GHS - Grup d'Hidrologia Subterrània
http://hdl.handle.net/2117/3289
2024-03-29T09:58:36ZSmoothed Particle Hydrodynamics for anisotropic dispersion in heterogeneous porous media
http://hdl.handle.net/2117/405478
Smoothed Particle Hydrodynamics for anisotropic dispersion in heterogeneous porous media
Pérez Illanes, Rodrigo Alfonso; Solé Marí, Guillem; Fernández García, Daniel
In the context of modeling solute transport through heterogeneous porous media, particle methods possess inherent advantages with respect to mesh-based (Eulerian) methods. In Smoothed Particle Hydrodynamics (SPH), particles represent fluid volumes exchanging concentrations with their neighbors to emulate hydrodynamic dispersion, and advection is simulated by the particles’ displacement. This crucially prevents problems that are otherwise typically associated with Eulerian advection schemes (especially at high grid-Péclet numbers), such as numerical diffusion. Despite the advantages of SPH, modeling dispersion with anisotropic coefficients remains a challenge for the approach, with studies reporting unphysical negative concentrations in conservative problems. This has likely hindered its practical use because dispersion is intrinsically anisotropic in porous media. This article provides a review and numerical evaluation of SPH for simulating dispersion, focusing on three formulations compatible with anisotropic dispersion coefficients. The analysis includes a scheme for which negative concentrations have been formerly reported, plus two more recently developed methods which are applied here for the first time to the problem of anisotropic dispersion in heterogeneous porous media. The SPH schemes are tested under different degrees of dispersion anisotropy for both homogeneous and heterogeneous velocity fields. The results indicate that the newer SPH schemes can produce accurate results without negative concentrations while considering anisotropic dispersion, providing a valid alternative to simulate solute transport through heterogeneous domains.
2024-03-27T18:32:37ZPérez Illanes, Rodrigo AlfonsoSolé Marí, GuillemFernández García, DanielIn the context of modeling solute transport through heterogeneous porous media, particle methods possess inherent advantages with respect to mesh-based (Eulerian) methods. In Smoothed Particle Hydrodynamics (SPH), particles represent fluid volumes exchanging concentrations with their neighbors to emulate hydrodynamic dispersion, and advection is simulated by the particles’ displacement. This crucially prevents problems that are otherwise typically associated with Eulerian advection schemes (especially at high grid-Péclet numbers), such as numerical diffusion. Despite the advantages of SPH, modeling dispersion with anisotropic coefficients remains a challenge for the approach, with studies reporting unphysical negative concentrations in conservative problems. This has likely hindered its practical use because dispersion is intrinsically anisotropic in porous media. This article provides a review and numerical evaluation of SPH for simulating dispersion, focusing on three formulations compatible with anisotropic dispersion coefficients. The analysis includes a scheme for which negative concentrations have been formerly reported, plus two more recently developed methods which are applied here for the first time to the problem of anisotropic dispersion in heterogeneous porous media. The SPH schemes are tested under different degrees of dispersion anisotropy for both homogeneous and heterogeneous velocity fields. The results indicate that the newer SPH schemes can produce accurate results without negative concentrations while considering anisotropic dispersion, providing a valid alternative to simulate solute transport through heterogeneous domains.The worth of stochastic inversion for identifying connectivity by means of a long-lasting large-scale hydraulic test: the Salar de Atacama case study
http://hdl.handle.net/2117/403547
The worth of stochastic inversion for identifying connectivity by means of a long-lasting large-scale hydraulic test: the Salar de Atacama case study
Trabucchi, Michela; Fernández García, Daniel; Carrera Ramírez, Jesús
Understanding groundwater flow involves characterizing the spatial variability of aquifer attributes and possible hydraulic connectivity structures. The latter are of crucial importance because high permeability channels may control groundwater flow and contaminant transport. In evaporitic aquifer systems, these preferential channels can consist of karst conduits, developed at different scales, as well as fault zones. These features condition the economic development of salt flats at the Central Andes. Hydraulic connectivity may affect exploitation efficiency by enhancing the inflow of less evaporated brine thus diminishing its mineral content (i.e., concentration of Li and K). In this context, we investigate if it is possible to use (tomographic) stochastic inversion (regularized pilot point method) in order to characterize the presence of connectivity structures in an evaporitic aquifer of great extension (some 1,500 km2) from head response measured at numerous observation points during a year long sequence of three hydraulic tests. Results show that, even though the solution is nonunique, the main preferential flow zones are identified. Numerous inversions yield similar fits to observed drawdowns with maximum errors of few centimeters. Preferential flow is identified not only by elongated high permeability regions, but also by a marked scale effect (model transmissivities are some 30 times larger than their local tests counterparts). The main high conductivity zones are consistent with independent information based on geophysics, isotopes, mixing ratios, piezometric data, and the expected dissolution processes.
