Subsurface Environments Research Articles

A unique prokaryotic vertical distribution in the groundwaters of deep sedimentary geological settings in Hokkaido, Japan

The purpose of this study is to clarify the vertical prokaryotic distribution in groundwater in a terrestrial subsurface sedimentary environment with a geological complex. Six groundwater samples were collected from a coastal 1200-m-deep borehole in which digging strata deposited between 2.3 and 1.5 Ma in Horonobe, Hokkaido, Japan. The studied succession was divided into three vertical zones that were geochemically differentiated according to their chloride contents and water-stable isotopes. The upper zone (UZ; shallower than 500 m) primarily contained fresh water supplied by penetrating meteoric water, the connate water zone (CWZ; deeper than 790 m) contained paleo-seawater, and the diffusion zone (DZ; 500–790 m depth) located between UZ and CWZ. Fluctuations in the prokaryotic density and constituents were observed across these three zones. The prokaryotic density decreased from UZ toward DZ, and the density of DZ was two orders of magnitude lower than that of UZ and CWZ. High prokaryotic activity was observed in CWZ below DZ. The upward expansion of prokaryotic distribution from CWZ, where high prokaryotic potential expressed by biomass can be maintained almost equivalent to that in the marine environment, probably occurred on a geological timescale from 80 ka to 1.3 Ma, as shown by the groundwater age of DZ. The DZ is a zone where the geochemistry has changed drastically owing to the mixing of penetrating meteoric water and the diffusion of deep paleo-seawater, preserving a unique subsurface environment. This chemically mixed zone might be considered as a buffering zone for prokaryotes to prevent the expansion of prokaryotic density and activity provided by diffusion and their in situ growth from both above and below the zones, which is expected to be maintained over a geological timescale. This zone is considered important for using subsurface space in the deep subsurface environment of the island arc.

Sedimentation kinetics and stability mechanisms of iron and manganese colloids in simulated groundwater

The occurrence of different forms of iron and manganese colloids in the subsurface environment has been widely reported.

Virus production in shallow groundwater at the bank of the Danube River.

Viruses play a crucial role in regulating prokaryotic populations, yet their impact on subsurface environments, specifically groundwater habitats, remains poorly understood. In this study, we employed the virus-dilution approach to measure lytic virus production rates in shallow groundwater located near the city of Vienna (Austria) during the period from July-November 2020. Physico-chemical parameters (pH, electrical conductivity, water temperature, concentration of dissolved oxygen), prokaryotic, and viral abundance, and viral decay rates were monitored as well. Our findings revealed low virus-to-prokaryote ratios varying between 0.9-3.9 throughout the study period and a lack of correlation between prokaryotic and viral abundance in groundwater. Virus production rates varied between 9-12% of viral abundance h-1 in July-August and between 34-36% of viral abundance h-1 in October-November. Seasonal variations in virus production rates were found to be correlated with electrical conductivity, revealing ~3.5 times higher virus production rates during periods with high electrical conductivity and low groundwater recharge in October-November compared to July-August with higher groundwater recharge and lower electrical conductivity. Our data indicate that groundwater recharge disrupts the balance between virus and prokaryotic host communities, resulting in a deficiency of suitable prokaryotic host cells for viral proliferation.

Mobility of biochar-derived dissolved organic matters and their effects on sulfamerazine transport through saturated soil porous media

Dissolved organic matter (DOM) released from biochar may impact antibiotics mobility and environmental fate in subsurface environments. Here, DOM derived from biochars (BDOMs) generated by pyrolyzing corn straw at 300,...

Advanced IoT-Based Wireless Sensors for Remote Geotechnical Monitoring and Structural Diagnostics

This paper presents an innovative design and implementation of a wireless sensor module using low-power Internet of Things (IoT) technologies for applications in geotechnical engineering and structural diagnostics, with a main focus on monitoring rock formations below the water surface in areas without access to electrical power. Designed for continuous monitoring of linear displacements and other critical parameters in structural engineering, geotechnical engineering and engineering diagnostics, this sensor module is particularly useful in remote locations. Utilizing wireless data transmission and advanced IoT technologies such as LoRa, IQRF and NB-IoT, this system allows for flexible coverage options and efficient remote management. The system allows users to remotely change measurement parameters, the period of messaging and set thresholds for alarm activation. The study highlights the importance of innovative IoT solutions to improve accuracy and efficiency in monitoring geotechnical and civil engineering structures, especially in challenging sub-surface environments, opening new opportunities for predictive maintenance and risk management in these specific applications.

