Tracer test modeling for characterizing heterogeneity and local-scale residence time distribution in an artificial recharge site

Artificial recharge of aquifers is a technique for improving water quality and increasing groundwater resources. Understanding the fate of a potential contaminant requires knowledge of the residence time distribution (RTD) of the recharged water in the aquifer beneath. A simple way to obtain the RTDs is to perform a tracer test. We performed a pulse injection tracer test in an artificial recharge system through an infiltration basin to obtain the breakthrough curves, which directly yield the RTDs. The RTDs turned out to be very broad and we used a numerical model to interpret them, to characterize heterogeneity, and to extend the model to other flow conditions. The model comprised nine layers at the site scaled to emulate the layering of aquifer deposits. Two types of hypotheses were considered: homogeneous (all flow and transport parameters identical for every layer) and heterogeneous (diverse parameters for each layer). The parameters were calibrated against the head and concentration data in both model types, which were validated quite satisfactorily against 1,1,2-Trichloroethane and electrical conductivity data collected over a long period of time with highly varying flow conditions. We found that the broad RTDs can be attributed to the complex flow structure generated under the basin due to three-dimensionality and time fluctuations (the homogeneous model produced broad RTDs) and the heterogeneity of the media (the heterogeneous model yielded much better fits). We conclude that heterogeneity must be acknowledged to properly assess mixing and broad RTDs, which are required to explain the water quality improvement of artificial recharge basins.Peer ReviewedPostprint (published version

Six artificial recharge pilot replicates to gain insight into water quality enhancement processes

The processes that control water quality improvement during artificial recharge (filtering, degradation, and adsorption) can be enhanced by adding a reactive barrier containing different types of sorption sites and promoting diverse redox states along the flow path, which increases the range of pollutants degraded. While this option looks attractive for renaturazing reclaimed water, three issues have to be analyzed prior to broad scale application: (1) a fair comparison between the system with and without reactive barrier; (2) the role of plants in prevention of clogging and addition of organic carbon; and (3) the removal of pathogens. Here, we describe a pilot installation built to address these issues within a waste water treatment plant that feeds on water reclaimed from the secondary outflow. The installation consists of six systems of recharge basin and aquifer with some variations in the design of the reactive barrier and the heterogeneity of the aquifer. We report preliminary results after one year of operation. We find that (1) the systems are efficient in obtaining a broad range of redox conditions (at least iron and manganese reducing), (2) contaminants of emerging concern are significantly removed (around 80% removal, but very sensitive to the compound), (3) pathogen indicators (E. coli and Enterococci) drop by some 3–5 log units, and (4) the recharge systems maintained infiltration capacity after one year of operation (only the system without plants and the one without reactive barrier displayed some clogging). Overall, the reactive barrier enhances somewhat the performance of the system, but the gain is not dramatic, which suggests that barrier composition needs to be improved.This study was supported by the Water Joint Programming Initiative (JPI)Water Challenges for a ChangingWorld 2014 through the project ACWAPUR (ACcelerated Water PURification during artificial recharge of aquifers: A tool to restore drinking water sources) and partially funded by the Spanish Ministry of Science, Innovation and Universities through PCIN-2015-245. We are very grateful to the staff of ‘Aguas de la Costa Brava' for their assistance, and to Ma Pau Serra-Roig and Ana Julia Acunha for their contribution to the chemical analysis and to Juli_a Garcia for his effort with the field site work.Peer ReviewedPostprint (published version

Reactive barriers for renaturalization of reclaimed water during soil aquifer treatment

Managed aquifer recharge (MAR) is known to increase available water quantity and to improve water quality. However, its implementation is hindered by the concern of polluting aquifers, which might lead to onerous treatment and regulatory requirements for the source water. These requirements might make MAR unsustainable both economically and energetically. To address these concerns, we tested reactive barriers laid at the bottom of infiltration basins to enhance water quality improvement during soil passage. The goal of the barriers was to (1) provide a range of sorption sites to favor the retention of chemical contaminants and pathogens; (2) favor the development of a sequence of redox states to promote the degradation of the most recalcitrant chemical contaminants; and (3) promote the growth of plants both to reduce clogging, and to supply organic carbon and sorption sites. We summarized our experience to show that the barriers did enhance the removal of organic pollutants of concern (e.g., pharmaceuticals and personal care products). However, the barriers did not increase the removal of pathogens beyond traditional MAR systems. We reviewed the literature to suggest improvements on the design of the system to improve pathogen attenuation and to address antibiotic resistance gene transfer.This research was funded by the Spanish Ministry of Science and Innovation CEX2018-000794-S), Water JPI (MARadentro-PCI2019-103603) and Catalan Water Agency (RESTORA-CA210/18/00040).Peer ReviewedPostprint (published version

