Subsurface Systems Research Articles

Responses of Water Temperature and Level to Large Earthquakes in Tibet

Well water levels can reflect the stress placed on a confined subsurface aquifer system in a similar manner to a strain meter. Based on observations of the geophysical field in Lhasa combined with digital data recorded at an underground fluid well at the Lhasa geomagnetic station in recent years, we comprehensively analyzed the characteristics of co-seismic changes caused by 14 different-magnitude M ≥ 5 earthquakes recorded in the well. The results show that (1) the co-seismic changes in water temperature and water level are different; the water level exhibits oscillation-type changes, while the water temperature variations indicate first heating and subsequent recovery. (2) The co-seismic changes are related to the epicentral distance, magnitude and focal depth of the earthquake. The closer the epicenter is to the well, the earlier the co-seismic responses occur, but the time interval between the co-seismic changes in the water level and temperature differs. (3) The co-seismic ratio of the water temperature is higher than that of the water level; this may be related to faulty water level instrumentation or segmented records.

Salinity and hydraulic retention time induce membrane phospholipid acyl chain remodeling in Halanaerobium congolense WG10 and mixed cultures from hydraulically fractured shale wells.

Bacteria remodel their plasma membrane lipidome to maintain key biophysical attributes in response to ecological disturbances. For Halanaerobium and other anaerobic halotolerant taxa that persist in hydraulically fractured deep subsurface shale reservoirs, salinity, and hydraulic retention time (HRT) are important perturbants of cell membrane structure, yet their effects remain poorly understood. Membrane-linked activities underlie in situ microbial growth kinetics and physiologies which drive biogeochemical reactions in engineered subsurface systems. Hence, we used gas chromatography-mass spectrometry (GC-MS) to investigate the effects of salinity and HRT on the phospholipid fatty acid composition of H. congolense WG10 and mixed enrichment cultures from hydraulically fractured shale wells. We also coupled acyl chain remodeling to membrane mechanics by measuring bilayer elasticity using atomic force microscopy (AFM). For these experiments, cultures were grown in a chemostat vessel operated in continuous flow mode under strict anoxia and constant stirring. Our findings show that salinity and HRT induce significant changes in membrane fatty acid chemistry of H. congolense WG10 in distinct and complementary ways. Notably, under nonoptimal salt concentrations (7% and 20% NaCl), H. congolense WG10 elevates the portion of polyunsaturated fatty acids (PUFAs) in its membrane, and this results in an apparent increase in fluidity (homeoviscous adaptation principle) and thickness. Double bond index (DBI) and mean chain length (MCL) were used as proxies for membrane fluidity and thickness, respectively. These results provide new insight into our understanding of how environmental and engineered factors might disrupt the physical and biogeochemical equilibria of fractured shale by inducing physiologically relevant changes in the membrane fatty acid chemistry of persistent microbial taxa. GRAPHICAL ABSTRACTSalinity significantly alters membrane bilayer fluidity and thickness in Halanaerobium congolense WG10.

Full cycle modeling of inter-seasonal compressed air energy storage in aquifers

To study the operational characteristics of inter-seasonal compressed air storage in aquifers, a coupled wellbore-reservoir 3D model of the whole subsurface system is built. The hydrodynamic and thermodynamic properties of the wellbore-reservoir system during the initial fill, energy injection, shut-in, and energy production periods are analysed. The effects of well spacing and air injection temperature on the seasonal storage process are investigated. The results show that the ranges of variation in wellbore-aquifer pressure and temperature are within the acceptable level during the whole operational process. The maximum wellhead pressure, reaching 13.08 MPa, occurs during the first injection in the initial fill period. The temperature of the air released from the wellhead is 6 °C lower than the initial injection temperature due to heat loss. The horizontal transport distance of injected air in the aquifer is 2173.5 m away from the central well at the end. The overall energy storage efficiency is 94.3% and the energy lost by the wellbore during production is 0.09%. Parametric analysis shows that the system has an optimal performance at a well spacing of 150 m. The energy storage efficiency is 5% higher at an air injection temperature of 20 °C than 50 °C. The results strongly confirm the feasibility of IS-CAESA.