Preliminary Assessment of Badajo Cave (Segovia, Spain) Stability Using Empirical, Numerical and Remote Techniques

Badajo cave is a shallow cavity (hemispherical rock shelter) located in the valley of Clamores River (Segovia city, Central Spain). This small canyon carved in Cretaceous dolostones has numerous geosites, as well as a rich archaeological and historical heritage. There are dozens of rock outcrops in the valley’s cliffs and slopes, on both banks, where various types of sedimentary rocks can be easily recognized and differentiated, especially carbonates (dolostones and limestones), and mixed carbonate-detrital (dolomitic sandstones, calcareous silts, marls). The cave was formed by karstic and gravitational processes within a mixed dolomitic sandstones and limestones, and it has an important archaeological interest. This study proposes a preliminary stability analyses of the cave applying: (i) empirical approaches based on geomechanical classifications using Barton’s Q Index, Rock Mass Rating (RMR) and the recently created Cave Geomechanical Index (CGI); (ii) three-dimensional model generated with the remote photogrammetric technique Structure from Motion (SfM) to allow acquisition of data to complete values collected in the geomechanical station, and to create the numerical model of the critical sections of the cave; and (iii) numerical simulations using a 2D model based on the generalized Hoek and Brown failure criterion and a 3D wedge analysis. The results of the analysis show that the cave is stable, although it presents some places with small problems (falls of slabs and blocks) that deserve monitoring. Furthermore, the evaluation by the geomechanical classification Q and the corresponding abacus of cave stability indicates that it is located in the “transition” zone where attention is required. In addition, SfM photogrammetric technique makes possible to generate a geometric 3D model that allowed the acquisition of data that were difficult to take in situ. The geotechnical parameters obtained from the different methods complement each other, resulting in a more realistic engineering representation of the subsurface environment. As a conclusion, a graph showing the two empirical methodologies (Barton’s Q Index and CGI), and some recommendation for a future analysis are given.

Soil Survey and Lithogeochemical Techniques in Mineral Exploration

This paper investigates the critical roles of soil surveys and lithologic evaluation in identifying potential mineral resources. Soil surveys involve the systematic mapping, examination, description, and classification of soils within a defined area. Through targeted sampling and laboratory analysis, these surveys can reveal the concentration of metals in the soil. By analyzing these metal signatures, geoscientists can infer the underlying geology and identify areas with a higher likelihood of hosting valuable mineral deposits. Lithologic evaluation complements soil surveys by focusing on the physical characteristics of rock units exposed at outcrops, in hand samples, or cores. Observable with the naked eye or a magnifying lens, these characteristics include color, texture, and structural features. Lithogeochemistry, or rock geochemistry, builds upon this foundation by analyzing the chemical composition of the bedrock. This analysis aims to identify spatial patterns of elements typically associated with specific types of mineral deposits. By integrating the findings from soil surveys and lithologic evaluations, geoscientists gain a comprehensive understanding of the subsurface environment, enabling them to prioritize areas for further mineral exploration activities. This paper delves into the fundamentals of these techniques, highlighting their strengths and limitations in the context of mineral resource exploration.

Microbial methane formation in deep aquifers associated with the sediment burial history at a coastal site

Abstract. Elucidating the mechanisms underlying microbial methane formation in subsurface environments is essential to understanding the global carbon cycle. This study examined how microbial methane formation (i.e., methanogenesis) occurs in natural-gas-bearing sedimentary aquifers throughout the sediment burial history. Water samples collected from six aquifers of different depths exhibited ascending vertical gradients in salinity from brine to fresh water and in temperature from mesophilic to psychrophilic conditions. Analyses of gas and water isotopic ratios and microbial communities indicated the predominance of methanogenesis via CO2 reduction. However, the hydrogen isotopic ratio of water changed along the depth and salinity gradient, whereas the ratio of methane changed little, suggesting that in situ methanogenesis in shallow sediments does not significantly contribute to methane in the aquifers. The population of methane-producing microorganisms (methanogens) was highest in the deepest saline aquifers, where the water temperature, salinity, and total organic carbon content of the adjacent mud sediments were the highest. Cultivation of the dominant hydrogenotrophic methanogens in the aquifers showed that the methanogenesis rate was maximized at the temperature corresponding to that of the deepest aquifer. These results suggest that high-temperature conditions in deeply buried sediments are associated with enhanced in situ methanogenesis and that methane that forms in the deepest aquifer migrates upward into the shallower aquifers by diffusion.

