Dark Carbon Fixation in the Columbia River’s Estuarine Turbidity Maxima: Molecular Characterization of Red-Type cbbL Genes and Measurement of DIC Uptake Rates in Response to Added Electron Donors     

S. L. Bräuer  K. Kranzler  N. Goodson  D. Murphy  H. M. Simon  A. M. Baptista  B. M. Tebo 《Estuaries and Coasts》2013,36(5):1073-1083

Dark CO₂ fixation has been shown to rival the importance of oxygenic photosynthesis in the global carbon cycle, especially in stratified environments, such as salt wedge estuaries. We investigated this process in the Columbia River estuary using a variety of techniques including functional gene cloning of cbbL (the large subunit of form I RuBisCO), quantitative real-time PCR (qPCR) estimations of cbbL abundance, and analyses of stimulated ¹⁴C-bicarbonate assimilation. A diversity of red-type cbbL genes were retrieved from clone libraries, with 28 unique operational taxonomic units determined from 60 sequences. The majority of the sequences formed two clusters that were distinct from the major clusters typically found in soil environments, revealing the presence of a unique community of autotrophic or facultatively autotrophic/mixotrophic microorganisms in the Columbia River estuary. qPCR estimates indicated that roughly 0.03–0.15 % of the microbial population harbored the cbbL gene, with greater numbers of total bacteria and cbbL gene copies found in the estuarine turbidity maxima (ETM) compared to non-ETM events. In vitro incubations with radiolabeled bicarbonate indicated maximum stimulation by thiosulfate and also suggested that a diversity of other potential electron donors may stimulate CO₂ fixation, including nitrite, ammonium, and Mn(II). Taken together, these results highlight the diversity of the microbial metabolic strategies employed and emphasize the importance of dark CO₂ fixation in the dynamic waters of the Columbia River estuary despite the abundance of organic material.  相似文献   

A new Oligocene (MP 24) mammal fauna (Dürrenberg, Canton Jura, NW Switzerland) from the eastern slope of the “Rauracian depression”     

Daniel Kälin 《Swiss Journal of Geoscience》2013,106(2):207-218

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Fault zone signatures from ambient vibration measurements: a case study in the region of Visp (Valais, Switzerland)     

Cyrill Baumann  Jan Burjánek  Clotaire Michel  Donat Fäh  Luis A. Dalguer 《Swiss Journal of Geoscience》2013,106(3):529-541

Investigations of tectonic features, such as faults, are important challenges for geologists and engineers. Although direct investigational methods, such as boreholes and trenches, have the potential to provide accurate data, these direct methods are usually expensive and time consuming, and give only punctual insights into subsurface structures. Geophysical methods, for example electric surveys and ground penetrating radar, are less expensive and faster to implement. However, these geophysical methods may be difficult or sometimes even impossible to apply in regions with rough topography or regions which are highly urbanized. In this study, we propose an easy-to-use and affordable method to detect fault zones based on ambient vibration observations. We apply this method in the region between Visp and Unterstalden (canton Valais, Switzerland) on a small fault branch, which has no explicit surface expression, and which is linked to a major fault zone, the Simplon Fault Zone. The assumption is that the fault of interest is surrounded by damage zone consisting of fractured rock, and that this results in lateral changes of both seismic velocity and attenuation. The objective was, first, to identify such lateral changes in the observed seismic wave-field, and second, to map any anomalies and combine them with the available geological information. In this way, we were able to follow the fault trace even without a clear surface expression of the fault. Our observations showed the existence of a signature in the power spectra of the seismic noise that may correspond to a damage zone. Such signature is observed along the trace of the expected fault.  相似文献   

Dong W, Ren F, Huang J and Guo Y: The atlas of climate change: based on SEAP-CMIP5     

Stephanie Hänsel 《Environmental Earth Sciences》2013,69(8):2799-2800

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Evaluation of delta change and bias correction methods for future daily precipitation: intermodel cross-validation using ENSEMBLES simulations   总被引：1，自引：0，他引：1  

