Hydrogeology of salt flats : the Salar de Atacama example

Aplicat embargament des de la data de defensa fins al 31 de desembre de 2021Premi extraordinari doctorat UPC curs 2019-2020, àmbit d’Enginyeria Civil i AmbientalThis thesis aims to advance the knowledge of the hydrogeological functioning of salt flats in order to achieve a sustainable management of their mineral resources and ecosystems. Salt flats are a major source of Li, B, I, K, Mg and NaCl, and they host some of the most outstanding ecosystems on earth. Around 25 % of Li world reserves are located in the Salar de Atacama (NE of Chile). The exploitation of this raw material, highly valued in the technological and pharmaceutical industries, is carried out by brine pumping. Brine pumping can affect the natural hydrogeological regime of salt flats and, in many cases, the possible impact on their ecosystems is unknown. This thesis contributes to (1) explain the geometry and groundwater flow of the mixing zone (saline interface) located around salt flats, (2) define the water balance and hydrodynamics of the Salar de Atacama under the natural regime, (3) analyse and quantify the impacts caused by brine pumping, (4) improve the design of the brine exploitations in salt flats and (5) question the traditional ideas on the origin of the Li-enrichment in the Salar de Atacama. The groundwater recharged in the mountains is forced to flow upward when it reaches the mixing zone around the salt flat due to its lower density, feeding the lake and wetland ecosystems. The first 3D mapping of a salt flat mixing zone has been carried out in the Salar de Atacama and it has shown a slope of the mixing zone much lower than previous assumptions. The 2D modelling of the mixing zone demonstrated as the permeability of the upper aquifer increases, the slope of the mixing zone decreases, resulting in a shallower mixing zone. Thus, the permeability of the upper aquifer, mostly constituted of very permeable karstified evaporites and alluvial deposits, is critical to the geometry of the mixing zone. The hydrogeological conceptual model of the Salar de Atacama, prior to brine pumping (natural regime), has been defined and validated using a 3D steady-state groundwater flow model. The asymmetric distribution of the recharge by infiltration of rainwater and, above all, the evaporation discharge results in a water table whose minimum hydraulic head is located in the easternmost nucleus, close to the eastern mixing zone. The 3D transient-state modelling of the Salar de Atacama basin from 1986 to 2018 has allowed to explain the hydrodynamics and water balance impacts caused by brine exploitation. From 1994 to 2015, under the mining regime, the brine pumping caused an additional drawdown of the water table that triggered a decrease of the phreatic evaporation. This effect has been defined as "damping capacity" and it allows to counteract the disturbances occasioned by natural or anthropogenic events on the water table and balance of salt flat basins. The damping capacity compensated, at least in part, the decrease of the evaporation discharge, but nowadays it is already amortized in the nucleus and the mixing zone begins to be impacted. The 3D modelling of a hypothetical salt flat under brine exploitation has contributed to optimize the spatial distribution of the pumping wells in terms of impact on the water balance. Brine exploitations should consider to distribute the pumping outflow in the greatest extent possible to take full advantage of the damping capacity. The results of the hydro-thermo-haline modelling of the Salar de Atacama basin has suggested the Salar Fault System as the main contributor for the extreme Li-enrichment, either through the rise of Li-rich brines from a deep hydrothermal reservoir or remobilization of ancient layers of Li-enriched salts and/or clays by non-evaporated recharge waters coming from the W. The persistence of the mixing zones in depth also dismissed previous ideas of (1) leaking of brines from the present salt flats or (2) leaching of hypothetical salt flats buried by volcanic eruptions in the Altiplano-Puna as sources for the extreme Li-enrichment of the Salar de Atacama brines.Esta tesis contribuye a avanzar en el conocimiento del funcionamiento hidrogeológico de los salares con el fin de mejorar la gestión de sus recursos minerales y ecosistemas. Los salares son una fuente principal de Li, B, I, K, Mg y NaCl, y albergan algunos