2024-02-29T19:07:50ZTrabucchi, MichelaFernández García, DanielCarrera Ramírez, JesúsUnderstanding groundwater flow involves characterizing the spatial variability of aquifer attributes and possible hydraulic connectivity structures. The latter are of crucial importance because high permeability channels may control groundwater flow and contaminant transport. In evaporitic aquifer systems, these preferential channels can consist of karst conduits, developed at different scales, as well as fault zones. These features condition the economic development of salt flats at the Central Andes. Hydraulic connectivity may affect exploitation efficiency by enhancing the inflow of less evaporated brine thus diminishing its mineral content (i.e., concentration of Li and K). In this context, we investigate if it is possible to use (tomographic) stochastic inversion (regularized pilot point method) in order to characterize the presence of connectivity structures in an evaporitic aquifer of great extension (some 1,500 km2) from head response measured at numerous observation points during a year long sequence of three hydraulic tests. Results show that, even though the solution is nonunique, the main preferential flow zones are identified. Numerous inversions yield similar fits to observed drawdowns with maximum errors of few centimeters. Preferential flow is identified not only by elongated high permeability regions, but also by a marked scale effect (model transmissivities are some 30 times larger than their local tests counterparts). The main high conductivity zones are consistent with independent information based on geophysics, isotopes, mixing ratios, piezometric data, and the expected dissolution processes.Influence of turn cycle structure on performance of elite alpine skiers assessed through an IMU in different slalom course settings
http://hdl.handle.net/2117/403546
Influence of turn cycle structure on performance of elite alpine skiers assessed through an IMU in different slalom course settings
Pérez-Chirinos Buxadé, Carla; Padullés Riu, Josep Maria; Gavaldà Castet, Dani; Trabucchi, Michela; Fernández-Valdés, Bruno; Tuyà Viñas, Sílvia; Moras Feliu, Gerard
Small differences in turn cycle structure, invisible to the naked eye, could be decisive in improving descent performance. The aim of this study was to assess the influence of turn cycle structure on the performance of elite alpine skiers using an inertial measurement unit (IMU) in different slalom (SL) course settings. Four SL courses were set: a flat-turned (FT), a steep-turned (ST), a flat-straighter (FS) and a steep-straighter (SS). Five elite alpine skiers (21.2 ± 3.3 years, 180.2 ± 5.6 cm, 72.8 ± 6.6 kg) completed several runs at maximum speed for each SL course. A total of 77 runs were obtained. Fast total times correlate with a longer initiation (INI) time in FT, a shorter steering time out of the turn (STEOUT) in the FT and FS and a shorter total steering time (STEIN+OUT) in the FT and SS courses. The linear mixed model used for the analysis revealed that in the FT-course for each second increase in the INI time, the total time is reduced by 0.45 s, and for every one-second increase in the STEOUT and STEIN+OUT times, the total time increases by 0.48 s and 0.31 s, respectively. Thus, to enhance descent performance, the skier should lengthen the INI time and shorten the STEOUT and STEIN+OUT time. Future studies could use an IMU to detect turn phases and analyze them using the other built-in sensors.
