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Patrick Materatski Anna-Maria Vafeiadou Tom Moens Helena Adão 《Estuaries and Coasts》2016,39(5):1478-1490
In 2008, the stable seagrass beds of the Mira estuary (SW Portugal) disappeared completely; however, during 2009, they have begun to present early symptoms of natural recovery, characterised by a strongly heterogeneous distribution. This study was designed to investigate the spatial and temporal variability patterns of species composition, densities and trophic composition of the benthic nematode assemblages in this early recovery process, at two sampling sites with three stations each and at five sampling occasions. Because of the erratic and highly patchy seagrass recovery and the high environmental similarity of the two sampling sites, we expected within-site variability in nematode assemblages to exceed between-site variability. However, contrary to that expectation, whilst nematode genus composition was broadly similar between sites, nematode densities differed significantly between sites, and this between-site variability exceeded within-site variability. This may be linked to differences in the Zostera recovery patterns between both sites. In addition, no clear temporal patterns of nematode density, trophic composition and diversity were evident. Nematode assemblages generally resembled those of other estuarine muddy intertidal areas, which have a high tolerance of stress conditions. 相似文献
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Paolo S. Garofalo Mattias B. Fricker Detlef Günther Paolo Forti Anna-Maria Mercuri Mara Loreti Bruno Capaccioni 《Earth and Planetary Science Letters》2010,289(3-4):560-569
Three hypogenic caves within the Naica mine of Mexico (Cueva de los Cristales — CLC, Ojo de la Reina — OR, and Cueva de las Velas — CLV) host spectacular gypsum crystals up to 11 m in length. These caves are close to another shallow cave of the area (Cueva de las Espadas — CLE), with which they cover a 160 m-deep vertical section of the local drainage basin. Similar to other hypogenic caves, all these caves lack a direct connection with the land surface and should be unrelated with climate.A record of multi-technique fluid inclusion data and pollen spectra from cave and mine gypsum indicates surprisingly that climatic changes occurring at Naica could have controlled fluid composition in these caves, and hence crystal growth. Microthermometry and LA-ICP-Mass Spectrometry of fluid inclusions indicate that the shallow, chemically peculiar, saline fluid (up to 7.7 eq. wt.%NaCl) of CLE could have formed from evaporation, during a dry and hot climatic period. The fluid of the deep caves was instead of low salinity (～ 3.5 eq. wt.% NaCl) and chemically homogeneous, and was poorly affected by evaporation. We propose that mixing of these two fluids, generated at different depths of the Naica drainage basin, determined the stable supersaturation conditions for the gigantic gypsum crystals to grow. Fluid mixing was controlled by the hydraulic communication between CLE and the other deep caves, and must have taken place during cycles of warm-dry and fresh-wet climatic periods, which are known to have occurred in the region. Pollen grains from a 35 ka-old gypsum crystal of CLC corresponds to a fairly homogenous catchment basin made of a mixed broadleaf wet forest, which suggests precipitation during a fresh-wet climatic period and confirms our interpretation of the fluid inclusion data.The unusual combination of geological and geochemical factors of Naica suggests that other hypogenic caves found elsewhere may not host similar crystals. However, this work shows that fluid inclusions and pollen spectra represent a useful tool for cave studies in general, and if used in future studies might be essential to unravel the mechanisms of hypogenic deposition. 相似文献
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Assunta Florenzano Anna Maria Mercuri Aurora Pederzoli Paola Torri Giovanna Bosi Linda Olmi Rossella Rinaldi Marta Bandini Mazzanti 《Geoarchaeology》2012,27(1):34-47