de los ecosistemas más excepcionales de la tierra. Alrededor del 25 % de las reservas mundiales de Li se localizan en el Salar de Atacama (NE de Chile). La explotación de esta materia prima, altamente valorada en las industrias tecnológica y farmacéutica, se realiza mediante bombeo de salmuera. El bombeo de salmuera puede afectar al régimen hídrico natural de los salares y, en muchos casos, se desconoce el posible impacto sobre sus ecosistemas. Esta tesis ayuda a (1) explicar la geometría y el flujo subterráneo de la zona de mezcla (interfaz salina) ubicada alrededor de los salares, (2) definir el balance hídrico y la hidrodinámica del Salar de Atacama en su régimen natural, (3) analizar y cuantificar los impactos causados por el bombeo de salmuera, (4) mejorar el diseño de las explotaciones de salmuera en salares y (5) cuestionar las ideas tradicionales que explican el origen del enriquecimiento en Li del Salar de Atacama. El agua subterránea recargada en las montañas es forzada a fluir hacia la superficie cuando alcanza la zona de mezcla que rodea al salar debido a su menor densidad, alimentando los ecosistemas lagunares y humedales. La primera cartografía 3D de la zona de mezcla de un salar se ha llevado a cabo en el Salar de Atacama, evidenciando una pendiente mucho menor que las predicciones anteriores. El modelado 2D de la zona de mezcla ha demostrado que cuanto mayor es la permeabilidad del acuífero superior, más baja es la pendiente y más superficial se vuelve la zona de mezcla. Por lo tanto, la permeabilidad del acuífero superior, principalmente constituido por evaporitas karstificadas y depósitos aluviales muy permeables, es crítica para la geometría de la zona de mezcla. El modelo hidrogeológico conceptual del Salar de Atacama, previo al bombeo de salmuera (régimen natural), se ha definido y validado utilizando un modelo estacionario 3D del flujo subterráneo. La distribución asimétrica de la recarga por infiltración del agua de lluvia y, sobre todo, de la descarga por evaporación da como resultado una superficie freática cuyo mínimo nivel hidráulico se localiza en el sector más oriental del núcleo, cerca de la zona de mezcla oriental. El modelado transitorio 3D de la cuenca del Salar de Atacama desde 1986 hasta 2018 ha permitido explicar los impactos causados por la explotación de salmuera sobre la hidrodinámica y el balance hídrico. Desde 1994 hasta 2015, el bombeo de salmuera causó una profundización de la superficie freática que desencadenó una reducción de la evaporación freática. Este efecto ha sido definido como la "capacidad de autorregulación" y permite a los salares contrarrestar las perturbaciones ocasionadas por eventos naturales o antropogénicos sobre la superficie freática y el balance hídrico. La capacidad de autorregulación compensó, al menos en parte, la disminución de la descarga por evaporación, pero hoy en día ya está amortizada en el núcleo y la zona de mezcla comienza a verse afectada. El modelado 3D de un hipotético salar bajo explotación de salmuera ha contribuido a optimizar la distribución espacial de los pozos de bombeo en términos de impacto sobre el balance hídrico. Para aprovechar al máximo la capacidad de autorregulación, las explotaciones de salmuera deben considerar distribuir el caudal bombeado en la mayor área posible. Los resultados del modelado hidro-termo-halino de una sección vertical Este-Oeste de la cuenca del Salar de Atacama han señalado al Sistema de Fallas Salar (SFS), localizado en el sector central del núcleo, como el principal contribuyente para explicar el enriquecimiento extremo en Li, ya sea por el ascenso de salmueras ricas en Li desde un reservorio hidrotermal profundo o por removilización de antiguas capas de sales y/o arcillas ricas en Li por aguas de recarga no evaporadas provenientes del Oeste. La localización del mínimo nivel hidráulico regional en el lado oriental del núcleo descarta considerar la evaporación avanzada como un mecanismo actual para alcanzar el alto contenido de Li de las salmueras ubicadas sobre el SFS. Además, la persistencia de las zonas de mezcla en profundidad también permite descartar las hipótesis previas de 1) infiltración de salmueras desde los salares actuales del Altiplano-Puna y 2) lixiviado de hipotéticos salares enterrados por erupciones volcánicas en el Altiplano-Puna como origen del enriquecimiento excepcional en Li de las salmueras de Salar de Atacama.Award-winningPostprint (published version

