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111.
Riccardo Cattaneo‐Vietti Valentina Cappanera Michela Castellano Paolo Povero 《Marine Ecology》2015,36(2):155-166
Since the 17th century, the Tonnarella of Camogli, a small tuna trap, has been used to catch pelagic fish along the western coast of the Portofino Promontory (Ligurian Sea, Northwestern Mediterranean). The availability of long‐term datasets on fish yields (1950–1974 and 1996–2011), with information related to the seawater temperatures and the North Atlantic Oscillation (NAO), has allowed us to study the qualitative and quantitative changes in fish yields in the last decade and the possible relationships with the seasonal anomalies of temperature that have occurred in the Ligurian Sea. In 1950–1974, yields remained relatively constant over time (average of 35.6 ± 8.7 t·year?1). From 1996 through 2011, yields were high (42.9 ± 15.9 t·year?1) but inconsistent with strong annual variability in catches. The primary catches are Seriola dumerili, Auxis rochei, Trachurus spp. and Sarda sarda. Changes in species composition have occurred as well: S. dumerili, Sardinella sp. and Belone belone have appeared recently. Moreover, a significant decrease in the boreal scombroid (Scomber scombrus) and an increase of warm‐temperate carangids and other typically Southern Mediterranean species such as Coryphaena hippurus and Sphyraena viridensis, appear to be linked to the warming of the surface water layer, particularly evident in the Ligurian Sea, for the last 10 years. The analysis of this kind of trend may be a powerful tool for assessing structural changes of the pelagic fish community in the Ligurian Sea (Northwestern Mediterranean). 相似文献
112.
Cyanobacterial toxins in Italian freshwaters 总被引:1,自引:0,他引:1
Valentina Messineo Serena Melchiorre Antonella Lugliè Maria Antonietta Mariani Antonio Di Corcia Ermanno Carloni 《Limnologica》2009,39(2):95-106
This study focuses on the occurrence and distribution of cyanobacterial toxins from 1989 to 2006 in several Italian lakes of different characteristics and human uses, the latter including drinking water abstraction and recreation. Phytoplankton and LC/MS/MS toxin analyses were performed on surface water samples collected from 28 lakes. The most widespread species associated with toxin production belonged to the genera Microcystis, Planktothrix and Anabaena. Extracellular concentrations varied from non-detectable values up to 226.16 ng/mL for microcystins (sum of all variants), to 126 ng/mL for total cylindrospermopsin, and to 100 μg/g (dry weight) for anatoxin-a.The toxin concentrations in the lake waters did not always correlate with the cyanobacteria cell densities. This implies a need for control studies including toxin detection in water together with microscopic cell evaluations, in order to avoid possible toxin underestimates. 相似文献
113.
Simone Lotti Teresa Mineo Christian Jacquey Monica Laurenza Valentina Fioretti Gabriele Minervini Giovanni Santin Silvano Molendi Tommaso Alberti Paolo Dondero Alfonso Mantero Vladimir Ivanchencko Claudio Macculi Luigi Piro 《Experimental Astronomy》2018,45(3):411-428
The experience gained with the current generation of X-ray telescopes like Chandra and XMM-Newton has shown that low energy “soft” protons can pose a severe threat to the possibility to exploit scientific data, reducing the available exposure times by up to 50% and introducing a poorly reproducible background component. These soft protons are present in orbits outside the radiation belts and enter the mirrors, being concentrated towards the focal plane instruments, losing energy along their path and finally depositing their remaining energy in the detectors. Their contribution to the residual background will be even higher for ATHENA with respect to previous missions, given the much higher collecting area of the mirrors, even if the instruments will likely suffer no significant radiation damage from this particles flux. As a consequence this soft proton flux shall be damped with the use of a magnetic diverter to avoid excess background loading on the WFI or X-IFU instruments. We present here a first complete evaluation of this background component for the two focal plane instruments of the ATHENA mission in absence of a magnetic diverter, and derive the requirements for such device to reduce the soft protons induced background below the level required to enable the mission science. We estimate the soft proton flux expected in L2 for the interplanetary component and for the component generated locally by acceleration processes in the magnetotail. We produce a proton response matrix for each of the two instruments of ATHENA focal plane, exploiting two independent Monte Carlo simulations to estimate the optics concentration efficiency, and Geant4 simulations to evaluate the energy loss inside the radiation filters and deposited in the detector. With this modular approach we derive the expected fluxes and spectra for the soft protons component of the background. Finally, we calculate the specifics of a magnetic diverter able to reduce such flux below the required level for both X-IFU and WFI. 相似文献
114.