Application of General Unit Hydrograph Model for Baseflow Separation from Rainfall and Streamflow Data

Baseflow separation from rainfall and streamflow data is a fundamental problem in applied hydrology, unsolved despite extensive investigations. For example, a part of baseflow is interflow, which results from rainfall infiltration, but almost all of the existing baseflow separation methods, such as graphic and filter methods, have nothing to do with it, which is a serious flaw from the viewpoint of science. The objective of this research is thus to present an innovative baseflow separation method based on the recent general unit hydrograph (UH) model and the classic Green-Ampt infiltration equation. Specifically, we divided a rainfall hyetograph into two parts using the Green-Ampt infiltration equation: one for surface flow that generates direct runoff and the other for subsurface flow that recharges groundwater and generates interflow. As with direct runoff from the surface system, we approximated the subsurface system as a linear system and thus applied the general UH model for interflow in the unsaturated soil zone, where excess infiltration is defined by analogy to excess rainfall. We assumed that groundwater flow could be described by the classic recession curve; we then added interflow and the groundwater flow to obtain the baseflow. We validated the proposed method with six real-world case studies representing four interflow patterns. Particularly, we found that, unlike direct runoff, the interflow UH model parameters are not unique, depending on stream stages. This implies that the subsurface system is a time-variant linear system, which can even make a negative interflow if groundwater is recharged from streams. We expect that this research will provide a better baseflow separation method and thus improve our understanding of watershed processes.

Resistivity analysis of geothermal system at cubadak village west sumatera using magnetoteluric method

Cubadak area was located in depression zone of great Sumatra fault zone which affected by normal faults. Geothermal in this area was characterized by the appearance of hot springs type chloride-bicarbonate on Cubadak, Sawah Mudik and Talu. The manifestation temperature on this area is about 37,1° - 74,8° C. This study purpose to recontruct model of subsurface geothermal system in Cubadak area based on MT data. Model 1-D was processed by apply Bostick inversion and NLCG (Nonlinear Conjugate Gradient) for model 2-D. The result showed that lowest resistivity was on Southwest to Northeast research area. Highest resistivity spread at West to Northeast. Geothermal system was composed by caprock (2-10 ohm), reservoar (20-300 ohm) and heat source (>300 ohm).

Application of remote sensing and gis to identify the vulnerability of ground-water pollution in topograhic karst

Karst or limestone is a landscape in the form of unique. Karst or limestone has sensitive properties and is easily dissolved in water so that the karst topography has a subsurface water system in the form of holes that are susceptible to degradation due to the very fast flow of water so that it is easy to pass water underground. The purpose of this study was to determine the level of vulnerability of karst underground water pollution based on remote sensing data and GIS in the Rengel-Tuban Indonesia karst region. This type of research is quantitative research. Data analysis techniques in this study used image interpretation and logistic regression tests. The researched result is known that Remote sensing imagery and GIS as a tool to identify the level of vulnerability of underground water pollution in the karst region. Utilization of remote sensing imagery and GIS is presented as information of vulnerability of underground water pollution, and the study showed that the average area of karst Rengel was classified as vulnerable to pollution. In conclusion that the average area study was classified as vulnerable to pollution, and the Rengel karst hills are in line with local levels of vulnerability and pollution

Compatibility investigation and techno-economic performance optimization of whole geothermal power generation system

Appropriate compatibility between exploitation and utilization systems is of critical importance to geothermal electricity. However, few research works focused on the optimal dynamic matching between subsurface heat extraction system and surface power generation system according to the dynamic process of enhanced geothermal system (EGS). In present work, a potential EGS with pinnate horizontal well is proposed to generate electricity by incorporating three typical power generation systems, namely single-flash (SF) system, double-flash (DF) system and single-flash with organic Rankine cycle (SFORC) system. System coupling is achieved to explore the optimum operation strategy of surface power generation system by considering the dynamic characteristics of geothermal fluid temperature and flow rate. The reliability of numerical method and thermodynamic model used in present work are validated by the theoretical model. Furthermore, the response surface methodology is employed to optimize the operation strategy of proposed EGS. Based on the maximization of exergy efficiency and minimization of total cost, the optimum running strategies and techno-economic performance of proposed power generation systems are obtained, respectively. The results indicate that temperature drop of thermal reservoir is significantly affected by the combined effect of injection flow rate and reservoir permeability. The net output exergy is proportional to branch well length and reservoir permeability, and inversely proportional to the injection temperature and injection flow rate. Compared with the SF and DF systems, SFORC system is more compatible and economical to be applied in the proposed EGS. After 30 years of operating, the net revenue of SFORC system can reach to 2.66 × 108 USD, which are 2.30 and 1.02 times more than those of SF and DF systems, respectively. The corresponding flash temperature of SFORC is the same as production temperature of the EGS. Meanwhile, the evaporation temperature of n-pentane will drop in four steps from 405.15 K to 399.15 K.

