The Experts below are selected from a list of 69 Experts worldwide ranked by ideXlab platform
Pietro Buzzini - One of the best experts on this subject based on the ideXlab platform.
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intra and inter cores fungal diversity suggests interconnection of different habitats in an antarctic frozen lake Boulder Clay northern victoria land
Environmental Microbiology, 2020Co-Authors: Ciro Sannino, Luigimaria Borruso, Ambra Mezzasoma, Dario Battistel, Laura Zucconi, Laura Selbmann, Maurizio Azzaro, Silvano Onofri, Benedetta Turchetti, Pietro BuzziniAbstract:A perennially frozen lake at Boulder Clay site (Victoria Land, Antarctica), characterized by the presence of frost mounds, have been selected as an in situ model for ecological studies. Different samples of permafrost, glacier ice and brines have been studied as a unique habitat system. An additional sample of brines (collected in another frozen lake close to the previous one) was also considered. Alpha- and beta-diversity of fungal communities showed both intra- and inter-cores significant (p < 0.05) differences, which suggest the presence of interconnection among the habitats. Therefore, the layers of frost mound and the deep glacier could be interconnected while the brines could probably be considered as an open habitat system not interconnected with each other. Moreover, the absence of similarity between the lake ice and the underlying permafrost suggested that the lake is perennially frozen based. The predominance of positive significant (p < 0.05) co-occurrences among some fungal taxa allowed to postulate the existence of an ecological equilibrium in the habitats systems. The positive significant (p < 0.05) correlation between salt concentration, total organic carbon and pH, and some fungal taxa suggests that a few abiotic parameters could drive fungal diversity inside these ecological niches.
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Intra‐ and inter‐cores fungal diversity suggests interconnection of different habitats in an Antarctic frozen lake (Boulder Clay, Northern Victoria Land)
Environmental microbiology, 2020Co-Authors: Ciro Sannino, Luigimaria Borruso, Ambra Mezzasoma, Dario Battistel, Laura Zucconi, Laura Selbmann, Maurizio Azzaro, Silvano Onofri, Benedetta Turchetti, Pietro BuzziniAbstract:A perennially frozen lake at Boulder Clay site (Victoria Land, Antarctica), characterized by the presence of frost mounds, have been selected as an in situ model for ecological studies. Different samples of permafrost, glacier ice and brines have been studied as a unique habitat system. An additional sample of brines (collected in another frozen lake close to the previous one) was also considered. Alpha- and beta-diversity of fungal communities showed both intra- and inter-cores significant (p
Maurizio Azzaro - One of the best experts on this subject based on the ideXlab platform.
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The prokaryotic community in an extreme Antarctic environment: the brines of Boulder Clay lakes (Northern Victoria Land)
Hydrobiologia, 2021Co-Authors: Maurizio Azzaro, Giovanna Maimone, Rosabruna La Ferla, Alessandro Cosenza, Alessandro Ciro Rappazzo, Gabriella Caruso, Rodolfo Paranhos, Anderson S. Cabral, Emanuele Forte, Mauro GuglielminAbstract:During summer 2014, three hypersaline brines were discovered in two frozen lakes of Boulder Clay (Northern Victoria Valley, Antarctica). Ongoing research seeks to gain novel insights on the microbial ecology of such environments, in order to further the understanding of life adaptation to extreme conditions. To this aim, the abundance of prokaryotic cells (including cell morphologies and size for biomass conversion), the amount of viable cells (in terms of membrane-intact cells and respiring cells), the viral count, the physiological profiles at community level and the main microbial enzymatic activities were described. The brines differed each other in terms of prokaryotic cells’ abundance, size, and viability as well as viral abundance. Cell morphotypes and metabolic responses also varied among the brine samples. Underground interconnections were likely to occur, with the microbial community becoming more abundant and structured to better exploit the limited resource availability. Overall, complex interactions among multiple environmental factors, including marine water origin, depth horizon, isolation time of the brines, and climatic variations, reflected on the microbial community distribution patterns and highlighted the need to preserve these niches of extreme life.
