Exportación de solutos desde diferentes usos del suelo. Estudio experimental en el Pirineo Central Español

In the Aísa Valley Experimental Station nine different land-uses have been reproduced in closed plots, including cereal crop, meadows, fallow land, shifting agriculture, dense shrub cover and burnt shrub cover, among others. In this paper, solute concentration data from runoff yielded in each of the plots during two years (1996 and1997) are analysed. The results show the dramatic influence of human activites: The highest losses of nutrients are yielded by the fallow land, shifting agiculture and cerealplots. In contrast, dense shurb cover and meadows lose few nutrients, confirming the moderate outputs of both runoff and suspended sediment. Most of the exported dissolved solids are HCO; and Ca2+. Other nutrients are exported in very low quantities, in accordance with the poor nutrient content of the soil.En la Estación Experimental «Valle de Aísa" se han reproducido diferentes usos del suelo en parcelas cerradas, incluyendo cereales, prado, barbecho, agricultura cerealista itinerante, matorral denso y matorral quemado, entre otros. En este trabajo se analiza la concentración de solutos en la escorrentía procedente de cada una de las parcelas durante dos años (1996 y 1997). Los resultados muestran la gran influencia de las actividades humanas: las mayores pérdidas de nutrientes se producen en el barbecho, agricultura itinerante y cereal. Por el contrario, el matorral denso y el prado pierden pocos nutrientes, confirmando las moderadas exportaciones de agua y sedimentos en suspensión. La mayoría de los sólidos disueltos exportados son HCO; y Ca2+. Otros nutrientes salen en cantidades muy pequeñas, en relación con el pobre contenido en nutrientes del suelo

La necrópolis megalítica de los molares: estudio lítico preliminar de la industria tallada y pulimentada de Cañada Real y el Palomar. Análisis de caracterización de la materia prima, morfológico, técnico y tipométrico.

Presentamos aquí un análisis preliminar de la industria lítica tallada y pulimentada de los dólmenes de Cañada Real y El Palomar (Los Molares, Sevilla), como paso previo a la publicación conjunta de ambos monumentos funerarios que, pese a haber sido excavados en momentos distintos, pertenecieron a una necrópolis megalítica de la primera mitad del IV milenio a.n.e., junto con otros hoy desaparecidos, todos ellos de igual tipologí

Heating and cooling are fundamentally asymmetric and evolve along distinct pathways

According to conventional wisdom, a system placed in an environment with a different temperature tends to relax to the temperature of the latter, mediated by the flows of heat or matter that are set solely by the temperature difference. It is becoming clear, however, that thermal relaxation is much more intricate when temperature changes push the system far from thermodynamic equilibrium. Here, by using an optically trapped colloidal particle, we show that microscale systems under such conditions heat up faster than they cool down. We find that between any pair of temperatures, heating is not only faster than cooling but the respective processes, in fact, evolve along fundamentally distinct pathways, which we explain with a new theoretical framework that we call thermal kinematics. Our results change the view of thermalization at the microscale and will have a strong impact on energy-conversion applications and thermal management of microscopic devices, particularly in the operation of Brownian heat engines.Projects EQC2018-004693-P, PID2020-116567GB-C22, PID2021-128970OA-I00 and PID2021-127427NB-I00 funded by MCIN/AEI/10.13039/501100011033/ FEDER, UEFEDER/Junta de Andalucía-Consejería de Transformación Económica, Industria, Conocimiento y Universidades through projects P18-FR-3583 and A-FQM-644-UGR20Ministerio de Universidades (Spain) and Universidad de Granada under the FPU grant FPU21/02569Studienstiftung des Deutschen VolkesGerman Research Foundation through the Emmy Noether Program GO 2762/1-2Open access funding provided by Max Planck Society