I.amAble: la ciencia (química) al alcance de toda la sociedad

En este proyecto de innovación, que nace con vocación de continuar en años sucesivos, se persigue mejorar la calidad de la formación de los estudiantes de la Facultad de Ciencias Químicas (F. CC.QQ.) en el ámbito de la docencia teórico-práctica y de la divulgación científica. El trabajo ha consistido en la preparación de unos experimentos prácticos para llevarlos a cabo en centros educativos no universitarios en los que se ha tenido en cuenta la participación conjunta de personas con y sin diversidad funcional, desde una perspectiva inclusiva colaborativa. Estas actividades las han realizado los estudiantes bajo la supervisión de profesores (PDI) y personal de administración y servicios (PAS). Los experimentos se han recogido en fichas didácticas para facilitar su desarrollo y aplicación por parte de otros usuarios. En estas fichas se explica detalladamente cómo realizar las experiencias en formato de taller. Las fichas de los talleres realizados están disponibles en una página web vinculada a la Universidad Complutense bajo el título I.amAble (iamable.ucm.es). Está página ha sido construida por un estudiante de la Facultad de Informática , bajo la supervisión de profesionales, tanto de esa facultad como del Instituto de Tecnología del Conocimiento, y está abierta a contribuciones similares de otras facultades y otras instituciones. La página web está diseñada de manera que resulte lo más intuitiva y accesible posible para todo tipo de público. Entre todos los experimentos se han elegido cuatro para llevarlos a la práctica en centros educativos como actividades inclusivas en las que han participado conjuntamente personas con y sin discapacidad. Con este proyecto se pretende mejorar la calidad docente al ofrecer a los estudiantes la posibilidad de aprender enseñando mediante una actividad semipresencial. El desarrollo por parte de los estudiantes de competencias transversales en educación y en divulgación de la ciencia facilitarán algunas salidas profesionales en el ámbito educativo formal (centros de enseñanza) o informal (museos, animación sociocultural). Otro aspecto importante a resaltar es la potenciación de la colaboración entre todos los miembros de la institución universitaria. Este proyecto pretende contribuir a la mejora de la cultura científica, así como al establecimiento de puentes entre la UCM y la sociedad a la que debe servir. Finalmente, es importante subrayar que incidirá en la inclusión de las personas con discapacidad como parte de la sociedad, a través del acercamiento compartido a la ciencia (Dimensiones de inclusión social y derechos de Schalock; NAVAS MACHO, P. y otros, 2012. Derechos de las personas con discapacidad intelectual: implicaciones de la Convención de Naciones Unidas. Siglo Cero. 43 (243): 7-28.)

The development of a colour liquid crystal display spatial light modulator and applications in polychromatic optical data processing

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN039137 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Funcionamiento hidrogeológico de un acuífero termal (La Garriga-Samalús)