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intra and inter cores fungal diversity suggests interconnection of different habitats in an antarctic frozen lake Boulder Clay northern victoria land
Environmental Microbiology, 2020Co-Authors: Ciro Sannino, Luigimaria Borruso, Ambra Mezzasoma, Dario Battistel, Laura Zucconi, Laura Selbmann, Maurizio Azzaro, Silvano Onofri, Benedetta Turchetti, Pietro BuzziniAbstract:A perennially frozen lake at Boulder Clay site (Victoria Land, Antarctica), characterized by the presence of frost mounds, have been selected as an in situ model for ecological studies. Different samples of permafrost, glacier ice and brines have been studied as a unique habitat system. An additional sample of brines (collected in another frozen lake close to the previous one) was also considered. Alpha- and beta-diversity of fungal communities showed both intra- and inter-cores significant (p < 0.05) differences, which suggest the presence of interconnection among the habitats. Therefore, the layers of frost mound and the deep glacier could be interconnected while the brines could probably be considered as an open habitat system not interconnected with each other. Moreover, the absence of similarity between the lake ice and the underlying permafrost suggested that the lake is perennially frozen based. The predominance of positive significant (p < 0.05) co-occurrences among some fungal taxa allowed to postulate the existence of an ecological equilibrium in the habitats systems. The positive significant (p < 0.05) correlation between salt concentration, total organic carbon and pH, and some fungal taxa suggests that a few abiotic parameters could drive fungal diversity inside these ecological niches.
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Intra‐ and inter‐cores fungal diversity suggests interconnection of different habitats in an Antarctic frozen lake (Boulder Clay, Northern Victoria Land)
Environmental microbiology, 2020Co-Authors: Ciro Sannino, Luigimaria Borruso, Ambra Mezzasoma, Dario Battistel, Laura Zucconi, Laura Selbmann, Maurizio Azzaro, Silvano Onofri, Benedetta Turchetti, Pietro BuzziniAbstract:A perennially frozen lake at Boulder Clay site (Victoria Land, Antarctica), characterized by the presence of frost mounds, have been selected as an in situ model for ecological studies. Different samples of permafrost, glacier ice and brines have been studied as a unique habitat system. An additional sample of brines (collected in another frozen lake close to the previous one) was also considered. Alpha- and beta-diversity of fungal communities showed both intra- and inter-cores significant (p
Massimo Frezzotti - One of the best experts on this subject based on the ideXlab platform.
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Multi-temporal investigation of the Boulder Clay Glacier and Northern Foothills (Victoria Land, Antarctica) by integrated surveying techniques.
Remote Sensing, 2019Co-Authors: Stefano Urbini, Gianluca Bianchi-fasani, Paolo Mazzanti, Alfredo Rocca, Luca Vittuari, Antonio Zanutta, Valentina Alena Girelli, Michelina Serafini, Achille Zirizzotti, Massimo FrezzottiAbstract:The paper aims to detect the main changes that occurred in the area surrounding the Mario Zucchelli Station (MZS) through analysis of multi-temporal remote sensing integrated by geophysical measurements. Specific attention was directed at realizing an integrated geomorphological study of the Boulder Clay Glacier, a partially debris-covered glacier belonging to the Northern Foothills (Victoria Land, Antarctica). This area was recently chosen as the location for the construction of a new semi-permanent gravel runway for MZS logistical airfreight operations. Photogrammetric analysis was performed by comparing three historical aerial photogrammetric surveys (carried out in 1956, 1985, and 1993) and Very High Resolution (VHR) GeoEye-1 satellite stereo-image coverage acquired in 2012. The comparison of geo-referenced orthophoto-mosaics allowed the main changes occurring in some particular areas along the coast nearby MZS to be established. Concerning the study of the Boulder Clay Glacier, it has to be considered that glaciers and moraines are not steady-state systems by definition. Several remote sensing and geophysical investigations were carried out with the main aim of determining the general assessment of this glacier: Ground Penetrating Radar (GPR); Geodetic Global Positioning System (GPS) network; multi-temporal satellite Synthetic Aperture Radar (SAR) interferometry. The analysis of Boulder Clay Glacier moraine pointed out a deformation of less than 74 mm y−1 in a time span of 56 years, value that agrees with velocity and deformation data observed by GPS and InSAR methods. The presence of unexpected brine ponds at the ice/bedrock interface and the deformation pattern observed in the central part of the moraine has to be monitored and studied, especially under the long-term maintenance of the future runway.
