Extreme precipitation events induce high fluxes of groundwater and associated nutrients to the coastal ocean

Current Submarine Groundwater Discharge (SGD) studies are commonly conducted under aquifer baseflow conditions, neglecting the influence of episodic events that can significantly increase the supply of nutrients and water. This limits our understanding of the social, biogeochemical, and ecological impacts of SGD. In this study, we evaluated the influence of an extreme precipitation event (EPE) on the magnitude of both the terrestrial and marine components of SGD. To do so, three seawater sampling campaigns were performed at a Mediterranean ephemeral stream-dominated basin after an extreme precipitation event (~90 mm in few hours) and in baseflow conditions. Results indicate that the groundwater flows of terrestrial and marine SGD after the extreme precipitation event were 1 order of magnitude higher than those in baseflow conditions. SGD induced by extreme precipitation events, which only take place a few days per year, represented up to one third of the annual discharge of groundwater and associated nutrients at the study site. This work accentuates the need to account for episodic increases in the supply of water and nutrients when aiming at providing reliable annual SGD estimates, particularly in the current context of climate change, since the occurrence of such events is expected to increase worldwide.This work was partly funded by the projects PID2019-110212RB- C22, CGL2016-77122-C2-1-R/2-R and PID2019-110311RB-C21 of the Spanish Government and the project TerraMar ACA210/18/00007 of the Catalan Water Agency. The authors want to express their thanks for the support of the Generalitat de Catalunya for MERS (2017 SGR-1588) and GHS (2017 SGR 1485) for additional funding. The authors would like to thank Maravillas Abad from ICM-CSIC for the analysis of nutrients. M. Diego-Feliu acknowledges the economic support from the FI-2017 fellowships of the Generalitat de Catalunya autonomous government (2017FI_B_00365). V. Rodellas acknowledges financial support from the Beatriu de Pinós postdoctoral program of the Generalitat de Catalunya autonomous government (2019-BP-00241). A. Alorda-Kleinglass acknowledges financial support from ICTA “Unit of Excellence” (MinECo, MDM2015‐440 0552‐17‐1) and PhD fellowship, BES‐2017‐080740. Albert Folch is a Serra Hunter Fellow. We would like to thank all colleagues from the Grup de Recerca en Radioactivitat Ambiental de Barcelona - GRAB (Universitat Autònoma de Barcelona). We would like to thank SIMMAR (Serveis Integrals de Manteniment del Maresme) and the Consell Comarcal del Maresme for the construction of the research site.Peer ReviewedPostprint (published version

The social implications of Submarine Groundwater Discharge from an Ecosystem Services perspective: A systematic review

Altres ajuts: Acord transformatiu CRUE-CSICUnidad de excelencia María de Maeztu CEX2019-000940-MSubmarine Groundwater Discharge (SGD) is recognized as a fundamental hydrological process that supports many coastal biogeochemical cycles and social-ecological systems. However, very little has been investigated about how SGD affects society and, specifically, human well-being. This study systematically examines the published scientific literature on the social implications of SGD by using an Ecosystem Service (ES) perspective. Coastal services provided by ecosystems dependent on SGD are analyzed and clustered in the four main categories of Ecosystem Services (i.e., Provisioning, Supporting, Regulating and Cultural), which are in turn divided into subcategories defined as outcomes. This allows identifying and discussing both benefits and threats to coastal societies resulting from SGD outcomes. From the 1532 articles initially reviewed, the most frequently mentioned category was the supporting services (835) due to the mainstream trend in scientific literature to focus on the role of SGD as a process influencing coastal biogeochemical cycles. Conversely, cultural ES were mentioned in only 49 cases, which should not necessarily be interpreted as a lack of research or interest in this topic, but that this type of references are often not found in the scientific literature but in the grey literature. A detailed publication review was additionally conducted, identifying 114 case studies from 96 different locations worldwide that reported cases in which SGD had social implications on the well-being. Our review also shows how the different types of Ecosystem Services can have multiple synergies and trade-offs between them, resulting in unequal impacts among stakeholder groups. Overall, this study identifies research gaps related to Ecosystem Services provided by SGD as well as opportunities for further studies, while developing an analytical framework that relies on the Ecosystem Services approach to guide future research on the social implications of SGD

Groundwater discharge as a driver of methane emissions from Arctic lakes

Lateral CH4 inputs to Arctic lakes through groundwater discharge could be substantial and constitute an important pathway that links CH4 production in thawing permafrost to atmospheric emissions via lakes. Yet, groundwater CH4 inputs and associated drivers are hitherto poorly constrained because their dynamics and spatial variability are largely unknown. Here, we unravel the important role and drivers of groundwater discharge for CH4 emissions from Arctic lakes. Spatial patterns across lakes suggest groundwater inflows are primarily related to lake depth and wetland cover. Groundwater CH4 inputs to lakes are higher in summer than in autumn and are influenced by hydrological (groundwater recharge) and biological drivers (CH4 production). This information on the spatial and temporal patterns on groundwater discharge at high northern latitudes is critical for predicting lake CH4 emissions in the warming Arctic, as rising temperatures, increasing precipitation, and permafrost thawing may further exacerbate groundwater CH4 inputs to lakes