Sedimentología de depósitos fluviales pleistocenos de la región de Zuera. Sector central de la Cuenca del Ebro.

En el presente trabajo se exponen los resultados obtenidos del estudio estratigráfico, sedimentológico y de deformaciones realizado en los depósitos de la parte baja del río Gállego, a la altura de Zuera. Los materiales estudiados se localizan en la terraza T5, de edad Pleistoceno Inferior. A través del estudio estratigráfico de la gravera se han podido diferenciar cuatro unidades estratigráficas. Las unidades 1 y 3 están formadas por gravas principalmente masivas, la unidad 2 está compuesta por arenas y lutitas con laminación horizontal, y la unidad 4, que se apoya mediante una discordancia angular, está compuesta por gravas con intercalaciones de arenas, presentando geometría tabular. Se han podido diferenciar diez tipos de facies y cinco elementos arquitecturales, todos ellos interpretados dentro de un sistema fluvial braided de gravas con desarrollo de barras y canales. Las zonas deprimidas, denominadas dolinas, quedarían inundadas dando lugar a depósitos lutíticos. Estos materiales se encuentran deformados y fracturados a consecuencia de los procesos kársticos que afectan a los depósitos evaporíticos infrayacentes. Esto genera una fracturación con patrones cónicos o cilíndricos alrededor de los paleocolapsos, presentando planos de fracturación curvos. La disolución de los yesos infrayacentes se concentra principalmente a través de la fracturación Neógena, con orientaciones N-S y NW-SE. Las correlaciones realizadas muestran una variación de espesor importante de las unidades 2 y 3, asociada a una deformación sinsedimentaria

A geological model for the management of subsurface data in the urban environment of Barcelona and surrounding area

The overdevelopment of cities since the industrial revolution has shown the need to incorporate a sound geological knowledge in the management of required subsurface infrastructures and in the assessment of increasingly needed groundwater resources. Additionally, the scarcity of outcrops and the technical difficulty to conduct underground exploration in urban areas highlights the importance of implementing efficient management plans that deal with the legacy of heterogeneous subsurface information. To deal with these difficulties, a methodology has been proposed to integrate all the available spatio-temporal data into a comprehensive spatial database and a set of tools that facilitates the analysis and processing of the existing and newly added data for the city of Barcelona (NE Spain). Here we present the resulting actual subsurface 3-D geological model that incorporates and articulates all the information stored in the database. The methodology applied to Barcelona benefited from a good collaboration between administrative bodies and researchers that enabled the realization of a comprehensive geological database despite logistic difficulties. Currently, the public administration and also private sectors both benefit from the geological understanding acquired in the city of Barcelona, for example, when preparing the hydrogeological models used in groundwater assessment plans. The methodology further facilitates the continuous incorporation of new data in the implementation and sustainable management of urban groundwater, and also contributes to significantly reducing the costs of new infrastructures.Peer ReviewedPostprint (published version

Geothermal anomaly identified under a dense urban area in the metropolitan region of Barcelona, Spain

During the drilling of the Barcelona Metro L9 line, at the Fondo station of Santa Coloma de Gramanet (Barcelona) a geothermal anomaly was detected, in which groundwater temperature was found to be up to 55°C. This anomaly was attributed to a rise of deep groundwater through some tectonic structures, in a similar way to other geothermal zones of Catalonia (Spain). This geothermal area is located under a dense urban area where the information of its hydrogeological and geothermal features is limited. Due to the economic benefits of geothermal energy to society, studying and understanding the dynamics of the geothermal system, as well as, assessing its potential for future exploitation of the resource in this dense urban area, are of great interest. In order to study the feasibility of a future energy exploitation of the geothermal resource, a study is being undertaken at local and regional scale. In the regional study, whose first results are presented in this work, the objective is to understand the hydrothermal operation of the system. To achieve this, different works have been performed as are: geological review, borehole drilling, petrology, borehole logging, hydrochemical and isotopic assessment, thermography images, etc. This information has been integrated in numerical models of flow and heat transport.Postprint (published version

Reactive transport modelling for the study of geochemical impacts induced by shallow geothermal exploitation