Intraparticle sorption and desorption of antibiotics

Intraparticle domains are the critical locations for storing contaminants and retarding contaminant transport in subsurface environments. While the kinetics and extent of antibiotics sorption and desorption in subsurface materials have been extensively studied, their behaviors in intraparticle domains have not been well understood. This study investigated the sorption and desorption of antibiotics (ATs) in the intraparticle domains using quartz grains and clay, and antibiotic tetracycline (TC) and levofloxacin (LEV) as examples that are commonly present in groundwater systems. Batch experiments coupled with the analyses using various microscopic and spectroscopic techniques were performed to investigate the sorption and desorption kinetics, and to provide insights into the intraparticle sorption and desorption of TC and LEV. Results indicated that both TC and LEV with different physiochemical properties can migrate into intraparticle domains that were consistent with sorptive diffusion. The rate and extent of the sorption are a function of intraparticle surface area and properties, pore volume and connectivity, and ionic properties of the ATs. The sorptive diffusion led to the slow desorption of both TC and LEV after their sorption, apparently showing an irreversible desorption behavior (with desorption percentage about 1.86–20.51%). These results implied that intraparticle domains can be important locations for storing ATs, retarding ATs transport, and may serve as a long-term secondary source for groundwater contamination.

E. coli cotransport with composite colloid in unsaturated porous media: Multi-risk on migration and biomolecular response

The diversity of colloidal types and the differences in the composite ratios in porous media are important factors governing the migration and biological risk of pathogenic microorganisms in the subsurface environment. In this study, E. coli O157:H7 was subjected to co-migration experiments with different compositions of the composite colloid montmorillonite (MMT)-Fe2O3, and the biomolecular response of E. coli under the action of colloids was analyzed by Raman spectroscopy to quantify the risk of E. coli under the action of composite colloids based on both. The results showed that Fe2O3 colloids inhibited E. coli migration mainly by electrostatic adsorption and reduced E. coli metabolism. MMT colloid inhibited E. coli migration mainly by blockage, and E. coli metabolism increased, and surface macromolecules decreased to reduce E. coli adhesion. MMT-Fe2O3 complex colloids inhibited migration through electrostatic attraction between the two and formation of cohesive colloids, with reduced E. coli metabolism and insignificant biomolecular response. It was briefly assessed that the composite colloids reduced E. coli risk less strongly than single colloids, stemming from the difference in the mechanism of influence and the actual need to consider colloid interactions. This conclusion can inform the management and control of pathogen risk in porous media environments.

Multitechnique characterization of secondary minerals near HI-SEAS, Hawaii, as Martian subsurface analogues

Secondary minerals in lava tubes on Earth provide valuable insight into subsurface processes and the preservation of biosignatures on Mars. Inside lava tubes near the Hawaii-Space Exploration and Analog Simulation (HI-SEAS) habitat on the northeast flank of Mauna Loa, Hawaii, a variety of secondary deposits with distinct morphologies were observed consisting of mainly sodium sulphate powders, gypsum crystalline crusts, and small coralloid speleothems that comprise opal and calcite layers. These secondary deposits formed as a result of hydrological processes shortly after the formation and cooling of the lava tubes and are preserved over long periods of time in relatively dry conditions. The coralloid speleothem layers are likely related to wet and dry periods in which opal and calcite precipitates in cycles. Potential biosignatures seem to have been preserved in the form of porous stromatolite-like layers within the coralloid speleothems. Similar secondary deposits and lava tubes have been observed abundantly on the Martian surface suggesting similar formation mechanisms compared to this study. The origin of secondary minerals from tholeiitic basalts together with potential evidence for microbial processes make the lava tubes near HI-SEAS a relevant analog for Martian surface and subsurface environments.