3-D quantitative seismic imaging of tectonically-influenced Middle-Eocene carbonates stratigraphic traps of SE-Asian basins using spectral decomposition: Implications for hydrocarbon exploration

Carbonates form energetic stratigraphic petroleum systems. The tectonic uplifting and subsidence significantly affect the overall reservoir configurations. During these stratigraphic scenarios, the prediction of accurate thickness for subsidence and uplifting zones becomes challenging. The band-limited seismic data interpretation tools fail to detect the zones of thinning and thickening of sediments along with uplifting and subsidence. The band-limited seismic does not have the tuning frequency, that can be used to predict the accurate vertical thickness of the thin-bedded carbonates. The constant wavelet-based transformation tool (WT) and inverted reservoir simulations have robust implications for the quantification of any depositional system. Especially, when the reservoir is shallow marine, the application of WT has resolved a variety of stratigraphic traps in terms of their seismic and sedimentological aspects. The stratigraphic traps are comprised of thin beds, which are not resolvable on conventional seismic. These traps require a specific tuning frequency, which is the key ingredient for the prediction of oil and gas inside them and can only be obtained by the implementation of the WT tool. Therefore, the WT, static stratigraphic thickening wedge models (SSTWM), and WT–based instantaneous spectral thickness modeling (ISTM) tools are applied on a gas field in Indus Basin, Pakistan. The 43-Hz CWT images the densely fractured and faulted network within the shoal reservoir limestone lenticular lens (SRLL) with an aerial extent of 208 km2 in southwest-northeast orientations. The band-limited attributes revealed poor imaging of sub-surface carbonate systems. The 43-Hz wavelet-based SSTWM predicts a 15-m-thick coarse-grained SRLL along subsidence and a 12-m-thick fine-grained SRLL along uplifting zones. Post-stack processing at 43-Hz CWT tuning frequency predicts the 18 and 10 m thick sediments for SRLL along the subsidence and uplifting zone. The ISTM predicts a thickness of 31 m during subsidence within the SRLL and 14 m for uplifting zones. The 43-Hz tuning frequency-based processing at ISTM predicts enhanced thicknesses of 41 and 18 m for subsiding and uplifting sediments that are trapped inside the shoal limestone petroleum systems. The quantitative visualization of AI with the predicted thicknesses at ISTM has provided robust clues for imaging the internal stratigraphic architecture of the SRLL. The linear regression analysis remained a very successful tool for assessing the quantitative aspects of SRLL with a strong R2 > 0.95, which has implicated the real-time imagining of sea-level fall and rise. Only post-stack seismic data processing at 43-Hz found a very effective exploration tactic in predicting the enhanced thicknesses, and lateral continuity of the reservoir, and improved the S/N by removing the tuning effect of ambiguous lithology/fluids, which have accurately predicted the exact location along the subsidence zones. This workflow can act as an analogue stratigraphic exploration of remaining gas fields within Asian Basins and similar geological settings.

High-magnitude stresses induced by mineral-hydration reactions

AbstractFluid-rock interactions play a critical role in Earth’s lithosphere and environmental subsurface systems. In the absence of chemical mass transport, mineral-hydration reactions would be accompanied by a solid-volume increase that may induce differential stresses and associated reaction-induced deformation processes, such as dilatant fracturing to increase fluid permeability. However, the magnitudes of stresses that manifest in natural systems remain poorly constrained. We used optical and electron microscopy to show that one of the simplest hydration reactions in nature [MgO + H2O = Mg(OH)2] can induce stresses of several hundred megapascals, with local stresses of as much as ∼1.5 GPa. We demonstrate that these stresses not only cause fracturing but also induce plastic deformation with dislocation densities (1015 m−2) exceeding those typical of tectonically deformed rocks. If these reaction-induced stresses can be transmitted across larger length scales, they may influence the bulk stress state of reacting regions. Moreover, the structural damage induced may be the first step toward catastrophic rock failure, triggering crustal seismicity.

