weeks. Five intervals of solar burst activity, each one lasting for a couple of minutes, were observed. Predominantly, two classes of fast bursts were observed: viz: spike and blips. However, some of these bursts were two orders of magnitude less intense than those reported earlier.Low-level blips have typical duration 350 ms, excitation time 200 ± 25 ms, decay time 130 ± 25 ms and a low degree of circular polarization of about 15%. Detailed investigations of decay times of the blips have been carried out in terms of collisional damping and Landau damping. Observed decay times of the blips seem to favour the hypothesis of collisional damping. This investigation suggests that blips probably originate at second harmonic by beam plasma interaction as that of metric type III bursts. Also, low-level ms-spikes with the half power duration in the range of 5 to 20 ms suggest that source sizes be smaller than 50 km if the process of emission is electron-cyclotron maser.Proceedings of the Second CESRA Workshop on Particle Acceleration and Trapping in Solar Flares, held at Aubigny-sur-Nère (France), 23–26 June, 1986.     

Nonlinear Evolution of Thermal Structures. Numerical Approach

A numerical algorithm using a two stage, two level difference scheme has been developed to solve the heat transfer equation with nonlinear heat diffusion and bulk energy losses. The algorithm is an extension of the scheme developed by Meek and Norbury (1982). The first stage calculates an intermediate value which is used in a second stage to estimate a new value. The scheme is consistent, second-order convergent in space and almost second order in time. It has been applied to the nonlinear stability and time evolution of thermal structures constituted by optically thin plasmas with solar abundances. The configuration has been assumed to be heated at a rate T^m, cooled at a rate Tⁿ and a thermal conduction coefficient T^k. In particular, the second order analytical approximation considered in previous papers (Ibáñez and Rosenzweig, 1995; Steele and Ibáñez, 1997) has been worked out for arbitrary amplitude of the initial temperature disturbance. Particular cases of interest in Astrophysics are considered.     

Nutrient contents in bottom sediment samples from a southern Brazilian microbasin

The nutrients, carbon, nitrogen and phosphorus, significantly affect the quality of aquatic environments, especially when present at concentrations above natural levels. In this context, the sedimentary column can act as an environment for storage or accumulation of these nutrients and for the reprocessing of such substances in the water column and aquatic biota. In this context, this study aimed to estimate the concentration of total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), inorganic phosphorus (IP) and organic phosphorus (OP) in seven sediment samples that were collected from the Marrecas Stream microbasin (Caxias do Sul, Rio Grande do Sul State, Brazil). The relationships among the sediment nutrient concentrations and the levels of organic matter (OM), fine material (silt–clay) and the concentration of the metal species, Al, Fe and Mn, as well as the possible nutrient sources to the stream studied were also evaluated. The data set suggest that the TOC and IP appear to have a direct correlation with the vast riparian vegetation present in areas adjacent to the sampling points and to the physico-chemical properties of the water and sedimentary column. Moreover, the results obtained for TN suggest that its concentration possibly suffers interference from the temperature of the water and its oxygenation, in addition to other biological activities. On the other hand, one cannot rule out human interference, mainly in the levels of OP, possibly due to the inflow of domestic sewage to the stream.     

Assessment of nitrate contamination risk: The Italian experience

The purpose of this study is to show the results of the Italian research project of national interest (PRIN) launched in 2006 and finished in 2008, concerning the “assessment of groundwater contamination risk by nitrates assessment”. The project verified the IPNOA method for nitrate groundwater contamination risk assessment in four test-sites of Italy. The IPNOA is a parametric index which assesses the potential hazard of nitrate contamination originating from agriculture on a regional scale. The method integrates two categories of parameters: the hazard factors (HF), which represent all farming activities that cause, or might cause, an impact on soil quality in terms of nitrate (use of fertilisers, application of livestock and poultry manure, food industry wastewater and urban sludge), and the control factors (CF) which adapt the hazard factors to the characteristics of the site (geographical location, climatic conditions and agronomic practices). Finally, the Potential Risk Map is obtained by coupling the potential hazard of nitrate pollution (IPNOA) and the aquifer Contamination Vulnerability Map. The project was carried out by five Research Units (RU) from the Politecnico di Torino, Universities of Piacenza, Florence, Naples and Palermo. The geochemistry of groundwaters from the four test-sites was studied to determine the distribution of nitrate, and to evaluate groundwater chemical facies. All the study areas are affected by groundwater nitrate contamination and often by hydrogeochemical peculiarities. In some cases isotopic study, δ¹⁸O–NO₃δ¹⁵N–NO₃, allowed to differentiate nitrates of chemical fertilisers from those of biological origin, as well as denitrification processes.     