In 2002,2004 and 2017 we conducted high precision CCD photometry observations of the eclipsing binary system AS Cam.By analysis of the light curves from 1967 to 2017(our data + data from the literature) we obtained photometric elements of the system and found a change in the system's orbital eccentricity of ?e = 0.03 ± 0.01.This change can indicate that there is a third companion in the system in a highly inclined orbit with respect to the orbital plane of the central binary,and its gravitational influence may cause the discrepancy between observed and theoretical apsidal motion rates of AS Cam. 相似文献
115.
The impact of the scyphomedusa Aurelia sp. on planktonic assemblages was experimentally studied in enclosures incubated in situ in the sea lake of Mljet Island (Big Lake, Southern Adriatic), where jellyfish are present throughout the year. In situ feeding experiments using plankton at natural densities indicated a reduction in abundance for small calanoid and cyclopoid copepods, copepodites, nauplii and ciliates in the presence of Aurelia sp. In addition to direct predatory pressure, Aurelia sp. exerted an indirect cascading effect on autotrophic and heterotrophic microbial plankton. Phytoplankton biomass increases of up to 0.5 μg C·l?1·h?1 were mainly related to 19′‐hexanoyloxyfucoxanthin‐ and 19′‐butanoyloxyfucoxanthin‐containing phytoplankton. Bacterial production was about twice as high in the presence of Aurelia sp. and biomass was also consistently higher. It appears that the top‐down effect of predation along with material release by Aurelia sp. results in increases in microbial biomass and production. 相似文献
116.
The Early Cretaceous coal‐forming plants of southern part of East Siberia and Russian Far East
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For the first time the plants that gave rise to the Early Cretaceous coals of Transbaikalia (Khilok, Chita‐Ingoda, Bukachacha, and Turga‐Kharanor basins), Amur River region (Bureya Basin), and Primorye region (Razdolnaya River and Partizansk River basins) have been obtained. The plants that produced coals mainly belong to the ginkgoaleans (Pseudotorellia, Sphenobaiera, and Baierella), bennettites, and conifers having pinaceous, taxodiaceous, araucariaceous affinity, as well as extinct cheirolepidiaceous and miroviaceous plants. A parallel palynological study has identified a number of the same elements in addition to the cyatheaceous, gleicheniaceous, osmundaceous, and schizaeaceous ferns. 相似文献
117.
泾河上游流域实际蒸散量及其各组分的估算 总被引:6,自引:1,他引:6
利用分布式生态水文模型SWIM,基于泾河上游(泾川测站以上) 植被、土壤、气象和水文数据对研究区进行了水文过程的模拟,从而估算了流域的实际蒸散量及其各组分。结果表明:SWIM模型能够较好的模拟泾河上游流域的水文过程,模拟的流域多年(1997-2003 年) 平均实际蒸散量为443 mm,其中土壤蒸发量为259 mm,植被蒸腾量为157 mm,冠层截持量为27 mm。石质山区的森林覆盖区和非森林地的年蒸散总量在整个流域分别具有最大值和最小值,为484 mm和418 mm;黄土区实际蒸散量介于二者之间,平均为447 mm。森林覆盖地区土壤蒸发明显小于其它区域,而蒸腾和冠层截留明显大于其它区域。年内蒸散量主要集中在5-8 月份,占全年总蒸散量的60%,且冠层蒸散比例较大达63%。整个流域湿润年份较干旱年份蒸散量增加了78 mm,其中土壤蒸发增加最多,其次是冠层蒸腾,冠层截留蒸发最小。 相似文献
118.