Efficient Underwater Sensor Data Recovery Method for Real-Time Communication Subsurface Mooring System

Marine submerged buoys can effectively obtain various parameters of seawater, which plays an important role in the research of marine physical phenomena, marine environmental changes, and climate change. However, traditional self-contained submerged buoys usually work underwater at a depth of about 100 m, and the observation data cannot be obtained before their recovery, which cannot satisfy the needs of real-time data acquisition for marine scientific research. To solve this problem, this paper proposes a real-time communication subsurface mooring system that consists of a satellite communication buoy (SCB), conductivity–temperature–depth sensors (CTD), and an inductive coupling mooring cable. The underwater inductive coupling link collects the data from the underwater sensors and transmit it to the SCB. Then, the data will be transmitted to the station receiver via satellite communication module integrated into the SCB. In order to ensure a high success rate of data recovery, the stress analysis and hydrodynamic simulation of the SCB were carried out in this paper. The results show that the SCB maintained a relatively stable attitude in the 3–4 sea state. The attitude data obtained from the subsequent sea trial was consistent with the simulation results, and the success rate of satellite communication during this period was more than 95%. In this paper, a modular embedded hardware circuit was designed to meet the functional requirements of the subsurface mooring system. An efficient data recovery strategy was also developed, which ensured that the average power consumption of the system was low and the success rate of data recovery is not less than 90% when operating in the severe sea state for a long time. The system underwent sea trials in the South China Sea for more than 3 months from the end of 2021 to the beginning of 2022. It transmitted more than 2034 sets of seawater profile temperature, salinity, and depth data in real-time, with a success rate of over 91% of the total sample data. The CTD data returned in real-time from our system is consistent with the data of the HYCOM and World Ocean Atlas (WOA), and a cyclonic mesoscale eddy was detected in the operation area.

Experimental Characterization and Pore-Scale Modeling of Iron Precipitation in Shale Reservoirs by Interacting with Hydraulic Fracturing Fluid

It has been reported that ∼60% of total U.S. hydrocarbon production comes from shale reservoirs. Understanding of reactive transport is of fundamental importance to the application in subsurface systems of natural shales that have rich compositions of carbonate, clay, and sulfide, which have high reactivity with water. In this study, we focus on the interaction between pyrite (sulfide) and hydraulic fracturing fluid in shale to investigate the potential impact of iron precipitation on fluid transport. We first conducted the experiments with pyrite samples to calibrate the reaction rate constants for pyrite oxidation (at the pyrite surface) and Fe2+ oxidation (in solution). The obtained reaction rate constants were utilized to establish the pore-scale numerical model to track these oxidation reactions. In other words, the reaction rate constants of pyrite surface oxidation and Fe2+ oxidation were calibrated by matching the results of numerical simulations with the experimental measurements of ion concentrations. By doing so, we could also obtain confidence in our developed numerical simulator. In numerical simulation case 1, where the reactions of pyrite oxidation and Fe2+ oxidation mainly occurred, the transport patterns in the systems were investigated based on the digital rock image model. In numerical simulation case 2, the level-set method was coupled with the reactive transport model to simulate iron(III) hydroxide precipitation on the pyrite surface. The precipitation patterns in the digital rock image model were investigated under different Damköhler numbers (DaII). Under the larger DaII, the precipitated iron(III) hydroxides had a longer dendritic shape, and the precipitation pattern was highly random. The quantified pore-scale parameters obtained from this study are expected to improve continuum-scale models to accurately predict the potential impact of the interaction between pyrite in shale and hydraulic fracturing fluid.

Wetting Patterns in a Subsurface Irrigation System Using Reservoirs of Different Permeabilities: Experimental and HYDRUS-2D/3D Modeling

Precipitation in arid lands is low and often highly variable; therefore, efficient irrigation is the best approach for managing limited water supplies and irregular precipitation events for establishing seedlings. The HYDRUS-2D/3D software is a useful tool for simulating water content distribution in the design of subsurface irrigation systems, determining the proper locations of reservoir and plant, irrigation scheduling and maximizing water use efficiency. In this study, wetting patterns around the reservoirs with different permeabilities (low, medium, and high) were assessed in the field and simulated using the HYDRUS-2D/3D software. Different amounts of animal manure and wheat straw were mixed with clay fractions to produce the reservoirs with different permeabilities. The results showed that the highest soil water content was observed near the reservoir, and it decreased with distancing from the reservoir. In the high permeability treatment (with saturated hydraulic conductivity, Ks = 0.2 cm/day), a large volume of water was released for almost three days, so that more water was deep-percolated and lowered the soil water available to plant roots. In the low and medium permeability treatments (Ks = 0.08, and 0.06 cm/day, respectively), the water slowly leaked, and the maximum soil water content was observed in the 20–40 cm layer over time. The HYDRUS-2D/3D software was able to simulate water flow and soil water content during the growth period of plants, with a high correspondence between measured and simulated soil water contents (R2 = 0.90–0.95), which was higher in the lower discharges.