Congress on Groundwater and Global Change in the Western Mediterranean (2017. Granada)The extensive implementation of shallow geothermal systems in urban aquifers is a matter of concern regarding groundwater quality and the long-term sustainability of geothermal systems. Quantitative assessment of the geochemical impact due to poor insulation of groundwater from atmospheric CO2 partial pressure conditions in open-loop systems is presented. The use of two reactive transport models allowed to reproduce and explain the processes of chemical clogging and dissolution subsidence phenomena observed in the alluvial aquifer of the city of Zaragoza (Spain). The numerical models used couple groundwater flow, heat and solute transport in addition to chemical reactions involved. To achieve a more realistic approach, the permeability field in each model is updated over time as a function of the heterogeneous precipitation-dissolution reactions taking place in the process. The simulations show a spatial and temporal distribution of massive calcite precipitation accompanied by a reduction of the porosity-permeability in the proximities of the injection well depending on the existing hydraulic gradients and the magnitude of the CO2 exolution process under atmospheric conditions. Finally, the efficiency of the reinjection wells over time under different injection scenarios is evaluated until total clogging occurs. Simulations showed that a reduction of the hydraulic conductivity forces a downward flow of the injected water. In cases where there is an evaporite basement this situation can lead to a dissolution of the basement itself, thus compromising the geomechanical stability of the terrain surrounding the well. The obtained results evidence the need to control the pressurization of the captation-injection system, the water level in the injection well and the adjacent control points as a good practice procedure in the management of efficiency and safety in the systems studied. In addition, the reactive transport models provide technical criteria for the design of groundwater sampling strategies to identify the geochemical processes producing the clogging of injection wells and to avoid possible collapses of the terrain.Unidad de Zaragoza, Instituto Geológico y Minero de España, EspañaUniversidad de Zaragoza, EspañaInstituto de Diagnóstico Ambiental y Estudios del Agua, Consejo Superior de Investigaciones Científicas, EspañaPeer reviewe

La importancia de incorporar la hidrodinámica de la interfaz salina en la gestión de los recursos minerales y ecosistemas de los salares

Texto en español con resumen y palabras claves en español e inglésLos salares son una fuente importante de minerales y especialmente de litio. Además, lagunas y humedales de alto valor ecológico están asociados frecuentemente a la zona de la interfaz salina (zona de mezcla) resultante del contraste de densidades entre el agua dulce recargada en el frente montañoso y la salmuera evaporada desde el salar que se ha instalado en la depresión. Esta zona se caracteriza por la presencia de flujos verticales, que condicionan la hidrodinámica a escala de cuenca. Es necesario establecer una metodología que permita incorporar el efecto de la interfaz salina en los modelos de agua subterránea que están enfocados a la gestión de sus recursos minerales y valores ecológicos. Dicha metodología consta de 3 fases: 1) recogida de datos físico-químicos en campo, 2) cartografía 3D de la zona de mezcla y 3) modelación numérica. Se presenta una cartografía tridimensional (3D) de la zona de mezcla del Salar de Atacama. Las diferentes geometrías de la zona de mezcla se han interpretado utilizando un modelo numérico de flujo y transporte de solutos. El resultado del modelo muestra una pendiente de la zona de mezcla similar a la obtenida a través de los datos de campo, la cual es más laxa que en los modelos previos, que consideraron un medio poroso homogéneo. Cuanto mayor es la permeabilidad del acuífero superior, menores son los niveles hidráulicos y, por lo tanto, menor es la pendiente de la interfaz salina. La presencia de unos pocos metros de materiales altamente permeables (abanicos aluviales o evaporitas karstificadas) en las unidades estratigráficas superiores de los salares es suficiente para modificar la geometría regional de la zona de mezcla. Se propone utilizar esta cartografía 3D como base para corregir los niveles piezométricos de agua dulce y de agua mezcla a niveles equivalentes de salmuera, con el fin de reducir el coste computacional de futuros modelos numéricos tridimensionales enfocados a la gestión de las aguas subterráneas de los salares = Salt flats are an important source of minerals and especially of lithium. In addition, lakes and wetlands of high ecological value are frequently associated with the saline interface zone (mixing zone) resulting from the density contrast between the freshwater coming from the rainfal infiltration on the mountains and the brine produced mainly by evaporation in the depressions. This zone is characterized by vertical flows that condition the hydrodynamics at a basin scale. It is necessary to establish a methodology that allows the incorporation of the effect of the saline interface into groundwater models for the management of the mineral resources and ecological values. This methodology consists of 3 steps: 1) physical-chemical data collection in the field, 2) 3D mapping of the mixing zone and 3) numerical modelling. A three-dimensional (3D) mapping of the mixing zone of the Salar de Atacama is presented. The mixing zone geometry was interpreted using a numerical flow and solute transport model. The results from the model show a slope of the mixing zone that is similar to that obtained with the field data, which is more relaxed than in the previous models that considered a homogeneous porous medium. The higher the permeability of the upper aquifer is, the lower the slope and the shallower the mixing zone become. The presence of a few metres of highly permeable materials (alluvial fans or karstified evaporites) in the upper stratigraphic units of the salt flats is enough to condition the regional geometry of the saline interface. The use of this 3D mapping is proposed as a basis for the correction of the freshwater and mixing water heads to brine heads to reduce the computational cost of 3D numerical models for groundwater management in salt flats.Instituto de Diagnóstico Ambiental y Estudios del Agua, Consejo Superior de Investigaciones Científicas, EspañaDepartament d'Enginyeria Civil i Ambiental, Universitat Politècnica de Catalunya, EspañaCentre for Microbiology and Environmental Systems Science, Environmental Geosciences,University of Vienna, AustriaReal Academia de Ciencias Exactas, Físicas y Naturales de España, EspañaUnidad de Zaragoza, Instituto Geológico y Minero de España, Españ