Estimation of Evapotranspiration from the People’s Victory Irrigation District Based on the Data Mining Sharpener Model

Reasonable evaluation of evapotranspiration (ET) is crucial for optimizing agricultural water resource management. In the study, we utilized the Data Mining Sharpener (DMS) model; the Landsat thermal infrared images were sharpened from a spatial resolution of 100 m to 30 m. We then used the Surface Energy Balance System (SEBS) to estimate daily ET during the winter wheat growing season in the People’s Victory Irrigation District in Henan, China. It was concluded that the spatiotemporal patterns of land surface temperature and daily evapotranspiration remained consistent before and after sharpening. Results showed that the R2 value between the ET of 30 m spatial resolution and the value by eddy covariance method reached 0.814, with an RMSE of 0.516 mm and an MAE of 0.245 mm. All of these were higher than those of 100 m spatial resolution (R2 was 0.802, the RMSE was 0.534 mm, and the MAE was 0.253 mm). Furthermore, the daily ET image with a 30 m spatial resolution exhibited clear texture and distinct boundaries, without any noticeable mosaic effects. The changes in surface temperature and ET were more consistent in complex subsurface environments. The daily evapotranspiration of winter wheat was significantly higher in areas with intricate drainage systems compared to other regions. During the early growth stage, daily evapotranspiration decreased steadily until the overwintering stage. After the greening and jointing stages, it began to increase and peaked during the sizing period. The correlation between net solar radiation and temperature with ET was significant, while relative humidity and soil moisture were negatively correlated with ET. Throughout the growth period, net solar radiation had the greatest effect on ET.

A computational investigation of diffusivities and heat transfer in the flow of viscoelastic fluid through Darcy–Brinkman–Forchheimer medium

The main objective of this work is to examine the effects of non-linear thermal radiation and induced magnetic fields on the behavior of viscoelastic fluid as it flows through a porous material that does not follow Darcy’s law. Hence, the Darcy–Brinkman–Forchheimer model has been employed when formulating the momentum equation. The research postulates the presence of a chemical process involving two chemical species, A and B. The research utilizes the spectral relaxation method (SRM) for the numerical solution of the altered governing equations. The present algorithm is formulated and executed on computational software MATLAB. The findings demonstrate a high level of concurrence with previously known numerical outcomes in the context of a specific scenario. The findings of this research demonstrate that chemical species B functions as a catalyst in a horizontally subsurface environment. Consequently, the relationship between the homogeneous-heterogeneous scheme may be seen in the context of isothermal cubic autocatalytic events and first-order processes, respectively. The use of the heterogeneous reaction parameter offers significant benefits in reducing the concentration of the bulk fluid while increasing the concentration of the catalyst located on the subsurface. Moreover, the results indicate that the impacts of induced magnetic and viscoelastic factors on velocity and induced magnetic fields are similar in their outcomes but differ in their fundamental nature.

Microbiological insight into various underground gas storages in Vienna Basin focusing on methanogenic Archaea.

In recent years, there has been a growing interest in extending the potential of underground gas storage (UGS) facilities to hydrogen and carbon dioxide storage. However, this transition to hydrogen storage raises concerns regarding potential microbial reactions, which could convert hydrogen into methane. It is crucial to gain a comprehensive understanding of the microbial communities within any UGS facilities designated for hydrogen storage. In this study, underground water samples and water samples from surface technologies from 7 different UGS objects located in the Vienna Basin were studied using both molecular biology methods and cultivation methods. Results from 16S rRNA sequencing revealed that the proportion of archaea in the groundwater samples ranged from 20 to 58%, with methanogens being the predominant. Some water samples collected from surface technologies contained up to 87% of methanogens. Various species of methanogens were isolated from individual wells, including Methanobacterium sp., Methanocalculus sp., Methanolobus sp. or Methanosarcina sp. We also examined water samples for the presence of sulfate-reducing bacteria known to be involved in microbially induced corrosion and identified species of the genus Desulfovibrio in the samples. In the second part of our study, we contextualized our data by comparing it to available sequencing data from terrestrial subsurface environments worldwide. This allowed us to discern patterns and correlations between different types of underground samples based on environmental conditions. Our findings reveal presence of methanogens in all analyzed groups of underground samples, which suggests the possibility of unintended microbial hydrogen-to-methane conversion and the associated financial losses. Nevertheless, the prevalence of methanogens in our results also highlights the potential of the UGS environment, which can be effectively leveraged as a bioreactor for the conversion of hydrogen into methane, particularly in the context of Power-to-Methane technology.