2024-02-29T18:57:26ZPérez-Chirinos Buxadé, CarlaPadullés Riu, Josep MariaGavaldà Castet, DaniTrabucchi, MichelaFernández-Valdés, BrunoTuyà Viñas, SílviaMoras Feliu, GerardSmall differences in turn cycle structure, invisible to the naked eye, could be decisive in improving descent performance. The aim of this study was to assess the influence of turn cycle structure on the performance of elite alpine skiers using an inertial measurement unit (IMU) in different slalom (SL) course settings. Four SL courses were set: a flat-turned (FT), a steep-turned (ST), a flat-straighter (FS) and a steep-straighter (SS). Five elite alpine skiers (21.2 ± 3.3 years, 180.2 ± 5.6 cm, 72.8 ± 6.6 kg) completed several runs at maximum speed for each SL course. A total of 77 runs were obtained. Fast total times correlate with a longer initiation (INI) time in FT, a shorter steering time out of the turn (STEOUT) in the FT and FS and a shorter total steering time (STEIN+OUT) in the FT and SS courses. The linear mixed model used for the analysis revealed that in the FT-course for each second increase in the INI time, the total time is reduced by 0.45 s, and for every one-second increase in the STEOUT and STEIN+OUT times, the total time increases by 0.48 s and 0.31 s, respectively. Thus, to enhance descent performance, the skier should lengthen the INI time and shorten the STEOUT and STEIN+OUT time. Future studies could use an IMU to detect turn phases and analyze them using the other built-in sensors.Role of soil biofilms in clogging and fate of pharmaceuticals: a laboratory-scale column experiment
http://hdl.handle.net/2117/398956
Role of soil biofilms in clogging and fate of pharmaceuticals: a laboratory-scale column experiment
Muñoz Vega, Edinsson; Schulz, Stephan; Rodríguez Escales, Paula-Felicidad; Behle, Vera Rebecca; Spada, Lucas; Vogel, Alexander L.; Sánchez Vila, Francisco Javier; Schüth, Christoph
Contamination of groundwater with pharmaceutical active compounds (PhACs) increased over the last decades. Potential pathways of PhACs to groundwater include techniques such as irrigation, managed aquifer recharge, or bank filtration as well as natural processes such as losing streams of PhACs-loaded source waters. Usually, these systems are characterized by redox-active zones, where microorganisms grow and become immobilized by the formation of biofilms, structures that colonize the pore space and decrease the infiltration capacities, a phenomenon known as bioclogging. The goal of this work is to gain a deeper understanding of the influence of soil biofilms on hydraulic conductivity reduction and the fate of PhACs in the subsurface. For this purpose, we selected three PhACs with different physicochemical properties (carbamazepine, diclofenac, and metoprolol) and performed batch and column experiments using a natural soil, as it is and with the organic matter removed, under different biological conditions. We observed enhanced sorption and biodegradation for all PhACs in the system with higher biological activity. Bioclogging was more prevalent in the absence of organic matter. Our results differ from works using artificial porous media and thus reveal the importance of utilizing natural soils with organic matter in studies designed to assess the role of soil biofilms in bioclogging and the fate of PhACs in soils.
2024-01-09T19:01:46ZMuñoz Vega, EdinssonSchulz, StephanRodríguez Escales, Paula-FelicidadBehle, Vera RebeccaSpada, LucasVogel, Alexander L.Sánchez Vila, Francisco JavierSchüth, ChristophContamination of groundwater with pharmaceutical active compounds (PhACs) increased over the last decades. Potential pathways of PhACs to groundwater include techniques such as irrigation, managed aquifer recharge, or bank filtration as well as natural processes such as losing streams of PhACs-loaded source waters. Usually, these systems are characterized by redox-active zones, where microorganisms grow and become immobilized by the formation of biofilms, structures that colonize the pore space and decrease the infiltration capacities, a phenomenon known as bioclogging. The goal of this work is to gain a deeper understanding of the influence of soil biofilms on hydraulic conductivity reduction and the fate of PhACs in the subsurface. For this purpose, we selected three PhACs with different physicochemical properties (carbamazepine, diclofenac, and metoprolol) and performed batch and column experiments using a natural soil, as it is and with the organic matter removed, under different biological conditions. We observed enhanced sorption and biodegradation for all PhACs in the system with higher biological activity. Bioclogging was more prevalent in the absence of organic matter. Our results differ from works using artificial porous media and thus reveal the importance of utilizing natural soils with organic matter in studies designed to assess the role of soil biofilms in bioclogging and the fate of PhACs in soils.Enhancing mixing during groundwater remediation via engineered injection-extraction: the issue of connectivity
http://hdl.handle.net/2117/398934
Enhancing mixing during groundwater remediation via engineered injection-extraction: the issue of connectivity
Bertran Oller, Oriol; Fernández García, Daniel; Solé Marí, Guillem; Rodríguez Escales, Paula-Felicidad