Ciro Sannino - One of the best experts on this subject based on the ideXlab platform.
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intra and inter cores fungal diversity suggests interconnection of different habitats in an antarctic frozen lake Boulder Clay northern victoria land
Environmental Microbiology, 2020Co-Authors: Ciro Sannino, Luigimaria Borruso, Ambra Mezzasoma, Dario Battistel, Laura Zucconi, Laura Selbmann, Maurizio Azzaro, Silvano Onofri, Benedetta Turchetti, Pietro BuzziniAbstract:A perennially frozen lake at Boulder Clay site (Victoria Land, Antarctica), characterized by the presence of frost mounds, have been selected as an in situ model for ecological studies. Different samples of permafrost, glacier ice and brines have been studied as a unique habitat system. An additional sample of brines (collected in another frozen lake close to the previous one) was also considered. Alpha- and beta-diversity of fungal communities showed both intra- and inter-cores significant (p < 0.05) differences, which suggest the presence of interconnection among the habitats. Therefore, the layers of frost mound and the deep glacier could be interconnected while the brines could probably be considered as an open habitat system not interconnected with each other. Moreover, the absence of similarity between the lake ice and the underlying permafrost suggested that the lake is perennially frozen based. The predominance of positive significant (p < 0.05) co-occurrences among some fungal taxa allowed to postulate the existence of an ecological equilibrium in the habitats systems. The positive significant (p < 0.05) correlation between salt concentration, total organic carbon and pH, and some fungal taxa suggests that a few abiotic parameters could drive fungal diversity inside these ecological niches.
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Intra‐ and inter‐cores fungal diversity suggests interconnection of different habitats in an Antarctic frozen lake (Boulder Clay, Northern Victoria Land)
Environmental microbiology, 2020Co-Authors: Ciro Sannino, Luigimaria Borruso, Ambra Mezzasoma, Dario Battistel, Laura Zucconi, Laura Selbmann, Maurizio Azzaro, Silvano Onofri, Benedetta Turchetti, Pietro BuzziniAbstract:A perennially frozen lake at Boulder Clay site (Victoria Land, Antarctica), characterized by the presence of frost mounds, have been selected as an in situ model for ecological studies. Different samples of permafrost, glacier ice and brines have been studied as a unique habitat system. An additional sample of brines (collected in another frozen lake close to the previous one) was also considered. Alpha- and beta-diversity of fungal communities showed both intra- and inter-cores significant (p
C. O. Menkiti - One of the best experts on this subject based on the ideXlab platform.
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Soil Nailing in Dublin Boulder Clay
Geotechnical and Geological Engineering, 2014Co-Authors: C. O. Menkiti, M. Long, G. W. E. Milligan, P. HigginsAbstract:Extensive areas of Dublin City are underlain by a very stiff to hard lodgement till, known locally as Dublin Boulder Clay. Over the past number of years there has been increasing use of soil nails mostly to support temporary slopes for excavations, road widening and cut and cover tunnels. Although guidance for nailing in stiff Clays exists, the very high strength and stiffness of the Dublin soils mean that it is conservative to use these established techniques and further optimisation may be possible. This paper presents data from the Dublin Port Tunnel project for a large set of short term pullout tests carried out on nails from a slope some 12 m in height together with slope monitoring data. The significant influence of drilling technique is discussed. Optimisation of temporary soil nails in Dublin Boulder Clay is appraised. The relationship between bond strength and actual nail performance is discussed drawing on data from a heavily monitored slope. Measured data on the vertical and horizontal movements of the slope together with data from piezometers confirm the excellent behaviour of the soil nailed slopes.