This paper presents the study of parasite remains recovered in pollen samples collected from archaeological layers. Laboratory treatment enabled us to obtain very high concentrations of both pollen and parasite eggs from the same samples. The case study of the site of Piazza Garibaldi in Parma, a town in the Po plain, is reported. The site was a sacred area in Roman times and a market square in Medieval times (10th–11th century A.D.). Pollen, seeds, and fruits from the latter phase were collected from four Medieval pits and one cesspit. After a palynological treatment including sieving, floating, and light acetolysis, abundant quantities of parasite eggs were extracted. Human and animal parasite eggs belonging to Trichuris, Ascaris, Taenia/Echinococcus, Capillaria, Dicrocoelium, and Diphyllobothrium were found. The analyses of animal and plant remains identified in the same samples suggested that the pit infillings consisted of waste, human and animal excrements, deteriorated plant food, and refuse of grapes. Therefore, parasite remains help the interpretation of archaeobotanical data in identifying human behaviors and site functions. 相似文献
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Sorption of Ni(II) onto chlorite surfaces was studied as a function of pH (5–10), ionic strength (0.01–0.5 M) and Ni concentration (10−8–10−6 M) in an Ar atmosphere using batch sorption with radioactive 63Ni as tracer. Such studies are important since Ni(II) is one of the major activation products in spent nuclear fuel and sorption data on minerals such as chlorite are lacking. The sorption of Ni(II) onto chlorite was dependent on pH but not ionic strength, which indicates that the process primarily comprises sorption by surface complexation. The maximum sorption was at pH ∼ 8 (Kd = ∼10−3 cm3/g). Desorption studies over a period of 1–2 weeks involving replacement of the aqueous solution indicated a low degree of desorption. The acid–base properties of the chlorite mineral were determined by titration and described using a non-electrostatic surface complexation model in FITEQL. A 2-pK NEM model and three surface complexes, Chl_OHNi2+, Chl_OHNi(OH)+ and Chl_OHNi(OH)2, gave the best fit to the sorption results using FITEQL. The high Kd values and low degree of desorption observed indicate that under expected groundwater conditions, a large fraction of Ni(II) that is potentially leachable from spent nuclear fuel may be prevented from migrating by sorption onto chlorite surfaces. 相似文献
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Central Sahara rock shelters offer an early and middle Holocene environmental reconstruction. This paper summarises palynological research carried out within a multidisciplinary archaeological research project on the Wadi Teshuinat area (Tadrart Acacus Mts., in south-western Fezzan, Libya). The sites were occupied by hunter-gatherer and pastoralist cultures. On-site pollen data, treated as a single ‘regional site’, showed that different pollen stratigraphies and flora characterised the past phases. Plant macro-remains also helped to understand local plant exploitation and landscape evolution. Pollen spectra showed the following climate oscillations: wet and cool (approx. 8800–8250 cal. BC), dry and warm (approx. 7920–7520 cal. BC), wet (approx. 7550–7200 cal. BC), dry (approx. 6340–6210 cal. BC—geoarchaeological evidence), wet and warm (approx. 6250–4300 cal. BC, including a wetter and warmer phase at approx. 5500–4600 cal. BC); dry and warm (approx. 4250–2900 cal. BC); drier and warm (approx. 2900–1600 cal. BC, up to the present). Since the early Holocene, both climatic and anthropic factors have played an important and strictly interconnected role in transforming the environment. Thus, while subsistence strategies were adjusting to climatic and environmental changes, the plant landscape was also being slowly and continuously shaped by humans. 相似文献
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Anna-Maria?Soja Károly?Kutics Karl?Maracek Gábor?Molnár Gerhard?SojaEmail author 《Climatic change》2014,124(1-2):119-132