In the context of in situ groundwater remediation, mixing is vital for a successful outcome. A slow mixing rate between the contaminated groundwater and the injected treatment solution can severely weaken the effective degradation rate. Engineered Injection-Extraction (EIE) has been proposed as a means to accelerate dilution within the porous medium. However, existing studies on the subject have not considered the potential impact of connectivity and preferential flow-paths. Neglecting connectivity can lead to an overestimation of EIE's capabilities, since the fluid may in reality be carried mainly through a few high-permeability channels, thus hampering mixing and reaction. Due to the fact that channeling can be found in many actual sites, in this work we aim to evaluate EIE methods in both poorly connected (represented as Multigaussian fields) and well-connected fields (represented as non-Multigaussians). The approach is to identify, for each given medium, a stirring protocol—defined by a specific combination of rotation angle and rotation rate—which maximizes mixing. To that end, metrics are proposed in order to (a) quantify both the mixing and the containment of the treatment solution within a given remediation volume, and (b) characterize the particle trajectories to explicitly evaluate if preferential paths are broken. The results obtained from these metrics are quite similar for both types of fields, proving that the enhancing of mixing by means of EIE is effective regardless of the presence of preferential flow paths. This study demonstrates that EIE via rotating dipoles diminishes the remediation outcome uncertainty induced by medium heterogeneity.
2024-01-09T15:52:30ZBertran Oller, OriolFernández García, DanielSolé Marí, GuillemRodríguez Escales, Paula-FelicidadIn the context of in situ groundwater remediation, mixing is vital for a successful outcome. A slow mixing rate between the contaminated groundwater and the injected treatment solution can severely weaken the effective degradation rate. Engineered Injection-Extraction (EIE) has been proposed as a means to accelerate dilution within the porous medium. However, existing studies on the subject have not considered the potential impact of connectivity and preferential flow-paths. Neglecting connectivity can lead to an overestimation of EIE's capabilities, since the fluid may in reality be carried mainly through a few high-permeability channels, thus hampering mixing and reaction. Due to the fact that channeling can be found in many actual sites, in this work we aim to evaluate EIE methods in both poorly connected (represented as Multigaussian fields) and well-connected fields (represented as non-Multigaussians). The approach is to identify, for each given medium, a stirring protocol—defined by a specific combination of rotation angle and rotation rate—which maximizes mixing. To that end, metrics are proposed in order to (a) quantify both the mixing and the containment of the treatment solution within a given remediation volume, and (b) characterize the particle trajectories to explicitly evaluate if preferential paths are broken. The results obtained from these metrics are quite similar for both types of fields, proving that the enhancing of mixing by means of EIE is effective regardless of the presence of preferential flow paths. This study demonstrates that EIE via rotating dipoles diminishes the remediation outcome uncertainty induced by medium heterogeneity.An assessment tool to improve rural groundwater access: integrating hydrogeological modelling with socio-technical factors
http://hdl.handle.net/2117/398866
An assessment tool to improve rural groundwater access: integrating hydrogeological modelling with socio-technical factors
Cid Escobar, Daniela; Folch Sancho, Albert; Ferrer Ramos, Nuria; Katuva, Jacob; Sánchez Vila, Francisco Javier
Sustainable exploitation of groundwater resources for drinking water provision in rural communities in sub-Sahara Africa remains elusive due to the limited knowledge of these hydrogeological systems. This is exacerbated by poor maintenance of existing infrastructure, limited technical capacity, the socio-economic characteristics of the area and poor governance. Assessing the likelihood of a given individual user experiencing water shortage calls for an interdisciplinary approach. After a preliminary multifactorial analysis incorporating a range of variables from technical to societal, it was found that most of the overall risk of water shortage for an individual household could be attributed to three factors; (1) Proximity, specified as the distance to the closest supply well (determined by geographical parameters), (2) Availability of good quality water in the wells (determined by hydrogeological understanding and modelling), and (3) Sustainability (determined by socio-technical and socio-economic parameters). In the latter case, a distinction was made between hardware functionality- the water point's performance considering a sufficient yield and reliability through time- and software functionality, based on a combination of socioeconomic data from surveys and analysed using Multiple Factor Analysis (MFA). All three factors are eventually mapped onto indicators in the range of [0–1] and then represented in a Geographical Information System based on the partition of the entire spatial domain (e.g., counties, villages, and neighbourhoods). The three indicators are then combined in a final index based on the product of the three factors, thus mapping time-dependent overall risk and allowing the assessment of temporal risk-evolution scenarios. The methodology is applied to Kwale County, Kenya, where community handpumps and groundwater points comprise the main water supply system. Apart from mapping the present situation, the methodology is finally used to assess the impact of future climate scenarios.
