Rocky-shore communities as indicators of water quality: a case study in the Northwestern Mediterranean     

Pinedo S  García M  Satta MP  de Torres M  Ballesteros E 《Marine pollution bulletin》2007,55(1-6):126-135

The collection of 152 samples from the upper sublittoral zone along the rocky coasts of Catalonia (Northwestern Mediterranean) was carried out in 1999 in order to test the suitability of littoral communities to be used as indicators of water quality in the frame of the European Water Framework Directive. Detrended correspondence analysis were performed to distinguish between different communities and to relate communities composition to water quality. Samples collected in reference sites were included in the analysis. Mediterranean rocky shore communities situated in the upper sublittoral zone can be used as indicators of the water quality: there is a gradient from high to bad status that comprises from dense Cystoseira mediterranea forests to green algae dominated communities. The geographical patterns in the distribution of these communities show that the best areas are situated in the Northern coast, where tourism is the main economic resource of the area, and the worst area is situated close to the metropolitan zone of Barcelona with high population and industrial development. Thus, Mediterranean sublittoral rocky shore communities are useful indicators of water quality and multivariate analysis are a suitable statistical tool for the assessment of the ecological status.  相似文献   

Antioxidant responses to variations in dissolved oxygen of Scapharca inaequivalvis and Tapes philippinarum, two bivalve species from the lagoon of Venice     

Irato P  Piccinni E  Cassini A  Santovito G 《Marine pollution bulletin》2007,54(7):1020-1030

The aim of the present work was to determine the activities of selected antioxidant enzymes (SOD, Se-GPX, CAT) in two species of bivalves, Scapharca inaequivalvis and Tapes philippinarum, from two sites of the lagoon of Venice that are characterized by different pO(2) (Marghera and Chioggia). The specimens were collected at four times during a 1-year period. In the two species studied, enzyme activities were found to be present in both digestive glands and gills, but with some species-specific differences that may also represent a different adaptation to seasonal variations. The presence of high SOD activities in the gills of both species may be related to their physiological role in respiration. Scapharca inaequivalvis is less sensitive than T. philippinarum to environmental changes, perhaps due to the presence of hemoglobins in this species. Moreover, in the digestive gland of T. philippinarum we found a significant negative correlation between the activities of SOD and GPX that may indicate the presence of oxidative stress. Some correlations between temperature/dissolved oxygen and antioxidant enzyme activity were present in specimens sampled in Marghera. Only GPX adequately responded to changes in dissolved oxygen and temperature, while the decrease in the activity of SOD and CAT in winter may be directly responsible for an enhanced susceptibility of mussels to oxidative stress during this period. We can conclude that the observed differences between Chioggia and Marghera are due to different concentrations of dissolved oxygen. Marghera is an appropriate location to study seasonal variations in water temperature. In fact, in this site, the differences between hot and cold months are quite evident.  相似文献   

Isotopic-geochemical study of nitrogen and carbon in peat from the Tunguska Cosmic Body explosion site     

Evgeniy M. Kolesnikov  Giuseppe Longo  Tatjana Boettger  Paola Gioacchini  Roberto Giampieri 《Icarus》2003,161(2):235-243

Isotopic-geochemical investigations were carried out on peat samples from the 1908 Tunguska Cosmic Body (TCB) explosion area. We analyzed two peat columns from the Northern peat bog, sampled in 1998, and from the Raketka peat bog, sampled during the 1999 Italian expedition, both located near the epicenter of the TCB explosion area. At the depth of the “catastrophic” layer, formed in 1908, and deeper, one can observe shifts in the isotopic composition of nitrogen (up to Δ¹⁵N = +7.2‰) and carbon (up to Δ¹³C = +2‰) and also an increase in the nitrogen concentration compared to those in the normal, upper layers, unaffected by the Tunguska event. One possible explanation for these effects could be the presence of nitrogen and carbon from TCB material and from acid rains, following the TCB explosion, in the “catastrophic” and “precatastrophic” layers of peat. We found that the highest quantity of isotopically heavy nitrogen fell near the explosion epicenter and along the TCB trajectory. It is calculated that 200,000 tons of nitrogen fell over the area of devastated forest, i.e., only about 30% of the value calculated by Rasmussen et al. (1984). This discrepancy is probably caused by part of the nitrogen having dispersed in the Earth’s atmosphere. The isotopic effects observed in the peat agree with the results of previous investigations [Kolesnikov et al 1998a], [Kolesnikov et al 1998b], [Kolesnikov et al 1999] and [Rasmussen et al 1999] and also with the increased content of iridium and other platinoids found in the corresponding peat layers of other columns [Hou et al 1998] and [Hou et al 2000]. These data favor the hypothesis of a cosmochemical origin of the isotopic effects.  相似文献   