Olle Räty  Jouni Räisänen  Jussi S. Ylhäisi 《Climate Dynamics》2014,42(9-10):2287-2303

Due to inherent limitations in climate models, their output is biased in relation to observed climate and as such does not provide reliable climate projections. In this study, nine methods used to account for biases in daily precipitation are tested. First, cross-validation tests were made using a set of ENSEMBLES regional model simulations to gain insights in the potential performance of the methods in the future climate. The results show that quantile mapping type methods, being able to modify the shape of the precipitation distribution, often outperform other types of methods. Yet, as the performance depends on time of the year, location and part of the distribution considered, it is not possible to distinguish one universally best performing method. In addition, the improvement relative to the projections that would have been obtained assuming unchanged climate is relatively modest, particularly in the early twentyfirst century conditions. Further tests with different method combinations show that the projections could be potentially improved by using several well performing methods in parallel. In the second part of the study, contributions of method and model differences to the overall variation of precipitation projections are assessed. It is shown that although intermodel differences play an important role, uncertainties related to intermethod differences are substantial, particularly in the tails of the distribution. This suggests that method uncertainty should be taken into account when constructing daily precipitation projections, possibly by using several methods in parallel.  相似文献   

GOCE: precise orbit determination for the entire mission   总被引：4，自引：3，他引：1  

Heike Bock  Adrian Jäggi  Gerhard Beutler  Ulrich Meyer 《Journal of Geodesy》2014,88(11):1047-1060

The Gravity field and steady-state Ocean Circulation Explorer (GOCE) was the first Earth explorer core mission of the European Space Agency. It was launched on March 17, 2009 into a Sun-synchronous dusk-dawn orbit and re-entered into the Earth’s atmosphere on November 11, 2013. The satellite altitude was between 255 and 225 km for the measurement phases. The European GOCE Gravity consortium is responsible for the Level 1b to Level 2 data processing in the frame of the GOCE High-level processing facility (HPF). The Precise Science Orbit (PSO) is one Level 2 product, which was produced under the responsibility of the Astronomical Institute of the University of Bern within the HPF. This PSO product has been continuously delivered during the entire mission. Regular checks guaranteed a high consistency and quality of the orbits. A correlation between solar activity, GPS data availability and quality of the orbits was found. The accuracy of the kinematic orbit primarily suffers from this. Improvements in modeling the range corrections at the retro-reflector array for the SLR measurements were made and implemented in the independent SLR validation for the GOCE PSO products. The satellite laser ranging (SLR) validation finally states an orbit accuracy of 2.42 cm for the kinematic and 1.84 cm for the reduced-dynamic orbits over the entire mission. The common-mode accelerations from the GOCE gradiometer were not used for the official PSO product, but in addition to the operational HPF work a study was performed to investigate to which extent common-mode accelerations improve the reduced-dynamic orbit determination results. The accelerometer data may be used to derive realistic constraints for the empirical accelerations estimated for the reduced-dynamic orbit determination, which already improves the orbit quality. On top of that the accelerometer data may further improve the orbit quality if realistic constraints and state-of-the-art background models such as gravity field and ocean tide models are used for the reduced-dynamic orbit determination.  相似文献   

HydrIS: An open source GIS decision support system for groundwater management (Morocco)     

Hassane Jarar Oulidi  Ralf Löwner  Lahcen Benaabidate  Joachim Wächter 《地球空间信息科学学报》2013,16(3):212-216

A regional groundwater management system has been elaborated, integrating Relational Database Management System (RDBMS) and various web services. It consists of web geospatial application so-called HydrIS (Hydrogeological Information System) based on Open Source components and technologies, leading to a feasible and low-cost solution. Therefore, HydrIS permits delivery of data from a number of heterogeneous sources to standards supported by the Open Geospatial Consortium (OGC). The protocols used for exchanging data are also derived from OGC standards, i.e., WMS (Web Mapping Service), WFS (Web Feature Service), and WCS (Web Coverage Service). Finally, a geoportal was developed, which consists of client-applications that communicate with different Web Services (WMS, WCS, and WFS) through http-requests.  相似文献   