The bar formation is still an open problem in modern astrophysics. In this paper we present numerical simulations performed
with the aim of analyzing the growth of the bar instability inside stellar-gaseous disks, where the star formation is triggered,
and a central black hole is present. The aim of this paper is to point out the impact of such a central massive black hole
on the growth of the bar. We use N-body-SPH simulations of the same isolated disk-to-halo mass systems harboring black holes
with different initial masses and a different energy feedback on the surrounding gas. We compare the results of these simulations
with the one of the same disk without a black hole in its center. We make the same comparison (disk with and without black
hole) for a stellar disk in a fully cosmological scenario. A stellar bar, lasting 10 Gyrs, is present in all our simulations. 相似文献
119.
Mangialajo L Ruggieri N Asnaghi V Chiantore M Povero P Cattaneo-Vietti R 《Marine pollution bulletin》2007,55(1-6):30-41
The assessment of the ecological status, as required by the Water Framework Directive (WFD), plays an important role in coastal zone management, but only a small number of ecological indices are applicable on rocky bottoms. In this study, we apply a previously defined ecological quality index based on the cartography of littoral and upper-sublittoral rocky-shore communities (CARLIT), based on the sensitivity of algae dominated communities to anthropogenic impacts along a moderate urban gradient. We also apply this index in four Marine Protected Areas (MPAs), proposed as reference sites at a regional scale. After comparing the outputs with water variables and other quality indices, we can affirm that (1) the CARLIT index is suitable to detect different kinds of anthropogenic pressures, that (2) the choice of proper reference sites is a focal point in the fulfilment of the WFD (Water Framework Directive) and that (3) historical data are important to define reference conditions and the degradation of ecological status. 相似文献
120.
Roland Hischier Francesca Reale Valentina Castellani Serenella Sala 《Chemie der Erde / Geochemistry》2010
Assessing the environmental impact due to consumption of goods and services is a pivotal step towards achieving the sustainable development goal related to responsible production and consumption (i.e. SDG 12). Household appliances plays a crucial role and should be assessed in a systemic manner, namely considering all life cycle stages, technological efficiency, and affluence aspects. The present study assess the impact of such household appliances used in Europe, and tests scenarios of potential impact reduction at various scales. Life cycle assessment is applied to 14 different household appliances (ranging from dishwashers to television devices) selected to build a set of representative products, based on their economic value and diffusion in households in Europe. Related impacts are calculated with the Environmental Footprint method for calculating a Consumer Footprint “appliances” for the baseline year 2010. A number of scenarios encompassing eco-solutions on a technical level, changes in consumption pattern, behavioral changes, as well as the combination of all these aspects are run to estimate the Consumer Footprint related to household appliances for the year 2030, compared against this baseline scenario. The baseline Consumer Footprint is confirming the importance of the use phase in leading the impacts in almost all impact categories. Testing different scenarios concludes that there is a reduction of the impact for most of the categories (with up to 67% for the ozone depletion potential, and still around 35% for the global warming potential), while two of the here examined impact categories (i.e. land-use and mineral resource depletion) show an overall potential that is even negative – i.e. the results of all scenarios are higher than the ones of the 2010 baseline scenario. The increase in purchase and use of such appliances may offset energy efficiency benefits in some of the examined categories. Hence, the assessment of sustainability of appliances consumption should always include several scales, from the efficiency of the products (micro scale), to the improvement of the energy mix (meso scale), up to accounting for socio-economic drivers and patterns of consumption affecting the overall appliances stock (macro scale). 相似文献