Variations in fluid chemistry and membrane phospholipid fatty acid composition of the bacterial community in a cold storage groundwater system during clogging events     

Alexandra Vetter  Kai Mangelsdorf  Markus Wolfgramm  Kerstin Rauppach  Georg Schettler  Andrea Vieth-Hillebrand 《Applied Geochemistry》2012

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Use of LIDAR in landslide investigations: a review   总被引：13，自引：0，他引：13  

Michel Jaboyedoff  Thierry Oppikofer  Antonio Abellán  Marc-Henri Derron  Alex Loye  Richard Metzger  Andrea Pedrazzini 《Natural Hazards》2012,61(1):5-28

This paper presents a short history of the appraisal of laser scanner technologies in geosciences used for imaging relief by high-resolution digital elevation models (HRDEMs) or 3D models. A general overview of light detection and ranging (LIDAR) techniques applied to landslides is given, followed by a review of different applications of LIDAR for landslide, rockfall and debris-flow. These applications are classified as: (1) Detection and characterization of mass movements; (2) Hazard assessment and susceptibility mapping; (3) Modelling; (4) Monitoring. This review emphasizes how LIDAR-derived HRDEMs can be used to investigate any type of landslides. It is clear that such HRDEMs are not yet a common tool for landslides investigations, but this technique has opened new domains of applications that still have to be developed.  相似文献   

Pharmaceuticals as indictors of sewage-influenced groundwater   总被引：1，自引：0，他引：1  

Beate Müller  Traugott Scheytt  Martin Asbrand  Andrea Mross de Casas 《Hydrogeology Journal》2012,20(6):1117-1129

A set of human pharmaceuticals enables identification of groundwater that is influenced by sewage and provides information on the time of recharge. As the consumption rates of the investigated pharmaceuticals have changed over time, so too has the composition of the sewage. At the study area, south of Berlin (Germany), irrigation was performed as a method of wastewater clean-up at sewage irrigation farms until the early 1990s. Today, treated wastewater is discharged into the surface-water-stream Nuthegraben. Groundwater and surface-water samples were analyzed for the pharmaceutical substances clofibric acid, bezafibrate, diclofenac, carbamazepine and primidone, the main ions and organic carbon. The pharmaceutical substances were detected at concentrations up to microgram-per-liter level in groundwater and surface-water samples from the Nuthegraben Lowland area and from the former irrigation farms. Concentrations detected in groundwater are generally much lower than in surface water and there is significant variation in the distribution of pharmaceutical concentrations in groundwater. Groundwater influenced by the irrigation of sewage water shows higher primidone and clofibric-acid concentrations. Groundwater influenced by recent discharge of treated sewage water into the surface water shows high carbamazepine concentrations while concentrations of primidone and clofibric acid are low.  相似文献   

Syn-thrust deformation across a transverse zone: the Grem–Vedra fault system (central Southern Alps, N Italy)     

Andrea Zanchi  Paolo D’Adda  Stefano Zanchetta  Fabrizio Berra 《Swiss Journal of Geoscience》2012,105(1):19-38

The lateral continuity of the E?CW trending thrust sheets developed within the Lower to Middle Triassic cover of the central Southern Alps (Orobic belt) is disturbed by the occurrence of several N?CS trending transverse zones, such as the poorly known Grem?CVedra Transverse Zone (GVTZ). The GVTZ developed during the emplacement of the up to six S-verging thrust sheets consisting of Lower to Middle Triassic units, occurring immediately south of the Orobic Anticlines. The transverse zone, active during thrust emplacement related to the early Alpine compressions which pre-date the Adamello intrusion, includes three major vertical shear zones, the Grem, Pezzel and Zuccone faults. The major structure of the transverse zone is the dextral Grem fault, forming a deep lateral ramp between thrust sheets 3 and 5. A similar evolution also occurred along the Zuccone and Pezzel faults, which show a left-lateral displacement of syn-thrust folds. The Grem fault was later reactivated as an oblique tear fault during the emplacement of the Orobic Anticlines, due to back-thrusting along out-of-sequence thrust surfaces (Clusone fault). Transpressional deformations along the fault zone are recorded by the rotation of major syn-thrust folds, which also suggest a horizontal offset close to 0.5?km. Records of the first stage of evolution of the Grem fault are better preserved along its northern segment, and structural relationships suggest that it propagated southward and downward in the growing thrust stack. The study of the meso and megascopic structures developed along the GVTZ constrains the evolution of the transverse zone, illustrating the complex deformational phenomena occurring in a transpressional regime. The GVTZ probably reflects the existence of pre-existing tectonic lineaments with a similar orientation. Evidence of pre-existing structures are not preserved in the exposed units, nevertheless the N?CS extensional fault systems that characterize the Norian to Jurassic rifting history of the Lombardian basin are valid candidates.  相似文献   