A city scale study on the effects of intensive groundwater heat pump systems on heavy metal contents in groundwater

As a result of the increasing use of shallow geothermal resources, hydraulic, thermal and chemical impacts affecting groundwater quality can be observed with ever increasing frequency (Possemiers et al., 2014). To overcome the uncertainty associated with chemical impacts, a city scale study on the effects of intensive geothermal resource use by groundwater heat pump systems on groundwater quality, with special emphasis on heavy metal contents was performed. Statistical analysis of geochemical data obtained from several field campaigns has allowed studying the spatiotemporal relationship between temperature anomalies in the aquifer and trace element composition of groundwater. The relationship between temperature and the concentrations of trace elements resulted in weak correlations, indicating that temperature changes are not the driving factor in enhancing heavy metal contaminations. Regression models established for these correlations showed a very low reactivity or response of heavy metal contents to temperature changes. The change rates of heavy metal contents with respect to temperature changes obtained indicate a low risk of exceeding quality threshold values by means of the exploitation regimes used, neither producing nor enhancing contamination significantly. However, modification of pH, redox potential, electrical conductivity, dissolved oxygen and alkalinity correlated with the concentrations of heavy metals. In this case, the change rates of heavy metal contents are higher, with a greater risk of exceeding threshold values

A geological model for the management of subsurface data in the urban environment of Barcelona and surrounding area

The overdevelopment of cities since the industrial revolution has shown the need to incorporate a sound geological knowledge in the management of required subsurface infrastructures and in the assessment of increasingly needed groundwater resources. Additionally, the scarcity of outcrops and the technical difficulty to conduct underground exploration in urban areas highlights the importance of implementing efficient management plans that deal with the legacy of heterogeneous subsurface information. To deal with these difficulties, a methodology has been proposed to integrate all the available spatio-temporal data into a comprehensive spatial database and a set of tools that facilitates the analysis and processing of the existing and newly added data for the city of Barcelona (NE Spain). Here we present the resulting actual subsurface 3-D geological model that incorporates and articulates all the information stored in the database. The methodology applied to Barcelona benefited from a good collaboration between administrative bodies and researchers that enabled the realization of a comprehensive geological database despite logistic difficulties. Currently, the public administration and also private sectors both benefit from the geological understanding acquired in the city of Barcelona, for example, when preparing the hydrogeological models used in groundwater assessment plans. The methodology further facilitates the continuous incorporation of new data in the implementation and sustainable management of urban groundwater, and also contributes to significantly reducing the costs of new infrastructures.Peer Reviewe

Procesos de pseudo-pasteurización de bacterias patógenas en agua subterránea inducidos por intercambiadores geotérmicos