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Retaining walls in Dublin Boulder Clay, Ireland
Proceedings of the Institution of Civil Engineers - Geotechnical Engineering, 2012Co-Authors: Michael Long, C. O. Menkiti, Carl Brangan, Michael Looby, Patrick CaseyAbstract:A good number of deep excavations have been recently completed in Dublin Boulder Clay, Ireland. These have included propped walls up to 25 m deep and permanent cantilevers 7·5 m high. Experience elsewhere in the world was used to design and construct these walls. However, case history data have shown that the behaviour of the walls in Dublin Boulder Clay is very rigid and much stiffer than comparable systems worldwide. It appears this behaviour is due to the inherent natural strength and stiffness of the soil and the slow dissipation of excavation-induced depressed pore pressures or suctions. There appears to be scope for developing more efficient designs and in particular for reducing propping requirements. For temporary works, the use of undrained parameters in serviceability limit state calculations together with implementation of the observational approach on site could be considered for future schemes.
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Finite element analyses of steep man-made cuts in Dublin Boulder Clay
Canadian Geotechnical Journal, 2008Co-Authors: N Kovacevic, C. O. Menkiti, Michael Long, G. W.e. Miligan, David M. PottsAbstract:This paper describes finite element analyses undertaken to gain an insight into the short-term behaviour of temporary steep slopes in Dublin Boulder Clay for cut and cover sections of the recently completed Dublin Port Tunnel. The analyses of two steep slopes are reported: (i) an unsupported slope for a full-scale trial excavation and (ii) a partly nailed slope for a prototype cut and cover structure. It has been found that a major contribution to the stability of these cuts is an increase in the effective stress (and thus strength) due to both (i) depressed pore-water pressures (suctions) and (ii) a tendency of the Dublin Boulder Clay to dilate during undrained excavation in this low permeability and very dense material. However, the presence of even thin, discontinuous but recharged granular lenses of a higher permeability significantly reduces the time to failure.
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Geotechnical properties of Dublin Boulder Clay
Géotechnique, 2007Co-Authors: Michael Long, C. O. MenkitiAbstract:Geotechnical characteristics of Dublin Boulder Clay (DBC), based on detailed site investigation and site experience from some recent large projects in Dublin, are presented. This paper attempts to synthesise available information in parallel with recent work by Skipper et al., who provide an updated understanding of the geology of the DBC. Having assessed the effects of sampling disturbance, the paper characterises the various formations and sub-units of the DBC. The interpreted material behaviour is related to observed engineering performance. It was found from the behaviour of earth retained structures that intact, Clayey, DBC formations are two to three times stiffer than assessed from high-quality laboratory tests on block samples. DBC is shown to be significantly stiffer than other well-characterised tills. Relatively inexpensive multichannel surface wave techniques can give very reliable estimates of in situ small-strain stiffness. High undrained triaxial compression strengths were measured, and it ...
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The engineering geology and characterization of Dublin Boulder Clay
Quarterly Journal of Engineering Geology and Hydrogeology, 2005Co-Authors: J. Skipper, C. O. Menkiti, Michael Long, Ben Follett, J. Clark-hughesAbstract:The ground investigation and construction for the North Cut and Cover Section of the Dublin Port Tunnel (north Dublin, Co. Dublin, Ireland) involved high resolution ground investigation and excavation logging. As a result, our interpretation of the glacially derived Quaternary geology encountered presents a more complex picture than previously described. A detailed description of the stratigraphy and lithology of the glacial deposits formerly known as the ‘Dublin Boulder Clay’ is presented, and palaeoenvironmental interpretations are suggested for the various units. The ‘Dublin Boulder Clay’ is reinterpreted to comprise four major units and associated subunits. Possible construction hazards, including discontinuities, lithological variability, glacio-tectonic rafting and the presence of large water-bearing units, are identified and linked with the stratigraphy. Preliminary data on the geotechnical and engineering behaviour of each unit are presented. The encountered lithologies generally demonstrated high in-situ strength and stiffness but low permeability and plasticity.