Radium isotopes as submarine groundwater discharge (SGD) tracers: review and recommendations

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Garcia-Orellana, J., Rodellas, V., Tamborski, J., Diego-Feliu, M., van Beek, P., Weinstein, Y., Charette, M., Alorda-Kleinglass, A., Michael, H. A., Stieglitz, T., & Scholten, J. Radium isotopes as submarine groundwater discharge (SGD) tracers: review and recommendations. Earth-Science Reviews, 220, (2021): 103681, https://doi.org/10.1016/j.earscirev.2021.103681.Submarine groundwater discharge (SGD) is now recognized as an important process of the hydrological cycle worldwide and plays a major role as a conveyor of dissolved compounds to the ocean. Naturally occurring radium isotopes (223Ra, 224Ra, 226Ra and 228Ra) are widely employed geochemical tracers in marine environments. Whilst Ra isotopes were initially predominantly applied to study open ocean processes and fluxes across the continental margins, their most common application in the marine environment has undoubtedly become the identification and quantification of SGD. This review focuses on the application of Ra isotopes as tracers of SGD and associated inputs of water and solutes to the coastal ocean. In addition, we review i) the processes controlling Ra enrichment and depletion in coastal groundwater and seawater; ii) the systematics applied to estimate SGD using Ra isotopes and iii) we summarize additional applications of Ra isotopes in groundwater and marine studies. We also provide some considerations that will help refine SGD estimates and identify the critical knowledge gaps and research needs related to the current use of Ra isotopes as SGD tracers.J.Garcia-Orellana acknowledges the financial support of the Spanish Ministry of Science, Innovation and Universities, through the “Maria de Maeztu” programme for Units of Excellence (CEX2019-000940-M), the Generalitat de Catalunya (MERS; 2017 SGR – 1588) and the project OPAL (PID2019-110311RB-C21). V. Rodellas acknowledges financial support from the Beatriu de Pinós postdoctoral program of the Generalitat de Catalunya (2017-BP-00334 and 2019-BP-00241). M. Charette received support from the U.S. National Science Foundation (OCE-1736277). J. Scholten acknowledges the support through the SEAMOUNT BONUS project (art. 185), which is funded jointly by the EU and the Federal Ministry of Education and Research of Germany (BMBF, grant no. 03F0771B). P. van Beek and T. Stieglitz acknowledge support from the French ANR project MED-SGD (ANR-15-01CE-0004) and chair @RAction MED-LOC (ANR-14-ACHN-0007-01). A. Alorda-Kleinglass acknowledges financial support from ICTA “Unit of Excellence” (MinECo, MDM2015-0552-17-1) and PhD fellowship, BES-2017-080740. H. Michael acknowledges support from the U.S. National Science Foundation (EAR-1759879). M. Diego-Feliu acknowledges the financial support from the FI-2017 fellowships of the Generalitat de Catalunya (2017-FIB-00365). Fig. 3, Fig. 4, Fig. 7, Fig. 12 were designed by Gemma Solà (www.gemmasola.com)