2024-01-08T20:13:59ZCid Escobar, DanielaFolch Sancho, AlbertFerrer Ramos, NuriaKatuva, JacobSánchez Vila, Francisco JavierSustainable exploitation of groundwater resources for drinking water provision in rural communities in sub-Sahara Africa remains elusive due to the limited knowledge of these hydrogeological systems. This is exacerbated by poor maintenance of existing infrastructure, limited technical capacity, the socio-economic characteristics of the area and poor governance. Assessing the likelihood of a given individual user experiencing water shortage calls for an interdisciplinary approach. After a preliminary multifactorial analysis incorporating a range of variables from technical to societal, it was found that most of the overall risk of water shortage for an individual household could be attributed to three factors; (1) Proximity, specified as the distance to the closest supply well (determined by geographical parameters), (2) Availability of good quality water in the wells (determined by hydrogeological understanding and modelling), and (3) Sustainability (determined by socio-technical and socio-economic parameters). In the latter case, a distinction was made between hardware functionality- the water point's performance considering a sufficient yield and reliability through time- and software functionality, based on a combination of socioeconomic data from surveys and analysed using Multiple Factor Analysis (MFA). All three factors are eventually mapped onto indicators in the range of [0–1] and then represented in a Geographical Information System based on the partition of the entire spatial domain (e.g., counties, villages, and neighbourhoods). The three indicators are then combined in a final index based on the product of the three factors, thus mapping time-dependent overall risk and allowing the assessment of temporal risk-evolution scenarios. The methodology is applied to Kwale County, Kenya, where community handpumps and groundwater points comprise the main water supply system. Apart from mapping the present situation, the methodology is finally used to assess the impact of future climate scenarios.A novel application of entropy analysis for assessing changes in movement variability during cumulative tackles in young elite rugby league players
http://hdl.handle.net/2117/397583
A novel application of entropy analysis for assessing changes in movement variability during cumulative tackles in young elite rugby league players
Fernández-Valdés, Bruno; Jones, Ben; Hendricks, Sharief; Weaving, Dan; Ramírez López, Carlos; Whitehead, Sarah; González, Jacob; Gisbert Orozco, Jose; Trabucchi, Michela; Moras, Gerard
The aim of this study was to identify between-position (forwards vs. backs) differences in movement variability in cumulative tackle events training during both attacking and defensive roles. Eleven elite adolescent male rugby league players volunteered to participate in this study (mean ± SD, age; 18.5 ± 0.5 years, height; 179.5 ± 5.0 cm, body mass; 88.3 ± 13.0 kg). Participants performed a drill encompassing four blocks of six tackling (i.e. tackling an opponent) and six tackled (i.e. being tackled by an opponent while carrying a ball) events (i.e. 48 total tackles) while wearing a micro-technological inertial measurement unit (WIMU, Realtrack Systems, Spain). The acceleration data were used to calculate sample entropy (SampEn) to analyse the movement variability during tackles performance. In tackling actions SampEn showed significant between-position differences in block 1 (p = 0.0001) and block 2 (p = 0.0003). Significant between-block differences were observed in backs (block 1 vs 3, p = 0,0021; and block 1 vs 4, p = 0,0001) but not in forwards. When being tackled, SampEn showed significant between-position differences in block 1 (p = 0.0007) and block 3 (p = 0.0118). Significant between-block differences were only observed for backs in block 1 vs 4 (p = 0,0025). Movement variability shows a progressive reduction with cumulative tackle events, especially in backs and when in the defensive role (tackling). Forwards present lower movement variability values in all blocks, particularly in the first block, both in the attacking and defensive role. Entropy measures can be used by practitioners as an alternative tool to analyse the temporal structure of variability of tackle actions and quantify the load of these actions according to playing position.