Surrogate models of heat transfer in fractured rock and their use in parameter estimation

Fracture distribution plays a significant role in the behavior of subsurface environments, affecting such activities as geothermal production, exploitation and management of groundwater resources, and long-term storage of nuclear waste and carbon dioxide. A key challenge in these and other applications is to estimate the fracture network properties from sparse and noisy observations. We evaluate the utility of cross-borehole thermal experiments for this task, using both physics-based particle-tracking (PBPT) heat-transfer approach and its deep neural network (DNN) surrogates. Synthetic data are provided by the PBPT simulations and used to train and test the DNN surrogates over a full range of the fracture network properties. We propose regionalized and step-by-step training techniques to reduce the computational cost of expensive PBPT forward solves over large ranges of the (to-be-estimated) parameters. Our numerical experiments suggest the feasibility of training a regionalized DNN surrogate over parameter ranges for which the PBPT solves are fast and extrapolating its predictions to parameter ranges with few additional data. We analyze the balance between computational cost and model accuracy, and provide both PBPT and DNN models for applications to others kinds of data.

Influence of magnetite and its weathering originated maghemite and hematite minerals on sedimentation and transport of nanoplastics in the aqueous and subsurface environments

Persistent nanoplastics (NPs) and their interaction with ubiquitous iron oxide minerals (IOMs) require a detailed understanding to dictate NPs fate and transport in aqueous and subsurface environments. Current study emphasizes on understanding nanoplastics (NPs) interaction with magnetite, and its weathering-originated mineral colloids, i.e., maghemite and hematite under varying environmental conditions (pH, humic acid, ionic strength and water matrix). Results showed that the higher surface hydroxyl group, smaller particle size, and positive surface charge of magnetite led to maximum NPs sorption (805.8 mg/g) in comparison to maghemite (602 mg/g) and hematite (384.3 mg/g). Charge distribution and sedimentation kinetic studies in bimodal systems showed enhanced coagulation in magnetite-NPs system. FTIR and XPS analysis of NPs-IOMs reaction precipitate revealed the vital role of surface functionality in their interaction. Column experiments revealed higher NPs retention in IOMs-coated quartz sand than bare quartz sand. Further, in river water (RW), magnetite-coated sand has shown maximum NPs retention (>80 %) than maghemite (62 %) and hematite (52 %), suggesting limited NPs mobility in the presence of magnetite in subsurface conditions. These findings elucidated the dependence of NPs fate on IOMs in freshwater systems and illustrated IOMs impact on NPs mobility in the subsurface porous environment.

Characterisation, axial anisotropy, and formation conditions of celestine minerals from the Jabal Eghei (Nuqay) late Neogene – Pleistocene volcanic province, southeastern edge of the Sirt Basin, southern Libya: Constraints on the mineralogical geothermometer

AbstractFive celestine crystals were sampled from the (palaeo)surface intervening between the late Miocene to Pleistocene basaltic sequences of the Jabal Eghei (Nuqay) volcanic province in southern Libya and then characterised by applying a combination of the SEM–WDS, ICP/OES, PXRD and IR methods. Colour variations and related minerogenetic frameworks were also investigated. Three samples have greenish-blue-to-blue colour (480.4–482.5 nm), whereas the other two samples have blue–green colour (cyan; 489.1–494.1 nm). The colour purity ranges from 1.36–7.16. Their composition is similar, end-member celestine, in which only 1.6–4.1 at.% of Sr2+ content was substituted by Pb2+ (0.7–0.9 at.%), Ba2+ (0.5–0.7 at.%) and Ca2+ (0.2–0.8 at.%). Three samples contained vacancies, from 1.0 to 1.9 at.%. The content of other chemical elements is minor. The resulting unit-cell parameters have the ranges: a0 = 8.3578(9)–8.3705(6) Å; b0 = 5.3510(5)–5.3568(4) Å; c0 = 6.8683(7)–6.8767(2) Å and V0 = 307.17(5)–308.34(4) Å3. The PXRD and IR results are mainly in accordance with the SEM–WDS results, with a high level of correlation. However, a few discrepancies were found, producing several possible interpretations, the primary cause being a slight unit-cell axial anisotropy i.e. thermal expansion. As a consequence these results yield a new geothermometric tool that is based on the unit-cell axial anisotropy. The celestines investigated were formed during a Miocene intraplate volcanism with basaltic magmas, and associated brines lifted by the structural conduits (normal faults crosscutting the Sirt basin). The Sr-bearing fluids then poured into and over the faulted and fractured lagoon-type gypsum, anhydrite Eocene sediments. The celestine mineralisation formed within a ~368–430 K (~95–157°C) temperature range. The celestine formed at slightly elevated temperature and pressure conditions, close to the shallow subsurface environment (over 250 bars).