Submarine groundwater discharge feedbacks on ecosystem services

Els éssers humans tenen una important capacitat per modificar l’entorn en benefici propi. No obstant això, alguns canvis antropogènics han tingut conseqüències globals, provocant la degradació dels ecosistemes del planeta. Amb la finalitat d’analitzar aquestes interaccions entre persones i la natura, el marc de Serveis Ecosistèmics (SE) proposa quatre categories de serveis (Suport, Proveïment, Regulació i Culturals), que fan referència als beneficis que la societat obté de l’ús i modificació dels ecosistemes per al seu benestar. Les zones costaneres són una font fonamental de SE per a les persones, caracteritzades per ser de les zones més productives i sensibles que podem trobar. Els ecosistemes costaners, reconeguts per la seva diversitat i productivitat, depenen de la connexió hidrològica entre la terra i l’oceà regulada per processos com els rius, rierols i la Descàrrega Submarina d’Aigua subterrània (SGD de les seves sigles en anglès). Entre ells, la SGD està reconeguda com un procés hidrològic fonamental que sosté molts cicles biogeoquímics costaners i sistemes soci-ecològics. No obstant això, s’ha investigat molt poc sobre com la SGD afecta a la societat i el benestar humà. Per omplir aquest buit, aquesta tesi té com a objectiu avançar en el coneixement de la dimensió social de la SGD, contribuint a abordar la desconnexió existent entre les ciències naturals i socials en aquest camp. Amb aquesta finalitat, aquesta tesi avalua tant els impactes d’activitats antropogèniques altament contaminants en la SGD, com les implicacions socials d’aquest procés mitjançant el desenvolupament i l’aplicació del marc conceptual de SE (marc conceptual per a l’anàlisi de sistemes soci-ecològics). Els resultats d’aquesta tesi demostren com les activitats antropogèniques altament contaminants poden induir grans fluxos de metalls i nutrients dissolts en l’oceà costaner, tenint un impacte significatiu en els ecosistemes marins. Així mateix, la diversitat de subprocessos que componen la SGD juguen un paper fonamental en el control dels fluxos de soluts subministrats a l’oceà costaner. En aquesta tesi també mostren que l’alta pressió exercida sobre les zones costaneres per les activitats turístiques pot provocar alteracions en els fluxos de SGD, posant en perill els ecosistemes costaners i els serveis que proporcionen. Per poder avançar en la coneixement de les implicacions socials de la SGD, aquesta tesi desenvolupa el primer marc teòric per identificar i classificar els Serveis Ecosistèmics proporcionats per la SGD i els seus efectes en el benestar de les societats locals. Els resultats mostren que la SGD, des del seu ús com a recurs hídric fins a la seva influència cultural, està profundament arrelada en moltes societats costaneres a escala global, i els ecosistemes dependents de la SGD tenen un impacte significatiu en les comunitats locals. D’acord amb els resultats obtinguts de la percepció local de dues societats mediterrànies (Mallorca i Salento) sobre el seu ús i paper en les comunitats costaneres, s’evidencia la necessitat d’integrar dades de la literatura científica, informació disponible en la literatura grisa i coneixement local per a obtenir una comprensió completa de la dimensió cultural de la SGD. També mostren que la limitada documentació històrica sobre el SGD provoca biaixos en la recopilació de dades dels SE actuals en comparació amb el passat en les dues zones estudiades. La perspectiva interdisciplinària seguida en aquesta tesi representa un avanç en el coneixement de la SGD i aporta nous coneixements i evidències per a guiar les estratègies polítiques i de gestió en relació amb la SGD. Aquesta tesi ofereix una anàlisi detallada de l’estreta relació entre el SGD i el benestar de les comunitats costaneres, proporcionant evidència científica sòlida i una metodologia robusta per a comprendre la influència del SGD en aquestes societats des d’un enfocament socioecològic.Los seres humanos tienen una importante capacidad para modificar su entorno en beneficio propio. No obstante, algunos cambios antropogénicos han tenido consecuencias a escala global, provocando la degradación de los ecosistemas del planeta. Con el fin de analizar estas interacciones entre personas y la naturaleza, el marco de Servicios Ecosistémicos (SE) propone cuatro categorías de servicios (Apoyo, Abastecimiento, Regulación y Culturales), que hacen referencia a los beneficios que la sociedad obtiene del uso y modificación de los ecosistemas para su bienestar. Las zonas costeras son una fuente crucial de SE para las personas, caracterizadas por ser de las más productivas y sensibles que podemos encontrar. Los ecosistemas costeros, reconocidos por su diversidad y productividad, dependen de la conectividad hidrológica entre la tierra y el océano regulada por procesos como los ríos, arroyos y la Descarga Submarina de Agua subterránea (SGD de sus siglas en inglés). Entre ellos, la SGD se reconoce como un proceso hidrológico fundamental que sostiene muchos ciclos biogeoquímicos costeros y sistemas socio-ecológicos. Sin embargo, se ha investigado muy poco sobre cómo la SGD afecta a la sociedad y el bienestar humano. Para llenar este vacío, esta tesis tiene como objetivo avanzar en el entendimiento de la dimensión social de la SGD, contribuyendo a abordar la desconexión existente entre las ciencias naturales y sociales en este campo. Con este fin, esta tesis evalúa tanto los impactos de actividades antropogénicas altamente contaminantes en la SGD como las implicaciones sociales de este proceso mediante el desarrollo y la aplicación del marco conceptual de SE (marco conceptual para el análisis de sistemas socio-ecológicos) a la investigación de la SGD. Los resultados de esta