Les Mouvements Tectoniques Récents en Sicile. Hypothèses et Problèmes

Zusammenfassung Die quartären tektonischen Bewegungen in Sizilien waren in ihrem Stil und ihrer Amplitude in den einzelnen Zonen unterschiedlich. Diese Zonen decken sich mit bestimmten paläogeographischen Einheiten. Die marinen Ablagerungen des Calabrien sind teilweise schwach gefaltet, teilweise nur geneigt. Die Verstellung des marinen Quartär ist dort am stärksten, wo auch das Pliozän selbst kräftiger disloziert war. Auf dem Plateau von Syracus, einer deutlich abgegrenzten paläogeographischen Einheit, erreicht das Pliozän nur eine Höhe von 150 m, während Calabrien und Sicilien unbekannt sind.     

Normal mode theory of lee cyclogenesis and the initial value problem

Summary An initial value problem is proposed to study the influence of mountains upon atmospheric flows. The normal mode, quasigeostrophic theory of lee cyclogenesis is revisited; in order to model Alpine cyclogenesis, the flow, upon which the mountain acts, should represent a cyclone wave propagating eastward in a sheared zonal current. Two different models are considered in order to describe cyclone waves: an unstable Eady normal mode and a finite amplitude, neutral Rossby mode in the two layer model. It is shown that the topographic modifications proper of normal modes emerge very rapidly from the integration of the initial value problem. It is also shown that an enhanced deepening of the upper level trough can occur when finite amplitude effects are taken into account.With 8 Figures     

Diatom responses to environmental changes in the Upper Paraná River floodplain (Brazil) during the last ~ 1000 years

The floodplain of the Upper Paraná River, Brazil, is strongly influenced by hydrology, which in turn affects geomorphological and environmental conditions, and controls the form of islands in the river. Such islands develop by deposition of river-borne sediment that creates small lateral sediment bars. Geomorphological processes can produce a variety of aquatic environments on such islands, e.g. channels, backwaters, lakes, transitional areas, and swamps. Our objective was to test whether subfossil diatoms preserved in the sediment on an island in the Upper Paraná River floodplain responded to changes in limnological conditions brought about by such geomorphological modifications. We hypothesized that the composition of diatom assemblages in the sediment shifted in response to past geomorphic, and hence limnological conditions. We analyzed diatom subfossils in a 2-m-long sediment core with a calibrated date near the base of 1047–1224 cal yr AD. Absence of diatoms at the bottom of the sequence was associated with the channel phase, followed by appearance of diatoms 1229–1381 cal yr AD that were adapted to flow, in the backwater phase. After another 100–200 years, presence of Eunotia species in the lake phase suggests a decrease in pH, phosphorus and nitrogen. Replacement of Eunotia spp. by Diadesmis species, following a transition phase, suggests different environmental conditions, with reduced water depth. Diatoms in surface deposits are distinct from assemblages in the other phases in the core and contain taxa that suggest a disturbed environment, with variations in water depth and flow. The data illustrate the importance of physical and hydrological factors in shaping diatom communities and show the utility of diatoms as bioindicators in this floodplain environment.     

High-resolution coastal hazard assessment along the French Riviera from co-seismic tsunamis generated in the Ligurian fault system

Natural Hazards - The French Riviera is a densely populated and touristic coast. It is also one of the most seismically active areas of the Western Mediterranean. This is evidenced by the Mw...