Bioenergy in energy transformation and climate management     

Steven K. Rose  Elmar Kriegler  Ruben Bibas  Katherine Calvin  Alexander Popp  Detlef P. van Vuuren  John Weyant 《Climatic change》2014,123(3-4):477-493

This study explores the importance of bioenergy to potential future energy transformation and climate change management. Using a large inter-model comparison of 15 models, we comprehensively characterize and analyze future dependence on, and the value of, bioenergy in achieving potential long-run climate objectives. Model scenarios project, by 2050, bioenergy growth of 1 to 10 % per annum reaching 1 to 35 % of global primary energy, and by 2100, bioenergy becoming 10 to 50 % of global primary energy. Non-OECD regions are projected to be the dominant suppliers of biomass, as well as consumers, with up to 35 % of regional electricity from biopower by 2050, and up to 70 % of regional liquid fuels from biofuels by 2050. Bioenergy is found to be valuable to many models with significant implications for mitigation and macroeconomic costs of climate policies. The availability of bioenergy, in particular biomass with carbon dioxide capture and storage (BECCS), notably affects the cost-effective global emissions trajectory for climate management by accommodating prolonged near-term use of fossil fuels, but with potential implications for climate outcomes. Finally, we find that models cost-effectively trade-off land carbon and nitrous oxide emissions for the long-run climate change management benefits of bioenergy. The results suggest opportunities, but also imply challenges. Overall, further evaluation of the viability of large-scale global bioenergy is merited.  相似文献   

Metal concentration and structural changes in Corallina elongata (Corallinales, Rhodophyta) from hydrothermal vents     

Ruben P. Couto  Ana I. Neto  Armindo S. Rodrigues 《Marine pollution bulletin》2010,60(4):509-287

Shallow-water hydrothermal activity is widely present at Azores archipelago. Organisms in such environments present great potential as sentinels of the effects derived from chronically exposure to increased temperature, metal concentrations and reduced pH. This study aimed to evaluate metal concentration in Corallina elongata collected at locations exposed and not exposed to shallow-water hydrothermal activity and evaluate changes in its calcareous structure. Elemental concentration was determined and morphometric analysis was performed by scanning electron microscopy. Thicker cell walls and a bleached appearance were observed on C. elongata specimens from the hydrothermally active location, as well as increased concentrations of elements associated to volcanic activity.This study reports on metal accumulation and morphometric changes in the calcareous structure of C. elongata from a hydrothermally active location, adding new data for further research on such habitats and communities, providing an insight on how coralline algae might be affected by ocean acidification.  相似文献   

Adsorption of hydroxamate siderophores and EDTA on goethite in the presence of the surfactant sodium dodecyl sulfate     

Naraya Carrasco  Ruben Kretzschmar  Jide Xu  Stephan M Kraemer 《Geochemical transactions》2009,10(1):5-9

Siderophore-promoted iron acquisition by microorganisms usually occurs in the presence of other organic molecules, including biosurfactants. We have investigated the influence of the anionic surfactant sodium dodecyl sulfate (SDS) on the adsorption of the siderophores DFOB (cationic) and DFOD (neutral) and the ligand EDTA (anionic) onto goethite (α-FeOOH) at pH 6. We also studied the adsorption of the corresponding 1:1 Fe(III)-ligand complexes, which are products of the dissolution process. Adsorption of the two free siderophores increased in a similar fashion with increasing SDS concentration, despite their difference in molecule charge. In contrast, SDS had little effect on the adsorption of EDTA. Adsorption of the Fe-DFOB and Fe-DFOD complexes also increased with increasing SDS concentrations, while adsorption of Fe-EDTA decreased. Our results suggest that hydrophobic interactions between adsorbed surfactants and siderophores are more important than electrostatic interactions. However, for strongly hydrophilic molecules, such as EDTA and its iron complex, the influence of SDS on their adsorption seems to depend on their tendency to form inner-sphere or outer-sphere surface complexes. Our results demonstrate that surfactants have a strong influence on the adsorption of siderophores to Fe oxides, which has important implications for siderophore-promoted dissolution of iron oxides and biological iron acquisition.  相似文献   