tesis demuestran cómo las actividades antropogénicas altamente contaminantes pueden inducir grandes flujos de metales y nutrientes disueltos en el océano costero, teniendo un impacto significativo en los ecosistemas marinos. Además, la diversidad de subprocesos que componen la SGD juegan un papel fundamental en el control de los flujos de solutos suministrados al océano costero. La alta presión ejercida sobre las zonas costeras por las actividades turísticas puede provocar alteraciones en los flujos de SGD, poniendo en peligro los ecosistemas costeros y los servicios que proporcionan. Para poder avanzar en el conocimiento de las implicaciones sociales de la SGD, esta tesis desarrolla el primer marco teórico para identificar y clasificar los SE proporcionados por la SGD y sus efectos en el bienestar de las sociedades locales. La SGD, desde su uso como recurso hídrico hasta su influencia cultural, está profundamente arraigada en muchas sociedades costeras a escala global, y los ecosistemas dependientes de la SGD tienen un impacto significativo en las comunidades locales. De acuerdo con los resultados obtenidos de la percepción local de dos sociedades mediterráneas (Mallorca y Salento) sobre su uso y papel en las comunidades costeras, se evidencia la necesidad de integrar datos de la literatura científica, información disponible en la literatura gris y conocimiento local para obtener una comprensión completa de la dimensión cultural de la SGD. La limitada documentación histórica sobre el SGD provoca sesgos en la recopilación de datos de los SE actuales en comparación con el pasado en las dos zonas estudiadas. El enfoque interdisciplinario seguido en esta tesis representa un avance en el conocimiento de la SGD y aporta nuevos conocimientos y evidencias para guiar las estrategias políticas y de gestión con relación a la SGD. En conclusión, esta tesis ofrece un análisis detallado de la estrecha relación entre el SGD y el bienestar de las comunidades costeras, proporcionando evidencia científica sólida y una metodología robusta para comprender la influencia del SGD en estas sociedades desde un enfoque socioecológico.Humans have a notable ability to modify their surrounding environment for their own benefit. Nonetheless, some anthropogenic changes have led to global-scale consequences, causing the degradation of Earth’s ecosystems. To analyze these human-nature interactions, the Ecosystem Services framework poses four categories of services referred to the benefits to society of using and modifying ecosystems toward their well-being (i.e., Supporting, Provisioning, Regulating and Cultural). Coastal areas are a crucial source of ecosystem services for humans, being both productive and sensitive. Coastal ecosystems, renowned for their diversity and productivity, depend on hydrological land-ocean connectivity regulated by processes such as rivers, streams, and Submarine Groundwater Discharge (SGD). Among them, SGD is recognized as a fundamental hydrological process that supports many coastal biogeochemical cycles and social-ecological systems. However, very little has been investigated about how SGD affects society and human well-being. To bridge this gap of knowledge, this thesis aims to advance the understanding of the social dimension of Submarine Groundwater Discharge, contributing to address the existing disconnection between the natural and social sciences in this field. To this aim, this thesis assesses both the impacts of highly polluting anthropogenic activities on SGD and the societal implications of this process by developing and applying the Ecosystem Services framework (a socio- ecological system approach) to SGD research. The results of this thesis demonstrate how polluting anthropogenic activities can induce large fluxes of dissolved metals and nutrients into the coastal ocean, having a significant impact on coastal marine ecosystems. In addition, the diversity of pathways of SGD play a relevant role on controlling the solutes fluxes supplied into the coastal ocean. The findings of this thesis also show that the high pressure exerted on coastal areas by tourism activities can lead to alterations in SGD fluxes, thereby endangering coastal ecosystems and the services they provide. To advance the understanding of the social implications of SGD, this thesis develops the first framework for identifying and classifying the Ecosystem Services provided by SGD and their effects on the well-being of local societies. Results show that SGD, from its use as a water resource to its cultural influence, is deeply rooted in many coastal societies at a global scale, and SGD-dependent ecosystems have a significant impact on the local communities. Additionally, results from the local perceptions of two Mediterranean societies (Mallorca and Salento) towards SGD, including its uses and its role in coastal communities, highlight the necessity of integrating data from the scientific literature, together with the information available in the grey literature and local knowledge for a complete understanding of the cultural dimension of SGD. Findings also show that the limited historical documentation on SGD causes bias in reporting present ecosystem services compared to the past in the two studied areas. The interdisciplinary approach followed in this thesis represents a novelty and brings new knowledge and evidence to guide policy and management strategies regarding SGD. In sum, this thesis is a walkthrough of the strong bounds between SGD and coastal societies’ wellbeing, which provides both solid scientific evidence and robust methodological guidance on the influence of SGD on coastal societies from a social-ecological approach.Universitat Autònoma de Barcelona. Programa de Doctorat en Ciència i Tecnologia Ambiental