2023-12-04T10:18:43ZFernández-Valdés, BrunoJones, BenHendricks, ShariefWeaving, DanRamírez López, CarlosWhitehead, SarahGonzález, JacobGisbert Orozco, JoseTrabucchi, MichelaMoras, GerardThe aim of this study was to identify between-position (forwards vs. backs) differences in movement variability in cumulative tackle events training during both attacking and defensive roles. Eleven elite adolescent male rugby league players volunteered to participate in this study (mean ± SD, age; 18.5 ± 0.5 years, height; 179.5 ± 5.0 cm, body mass; 88.3 ± 13.0 kg). Participants performed a drill encompassing four blocks of six tackling (i.e. tackling an opponent) and six tackled (i.e. being tackled by an opponent while carrying a ball) events (i.e. 48 total tackles) while wearing a micro-technological inertial measurement unit (WIMU, Realtrack Systems, Spain). The acceleration data were used to calculate sample entropy (SampEn) to analyse the movement variability during tackles performance. In tackling actions SampEn showed significant between-position differences in block 1 (p = 0.0001) and block 2 (p = 0.0003). Significant between-block differences were observed in backs (block 1 vs 3, p = 0,0021; and block 1 vs 4, p = 0,0001) but not in forwards. When being tackled, SampEn showed significant between-position differences in block 1 (p = 0.0007) and block 3 (p = 0.0118). Significant between-block differences were only observed for backs in block 1 vs 4 (p = 0,0025). Movement variability shows a progressive reduction with cumulative tackle events, especially in backs and when in the defensive role (tackling). Forwards present lower movement variability values in all blocks, particularly in the first block, both in the attacking and defensive role. Entropy measures can be used by practitioners as an alternative tool to analyse the temporal structure of variability of tackle actions and quantify the load of these actions according to playing position.Exploring the biocapacitance in M3C-based biosensors for the assessment of microbial activity and organic matter
http://hdl.handle.net/2117/395313
Exploring the biocapacitance in M3C-based biosensors for the assessment of microbial activity and organic matter
Fernández Gatell, Marta; Sánchez Vila, Francisco Javier; Puigagut Juárez, Jaume
Reliable monitoring of microbial and water quality parameters in freshwater ecosystems (either natural or human-made) is of capital importance for improving both the management of water resources and the assessment of microbially-driven bio-geo-chemical processes. In this context, bioelectrochemical systems (BES), such as microbial three-cell electrodes (M3C), are very promising devices for their use as biosensors. However, current experiences on the use of BES-based devices for biosensing purposes are almost exclusively limited to water-saturated environments. This limitation hampers the use of this technology for a wider range of applications where the biosensor may work discontinuously (such as discontinuously saturated ecosystems). Discontinuous operation of M3C-based biosensors creates an electric current peak immediately after the reconnection of the system due to electron accumulation, in a process known as biocapacitance. The present work aimed at quantifying the bioindication potential of biocapacitance for the assessment of key ecosystem parameters such as microbial metabolic activity and biomass, as well as organic matter concentration. Significant linear regression coefficients (R2¿>¿0.9) were found for all combinations of parameters tested. Moreover, for most of the ecological parameters assessed, an electric charge accumulation of 1–5¿min (biocapacitance elapsed time) and discharge of 5¿min was enough to get reliable information. In conclusion, we have demonstrated for the first time that biocapacitance in M3C-based biosensors can be used as a proxy parameter for the assessment of microbial activity, microbial biomass and organic matter concentration in a model nature-based ecosystem.