Iron isotope fractionation in oxic soils by mineral weathering and podzolization     

Jan G. Wiederhold  Nadya Teutsch  Stephan M. Kraemer  Alex N. Halliday  Ruben Kretzschmar 《Geochimica et cosmochimica acta》2007,71(23):5821-5833

Stable iron isotope ratios in three soils (two Podzols and one Cambisol) were measured by MC-ICPMS to investigate iron isotope fractionation during pedogenic iron transformation and translocation processes under oxic conditions. Podzolization is a soil forming process in which iron oxides are dissolved and iron is translocated and enriched in the subsoil under the influence of organic ligands. The Cambisol was studied for comparison, representing a soil formed by chemical weathering without significant translocation of iron. A three-step sequential extraction procedure was used to separate operationally-defined iron mineral pools (i.e., poorly-crystalline iron oxides, crystalline iron oxides, silicate-bound iron) from the soil samples. Iron isotope ratios of total soil digests were compared with those of the separated iron mineral pools. Mass balance calculations demonstrated excellent agreement between results of sequential extractions and total soil digestions. Systematic variations in the iron isotope signature were found in the Podzol profiles. An enrichment of light iron isotopes of about 0.6‰ in δ⁵⁷Fe was found in total soil digests of the illuvial Bh horizons which can be explained by preferential translocation of light iron isotopes. The separated iron mineral pools revealed a wide range of δ⁵⁷Fe values spanning more than 3‰ in the Podzol profiles. Strong enrichments of heavy iron isotopes in silicate-bound iron constituting the residue of weathering processes, indicated the preferential transformation of light iron isotopes during weathering. Iron isotope fractionation during podzolization is probably linked to the ligand-controlled iron translocation processes. Comparison of iron isotope data from eluvial and illuvial horizons of the Podzol profiles revealed that some iron must have been leached out of the profile. However, uncertainties in the initial iron content and iron isotopic composition of the parent materials prevented thorough mass balance calculations of iron fluxes within the profiles. In contrast to the Podzol profiles, the Cambisol profile displayed uniform δ⁵⁷Fe values across soil depth and showed only a small enrichment of light iron isotopes of about 0.4‰ in the poorly-crystalline iron oxide pool extracted by 0.5 M HCl. This work demonstrates that significant iron isotope fractionations can occur during pedogenesis in oxic environments under the influence of organic ligands. Our findings provide new insights into fractionation mechanisms of iron isotopes and will help in the development of stable iron isotopes as tracers for biogeochemical iron cycling in nature.  相似文献   

Most similar neighbor imputation of forest attributes using metrics derived from combined airborne LIDAR and multispectral sensors     

Ruben Valbuena  Ana Hernando  Jose Antonio Manzanera  Eugenio Martínez-Falero  Antonio García-Abril  Blas Mola-Yudego 《International Journal of Digital Earth》2018,11(12):1205-1218

In the context of predicting forest attributes using a combination of airborne LIDAR and multispectral (MS) sensors, we suggest the inclusion of normalized difference vegetation index (NDVI) metrics along with the more traditional LIDAR height metrics. Here the data fusion method consists of back-projecting LIDAR returns onto original MS images, avoiding co-registration errors. The prediction method is based on non-parametric imputation (the most similar neighbor). Predictor selection and accuracy assessment include hypothesis tests and over-fitting prevention methods. Results show improvements when using combinations of LIDAR and MS compared to using either of them alone. The MS sensor has little explanatory capacity for forest variables dependent on tree height, already well determined from LIDAR alone. However, there is potential for variables dependent on tree diameters and their density. The combination of LIDAR and MS sensors can be very beneficial for predicting variables describing forests structural heterogeneity, which are best described from synergies between LIDAR heights and NDVI dispersion. Results demonstrate the potential of NDVI metrics to increase prediction accuracy of forest attributes. Their inclusion in the predictor dataset may, however, in a few cases be detrimental to accuracy, and therefore we recommend to carefully assess the possible advantages of data fusion on a case-by-case basis.  相似文献   

Bay breeze influence on surface ozone at Edgewood,MD during July 2011     

Ryan M. Stauffer  Anne M. Thompson  Douglas K. Martins  Richard D. Clark  Daniel L. Goldberg  Christopher P. Loughner  Ruben Delgado  Russell R. Dickerson  Jeffrey W. Stehr  Maria A. Tzortziou 《Journal of Atmospheric Chemistry》2015,72(3-4):335-353