Submarine groundwater discharge feedbacks on ecosystem services

Els éssers humans tenen una important capacitat per modificar l'entorn en benefici propi. No obstant això, alguns canvis antropogènics han tingut conseqüències globals, provocant la degradació dels ecosistemes del planeta. Amb la finalitat d'analitzar aquestes interaccions entre persones i la natura, el marc de Serveis Ecosistèmics (SE) proposa quatre categories de serveis (Suport, Proveïment, Regulació i Culturals), que fan referència als beneficis que la societat obté de l'ús i modificació dels ecosistemes per al seu benestar. Les zones costaneres són una font fonamental de SE per a les persones, caracteritzades per ser de les zones més productives i sensibles que podem trobar. Els ecosistemes costaners, reconeguts per la seva diversitat i productivitat, depenen de la connexió hidrològica entre la terra i l'oceà regulada per processos com els rius, rierols i la Descàrrega Submarina d'Aigua subterrània (SGD de les seves sigles en anglès). Entre ells, la SGD està reconeguda com un procés hidrològic fonamental que sosté molts cicles biogeoquímics costaners i sistemes soci-ecològics. No obstant això, s'ha investigat molt poc sobre com la SGD afecta a la societat i el benestar humà. Per omplir aquest buit, aquesta tesi té com a objectiu avançar en el coneixement de la dimensió social de la SGD, contribuint a abordar la desconnexió existent entre les ciències naturals i socials en aquest camp. Amb aquesta finalitat, aquesta tesi avalua tant els impactes d'activitats antropogèniques altament contaminants en la SGD, com les implicacions socials d'aquest procés mitjançant el desenvolupament i l'aplicació del marc conceptual de SE (marc conceptual per a l'anàlisi de sistemes soci-ecològics). Els resultats d'aquesta tesi demostren com les activitats antropogèniques altament contaminants poden induir grans fluxos de metalls i nutrients dissolts en l'oceà costaner, tenint un impacte significatiu en els ecosistemes marins. Així mateix, la diversitat de subprocessos que componen la SGD juguen un paper fonamental en el control dels fluxos de soluts subministrats a l'oceà costaner. En aquesta tesi també mostren que l'alta pressió exercida sobre les zones costaneres per les activitats turístiques pot provocar alteracions en els fluxos de SGD, posant en perill els ecosistemes costaners i els serveis que proporcionen. Per poder avançar en la coneixement de les implicacions socials de la SGD, aquesta tesi desenvolupa el primer marc teòric per identificar i classificar els Serveis Ecosistèmics proporcionats per la SGD i els seus efectes en el benestar de les societats locals. Els resultats mostren que la SGD, des del seu ús com a recurs hídric fins a la seva influència cultural, està profundament arrelada en moltes societats costaneres a escala global, i els ecosistemes dependents de la SGD tenen un impacte significatiu en les comunitats locals. D'acord amb els resultats obtinguts de la percepció local de dues societats mediterrànies (Mallorca i Salento) sobre el seu ús i paper en les comunitats costaneres, s'evidencia la necessitat d'integrar dades de la literatura científica, informació disponible en la literatura grisa i coneixement local per a obtenir una comprensió completa de la dimensió cultural de la SGD. També mostren que la limitada documentació històrica sobre el SGD provoca biaixos en la recopilació de dades dels SE actuals en comparació amb el passat en les dues zones estudiades. La perspectiva interdisciplinària seguida en aquesta tesi representa un avanç en el coneixement de la SGD i aporta nous coneixements i evidències per a guiar les estratègies polítiques i de gestió en relació amb la SGD. Aquesta tesi ofereix una anàlisi detallada de l'estreta relació entre el SGD i el benestar de les comunitats costaneres, proporcionant evidència científica sòlida i una metodologia robusta per a comprendre la influència del SGD en aquestes societats des d'un enfocament socioecològic.Los seres humanos tienen una importante capacidad para modificar su entorno en beneficio propio. No obstante, algunos cambios antropogénicos han tenido consecuencias a escala global, provocando la degradación de los ecosistemas del planeta. Con el fin de analizar estas interacciones entre personas y la naturaleza, el marco de Servicios Ecosistémicos (SE) propone cuatro categorías de servicios (Apoyo, Abastecimiento, Regulación y Culturales), que hacen referencia a los beneficios que la sociedad obtiene del uso y modificación de los ecosistemas para su bienestar. Las zonas costeras son una fuente crucial de SE para las personas, caracterizadas por ser de las más productivas y sensibles que podemos encontrar. Los ecosistemas costeros, reconocidos por su diversidad y productividad, dependen de la conectividad hidrológica entre la tierra y el océano regulada por procesos como los ríos, arroyos y la Descarga Submarina de Agua subterránea (SGD de sus siglas en inglés). Entre ellos, la SGD se reconoce como un proceso hidrológico fundamental que sostiene muchos ciclos biogeoquímicos costeros y sistemas socio-ecológicos. Sin embargo, se ha investigado muy poco sobre cómo la SGD afecta a la sociedad y el bienestar humano. Para llenar este vacío, esta tesis tiene como objetivo avanzar en el entendimiento de la dimensión social de la SGD, contribuyendo a abordar la desconexión existente entre las ciencias naturales y sociales en este campo. Con este fin, esta tesis evalúa tanto los impactos de actividades antropogénicas altamente contaminantes en la SGD como las implicaciones sociales de este proceso mediante el desarrollo y la aplicación del marco conceptual de SE (marco conceptual para el análisis de sistemas socio-ecológicos) a la