CLEAN: project overview on CO2 large-scale enhanced gas recovery in the Altmark natural gas field (Germany)     

Michael Kühn  Maja Tesmer  Peter Pilz  Robert Meyer  Kurt Reinicke  Andrea F?rster  Olaf Kolditz  Dirk Sch?fer 《Environmental Earth Sciences》2012,67(2):311-321

The joint research project CLEAN was conducted in the years 2008?C2011 by a German research and development (R&D) alliance of 16 partners from science and industry. The project was set-up as pilot project to investigate the processes relevant to enhanced gas recovery (EGR) by the injection of CO₂ into a subfield of the almost depleted Altmark natural gas field. Despite the setback that permission for active injection was not issued by the mining authority during the period of the project, important results fostering the understanding of processes linked with EGR were achieved. Work carried out led to a comprehensive evaluation of the EGR potential of the Altmark field and the Altensalzwedel subfield in particular. The calculated safety margins emphasize that technical well integrity of the 12 examined boreholes is given for EGR without a need for any further intervention. The laboratory and field tests confirm that the Altensalzwedel subfield is suitable for the injection of 100,000?t of CO₂. Numerical simulations provide sound predictions for the efficiency and safety of the EGR technology based on the CO₂ injection. The development and testing of different monitoring techniques facilitate an improved surveying of CO₂ storage sites in general. The CLEAN results provide the technological, logistic and conceptual prerequisites for implementing a CO₂-based EGR project in the Altmark and provide a benchmark for similar projects in the world.  相似文献   

Effects of increased CO2 levels on monsoons     

Annalisa Cherchi  Andrea Alessandri  Simona Masina  Antonio Navarra 《Climate Dynamics》2011,37(1-2):83-101

Increased atmospheric carbon dioxide concentration provided warmer atmospheric temperature and higher atmospheric water vapor content, but not necessarily more precipitation. A set of experiments performed with a state-of-the-art coupled general circulation model forced with increased atmospheric CO₂ concentration (2, 4 and 16 times the present-day mean value) were analyzed and compared with a control experiment to evaluate the effect of increased CO₂ levels on monsoons. Generally, the monsoon precipitation responses to CO₂ forcing are largest if extreme concentrations of carbon dioxide are used, but they are not necessarly proportional to the forcing applied. In fact, despite a common response in terms of an atmospheric water vapor increase to the atmospheric warming, two out of the six monsoons studied simulate less or equal summer mean precipitation in the 16×CO₂ experiment compared to the intermediate sensitivity experiments. The precipitation differences between CO₂ sensitivity experiments and CTRL have been investigated specifying the contribution of thermodynamic and purely dynamic processes. As a general rule, the differences depending on the atmospheric moisture content changes (thermodynamic component) are large and positive, and they tend to be damped by the dynamic component associated with the changes in the vertical velocity. However, differences are observed among monsoons in terms of the role played by other terms (like moisture advection and evaporation) in shaping the precipitation changes in warmer climates. The precipitation increase, even if weak, occurs despite a weakening of the mean circulation in the monsoon regions (??precipitation-wind paradox??). In particular, the tropical east-west Walker circulation is reduced, as found from velocity potential analysis. The meridional component of the monsoon circulation is changed as well, with larger (smaller) meridional (vertical) scales.  相似文献   

Fault Roughness at Seismogenic Depths from LIDAR and Photogrammetric Analysis     

Andrea Bistacchi  W. Ashley Griffith  Steven A. F. Smith  Giulio Di Toro  Richard Jones  Stefan Nielsen 《Pure and Applied Geophysics》2011,168(12):2345-2363

