Joaquin Jimenez-Martinez

Last Name

Jimenez-Martinez

First Name

Joaquin

ORCID

0000-0002-2063-6490

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Publications 1 - 10 of 53

Estimating mixing processes of sources contributing to baseflow in Alpine headwater catchments
Floriancic, Marius; Roques, Clément; Jimenez-Martinez, Joaquin (2020)
EGUsphere
Characterizing the Impact of Fractured Caprock Heterogeneity on Supercritical CO2 Injection
Hyman, Jeffrey D.; Jimenez-Martinez, Joaquin; Gable, Carl W.; et al. (2020)
Transport in Porous Media
We present a set of multiphase flow simulations where supercritical CO2 (scCO2) displaces water at hydrostatic conditions within three-dimensional discrete fracture networks that represent paths for potential leakage through caprock above CO2 storage reservoirs. The simulations are performed to characterize and compare the relative impact of hydraulic and structural heterogeneity in fractured media on the initial movement of scCO2 through these caprock formations. In one scenario, intrinsic fracture permeabilities are varied stochastically within a fixed network structure. In another scenario, we generate multiple independent, identically distributed network realizations with varying fracture network densities to explore a wide range of geometric and topological configurations. Analysis of the simulations indicates that network structure, specifically connectivity and the presence of hanging fractures, plays a larger role in controlling the displacement of water by scCO2 than variations in local hydraulic properties. We identify active surface area of the network as a single-phase feature that could provide a lower bound on the percentage of the network surface area reached by scCO2.
Global warming accelerates soil heterotrophic respiration
Nissan, Alon; Alcolombri, Uria; Peleg, Nadav; et al. (2023)
Nature Communications
Carbon efflux from soils is the largest terrestrial carbon source to the atmosphere, yet it is still one of the most uncertain fluxes in the Earth’s carbon budget. A dominant component of this flux is heterotrophic respiration, influenced by several environmental factors, most notably soil temperature and moisture. Here, we develop a mechanistic model from micro to global scale to explore how changes in soil water content and temperature affect soil heterotrophic respiration. Simulations, laboratory measurements, and field observations validate the new approach. Estimates from the model show that heterotrophic respiration has been increasing since the 1980s at a rate of about 2% per decade globally. Using future projections of surface temperature and soil moisture, the model predicts a global increase of about 40% in heterotrophic respiration by the end of the century under the worst-case emission scenario, where the Arctic region is expected to experience a more than two-fold increase, driven primarily by declining soil moisture rather than temperature increase.
Localization in Flow of Non-Newtonian Fluids Through Disordered Porous Media
Seybold, Hansjörg Florian; Eberhard, U.; Secchi, Eleonora; et al. (2021)
Frontiers in Physics
We combine results of high-resolution microfluidic experiments with extensive numerical simulations to show how the flow patterns inside a “swiss-cheese” type of pore geometry can be systematically controlled through the intrinsic rheological properties of the fluid. Precisely, our analysis reveals that the velocity field in the interstitial pore space tends to display enhanced channeling under certain flow conditions. This observed flow “localization”, quantified by the spatial distribution of kinetic energy, can then be explained in terms of the strong interplay between the disordered geometry of the pore space and the nonlinear rheology of the fluid. Our results disclose the possibility that the constitutive properties of the fluid can enhance the performance of chemical reactors and chromatographic devices through control of the channeling patterns inside disordered porous media.
Computing the spatial-temporal evolution of groundwater recharge to the Quaternary aquifer of Campo de Cartagena (SE Spain) from 1970 to 2022
Alcaraz, Mar; Polo, María José; Hornero, Jorge; et al. (2024)
Ingeniería del Agua
Los objetivos del trabajo son evaluar la evolución temporal y espacial de la recarga al Acuífero del Cuaternario del Campo de Cartagena desde 1970 a 2022 y generar mapas de entrada para un modelo numérico de flujo de agua subterránea. Para alcanzarlos se han recopilado datos meteorológicos, se ha compilado y contrastado la información disponible sobre los usos de suelo, poniendo especial atención en la evolución temporal de la distribución espacial, se ha calculado la recarga con el software VisualBALAN y se han generado mapas de recarga que reflejan la evolución espacial y temporal durante el periodo simulado, con el apoyo de QGIS. La recarga calculada se ha calibrado y validado con éxito con series piezométricas temporales. La recarga total media calculada es 91 hm3 año-1 para todo el periodo; los valores extremos son 24 hm3 en 1978 y 172 hm3 en 2008. Esto se traduce en un coeficiente de recarga promedio del 16%, un valor mínimo del 8% y un máximo del 24%.
Aquifer recharge estimation and its origins in intensive irrigated agriculture
Polo Molina , María José; Soliva , Lucas; Alcaraz , Mar; et al. (2025)
Agricultural Water Management
Intensive agriculture often occurs in water-scarce regions, relying on diverse water sources such as imported non-local water–water transfers, treated wastewater, desalination, and groundwater. Efficient water use is crucial to minimize aquifer losses and fertilizer leachates. Understanding the contributions of these sources to both irrigation and aquifer recharge is essential due to differences in volume, quality, and cost. This study presents a methodology combining: i) a spatially distributed approach using the water-table-fluctuation (WTF) method to estimate total aquifer recharge and ii) an experimental assessment of precipitation and irrigation water contributions via mixing calculations. The method is validated through unsaturated flow and stable water isotope transport modeling, applied to the Campo de Cartagena aquifer (SE Spain). Findings reveal that irrigated area contributes ∼ 30 % of total recharge — ∼ 26 % in wet years and ∼ 41 % in dry years— primarily from annual row crops. Groundwater supplies 49 ± 13 % of crop water needs. Recharge contributions from different sources within the irrigated area include precipitation (16 %), Water Transfer (29 %), shallow aquifer (26 %), and the underlying confined aquifer (29 %). These results underscore the importance of quantifying individual water source contributions to irrigation and aquifer recharge, especially if the aquifer is one more water source, for improved water resource management at the catchment scale.