investigación de la SGD. Los resultados de esta tesis demuestran cómo las actividades antropogénicas altamente contaminantes pueden inducir grandes flujos de metales y nutrientes disueltos en el océano costero, teniendo un impacto significativo en los ecosistemas marinos. Además, la diversidad de subprocesos que componen la SGD juegan un papel fundamental en el control de los flujos de solutos suministrados al océano costero. La alta presión ejercida sobre las zonas costeras por las actividades turísticas puede provocar alteraciones en los flujos de SGD, poniendo en peligro los ecosistemas costeros y los servicios que proporcionan. Para poder avanzar en el conocimiento de las implicaciones sociales de la SGD, esta tesis desarrolla el primer marco teórico para identificar y clasificar los SE proporcionados por la SGD y sus efectos en el bienestar de las sociedades locales. La SGD, desde su uso como recurso hídrico hasta su influencia cultural, está profundamente arraigada en muchas sociedades costeras a escala global, y los ecosistemas dependientes de la SGD tienen un impacto significativo en las comunidades locales. De acuerdo con los resultados obtenidos de la percepción local de dos sociedades mediterráneas (Mallorca y Salento) sobre su uso y papel en las comunidades costeras, se evidencia la necesidad de integrar datos de la literatura científica, información disponible en la literatura gris y conocimiento local para obtener una comprensión completa de la dimensión cultural de la SGD. La limitada documentación histórica sobre el SGD provoca sesgos en la recopilación de datos de los SE actuales en comparación con el pasado en las dos zonas estudiadas. El enfoque interdisciplinario seguido en esta tesis representa un avance en el conocimiento de la SGD y aporta nuevos conocimientos y evidencias para guiar las estrategias políticas y de gestión con relación a la SGD. En conclusión, esta tesis ofrece un análisis detallado de la estrecha relación entre el SGD y el bienestar de las comunidades costeras, proporcionando evidencia científica sólida y una metodología robusta para comprender la influencia del SGD en estas sociedades desde un enfoque socioecológico.Humans have a notable ability to modify their surrounding environment for their own benefit. Nonetheless, some anthropogenic changes have led to global-scale consequences, causing the degradation of Earth's ecosystems. To analyze these human-nature interactions, the Ecosystem Services framework poses four categories of services referred to the benefits to society of using and modifying ecosystems toward their well-being (i.e., Supporting, Provisioning, Regulating and Cultural). Coastal areas are a crucial source of ecosystem services for humans, being both productive and sensitive. Coastal ecosystems, renowned for their diversity and productivity, depend on hydrological land-ocean connectivity regulated by processes such as rivers, streams, and Submarine Groundwater Discharge (SGD). Among them, SGD is recognized as a fundamental hydrological process that supports many coastal biogeochemical cycles and social-ecological systems. However, very little has been investigated about how SGD affects society and human well-being. To bridge this gap of knowledge, this thesis aims to advance the understanding of the social dimension of Submarine Groundwater Discharge, contributing to address the existing disconnection between the natural and social sciences in this field. To this aim, this thesis assesses both the impacts of highly polluting anthropogenic activities on SGD and the societal implications of this process by developing and applying the Ecosystem Services framework (a socio- ecological system approach) to SGD research. The results of this thesis demonstrate how polluting anthropogenic activities can induce large fluxes of dissolved metals and nutrients into the coastal ocean, having a significant impact on coastal marine ecosystems. In addition, the diversity of pathways of SGD play a relevant role on controlling the solutes fluxes supplied into the coastal ocean. The findings of this thesis also show that the high pressure exerted on coastal areas by tourism activities can lead to alterations in SGD fluxes, thereby endangering coastal ecosystems and the services they provide. To advance the understanding of the social implications of SGD, this thesis develops the first framework for identifying and classifying the Ecosystem Services provided by SGD and their effects on the well-being of local societies. Results show that SGD, from its use as a water resource to its cultural influence, is deeply rooted in many coastal societies at a global scale, and SGD-dependent ecosystems have a significant impact on the local communities. Additionally, results from the local perceptions of two Mediterranean societies (Mallorca and Salento) towards SGD, including its uses and its role in coastal communities, highlight the necessity of integrating data from the scientific literature, together with the information available in the grey literature and local knowledge for a complete understanding of the cultural dimension of SGD. Findings also show that the limited historical documentation on SGD causes bias in reporting present ecosystem services compared to the past in the two studied areas. The interdisciplinary approach followed in this thesis represents a novelty and brings new knowledge and evidence to guide policy and management strategies regarding SGD. In sum, this thesis is a walkthrough of the strong bounds between SGD and coastal societies' wellbeing, which provides both solid scientific evidence and robust methodological guidance on the influence of SGD on coastal societies from a social-ecological approach