Peer Reviewe

EVALUACIÓN DE UNA EXPERIENCIA DE APRENDIZAJE BASADO EN PROBLEMAS (ABP) EN ESTUDIANTES UNIVERSITARIOS

L’Apernentatge Basat en Problemes (ABP) implica posar l’èmfasi en l’alumnat com a responsable del seu aprenentatge. Existeixen moltes experències en ABP en diferents titulacions. Malgrat tot, són molt poques les que presenten una anàlisi sobre els resultats i les implicacions en l’avaluació que es realitza en el professorat i el compromís amb l’assignatura. En aquest article es presenten dos estudis en els quals s’avalua una experiència d’ABP. En el primer, 190 estudiants de Psicologia Social en dues titulacions diferents completen un qüestionari en el qual s’avalua l’experiència de l’ABP al professorat i el compromís amb l’assignatura, comparada amb una experiència d’aprenentatge tradicional. En el segon, un grup de 91 alumnes realitzen una avaluació comparada d’una experiència d’aprenentatge amb metodologia tradicional i amb ABP en dos temps. Els resultats mostren que els estudiants avaluen millor tant al professorat com a l’experiència d’aprenentage quan s’utilitza ABP, però no es produeix una millora pel que fa al compromís amb l’assignatura. A més a més, es produeixen diferències entre grups en quant a l’avaluació de l’ABP, però no sobre els resultats o el professorat. Quan l’experiència de l’ABP es repeteix es produeix una millora dels resultats en totes les dimensions, avaluació de l’ABP, del professorat i del compromís amb l’assignatura. Per tant, l’aprenentage amb aquesta experiència produeix millors resultats si té continuïtat.The Problem Based Learning (PBL) involves emphasizing the students’ responsibility for their own learning. There are many experiences in PBL in different degrees. However, very few presenting an evaluation of the results and the implications it has in the evaluation on the teacher and their commitment to the subject. In this paper, we present two studies that evaluated a PBL experience. In Study 1, 190 students of Social Psychology on two different degrees, completed a questionnaire that assesses the experience of PBL, the teacher and their commitment to the subject, compared to a traditional learning experience. In Study 2, a group of 91 students performed a comparative evaluation of a learning experience with traditional and PBL methodology rebound. The results show that students evaluate better both the teacher and the learning experience when using ABP, however, there is not an improvement of their commitment with the subject. In addition, there are differences between groups in terms of their assessment of PBL, but not in the outcomes or teacher evaluation. When the PBL experience is repeated, there is an improvement of the results in all dimensions, evaluation of PBL, the teacher and the commitment to the subject. Therefore, learning using this experience produces enhancements that increase if the experience is continued.El Aprendizaje Basado en Problemas (ABP)implica poner el énfasis en el alumnado como responsable de su propio aprendizaje. Existen múltiples experiencias en ABP en diferentes titulaciones. Sin embargo, son muy pocas las que presentan una evaluación sobre los resultados y sus implicaciones en la evaluación que se realiza sobre el profesor y el compromiso con la asignatura. En este artículo, se presentan dos estudios en los que se evalúa una experiencia de ABP. En el primero, 190 estudiantes de Psicología Social en dos titulaciones diferentes completan un cuestionario en el que se evalúa la experiencia del ABP, al profesor y el compromiso con la asignatura, comparada con una experiencia de aprendizaje tradicional. En el estudio 2 un grupo de 91 alumnos realizan una evaluación comparada de una experiencia de aprendizaje con metodología tradicional y con ABP en dos tiempos. Los resultados muestran que los estudiantes evalúan mejor tanto al profesor como a la experiencia de aprendizaje cuando se utiliza ABP, sin embargo, no se produce una mejora del compromiso con la asignatura. Además, se producen diferencias entre grupos en cuanto a su evaluación del ABP pero no de los resultados o del profesor. Cuando la experiencia de ABP se repite se produce una mejora de los resultados en todas las dimensiones, evaluación del ABP, del profesor y del compromiso con la asignatura. Por tanto, el aprendizaje mediante el uso de esta experiencia produce mejoras que aumentan si la experiencia es continuad

Structural geology and geophysics as a support to build a hydrogeologic model of granite rock

A method developed for low-permeability fractured media was applied to understand the hydrogeology of a mine excavated in a granitic pluton. This method includes (1) identifying the main groundwater-conducting features of the medium, such as the mine, dykes, and large fractures, (2) implementing this factors as discrete elements into a three-dimensional numerical model, and (3) calibrating these factors against hydraulic data (Martinez-Landa and Carrera 2006). A key question is how to identify preferential flow paths in the first step. Here, we propose a combination of several techniques. Structural geology, together with borehole sampling, geophysics, hydrogeochemistry, and local hydraulic tests aided in locating all structures. Integration of these data yielded a conceptual model of the site. A preliminary calibration of the model was performed against short-term (< 1 day) pumping tests, which facilitated the characterization of some of the fractures. The hydraulic properties were then used for other fractures that, according to geophysics and structural geology, belonged to the same families. Model validity was tested by blind prediction of a long-term (4 months) large-scale (1 km) pumping test from the mine, which yielded excellent agreement with the observations. Model results confirmed the sparsely fractured nature of the pluton, which has not been subjected to glacial loading-unloading cycles and whose waters are of Na-HCO3 type.Peer Reviewe

Use of hydraulic tests to identify the residual CO2 saturation at a geological storage site

Estimating long term capillary trapping of CO2 in aquifers remains a key challenge for CO2 storage. Zhang etal, (2011) proposed a combination of thermal, tracer, and hydraulic experiments to estimate the amount of CO2 trapped in the formation after a CO2 push and pull test. Of these three types of experiments, hydraulic tests are the simplest to perform and possibly the most informative. However, their potential has not yet been fully exploited. Here, we present a methodology to interpret these tests and analyze which parameters can be estimated. We use numerical and analytical solutions to a continuous injection in a medium where residual CO2 has caused a reduction in hydraulic conductivity and an increase in storage coefficient over a finite thickness (a few meters) skin around the injection well. We interpret the model results using conventional pressure buildup and diagnostic plots as well as the Agatwal (1980) recovery plots. We find that both skin hydraulic conductivity and storage coefficient (and thus residual CO2 saturation) can be obtained from the water injection test provided that water flow rate is carefully controlled and head buildup is measured with high frequency at the beginning of the test. (C) 2013 Elsevier Ltd. All rights reserved.Peer Reviewe