Quantitative Assessment of Organic Mass Fluxes and Natural Attenuation Processes in a Petroleum-Contaminated Subsurface Environment

We perceived a trend in the study and practice of petroleum-contaminate sites. Monitored natural attenuation (MNA) can reduce the contaminant concentrations in the soil and groundwater, and it is a method that can remediate the petroleum-contaminated site effectively. MNA is becoming a research focus. This study evaluated MNA using a series of lab-based bench-scale experiments and a large amount of monitoring data from field samplings. Based on the in-site total petroleum hydrocarbon (TPH) results, we used statistical methods, the Mann-Kendall test, and mass fluxes in order to evaluate the MNA of petroleum-contaminated sites in groundwater. The results showed that the TPH concentrations were decreasing, and the plume became smaller. The attenuation rate was from 0.00876 mg/d to 0.10095 mg/d; remediating the petroleum contamination site would cost 1.3 years to 10.6 years. The plume reached a quasi-steady state, and mass flux declined. The most essential process of MNA was biodegradation, and the second was sorption. During the monitoring period, 393 g of TPH was attenuated, including 355 g of TPH gradated by microbes. Biodegradation upstream of the plume was more serious. Iron(Ⅲ) and manganese were the main electron acceptors utilized by microbes during the monitored period. MNA was in progress, and it can be an effective method to remediate the petroleum-contaminated site. Lab-based bench-scale experiments were performed with much monitoring data from the field samplings in order to understand the fate and transport mechanism of the petroleum contamination from the land surface to shallow groundwater according to site conditions.

Fracture development around wellbore excavation: Insights from a 2D thermo-mechanical FDEM analysis

Insights into fracture development and excavation damaged zone (EDZ) formation around wellbore excavation sites are essential for understanding wellbore stability. In this study, a novel thermo-mechanical scheme is implemented in the 2D combined finite-discrete element method (FDEM) to investigate the fracturing process around a wellbore in a high-temperature subsurface environment. The developed scheme captures the isotropic/anisotropic thermal conduction characteristics within the rock formation. The coupled scheme and stress distributions around the wellbore subject to in-situ stress, drilling mud pressure, and temperature changes are validated by closed-form solutions. Fracture development and progressive EDZ formation by various mechanisms are analyzed. The results show that for an unsupported wellbore, fractures initiate in the region of the most severe stress concentration due to excavation unloading and constitute an EDZ that resembles the logarithmic-spiral rupture zone captured by experimental observations and Mohr-Coulomb models, resulting in potential water inrush due to the significantly increased fracture transmissivity of the EDZ and wellbore collapse. The shape and extent of the EDZ for wellbore excavation in the layered rock mass are dominated by the stress redistribution and the presence of low-strength bedding planes favorably oriented for bedding slippage. The excavation unloading-induced stresses can be effectively counteracted by properly applying drilling mud pressure, and the disturbance of the stress field occurs only within a small region, greatly reducing the extension of the EDZ. Thermal contraction of the surrounding rock due to its convective interaction with the cold drilling mud induces extra fractures around the wellbore. The extension of the EDZ is greater with increased thermal expansivity of the rock formation. Overall, the results indicate that the adopted thermo-mechanical FDEM simulation can provide unique geomechanical insight into wellbore stability behavior analysis, in which explicit consideration of the fracturing and fragmentation processes is of great significance.

Coupling water, solute, and sediment transport into a new computationally efficient hydrologic model

While surface–subsurface interactions strongly impact water quality and quantity in ecosystems, only relatively little attention has been given to solute mass transfers at this boundary. The KINEROS2 (K2) model solves the 1D kinematic wave equation for water flow and the advection–dispersion equation for non-absorbing solute (or sediment) transport at the surface, whereas the HYDRUS-1D (H1D) model solves the Richards equation for flow and the advection–dispersion equation for solute transport in the subsurface. We previously coupled water flow in the surface and subsurface environments using the K2 and H1D models (H1D-K2). Herein, an innovative framework was developed to additionally couple solute transport at the surface–subsurface boundary in the simple, accurate, and computationally efficient H1D-K2 model. To test the H1D-K2 model’s accuracy and robustness, simulation results are compared to analytical solutions, experimental data, and results from the two-dimensional HYDRUS-2D (H2D) code. The relative differences in water and solute balance components between the H2D and H1D-K2 models are less than 1% for homogeneous cases and 4% for heterogeneous cases. The simulated hydrograph and chemograph are almost identical for the two models. Furthermore, simulated Bromide (Br) concentration in runoff is in good agreement with observations. The proposed model also accurately reproduces soil erosion under different rainfall patterns and intensities.