2023-10-24T13:38:48ZFernández Gatell, MartaSánchez Vila, Francisco JavierPuigagut Juárez, JaumeReliable monitoring of microbial and water quality parameters in freshwater ecosystems (either natural or human-made) is of capital importance for improving both the management of water resources and the assessment of microbially-driven bio-geo-chemical processes. In this context, bioelectrochemical systems (BES), such as microbial three-cell electrodes (M3C), are very promising devices for their use as biosensors. However, current experiences on the use of BES-based devices for biosensing purposes are almost exclusively limited to water-saturated environments. This limitation hampers the use of this technology for a wider range of applications where the biosensor may work discontinuously (such as discontinuously saturated ecosystems). Discontinuous operation of M3C-based biosensors creates an electric current peak immediately after the reconnection of the system due to electron accumulation, in a process known as biocapacitance. The present work aimed at quantifying the bioindication potential of biocapacitance for the assessment of key ecosystem parameters such as microbial metabolic activity and biomass, as well as organic matter concentration. Significant linear regression coefficients (R2¿>¿0.9) were found for all combinations of parameters tested. Moreover, for most of the ecological parameters assessed, an electric charge accumulation of 1–5¿min (biocapacitance elapsed time) and discharge of 5¿min was enough to get reliable information. In conclusion, we have demonstrated for the first time that biocapacitance in M3C-based biosensors can be used as a proxy parameter for the assessment of microbial activity, microbial biomass and organic matter concentration in a model nature-based ecosystem.Multirate mass transfer simulation of denitrification in a woodchip bioreactor
http://hdl.handle.net/2117/392153
Multirate mass transfer simulation of denitrification in a woodchip bioreactor
Wang, Jingjing; Carrera Ramírez, Jesús; Valhondo González, Cristina; Saaltink, Maarten Willem; Petchamé Guerrero, Jordi; Zhang, Fengshou; Herbert, Roger
Denitrifying woodchip bioreactors (DWBs) have proven to be an efficient nature-based solution for nitrate removal. Modeling DWBs is required for improving their design and operation, but is hindered by the complexity of the modeled system where numerous chemical species and model parameters are needed. Reactions inside the woodchips are different from those at the edges, causing chemical localization (i.e., apparent simultaneous occurrence of incompatible reactions). We used the Multi Rate Mass Transfer (MRMT) approach to overcome these problems when simulating reactive transport processes in a DWB located at Kiruna, Sweden. Besides denitrification, other nitrogen-cycling processes (e.g., nitrification, dissimilatory nitrate reduction to ammonium, anammox) and alternative electron donors (e.g. oxygen, sulfate) were also considered. Biomass concentration is incorporated into the biochemical reaction rates, including growth and decay, to characterize microbial catalysis. We found that the MRMT model: 1) can account for the heterogeneity of the porous woodchips; 2) was capable of reproducing the nitrogen species evolution in the DWB with kinetic parameters from the literature; and 3) allows reproducing localized biochemical reactions (e.g., aerobic reactions on the woodchip edges, near the DWB entrance and anaerobic reactions inside); and 4) reproduces the full denitrification reactions sequence, but with the different reactions occurring in different portions of the woodchip (e.g., nitrate to nitrite near the edges and nitrite to nitrous oxide further inside). The latter observation suggests that increasing woodchip size may reduce the outflow of these undesired species.