Mid- and far-infrared variability of PV Cep     

D. Lorenzetti  S. Antoniucci  T. Giannini  G. Li Causi  A. Di Paola  A. A. Arkharov  V. M. Larionov 《Astrophysics and Space Science》2014,353(2):567-573

We present the collection of all the mid- and far-IR observations (λ=3–170 μm) of the young eruptive variable PV Cep available so far in the literature. These data allow us to confirm that flux variability is a prominent feature at mid-IR wavelength (λ=3–25 μm). Color-magnitude plots clearly indicate that the observed variability is not extinction-driven, but mainly influenced by fluctuations of the mass accretion rate. We interpret such variability as due to a hot spot created onto the stellar surface by the column of accreting matter, which heats the inner parts of the disk and determines the observed increase of the near- mid-IR luminosity. A quantitative characterization is given for both the spot itself and the additional thermal component created by it. Far-IR data (λ=60–170 μm) are consistent with the presence of a temperature stratification in a massive and quite un-evolved circumstellar disk.  相似文献   

The amino acid and hydrocarbon contents of the Paris meteorite: Insights into the most primitive CM chondrite          下载免费PDF全文

Zita Martins  Paola Modica  Brigitte Zanda  Louis Le Sergeant d'Hendecourt 《Meteoritics & planetary science》2015,50(5):926-943

The Paris meteorite is one of the most primitive carbonaceous chondrites. It is reported to be the least aqueously altered CM chondrite, and to have experienced only weak thermal metamorphism. We have analyzed for the first time the amino acid and hydrocarbon contents of this pristine meteorite by gas chromatography–mass spectrometry (GC–MS). When plotting the relative amino acids abundances of several CM chondrites according to the increasing hydrothermal scale (petrologic subtypes), from the CM2.7/2.8 Paris to the CM2.0 MET 01070, Paris has the lowest relative abundance of β‐alanine/glycine (0.15), which fits with the relative abundances of β‐alanine/glycine increasing with increasing aqueous alteration for CM chondrites. These results confirm the influence of aqueous alteration on the amino acid abundances and distribution. The amino acid analysis shows that the isovaline detected in this meteorite is racemic (d /l  = 0.99 ± 0.08; l ‐enantiomer excess = 0.35 ± 0.5%; corrected d /l  = 1.03; corrected l ‐enantiomer excess = ?1.4 ± 2.6%). The identified hydrocarbons show that Paris has n‐alkanes ranging from C₁₆ to C₂₅ and 3‐ to 5‐ring nonalkylated polycyclic aromatic hydrocarbons (PAHs). The lack of alkylated PAHs in Paris seems to be also related to this low degree of aqueous alteration on its parent body. The extraterrestrial hydrocarbon content, suggested by the absence of any biomarker, may well have a presolar origin. The chemistry of the Paris meteorite may thus be closely related to the early stages of the solar nebula with a contribution from interstellar (molecular cloud) precursors.  相似文献   

Spatial distribution and seasonal variation in 18O/16O of modern precipitation and river water across the conterminous USA     

Andrea Dutton  Bruce H. Wilkinson  Jeffrey M. Welker  Gabriel J. Bowen  Kyger C. Lohmann 《水文研究》2005,19(20):4121-4146

We report a quantitative analysis of regional differences in the the oxygen isotope composition of river water and precipitation across the USA because data are now available to undertake a more geographically and temporally extensive analysis than was formerly possible. Maps of modern, mean annual δ¹⁸O values for both precipitation (δ¹⁸O_PPT) and river water (δ¹⁸O_RIV) across the 48 contiguous states of the USA have been generated using latitude and elevation as the primary predictors of stable isotope composition while also incorporating regional and local deviations based on available isotopic data. The difference between these two maps was calculated to determine regions where δ¹⁸O_RIV is significantly offset from local δ¹⁸O_PPT. Additional maps depicting seasonal and extreme values for δ¹⁸O_RIV and δ¹⁸O_PPT were also constructed. This exercise confirms the presence of regions characterized by differences in δ¹⁸O_RIV and δ¹⁸O_PPT and specifically identifies the magnitude and regional extent of these offsets. In particular, the Great Plains has δ¹⁸O_RIV values that are more positive than precipitation, while much of the western USA is characterized by significantly lower δ¹⁸O_RIV values in comparison with local δ¹⁸O_PPT. The most salient feature that emerged from this comparison is the ‘catchment effect’ for the rivers. Because river water is largely derived from precipitation that fell upstream of the sample locality (i.e. at higher elevations) δ¹⁸O_RIV values are often lower than local δ¹⁸O_PPT values, particularly in catchments with high‐elevation gradients. Seasonal patterns in the isotopic data substantiate the generally accepted notion that amplitudes of δ¹⁸O variation are greatly dampened in river water relative to those of local precipitation. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