This paper investigates how the role of climate in tourist destination choice has changed over the last 15 years. To this end, a demand model for international tourism is estimated, including the main classic determinants but allowing a time-varying climatic sensitivity of tourists. Moreover, a complete database considering international tourism movement between 178 countries for the period 1995 to 2010 is used. Results show how turning point temperatures in origin and destination countries have changed over the period of analysis, evidencing a loss of competitiveness for traditional warm destinations. Additionally, using data for the projected growth of Gross Domestic Product per capita and climatic conditions within A2, B1 and B2 scenarios, an updated vision of their expected impact on international tourism flows is assessed, evaluating how climate change would imply a greater loss of attractiveness for traditional warm destinations around the world but would increase attractiveness for high latitude countries. 相似文献
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A. A. Peyve S. G. Skolotnev M. Ligi N. N. Turko E. Bonatti S. Yu. Kolodyazhnyi N. P. Chamov N. V. Tsukanov Yu. E. Baramykov A. E. Eskin N. Grindlay J. G. Sclater D. Brunelly A. N. Pertsev A. Cipriani G. Bortoluzzi R. Mercuri E. Paganelli F. Muccini Ch. Takeuchi F. Zaffagnini K. O. Dobrolyubova 《Doklady Earth Sciences》2007,416(1):991-994
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A. A. Peyve S. G. Skolotnev M. Ligi N. N. Turko E. Bonatti S. Yu. Kolodyazhnyi N. P. Chamov N. V. Tsukanov Yu. E. Baramykov A. E. Eskin N. Grindlay J. G. Sclater D. Brunelly A. N. Pertsev A. Cipriani G. Bortoluzzi R. Mercuri E. Paganelli F. Muccini Ch. Takeuchi F. Zaffagnini K. O. Dobrolyubova 《Doklady Earth Sciences》2007,416(7):991-994
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Paolo Boncio Sara Amoroso Giovanna Vessia Marco Francescone Mauro Nardone Paola Monaco Daniela Famiani Deborah Di Naccio Alessia Mercuri Maria Rosaria Manuel Fabrizio Galadini Giuliano Milana 《Bulletin of Earthquake Engineering》2018,16(1):91-111
In this study, we analyse the susceptibility to liquefaction of the Pozzone site, which is located on the northern side of the Fucino lacustrine basin in central Italy. In 1915, this region was struck by a M 7.0 earthquake, which produced widespread coseismic surface effects that were interpreted to be liquefaction-related. However, the interpretation of these phenomena at the Pozzone site is not straightforward. Furthermore, the site is characterized by an abundance of fine-grained sediments, which are not typically found in liquefiable soils. Therefore, in this study, we perform a number of detailed stratigraphic and geotechnical investigations (including continuous-coring borehole, CPTu, SDMT, SPT, and geotechnical laboratory tests) to better interpret these 1915 phenomena and to evaluate the liquefaction potential of a lacustrine environment dominated by fine-grained sedimentation. The upper 18.5 m of the stratigraphic succession comprises fine-grained sediments, including four strata of coarser sediments formed by interbedded layers of sand, silty sand and sandy silt. These strata, which are interpreted to represent the frontal lobes of an alluvial fan system within a lacustrine succession, are highly susceptible to liquefaction. We also find evidence of paleo-liquefaction, dated between 12.1–10.8 and 9.43–9.13 kyrs ago, occurring at depths of 2.1–2.3 m. These data, along with the aforementioned geotechnical analyses, indicate that this site would indeed be liquefiable in a 1915-like earthquake. Although we found a broad agreement among CPTu, DMT and shear wave velocity “simplified procedures” in detecting the liquefaction potential of the Pozzone soil, our results suggest that the use and comparison of different in situ techniques are highly recommended for reliable estimates of the cyclic liquefaction resistance in lacustrine sites characterized by high content of fine-grained soils. In geologic environments similar to the one analysed in this work, where it is difficult to detect liquefiable layers, one can identify sites that are susceptible to liquefaction only by using detailed stratigraphic reconstructions, in situ characterization, and laboratory analyses. This has implications for basic (Level 1) seismic microzonation mapping, which typically relies on the use of empirical evaluations based on geologic maps and pre-existing sub-surface data (i.e., age and type of deposits, prevailing grain size, with particular attention paid to clean sands, and depth of the water table). 相似文献
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