Fault surface roughness is a principal factor influencing earthquake mechanics, and particularly rupture initiation, propagation, and arrest. However, little data currently exist on fault surfaces at seismogenic depths. Here, we investigate the roughness of slip surfaces from the seismogenic strike-slip Gole Larghe Fault Zone, exhumed from ca. 10 km depth. The fault zone exploited pre-existing joints and is hosted in granitoid rocks of the Adamello batholith (Italian Alps). Individual seismogenic slip surfaces generally show a first phase of cataclasite production, and a second phase with beautifully preserved pseudotachylytes of variable thickness. We determined the geometry of fault traces over almost five orders of magnitude using terrestrial laser-scanning (LIDAR, ca. 500 to <1 m scale), and 3D mosaics of high-resolution rectified digital photographs (10 m to ca. 1 mm scale). LIDAR scans and photomosaics were georeferenced in 3D using a Differential Global Positioning System, allowing detailed multiscale reconstruction of fault traces in Gocad^®. The combination of LIDAR and high-resolution photos has the advantage, compared with classical LIDAR-only surveys, that the spatial resolution of rectified photographs can be very high (up to 0.2 mm/pixel in this study), allowing for detailed outcrop characterization. Fourier power spectrum analysis of the fault traces revealed a self-affine behaviour over 3–5 orders of magnitude, with Hurst exponents ranging between 0.6 and 0.8. Parameters from Fourier analysis have been used to reconstruct synthetic 3D fault surfaces with an equivalent roughness by means of 2D Fourier synthesis. Roughness of pre-existing joints is in a typical range for this kind of structure. Roughness of faults at small scale (1 m to 1 mm) shows a clear genetic relationship with the roughness of precursor joints, and some anisotropy in the self-affine Hurst exponent. Roughness of faults at scales larger than net slip (>1–10 m) is not anisotropic and less evolved than at smaller scales. These observations are consistent with an evolution of roughness, due to fault surface processes, that takes place only at scales smaller or comparable to the observed net slip. Differences in roughness evolution between shallow and deeper faults, the latter showing evidences of seismic activity, are interpreted as the result of different weakening versus induration processes, which also result in localization versus delocalization of deformation in the fault zone. From a methodological point of view, the technique used here is advantageous over direct measurements of exposed fault surfaces in that it preserves, in cross-section, all of the structures which contribute to fault roughness, and removes any subjectivity introduced by the need to distinguish roughness of original slip surfaces from roughness induced by secondary weathering processes. Moreover, offsets can be measured by means of suitable markers and fault rocks are preserved, hence their thickness, composition and structural features can be characterised, providing an integrated dataset which sheds new light on mechanisms of roughness evolution with slip and concomitant fault rock production.  相似文献   

Principal Slip Zones in Limestone: Microstructural Characterization and Implications for the Seismic Cycle (Tre Monti Fault, Central Apennines, Italy)     

Steven A. F. Smith  Andrea Billi  Giulio Di Toro  Richard Spiess 《Pure and Applied Geophysics》2011,168(12):2365-2393

Earthquakes in central Italy, and in other areas worldwide, often nucleate within and rupture through carbonates in the upper crust. During individual earthquake ruptures, most fault displacement is thought to be accommodated by thin principal slip zones. This study presents detailed microstructural observations of the slip zones of the seismically active Tre Monti normal fault zone. All of the slip zones cut limestone, and geological constraints indicate exhumation from <2?km depth, where ambient temperatures are ?100°C. Scanning electron microscope observations suggest that the slip zones are composed of 100% calcite. The slip zones of secondary faults in the damage zone contain protocataclastic and cataclastic fabrics that are cross-cut by systematic fracture networks and stylolite dissolution surfaces. The slip zone of the principal fault has much more microstructural complexity, and contains a 2?C10?mm thick ultracataclasite that lies immediately beneath the principal slip surface. The ultracataclasite itself is internally zoned; 200?C300???m-thick ultracataclastic sub-layers record extreme localization of slip. Syn-tectonic calcite vein networks spatially associated with the sub-layers suggest fluid involvement in faulting. The ultracataclastic sub-layers preserve compelling microstructural evidence of fluidization, and also contain peculiar rounded grains consisting of a central (often angular) clast wrapped by a laminated outer cortex of ultra-fine-grained calcite. These ??clast-cortex grains?? closely resemble those produced during layer fluidization in other settings, including the basal detachments of catastrophic landslides and saturated high-velocity friction experiments on clay-bearing gouges. An overprinting foliation is present in the slip zone of the principal fault, and electron backscatter diffraction analyses indicate the presence of a weak calcite crystallographic preferred orientation (CPO) in the fine-grained matrix. The calcite c-axes are systematically inclined in the direction of shear. We suggest that fluidization of ultracataclastic sub-layers and formation of clast-cortex grains within the principal slip zone occurred at high strain rates during propagation of seismic ruptures whereas development of an overprinting CPO occurred by intergranular pressure solution during post-seismic creep. Further work is required to document the range of microstructures in localized slip zones that cross-cut different lithologies, and to compare natural slip zone microstructures with those produced in controlled deformation experiments.  相似文献   