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A paleointensity study of Cretaceous volcanic rocks from the Western Cordillera,Colombia     

Lisa Kapper  Juan Morales  Manuel Calvo-Rathert  Avto Goguitchaichvili  Victoria Mejia  Ana Caccavari  Alvaro Nivia Guevara  Ruben Cejudo Ruiz 《Studia Geophysica et Geodaetica》2017,61(2):264-289

The Cretaceous Normal Superchron is a period of great interest to investigate global scale variations of the geomagnetic field. Long periods of single polarity are still a matter of debate: up to now there are two contradicting theories, which try to relate geomagnetic field intensity and reversal rate. We aim to shed light on the geomagnetic field strength during the Cretaceous Normal Superchron because data are still scarce and of dissimilar quality. To obtain reliable, absolute paleointensity determinations we investigate volcanic rocks from the Western Cordillera of Colombia. Several age determinations allow relating the samples to an age of about 92.5 Ma. To characterize the samples, we investigate rock magnetic properties and determine the characteristic remanent magnetization behavior. To determine paleointensities, we use a multimethod approach: first, we apply the classic Thellier-Coe protocol, and then, the relatively new multispecimen method. Rock magnetic measurements indicate magnetite as the main ferrimagnetic mineral, a stable magnetization revealed by reversible and nearly reversible thermomagnetic curves, and grain sizes that are either in the pseudosingle domain range or a mixture of single and multidomain grains. Alternating field and thermal demagnetization are rather complex, although we observe a few vector diagrams with a single, essentially uni-vectorial component with a small viscous overprint. Paleointensity determination with the Thellier-Coe protocol was unsuccessful, while with the multispecimen protocol we obtained four successful determinations out of 20. The failure of the Thellier-Coe protocol can be attributed to multidomain grains, which were observed during demagnetization and in rock magnetic experiments, and to the inhomogeneity of the volcanic rocks. Our multispecimen paleointensity determinations support low field strength at around 90 Ma during the Cretaceous Normal Superchron.  相似文献   

The definition of the parsec     

G. Ruben  H.-J. Treder 《Astronomische Nachrichten》1989,310(6):443-444

A new definition is proposed for the parsec, because the distance definition of the IAU is not physically consistent.  相似文献   

A Programme to derive from terrestrial observations the rotation of the HIPPARCOS system with reference to the inertial system     

W. R. Dick  G. Ruben  E. Schilbach  R.-D. Scholz 《Astronomische Nachrichten》1987,308(3):211-216

The connection of the HIPPARCOS system with a quasi-inertial system can be reached by transforming the HIPPARCOS proper motions to absolute proper motions. The Tautenburg Schmidt telescope provides such proper motions with respect to extragalactic objects with an accuracy of 0″.6/100a. The telescope as well as the measuring and reduction technique are described. The accuracy of the link of the HIPPARCOS system to extragalactic objects depends on the accuracy of the transformation matrix which represents the time-depending part of the rotation matrix to be applied to the whole HIPPARCOS catalogue. To obtain a reliable estimate for the error of transformation we used the error propagation law. An accuracy of 0″.12/100a for the transformation can be achieved with six Tautenburg fields.  相似文献   

A combined assessment of beach occupancy and public perceptions of beach quality: A case study in the Costa Brava, Spain   总被引：1，自引：0，他引：1  

Elisabet Roca  Claudia Riera  Míriam Villares  Rosa Fragell  Rosa Junyent   《Ocean & Coastal Management》2008,51(12):839-846

The main objective of this paper is to present an approach that contributes to evaluate beach quality based on a combined analysis of beach occupancy and the perception of beach users. The study area is a major Mediterranean tourist destination in NE Spain. Six beaches that fulfilled different environmental and social criteria were assessed. Sampling took place during 2004 and 2005. An analysis of beach occupancy showed that highly accessible urban beaches suffer the most from overcrowding. A comparison of the two approaches (occupancy and perception) indicates that a higher sand availability increased user satisfaction, although not as much as might have been expected because other parameters are also highly relevant in evaluating beach quality from the perspective of beach user such as physical characteristics, landscape and facilities.  相似文献