Impact of mine tailing on SGD-driven metal fluxes in Portman Bay

Portman Bay is located in Cartagena-La Unión Pb and Zn mining district, Murcia, Spain. This site is considerated the biggest environmental impact of the Mediterranean Sea basin, where 57 million tons had been deposited between 1957 and 1991. The aim of this study is to study the role of submarine groundwater discharge (SGD) of metal in this contaminated environment. Ra isotopes and metal concentrations have been determined in sea and porewater samples. Cd, Pb and Zn concentrations were higher or similar to the highest concentrations reported until now in the Mediterranean Sea, reaching up to values of 488 nM for Zn, 5.59 nM for Pb, 2.58 nM for Cd and 0.124 nM for Ag. Short live Ra isotopes (223Ra and 224Ra) allowed the calculation of a SGD flow of 6382 m3·d-1. Metal average fluxes have resulted to be, 3 ± 1 mol·day-1 for Cd, 0.5 ± 0.1 mol·day-1 for Co, 1057 ± 222 mol·day-1 for Fe, 0.9 ± 0.2 mol·day-1 for Ni, 5 ± 1 mol·day-1 for Pb, 11 ± 2 mol·day-1 for V and 118 ± 25 mol·day1 for Zn, most of them the highest values calculated be now in the Mediterranean. Those results showed the significance of SGD in the transport of metals to the sea in Portman Bay after 30 years of the last deposited tailing.La Badia de Portman està situada al districte miner de Pb i Zn a localitat de Cartagena - La Unión, Murcia, Espanya. Lloc considerat com el impacte ambiental més gran del Mar Mediterrani, on 57 milions de tones varen ser dipositades des de 1957 fins al 1991. L'objectiu d'aquest estudi són els fluxos de metalls conduïts per la descarrega marina d'aigua subterrània (SGD). S'han mesurat tant isòtops de Ra com concentracions de metalls dissolts en aigua intersticial i aigua del mar. Els isòtops de vida curta (223Ra i 224Ra) ens han permès calcular el flux de SGD 6382 m3·d-1. Metalls com el Cd, el Pb i el Zn han resultat tenir unes de les concentracions més altes publicades fins al dia d'avui al Mar Mediterrani, fins a un màxim de 488 nM de Zn 5.59 nM de Pb, 2.58 nM de Cd i 0.124 nM de Ag. La mitjana dels fluxos de metalls han estat, 3 ± 1 mol·d-1 pel Cd, 0.5 ± 0.1 mol·d-1 per Co, 1057 ± 222 mol·d-1 pel Fe, 0.9 ± 0.2 mol·d-1 pel Ni, 5 ± 1 mol·d-1 pel Pb, 11 ± 2 mol·d-1 pel V i 118 ± 25 mol·d-1 pel Zn, la majoria d'ells els valors més alts del mediterrani fins ara calculats. Aquests resultats han mostrat la importància del SGD amb el transport de metalls al mar a la Badia de Portman després de 25 anys dels últims abocaments.La Bahía de Portmán está situada en el distrito minero de Pb y Zn en la localidad de Cartagena-La Unión, Murcia, España. Lugar considerado como el impacto ambiental más grande del Mar Mediterráneo, donde 57 millones de toneladas fueron depositadas des de 1957 hasta el 1991. El objetivo de este estudio son los flujos de metales conducidos por la descarga marina de agua subterránea (SGD). Se han medido isótopos de Ra y concentraciones de metales disueltos en agua intersticial y agua del mar. Los isótopos de vida corta (223Ra i 224Ra) nos han permitido calcular el flujo de SGD 6382 m3·d-1. Metales como el Cd, el Pb y el Zn han resultado tener unas de las concentraciones más altas publicadas hasta hoy en el Mar Mediterráneo, con un máximo de 488 nM de Zn, 5.59 nM de Pb, 2.58 nM de Cd y 0.124 nM de Ag. Las medias de los flujos de metales han sido, 3 ± 1 mol·d-1 para el Cd, 0.5 ± 0.1 mol·d-1 para el Co, 1057 ± 222 mol·d-1 para el Fe, 0.9 ± 0.2 mol·d-1 para el Ni, 5 ± 1 mol·d-1 para el Pb, 11 ± 2 mol·d-1 para el V y 118 ± 25 mol·d-1 para el Zn, la mayoría de ellos son los valores más altos del Mediterráneo hasta ahora calculados. Estos resultados han mostrado la importancia del SGD en el transporte de metales al mar a la Bahía de Portmán después de 25 años de los últimos vertidos

The connection between Submarine Groundwater Discharge and seawater quality : The threat of treated wastewater injected into coastal aquifers

Altres ajuts: acords transformatius de la UABUnidad de excelencia María de Maeztu CEX2019-000940-MSubmarine Groundwater Discharge (SGD) delivers nutrients to the coastal sea triggering phytoplankton blooms, eutrophication, and can also serve as a pathway for contaminants. Wastewater treatment plants (WWTP) including injection wells in coastal areas influence coastal aquifers and might impact the composition and magnitude of SGD fluxes. In tourist areas, wastewater treatment may be less efficient and larger in volume during high seasons, potentially impacting nutrient fluxes from SGD and exacerbating environmental impacts. This study analyzes the nutrient transfer from treated wastewater injection in karstic aquifers to the coastal sea via SGD, considering the impacts of tourism seasonality. This study is conducted in Cala Deià, a small cove in the Balearic Islands, a Mediterranean tourist destination. The findings suggest that the seasonality of tourism, leading to variations in the volume of wastewater treated in the WWTP, influences the dynamics of the coastal aquifer. This leads to increased SGD water and nutrient fluxes to the sea in summer, i.e. the peak tourist season. The measured DIN, DIP, and DSi inventories in the cove are much larger in August than in April (3, 10, and 1.5 times higher, respectively) due to higher input of nutrients in summer due to SGD impacted by the WWTP. These elevated nutrient flows can support algal blooms in the cove, compromising water quality for local swimmers and tourists. Indeed, in August, shoreline stations exhibited eutrophic Chl-a concentrations, with peaks reaching approximately 4 mg Chl-a L. These elevated levels suggest the presence of an algal bloom during the survey. The anthropogenic origin of SGD-driven nutrients is traced in seawater and seagrass meadows, as evidenced by high ∂N signatures indicative of polluted areas. Thus, the high pressure exerted on coastal areas by tourism activities increased the magnitude of SGD nutrient fluxes, thereby threatening coastal ecosystems and the services they provide

