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11.
José Antonio López-Sáez Francisca Alba-Sánchez Sandra Robles-López Sebastián Pérez-Díaz Daniel Abel-Schaad Silvia Sabariego-Ruiz Arthur Glais 《山地科学学报》2016,13(7):1139-1153
A high-altitude peat sequence from the heart of the Spanish Central System (Gredos range) was analysed through a multi-proxy approach to determine the sensitivity of high-mountain habitats to climate, fire and land use changes during the last seven hundred years, providing valuable insight into our understanding of the vegetation history and environmental changes in a mountain pass close to a traditional route of transhumance. The pollen data indicate that the vegetation was dominated by shrublands and grasslands with scattered pines in high-mountain areas, while in the valleys cereals, chestnut and olive trees were cultivated. Strong declines of high-mountain pines percentages are recorded at 1540, 1675, 1765, 1835 and 1925 cal AD, which may be related to increasing grazing activities and/or the occurrence of anthropogenic fires. The practice of mountain summer farming and transhumance deeply changed and redesigned the landscape of the high altitudes in central Spain (Gredos range) since the Middle Ages, although its dynamics was influenced in some way by climate variability of the past seven centuries. 相似文献
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13.
Alatorre-Ibargüengoitia Miguel A. Hernández-Urbina Karina Ramos-Hernández Silvia G. 《Natural Hazards》2021,106(1):1011-1035
Natural Hazards - The 1982 eruption of El Chichón volcano constitutes the worst volcanic disaster in Mexico producing more than 2000 fatalities, thousands of displaced people and severe... 相似文献
14.
Gerardo Grelle Laura Bonito Maresca Rosalba Silvia Iacurto Claudia Madiai Paola Revellino Giuseppe Sappa 《地震工程与工程振动(英文版)》2021,20(1):63-78
The estimate of seismic site effects by experimental approaches is based on different assumptions aimed at simplifying the complex actual site conditions and related uncertainties.However,the reliability of the results can increase if the experimental data is focused on quite strong seismic sequences and the on-site acquisition of a large number of signals is deemed strategic for the assessment of the expected phenomena.Based on these considerations,the ground motion at the Red Zone sector of Amatrice hill,violently struck by the 2016-2017 Central Italy seismic sequence,was analyzed via an observational approach.A large set of weak motions(moment magnitude Mw 2.5-3.9)was analyzed in this study by means of standard(SSR)and horizontal to vertical(HVSR)spectral ratio techniques.The results from the experimental analysis of the site effects by using weak motion and noise signals show a significant amplification at the top of Amatrice hill with a remarkable polarization of the motion and changes in spectral shapes according to the topographic setting of the relief. 相似文献
15.
Ugolini A Ungherese G Somigli S Galanti G Baroni D Borghini F Cipriani N Nebbiai M Passaponti M Focardi S 《Marine environmental research》2008,65(4):349-357
The present paper assesses the use of the supralittoral amphipod Talitrus saltator as a bioindicator of the effects of human trampling on the supralittoral sandy band. Samplings in delimited areas were carried out at sites subjected to different human impact. The results showed a strong negative correlation between the number of swimmers and the sandhopper population density, while there was no clear relationship between sandhopper abundance and the other factors considered: granulometry, compactness and organic carbon content of the sand, and trace metal contents in the sand and sandhoppers. A field test of trampling conducted in a confined space showed its direct negative effect on sandhopper survival. However, trace metal analysis confirmed the ability of T. saltator to bioaccumulate some elements (Hg, Zn, Cu, Cd). Our study demonstrates that T. saltator is a good bioindicator of human impact in the supralittoral zone of sandy shores. 相似文献
16.
Marsili L Casini S Bucalossi D Porcelloni S Maltese S Fossi MC 《Marine environmental research》2008,66(1):151-153
The aim of the present study was to propose the immunofluorescence technique in cultured fibroblasts from Mediterranean cetaceans as a new "in vitro" tool to explore the susceptibility of these marine mammals to different xenobiotic compounds. The cell lines were cultured from integument biopsies of free-ranging and stranded cetaceans (dead within 12h). Using the indirect immunofluorescence assay, we detected endogenous proteins induced by different contaminants. Here we present the method used for qualitative and quantitative evaluation of cytochromes P450 (CYP1A1 and CYP2B) induced by some POPs (DDTs and PCBs) and emerging contaminants (PBDEs) in fibroblast cell cultures of striped dolphin (Stenella coeruleoalba) and bottlenose dolphin (Tursiops truncatus). Immunofluorescence was quantified with a specially designed Olympus macro, DetectIntZ. A major result was the possibility of using this "in vitro" assay to quantify induction of endogenous proteins. 相似文献
17.