Converting to organic agriculture—Danish farmers' views and motivations     

Bärbel Tress 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(1):131-143

Expanded organic food production has been an issue of public debate in Denmark since its promotion by two government-sponsored plans. Yet the number of organic farms, constituting 5% of alt Danish farms, is still small. Farmers' attitudes and motivations around converting their farms to organic agriculture were surveyed in the counties of Ribe and Vestsj?lland in order to assess the feasibility of expansion. New organic farmers come either from the ranks of conventional farmers or from ‘beginners’ who initiate organic agriculture from the start. Only 7% of conventional farmers plan to convert their farms by the year 2003, but beginners will have increasing importance and augment the number. Farmers most frequently mentioned consideration for the environment as a reason for conversion. A considerable expansion of organic agriculture will be difficult, due to an insufficient number of farmers interested in organic agriculture. A high number of less productive hobby or spare-time farmers among new organic farmers also hinders expanded organic food production. Organic agriculture shows parallels to conventional agriculture, with a surplus of very small and very large farms, regional specialisation, and oil-farm specialisation.  相似文献   

A numerical study of the string function using a primitive equation ocean model     

R. H. Tyler  R. Käse 《地球物理与天体物理流体动力学》2013,107(1-2):65-83

Abstract

We use results from a primitive-equation ocean numerical model (SCRUM) to test a theoretical 'string function' formulation put forward by Tyler and Käse in another article in this issue. The string function acts as a stream function for the large-scale potential energy flow under the combined beta and topographic effects. The model results verify that large-scale anomalies propagate along the string function contours with a speed correctly given by the cross-string gradient. For anomalies having a scale similar to the Rossby radius, material rates of change in the layer mass following the string velocity are balanced by material rates of change in relative vorticity following the flow velocity. It is shown that large-amplitude anomalies can be generated when wind stress is resonant with the string function configuration.  相似文献   

Mean-field concept and direct numerical simulations of rotating magnetoconvection and the geodynamo     

Martin Schrinner  Karl-Heinz Rädler  Matthias Rheinhardt  Ulrich R. Christensen 《地球物理与天体物理流体动力学》2013,107(2):81-116

Mean-field theory describes magnetohydrodynamic processes leading to large-scale magnetic fields in various cosmic objects. In this study magnetoconvection and dynamo processes in a rotating spherical shell are considered. Mean fields are defined by azimuthal averaging. In the framework of mean-field theory, the coefficients which determine the traditional representation of the mean electromotive force, including derivatives of the mean magnetic field up to the first order, are crucial for analyzing and simulating dynamo action. Two methods are developed to extract mean-field coefficients from direct numerical simulations of the mentioned processes. While the first method does not use intrinsic approximations, the second one is based on the second-order correlation approximation. There is satisfying agreement of the results of both methods for sufficiently slow fluid motions. Both methods are applied to simulations of rotating magnetoconvection and a quasi-stationary geodynamo. The mean-field induction effects described by these coefficients, e.g., the α-effect, are highly anisotropic in both examples. An α²-mechanism is suggested along with a strong γ-effect operating outside the inner core tangent cylinder. The turbulent diffusivity exceeds the molecular one by at least one order of magnitude in the geodynamo example. With the aim to compare mean-field simulations with corresponding direct numerical simulations, a two-dimensional mean-field model involving all previously determined mean-field coefficients was constructed. Various tests with different sets of mean-field coefficients reveal their action and significance. In the magnetoconvection and geodynamo examples considered here, the match between direct numerical simulations and mean-field simulations is only satisfying if a large number of mean-field coefficients are involved. In the magnetoconvection example, the azimuthally averaged magnetic field resulting from the numerical simulation is in good agreement with its counterpart in the mean-field model. However, this match is not completely satisfactory in the geodynamo case anymore. Here the traditional representation of the mean electromotive force ignoring higher than first-order spatial derivatives of the mean magnetic field is no longer a good approximation.  相似文献