Análisis de la fábrica magnética en modelos analógicos de arcillas

Este estudio presenta el análisis de la fábrica magnética en una serie de modelos analógicos realizados con arcillas rojas comerciales. A partir de la disgregación de la arcilla en agua y su posterior decantación conseguimos reproducir la adquisición de una fábrica magnética deposicional (geometría oblata del elipsoide magnético con el eje mínimo de susceptibilidad perpendicular al plano de depósito). En un modelo de deformación de desgarre (experimento de Riedel), la lineación magnética se dispone paralela a la dirección de estiramiento. En el modelo de acortamiento, la lineación magnética se orienta perpendicular a la dirección de acortamiento. Los resultados obtenidos ponen de manifiesto el gran potencial de la arcilla roja comercial para ser utilizada en este tipo de modelos analógicos, así como su capacidad de registrar una fábrica magnética coherente en cada caso. This study shows the magnetic fabric analysis applied to several analogue models developed with common commercial red clays. By dispersing the clays in water and after allowing their subsequent decantation, we were able to reproduce the acquisition of a depositional magnetic fabric (oblate geometry of the magnetic ellipsoid with the minimum susceptibility axis perpendicular to the deposit plane). In a strike-slip deformation model (Riedel experiment), magnetic lineation is parallel to the stretching direction. In the shortening model, magnetic lineation orients perpendicular to the shortening direction. The obtained results illustrate the great potential of these commercial red clays to be used in this type of analogue models, as well as their capacity to register a coherent magnetic fabric in each case

Corrosion Behavior of VM12-SHC Steel in Contact with Solar Salt and Ternary Molten Salt in Accelerated Fluid Conditions

Ternary low melting point mixtures with the addition of LiNO3 and Ca(NO3)2 have been presented as direct system candidates for CSP technologies due to having better physical and chemical properties than those of Solar Salt. In this study, thermal, physical and chemical properties are measured as is the corrosive behavior of stainless alloy VM12 (Cr 12%) when in contact with Solar Salt, 60% NaNO3-40% KNO3 (wt.%) and ternary 46% NaNO3-19% Ca(NO3)2-35% LiNO3 (wt.%). Gravimetric weight change measurements were performed on the test specimens, which were tested under accelerated fluid conditions (0.2 m s−1) at 500 °C for 2000 h. This research confirms the potential of this novel formulation as a thermal storage medium and validates the suitability of ferritic VM12-SHC stainless steel as a structural material for CSP technology with Solar Salt. Meanwhile, the results obtained by scanning electron microscopy and X-ray diffraction indicate a reduction in the protective character of the oxide layer formed on this alloy when the medium contains calcium and lithium components.Depto. de Ingeniería Química y de MaterialesFac. de Ciencias QuímicasTRUEMinisterio de Ciencia, Innovaciónpu

Análisis de la fábrica magnética en modelos analógicos de arcillas

Este estudio presenta el análisis de la fábrica magnética en una serie de modelos analógicos realizados con arcillas rojas comerciales. A partir de la disgregación de la arcilla en agua y su posterior decantación conseguimos reproducir la adquisición de una fábrica magnética deposicional (geometría oblata del elipsoide magnético con el eje mínimo de susceptibilidad perpendicular al plano de depósito). En un modelo de deformación de desgarre (experimento de Riedel), la lineación magnética se dispone paralela a la dirección de estiramiento. En el modelo de acortamiento, la lineación magnética se orienta perpendicular a la dirección de acortamiento. Los resultados obtenidos ponen de manifiesto el gran potencial de la arcilla roja comercial para ser utilizada en este tipo de modelos analógicos, así como su capacidad de registrar una fábrica magnética coherente en cada caso. This study shows the magnetic fabric analysis applied to several analogue models developed with common commercial red clays. By dispersing the clays in water and after allowing their subsequent decan-tation, we were able to reproduce the acquisition of a depositional magnetic fabric (oblate geometry of the magnetic ellipsoid with the minimum susceptibility axis perpendicular to the deposit plane). In a strike-slip deformation model (Riedel experiment), magnetic lineation is parallel to the stretching direction. In the shortening model, magnetic lineation orients perpendicular to the shortening direction. The obtained results illustrate the great potential of these commercial red clays to be used in this type of analogue models, as well as their capacity to register a coherent magnetic fabric in each case