Congreso Ibérico sobre Agua subterránea, medio ambiente, salud y patrimonio (2018. Salamanca)Los efectos de un uso intensivo de recursos geotérmicos someros sobre los contenidos en bacterias patógenas en el agua subterránea son aún desconocidos. Ante el riesgo de un posible aumento de la concentración de ciertas bacterias patógenas para la salud humana en relación a las plumas de calor generadas por sistemas geotérmicos de tipo abierto, se realizó un muestreo microbiológico de muestras obtenidas de 31 piezómetros distribuidos en el acuífero aluvial presente bajo la ciudad de Zaragoza, que se encuentra energéticamente explotado por 70 sistemas geotérmicos. Este estudio se centra en organismos habitualmente presentes en el agua subterránea de medios urbanos: bacterias coliformes, Streptococci fecales, Escherichia coli, Clostridium perfringens, Salmonella spp., Staphylococcus aureus, Legionella pneumophila y Pseudomonas aeruginosa. Con el objetivo de identificar el posible aumento en estos organismos, se evaluaron las diferencias en contenido de bacterias patógenas entre los puntos de muestreo impactados y los no impactados térmicamente. Por otro lado, se calcularon los coeficientes de correlación entre los contenidos bacterianos y la temperatura en el agua subterránea. Los resultados obtenidos revelaron una disminución significativa y generalizada en los contenidos de las bacterias patógenas estudiadas en los piezómetros impactados térmicamente en comparación con los piezómetros no impactados. Se presume que esta disminución bacteriana está causada por un choque térmico producido dentro de los intercambiadores de calor de los sistemas geotérmicos. Los resultados obtenidos en este trabajo refuerzan el concepto de “energía limpia” asociado a los recursos geotérmicos someros, ya que además de proporcionar energía renovable podrían ayudar de forma indirecta a la remediación de la contaminación microbiológica en las masas de agua subterránea en entornos urbanos.Unidad de Zaragoza, Instituto Geologico y Minero de España, EspañaMammalian Genetics Unit, MRC Harwell Institut, Reino UnidoInstituto Geológico y Minero de España, EspañaGrupo de Hidrología Subterránea, Instituto de Diagnóstico Ambiental y Estudios del Agua, Consejo Superior de Investigaciones Científicas, EspañaGrupo de Hidrología Subterránea, Instituto de Diagnóstico Ambiental y Estudios del Agua, Universitat Politècnica de Catalunya, EspañaInstituto Municipal de Salud Pública, Ayuntamiento de Zaragoza, Españ

Combining fiber optic DTS, cross-hole ERT and time-lapse induction logging to characterize and monitor a coastal aquifer

The characterization of saline water intrusion (SWI) and its hydrodynamics is a key issue to understand submarine groundwater discharge (SGD) and manage groundwater resources in coastal areas. To test and compare different methods of characterization and monitoring, a new experimental site has been constructed in a coastal alluvial aquifer north of Barcelona city (Catalonia, Spain). The site is located between 30 and 90 m from the seashore and comprises 16 shallow piezometers organized in nests of three with depths ranging between 15 and 25 m and 4 solitary piezometers. The objective of this paper is to combine different recently developed monitoring techniques to evaluate temporal variations in the aquifer hydrodynamics of the site at different spatial scales before and after the dry season of 2015. At the site scale, fibre optic distributed temperature sensing (FO-DTS), for the first time applied to study SWI, and cross-hole electrical resistivity tomography (CHERT) has been applied. At the meter/borehole scale, electrical conductivity of the formation has been applied not only in a repeated manner (“time lapse”), but also for the first time at relatively high frequency (1 sample every 10 min). CHERT has provided a better characterization of the seawater intrusion than electrical conductivity data obtained from piezometers. The combination of techniques has allowed improving the understanding of the system by: 1) characterizing the extent and shape of SWI; 2) differentiating two different dynamics in the aquifer; and 3) identifying preferential flow paths over different time and spatial intervals. Future challenges and the application of these techniques in other areas are also discussed.This work was funded by the projects CGL2013-48869-C2-1-R/2-R and CGL2016-77122-C2-1-R/2-R of the Spanish Government. We would like to thank SIMMAR (Serveis Integrals de Manteniment del Maresme) and the Consell Comarcal del Maresme in the construction of the research site. The authors want to thank the support of the Generalitat de Catalunya to MERS (2018 SGR-1588). This work is contributing to the ICTA ‘Unit of Excellence’ (MinECo, MDM2015- 0552). Part of the funding was provided by the French network of hydrogeological observatories H+ (hplus/ore/fr/en) and the ANR project EQUIPEX CRITEX (grant ANR-11-EQPX-0011). V Rodellas acknowledges financial support from the Beatriu de Pinós postdoctoral program of the Generalitat de Catalunya (2017-BP-00334). M. Diego‐Feliu acknowledges the economic support from the FI‐2017 fellowships of the Generalitat de Catalunya autonomous government (2017FI_B_00365). This project also received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant Agreement No 722028.Peer ReviewedPostprint (author's final draft