2023-07-25T10:30:18ZWang, JingjingCarrera Ramírez, JesúsValhondo González, CristinaSaaltink, Maarten WillemPetchamé Guerrero, JordiZhang, FengshouHerbert, RogerDenitrifying woodchip bioreactors (DWBs) have proven to be an efficient nature-based solution for nitrate removal. Modeling DWBs is required for improving their design and operation, but is hindered by the complexity of the modeled system where numerous chemical species and model parameters are needed. Reactions inside the woodchips are different from those at the edges, causing chemical localization (i.e., apparent simultaneous occurrence of incompatible reactions). We used the Multi Rate Mass Transfer (MRMT) approach to overcome these problems when simulating reactive transport processes in a DWB located at Kiruna, Sweden. Besides denitrification, other nitrogen-cycling processes (e.g., nitrification, dissimilatory nitrate reduction to ammonium, anammox) and alternative electron donors (e.g. oxygen, sulfate) were also considered. Biomass concentration is incorporated into the biochemical reaction rates, including growth and decay, to characterize microbial catalysis. We found that the MRMT model: 1) can account for the heterogeneity of the porous woodchips; 2) was capable of reproducing the nitrogen species evolution in the DWB with kinetic parameters from the literature; and 3) allows reproducing localized biochemical reactions (e.g., aerobic reactions on the woodchip edges, near the DWB entrance and anaerobic reactions inside); and 4) reproduces the full denitrification reactions sequence, but with the different reactions occurring in different portions of the woodchip (e.g., nitrate to nitrite near the edges and nitrite to nitrous oxide further inside). The latter observation suggests that increasing woodchip size may reduce the outflow of these undesired species.Disparities in disruptions to public drinking water services in Texas communities during Winter Storm Uri 2021
http://hdl.handle.net/2117/390729
Disparities in disruptions to public drinking water services in Texas communities during Winter Storm Uri 2021
Tomko, Brianna; Nittrouer, Christine; Sánchez Vila, Francisco Javier; Sawyer, Audrey
Winter Storm Uri of February 2021 left millions of United States residents without access to reliable, clean domestic water during the COVID19 pandemic. In the state of Texas, over 17 million people served by public drinking water systems were placed under boil water advisories for periods ranging from one day to more than one month. We performed a geospatial analysis that combined public boil water advisory data for Texas with demographic information from the 2010 United States Census to understand the affected public water systems and the populations they served. We also issued a cross-sectional survey to account for people’s lived experiences. Geospatial analysis shows that the duration of boil water advisories depended partly on the size of the public water system. Large, urban public water systems issued advisories of intermediate length (5–7 days) and served racially diverse communities of moderate income. Small, mostly rural public water systems issued some of the longest advisories (20 days or more). Many of these systems served disproportionately White communities of lower income, but some served predominantly non-White, Hispanic, and Latino communities. In survey data, “first-generation” participants (whose parents were not college-educated) were more likely to be placed under boil water advisories, pointing to disparate impacts by socioeconomic group. The survey also revealed large communication gaps between public water utilities and individuals: more than half of all respondents were unsure or confused about whether they were issued a boil water advisory. Our study reinforces the need to improve resilience in public water services for large, diverse, urban communities and small, rural communities in the United States and to provide a clear and efficient channel for emergency communications between public water service utilities and the communities they serve. This article includes Accessible Data.
2023-07-12T14:21:26ZTomko, BriannaNittrouer, ChristineSánchez Vila, Francisco JavierSawyer, AudreyWinter Storm Uri of February 2021 left millions of United States residents without access to reliable, clean domestic water during the COVID19 pandemic. In the state of Texas, over 17 million people served by public drinking water systems were placed under boil water advisories for periods ranging from one day to more than one month. We performed a geospatial analysis that combined public boil water advisory data for Texas with demographic information from the 2010 United States Census to understand the affected public water systems and the populations they served. We also issued a cross-sectional survey to account for people’s lived experiences. Geospatial analysis shows that the duration of boil water advisories depended partly on the size of the public water system. Large, urban public water systems issued advisories of intermediate length (5–7 days) and served racially diverse communities of moderate income. Small, mostly rural public water systems issued some of the longest advisories (20 days or more). Many of these systems served disproportionately White communities of lower income, but some served predominantly non-White, Hispanic, and Latino communities. In survey data, “first-generation” participants (whose parents were not college-educated) were more likely to be placed under boil water advisories, pointing to disparate impacts by socioeconomic group. The survey also revealed large communication gaps between public water utilities and individuals: more than half of all respondents were unsure or confused about whether they were issued a boil water advisory. Our study reinforces the need to improve resilience in public water services for large, diverse, urban communities and small, rural communities in the United States and to provide a clear and efficient channel for emergency communications between public water service utilities and the communities they serve. This article includes Accessible Data.