A Model to Test the Internal Structure of the G31.41+0.31 Hot Molecular Core     

Mayra Osorio  Guillem Anglada  Susana Lizano  Paola D'Alessio 《Astrophysics and Space Science》2004,292(1-4):369-374

We investigate the physical conditions of the material around massive protostars by modelling the so-called hot molecular cores. We present a model for the spectral energy distribution (SED) as well as the ammonia line emission of the G31.41+0.31 hot core. We find that the best fit to the SED is achieved by assuming a density distribution corresponding to the collapse of a magnetized logatropic sphere. On the other hand, the line emission is reproduced by adopting a gas phase ammonia abundance increasing towards the center of the core, as a result of the release of the ammonia molecules trapped in ice grain mantles.  相似文献   

Known and unknown earthquakes through some European periodicals of the eighteenth century     

Paola Albini  Fernando Rodriguez de la Torre 《地学学报》1993,5(5):481-487

Since the eighteenth century, pioneer seismologists have used information from the periodical press to compile their lists of European earthquakes. A systematic reading of three eighteenth century periodicals –Gaceta de Madrid (1701–1750), Gazeta de Lisboa (1715–1751) and Mercure de France (1732–1763) – has been carried out in the frame of the EC project ‘Review of Historical Seismicity in Europe (RHISE)’. The retrieval of earthquake records provides data on European and Mediterranean earthquakes. Sources and records are here analysed to verify their reliability and to understand the significance of the earthquake information they supply. Special attention has been paid to earthquakes that affected Italian territory, by means of a comparison between records and space-time, intensity parameters of the Italian seismic catalogue: this comparison shows that about 45% of the earthquakes mentioned by the periodicals are unknown in the Italian catalogue, and that 30% of them are damaging earthquakes.  相似文献   

The shocked gas distribution around CepA: the H2S and SO2 picture     

Claudio Codella  Rafael Bachiller  Milena Benedettini  Paola Caselli 《Astrophysics and Space Science》2003,287(1-4):171-174

The preliminary results from a multiline mm-wave survey of H₂S and SO₂ emission towards the Cepheus A star forming region are presented. Large scale maps (? 5'×4') and high-resolution line profiles which clearly indicate the occurrence of multiple H₂S and SO₂ outflows are reported. In particular, a 0.6 pc long outflow flowing towards South from the CepA-East position has been discovered. In addition, besides the well known regions CepA-East and CepA-West other four clumps of shocked gas have been detected. These clumps exhibit distinct H₂S/SO₂ ratios, suggesting different chemical compositions for different regions and show that in Cepheus A the mass loss has strongly modified the chemistry of the quiescent gas.  相似文献   

Digitization and Scientific Exploitation of the Italian and Vatican Astronomical Plate Archives     

Cesare Barbieri  Carlo Blanco  Beatrice Bucciarelli  Regina Coluzzi  Andrea Di Paola  Luciano Lanteri  Gian Luca Li Causi  Ettore Marilli  Piero Massimino  Vincenzo Mezzalira  Stefano Mottola  Roberto Nesci  Alessandro Omizzolo  Fernando Pedichini  Francesca Rampazzi  Corinne Rossi  Ruggero Stagni  Milcho Tsvetkov  Roberto Viotti 《Experimental Astronomy》2003,15(1):29-43

There is a widespread interest to digitize the precious information contained in the astronomical plate archives, both for the preservation of their content and for its fast distribution to all interested researchers in order to achieve their better scientific exploitation. This paper presents the first results of our large-scale project to digitize the archive of plates of the Italian Astronomical Observatories and of the Specola Vaticana. Similar systems, composed by commercial flat-bed retro-illuminated scanners plus dedicated personal computers and acquisition and analysis software, have been installed in all participating Institutes. Ad-hoc codes have been developed to acquire the data, to test the suitability of the machines to our scientific needs, and to reduce the digital data in order to extract the astrometric, photometric and spectroscopic content. Two more elements complete the overall project: the provision of high quality BVRI CCD sequences in selected fields with the Campo Imperatore telescopes, and the distribution of the digitized information to all interested researchers via the Web. The methods we have derived in the course of this project have been already applied successfully to plates taken by other Observatories, for instance at Byurakan and at Hamburg.  相似文献