Reactive Transport with Fluid–Solid Interactions in Dual-Porosity Media
Nissan, Alon; Alcolombri, Uria; de Schaetzen, Frédéric; et al. (2021)
ACS ES&T Water
We study pore-scale dynamics of reactive transport in heterogeneous, dual-porosity media, wherein a reactant in the invading fluid interacts chemically with the surface of the permeable grains, leading to the irreversible reaction Aaq + Bs → Caq. A microfluidic porous medium was synthesized, consisting of a single layer of hydrogel pillars (grains), chemically modified to contain immobilized enzymes on the grain surfaces. Fluorescence microscopy was used to monitor the spatiotemporal evolution of the reaction product Caq at different flow rates (Péclet values) and to characterize the impact on its transport. The experimental setup enables delineation of three key features of the temporal evolution of the reaction product within the domain: (i) the characteristic time until the rate of Caq production reaches steady state, (ii) the magnitude of the reaction rate at steady state, and (iii) the rate at which Caq is flushed from the system. These features, individually, are found to be sensitive to the value of the Péclet number, because of the relative impact of diffusion (vs advection) on the production and spatiotemporal evolution of Caq within the system. As the Péclet number increases, the production of Caq is reduced and the transport becomes more localized within the vicinity of the grains. The dual-porosity feature causes the residence time of the transported species to increase, by forming stagnant zones and diffusive-dominant regions within the flow field, thus enhancing the reaction potential of the system. Using complementary numerical simulations, we explore these effects for a wider range of Péclet and Damköhler numbers and propose nonlinear scaling laws for the key features of the temporal evolution of Caq.
Reduced gravity promotes bacterially mediated anoxic hotspots in unsaturated porous media
Borer, Benedict; Jimenez-Martinez, Joaquin; Stocker, Roman; et al. (2020)
Scientific Reports
Human endeavours into deep space exploration and the prospects of establishing colonies on nearby planets would invariably involve components of bioregenerative life support for food production, cabin atmosphere renewal, and waste recycling. Growing plants and their microbiomes in porous media under different gravitational fields may present new challenges due to effects of liquid distribution on gaseous exchange with roots and microorganisms. We provide the first direct evidence that capillary driven liquid reconfiguration in porous media under reduced gravity conditions reduces oxygen diffusion pathways and enhances anoxic conditions within bacterial hotspots. Parabolic flight experiments using model porous media inoculated with aerobic and facultative anaerobic bacteria reveal the systematic enhancement of anoxic conditions during the reduced gravity periods in the presence but not in the absence of bacterial activity. The promotion of anoxic conditions under reduced gravity may lead to higher nitrous oxide and methane emissions relative to Earth conditions, on the other hand, anoxic conditions could be beneficial for perchlorate bioremediation of Martian soil. The results highlight changes in soil bacterial microhabitats under reduced gravity and the challenges of managing bioregenerative life support systems in space.
Microplastics in agricultural soils: The role of soil texture in modulating oxygen diffusivity and soil respiration
Nuñez, Jonathan; Jimenez-Martinez, Joaquin; Carminati, Andrea; et al. (2025)
Soil Biology and Biochemistry
The presence of microplastics (MPs) in soils impacts nutrient cycling and soil respiration. However, the mechanisms underpinning the direction and magnitude of these effects on soil are uncertain. We hypothesized that the presence of MPs affects pore connectivity, leading to changes in oxygen (O2) diffusivity and soil respiration. Furthermore, we anticipated that the magnitude of the effects would be dependent on both soil texture and MPs morphology. 1 % (w/w) PET MPs fibers (500 μm length) and fragments (125–250 μm) were spiked into rhizotrons filled with either clay or sandy loam soils. O2 diffusivity differences were determined in microcosm using an oxygen-free chamber. The O2 concentration in the soil was also measured in optimal conditions for respiration. O2 diffusivity and concentration were measured using optode imaging. Respiration was estimated from cumulative CO2 and changes in the size of the water-extractable carbon pool. Adding MPs decreased O2 concentration in the sandy loam soil (167.4 ± 6.1 mg L−1 air), with a greater reduction observed for fragments (15 %) compared to fibers (12 %). Soil respiration decreased by 40 % in both fragment and fiber treatments in alignment with the reduction in oxygen concentration. Conversely, in the clay soil, the addition of fibers and fragments resulted in a 13 and 7 % increase in O2 concentration compared to the control (177.9 ± 3.8 mg L−1 air). Both changes in oxygen concentration and diffusivity, show a similar response to MPs for the two soils. These findings indicate that the effects of MPs on soil respiration are likely driven by changes in O2 dynamics. However, the MPs' impact on O2 dynamics depends on soil particle size distribution. Future research should consider MP size, morphology, and soil particle distribution interactions to assess MPs' impacts on soil functions.
Eigenvector centrality for geometric and topological characterization of porous media
Negre, Christian F. A.; Jimenez-Martinez, Joaquin (2017)
Physical Review E

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Joaquin Jimenez-Martinez

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