Groundwater discharge as a driver of methane emissions from Arctic lakes

Lateral CH4 inputs to Arctic lakes through groundwater discharge could be substantial and constitute an important pathway that links CH4 production in thawing permafrost to atmospheric emissions via lakes. Yet, groundwater CH4 inputs and associated drivers are hitherto poorly constrained because their dynamics and spatial variability are largely unknown. Here, we unravel the important role and drivers of groundwater discharge for CH4 emissions from Arctic lakes. Spatial patterns across lakes suggest groundwater inflows are primarily related to lake depth and wetland cover. Groundwater CH4 inputs to lakes are higher in summer than in autumn and are influenced by hydrological (groundwater recharge) and biological drivers (CH4 production). This information on the spatial and temporal patterns on groundwater discharge at high northern latitudes is critical for predicting lake CH4 emissions in the warming Arctic, as rising temperatures, increasing precipitation, and permafrost thawing may further exacerbate groundwater CH4 inputs to lakes. CH4 inputs to Arctic lakes via groundwater discharge are an important pathway that links CH4 production in thawing permafrost to emission via lakes. Here the authors unravel the role and drivers of groundwater inflows for CH4 emissions from Arctic lakes.Funding Agencies|Umea University</p

New perspectives on the use of 224Ra/228Ra and 222Rn/226Ra activity ratios in groundwater studies

The naturally occurring Ra isotopes (223Ra; T1/2 = 11.4 d, 224Ra; T1/2 = 3.66 d, 226Ra; T1/2 = 1,600 y, and 228Ra; T1/2 = 5.7 y) and Rn (222Rn; T1/2 = 3.82 d) have been widely applied as environmental tracers. The application of these radioactive tracers has mainly been restricted to the evaluation of oceanographic and land-ocean interaction processes, although in recent years their use has also been extended to the study of groundwater systems. In this context, the activity ratios of 224Ra/228Ra and 222Rn/226Ra can be instrumental in providing key information on groundwater transit times in aquifers and those processes governing groundwater discharge into the coastal sea (often referred to as Submarine Groundwater Discharge or SGD). This work evaluates the potential use of these activity ratios as proxies for investigating groundwater systems through an advective transport model that integrates the radionuclides involved in these activity ratios (224Ra, 228Ra, 226Ra, and 222Rn) and their immediate parents into a single formulation. The results provided by the transport model indicate that the main factors controlling the 224Ra/228Ra and 222Rn/226Ra activity ratios are the alpha recoil supply, the retardation factor of Ra, and the groundwater transit times. The advective transport model and the activity ratios are used to present novel applications that interrelate the disciplines of hydrogeology and coastal oceanography. The main applications include the determination of groundwater transit times and the assessment of pathways and end-members related to submarine groundwater discharge processes. These applications were tested in a Mediterranean coastal aquifer.This work was partly funded by the projects PID2019-110212RB-C22, CGL2016-77122-C2-1-R/2-R and PID2019-110311RB-C21 of the Spanish Government and the project TerraMAr ACA210/18/00007 of the Catalan Water Agency. The authors want to thank the support of the Generalitat de Catalunya to MERS (2017 SGR-1588) and GHS (2017 SGR 1485) for additional funding. We would like to thank all the colleagues from the Laboratori de Radioactivitat Ambiental (Universitat Autònoma de Barcelona). We would also like to thank Leon Humphries for his detailed English corrections. 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. M. Diego‐Feliu acknowledges the economic support from the FI‐2017 fellowships of the Generalitat de Catalunya autonomous government (2017FI_B_00365). V. Rodellas acknowledges financial support from the Beatriu de Pinós postdoctoral program of the Generalitat de Catalunya autonomous government (2017‐BP‐00334). A. Alorda‐Kleinglass acknowledges financial support from ICTA “Unit of Excellence” (MinECo, MDM2015‐0552‐17‐1) and PhD fellowship, BES‐2017‐080740. T. Goyetche acknowledges PhD fellowship (BES‐2017‐080028) from the FPI Program by the Spanish Ministry of Economy, Industry and Competitiveness. A. Folch is a Serra Húnter Fellow.Peer reviewe