Riccardo Rodolfo‐Metalpa Chiara Lombardi Silvia Cocito Jason M. Hall‐Spencer Maria Cristina Gambi 《Marine Ecology》2010,31(3):447-456
There are serious concerns that ocean acidification will combine with the effects of global warming to cause major shifts in marine ecosystems, but there is a lack of field data on the combined ecological effects of these changes due to the difficulty of creating large‐scale, long‐term exposures to elevated CO2 and temperature. Here we report the first coastal transplant experiment designed to investigate the effects of naturally acidified seawater on the rates of net calcification and dissolution of the branched calcitic bryozoan Myriapora truncata (Pallas, 1766). Colonies were transplanted to normal (pH 8.1), high (mean pH 7.66, minimum value 7.33) and extremely high CO2 conditions (mean pH 7.43, minimum value 6.83) at gas vents off Ischia Island (Tyrrhenian Sea, Italy). The net calcification rates of live colonies and the dissolution rates of dead colonies were estimated by weighing after 45 days (May–June 2008) and after 128 days (July–October) to examine the hypothesis that high CO2 levels affect bryozoan growth and survival differently during moderate and warm water conditions. In the first observation period, seawater temperatures ranged from 19 to 24 °C; dead M. truncata colonies dissolved at high CO2 levels (pH 7.66), whereas live specimens maintained the same net calcification rate as those growing at normal pH. In extremely high CO2 conditions (mean pH 7.43), the live bryozoans calcified significantly less than those at normal pH. Therefore, established colonies of M. truncata seem well able to withstand the levels of ocean acidification predicted in the next 200 years, possibly because the soft tissues protect the skeleton from an external decrease in pH. However, during the second period of observation a prolonged period of high seawater temperatures (25–28 °C) halted calcification both in controls and at high CO2, and all transplants died when high temperatures were combined with extremely high CO2 levels. Clearly, attempts to predict the future response of organisms to ocean acidification need to consider the effects of concurrent changes such as the Mediterranean trend for increased summer temperatures in surface waters. Although M. truncata was resilient to short‐term exposure to high levels of ocean acidification at normal temperatures, our field transplants showed that its ability to calcify at higher temperatures was compromised, adding it to the growing list of species now potentially threatened by global warming. 相似文献
18.
Coalbed methane (CBM) is a worldwide exploration target of the petroleum industry. In Brazil, the most important coal-bearing succession is associated with the Permian Rio Bonito Formation of the Paraná Basin. The gas-prone areas are located at the southeastern margin of the Paraná Basin and possibly in the offshore region of the northern part of the Pelotas Basin. Coalfields end abruptly at the present day shoreline, a result of rifting of Gondwana and the evolution of the South Atlantic Ocean. All geologic indicators suggest that in pre-rift times the coal seams extended further eastwards, probably now lying deeply buried below the sedimentary succession of the Pelotas Basin. The present paper discusses structural, stratigraphic, seismic and aeromagenetic data that support the preservation of continental crust beneath ocean sediment. If the coal beds had similar lateral extent to known onshore coals, and coal beds extended across the projected extension of the Parana basin, and there was a conservative 5 m of cumulative coal thickness, then a potential methane volume can be estimated for this newly inferred resource. Average onshore coal gas content is 32 scf/ton (1.00 m3/ton). If this is similar in the offshore coal deposits, then the hypothetical methane volume in the offshore area could be in excess of 1.9 × 1012 scf (56 × 109 m3). Metamorphism from dikes associated with rifting are potential complicating factors in these deposits, and since no borehole reaching the deep-lying strata in the offshore area are available, this is a hypothetical gas resource with a certain level of uncertainty which should be tested in the future by drilling a deep borehole. 相似文献
19.
Renza Miorandi Andrea Borsato Silvia Frisia Ian J. Fairchild Detlev K. Richter 《水文研究》2010,24(21):3101-3114
Grotta di Ernesto is a cave site well suited for palaeoclimate studies because it contains annually laminated stalagmites and was monitored from 1995 to the end of 2008 for microclimate, hydrology and hydrochemistry. Long‐term monitoring highlighted that cave drips show three different hydrological responses to rainfall and infiltration: (1) fast seasonal drips in the upper part of the cave, which are mostly fed by fractures, (2) slow seasonal drips, located at mid‐depth in the cave characterized by mixed feeding and (3) slow drips, mostly located in the deeper gallery, which are fed by seepage flow from bulk porosity with a minor fracture‐fed component. The slow drips display daily cycles during spring thaw. Monitoring also indicated that drip waters are only slightly modified by degassing within the soil zone and aquifer and by prior calcite precipitation. Hydrochemical studies show a clear seasonality in calcite saturation index, which results in most cave calcite precipitation occurring during late autumn and winter with similar amounts of precipitated calcite on most stalagmites, regardless of drip rate (discharge) differences. Drip rate, and drip rate variability, therefore, has a minor role in modulating the amount of annual calcite formation. In contrast, drip rate, when associated with moderate reduction in calcite saturation index, clearly influences stalagmite morphology. Increasing drip rate yields a passage from candle‐, to cone‐ to dome‐shaped stalagmites. Very high drip rates feed speleothems with flowstone morphology. In summary, monitoring provides information about the karst aquifer and how hydrology influences those physical and chemical characteristics of speleothems which are commonly used as climate proxies. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
20.
Daniel Bernoulli Lukas Hottinger Silvia Spezzaferri Peter Stille 《Swiss Journal of Geoscience》2007,100(2):215-225
Shallow-water limestones of presumed Late Cretaceous and Eocene age, interbedded with basaltic lavas, were described by earlier authors from São Nicolau in the northwestern part of the Cabo Verde archipelago. If confirmed, these ages would imply late Mesozoic shallow-marine and subaerial volcanic activity in the Cabo Verde archipelago, and document a geological history very different from that known so far from other Cabo Verde Islands, from which no subaerial volcanic activity before the mid-Cenozoic is known. Our re-investigation of the foraminiferal fauna indicates a Late Miocene age for the presumed Late Cretaceous and Eocene limestones. The hypothesis of a long-lived hot spot, active by the Early Cretaceous, and of a major island-building stage in the Cabo Verde Islands during this period, is therefore not supported by the present bio- or chronostratigraphic data. 相似文献