Fault architecture in the Main Ethiopian Rift and comparison with experimental models: Implications for rift evolution and Nubia–Somalia kinematics     

Andrea Agostini  Marco Bonini  Giacomo Corti  Federico Sani  Francesco Mazzarini 《Earth and Planetary Science Letters》2011,301(3-4):479-492

The Main Ethiopian Rift (MER) offers a complete record of the time–space evolution of a continental rift. We have characterized the brittle deformation in different rift sectors through the statistical analysis of a new database of faults obtained from the integration between satellite images and digital elevation models, and implemented with field controls. This analysis has been compared with the results of lithospheric-scale analogue models reproducing the kinematical conditions of orthogonal and oblique rifting. Integration of these approaches suggests substantial differences in fault architecture in the different rift sectors that in turn reflect an along-axis variation of the rift development and southward decrease in rift evolution. The northernmost MER sector is in a mature stage of incipient continental rupture, with deformation localised within the rift floor along discrete tectono-magmatic segments and almost inactive boundary faults. The central MER sector records a transitional stage in which migration of deformation from boundary faults to faults internal to the rift valley is in an incipient phase. The southernmost MER sector is instead in an early continental stage, with the largest part of deformation being accommodated by boundary faults and almost absent internal faults. The MER thus records along its axis the typical evolution of continental rifting, from fault-dominated rift morphology in the early stages of extension toward magma-dominated extension during break-up. The extrapolation of modelling results suggests that a variable rift obliquity contributes to the observed along-axis variations in rift architecture and evolutionary stage, being oblique rifting conditions controlling the MER evolution since its birth in the Late Miocene in relation to a constant post ca. 11 Ma ~ N100°E Nubia–Somalia motion.  相似文献   

Seismic interferometry experiment in a shallow cased borehole using a seismic vibrator source‡     

Flavio Poletto  Lorenzo Petronio  Biancamaria Farina  Andrea Schleifer 《Geophysical Prospecting》2011,59(3):464-476

We present the results of a seismic interferometry experiment in a shallow cased borehole. The experiment is an initial study for subsequent borehole seismic surveys in an instrumented well site, where we plan to test other surface/borehole seismic techniques. The purpose of this application is to improve the knowledge of the reflectivity sequence and to verify the potential of the seismic interferometry approach to retrieve high‐frequency signals in the single well geometry, overcoming the loss and attenuation effects introduced by the overburden. We used a walkaway vertical seismic profile (VSP) geometry with a seismic vibrator to generate polarized vertical and horizontal components along a surface seismic line and an array of 3C geophones cemented outside the casing. The recorded traces are processed to obtain virtual sources in the borehole and to simulate single‐well gathers with a variable source‐receiver offset in the vertical array. We compare the results obtained by processing the field data with synthetic signals calculated by numerical simulation and analyse the signal bandwidth and amplitude versus offset to evaluate near‐field effects in the virtual signals. The application provides direct and reflected signals with improved bandwidth after vibrator signal deconvolution. Clear reflections are detected in the virtual seismic sections in agreement with the geology and other surface and borehole seismic data recorded with conventional seismic exploration techniques.  相似文献