La agricultura marginal como fuente de sedimentos en el Pirineo Central

[Resumen] La agricultura cerealista ha ocupado grandes extensiones en los valles pirenaicos, en exposiciones solanas por debajo de 1600 m de altitud. En este artículo se estudia el papel de la agricultura tradicional en la producción de sedimentos y la degradación del paisaje. Por medio de parcelas experimentales puede afirmarse que la agricultura itinerante y el barbecho han dado lugar a pérdidas de suelo muy elevadas y explican la pedregosidad superficial de mu.chas laderas. En el caso de la agricultura itinerante (articas), la quema de matorral y la incorporación de cenizas al suelo como fertilizante no contribuía a mejorar sustancialmente la calidad de los suelos.[Abstract] Cereal cropping has occupied large extent in the Pyrenean valleys, on sunny aspects under 1.600 m a.s.l. In this paper the role of traditional farming on sediment yield and landscape degradation is studied. By means of experimental plots the authors conclude than shifting agriculture an fallow land have caused great soil losses and explain the surface stoniness in many hillslopes. In the case of shifting agriculture, the burning of the shrub cover and the use of ashes as fertilizer did not contribute to improve the quality of soil

Tethyan versus Iberian extension during the Cretaceous period in the Eastern Iberian Peninsula: insights from magnetic fabrics

This work investigates how anisotropy of magnetic susceptibility (AMS) recorded the strain related to the Early Cretaceous extensional processes in synrift sediments of the Maestrat basin (eastern Spain). Forty-two sites, distributed throughout the Lower Cretaceous sequence with dominant gentle dips, were sampled. Minerals contributing to the AMS are mainly phyllosilicates. The parallelism between magnetic and sedimentary foliation seems to indicate that a primary (synsedimentary and early diagenetic) magnetic fabric was preserved at 84% of sites. Consequently, preferred orientations of magnetic lineations are interpreted to record the effect of extensional processes coeval with sedimentation and diagenesis during this period. At these 35 sites, two main magnetic lineation orientations are found, delimiting two large domains: a NE–SW orientation prevailing in the NW sector of the basin (parallel to the extension direction of the Iberian basin), and NW–SE to NNW–SSE orientations to the SE (parallel to the extension direction controlling the western Tethys margin). Directional variability demonstrates that the Maestrat basin is located at the boundary between two domains (Iberian and Tethyan) undergoing different plate-scale extensional processes. The subsequent Cenozoic tectonic inversion affected the synsedimentary magnetic fabrics at only a few sites at the borders of the basin, where compressive features are more developed

Multidisciplinary approach to constrain kinematics of fault zones at shallow depths: a case study from the Cameros–Demanda thrust (North Spain)

Determining transport direction in thrusts is one of the main issues to study deformation and to achieve reliable balanced cross-sections reconstruction of inverted basins and thrust systems. Anisotropy of Magnetic Susceptibility provides a tool to study deformation in fault rocks through the relationships between the magnetic susceptibility ellipsoid and deformational structures. The Cameros-Demanda Thrust (N Spain) shows a relatively simple history, with an average N-directed movement during the Cenozoic, and provides the possibility of determining the relationships between magnetic fabrics and transport directions in thrusts. The outcropping rocks are Mesozoic limestones in the hangingwall of the main thrust and Cenozoic conglomerates and Albian sandstones and coal in its footwall. Illite crystallinity and organic matter maturity indicate P-T conditions on the order of....The study of AMS in fault rocks (more than 400 samples distributed in 25 sites with fault gouge, breccia and microbreccia) in the Cameros thrust and its comparison with kinematic indicators (foliation, S/C structures and slickenside striations) indicates, in spite of the a priori simple relationships inferred from thrust geometry, a complex history of movements, changing from top-to-the-NW to top-to-the-NE along the history of Cenozoic thrusting. The transport direction is either oblique to the magnetic lineation and perpendicular to the strike of magnetic foliation, and can be checked with shear structures observed in thin sections and other kinematic indicators. The results obtained indicate that AMS can give clues about the transport direction in thrusts depending on the particular structures developed in each studied area