Control of Viral and Bacterial Contamination of Lettuce by Subsurface Drip Irrigation

Foodborne outbreaks have been associated with the use of irrigation water contaminated with human and animal wastes. The use of subsurface drip irrigation may reduce the contamination of leafy green produce. The goal of this study was to quantitatively assess the impact of a subsurface irrigation system on the contamination of romaine lettuce contaminated with a fecal bacterium and a virus. Plants were transplanted and grown in bottom watering pots. They were irrigated with contaminated water containing Escherichia coli and MS2 bacterial virus. The HYDRUS 2D/3D program was used to model the water movement in the soil to ensure that the soil surface did not become wet and consequently contaminated. Neither E. coli nor MS2 were detected on the surface or internally on/in romaine lettuce. The results demonstrated that subsurface irrigation may successfully reduce the risk of contamination by bacterial and viral pathogens so long as the contaminated irrigation water does not reach the soil surface and thereby come in direct contact with the aboveground portions of the plant.

Mapping Groundwater Potential Zone and Flood Risk Zone in the Visakhapatnam District, India.

Groundwater is a vital resource that significantly contributes to the annual supply. On the other hand, Overexploitation has resulted in a significant reduction in groundwater supplies and, in some cases, soil sinking. Therefore, it’s critical to assess the possible zone of groundwater rejuvenation to safeguard water quality and manage subsurface water systems. Potential groundwater zones are detected using RS and GIS technologies. GIS technologies were used to build the composite map. Accurate data is required to determine the criteria used to estimate the potential groundwater zone. DEM, soil, Rainfall, and LULC data are all generated by the satellites, and, at a scale of 1:50000, topo sheets are collected from the Survey of India (SOI). All the input data is combined with a weighted overlay in ArcGIS. Each of these criteria is given an appropriate ranking. The ability of various geomorphic units to store groundwater is assigned weight values. This procedure is repeated for each of the remaining layers, with the resulting layers being categorized. Extremely poor, poor, moderate, good, and exceptional are the five categories of potential groundwater zones. The method is used in a particular research area in the Visakhapatnam district. This data will help you figure out where you can get water, where water can be recharged, and where groundwater is limited.

Groundwater Responses to Earth Tides: Evaluation of Analytical Solutions Using Numerical Simulation

AbstractHarmonic Earth tide components in well water levels have been used to estimate hydraulic and geomechanical subsurface properties. However, the robustness of various methods based on analytical solutions has not been established. First, we review the theory and examine the latest analytical solution used to relate well water levels to Earth tides. Second, we develop and verify a novel numerical model coupling hydraulics and geomechanics to Earth tide strains. Third, we assess subsurface conditions over depth for a range of realistic properties. Fourth, we simulate the well water level response to Earth tide strains within a 2D poroelastic layered aquifer system confined by a 100 m thick aquitard. We find that the non‐linear inversion of analytical solutions to match two observations (amplitudes and phases) to multiple unknown parameters is sensible to the initial guess. We reveal that undrained, confined conditions are necessary for the analytical solution to be valid. This occurs for the dominant M2 frequency at depths >50 m and requires specific storage at constant strain of Sϵ ≥ 10−6 m−1, hydraulic conductivity of the aquitard of kl ≤ 5 ⋅ 10−5 ms−1 and aquifer of ka ≥ 10−4 ms−1. We further illustrate that the analytical solution is valid in unconsolidated systems, whereas consolidated systems require additional consideration of the Biot modulus. Overall, a priori knowledge of the subsurface system supports interpretation of the groundwater response. Our results improve understanding of the effect of Earth tides on groundwater systems and its interpretation for subsurface properties.

Integration of Deep Learning and Information Theory for Designing Monitoring Networks in Heterogeneous Aquifer Systems

AbstractGroundwater monitoring networks are direct sources of information for revealing subsurface system dynamic processes. However, designing such networks is difficult due to uncertainties in the spatial heterogeneity of aquifer parameters such as permeability (k). This study combines deep learning and information theory with an optimization framework to address network design problems in heterogeneous aquifer systems. The framework first employs a generative adversarial network to parameterize heterogeneous k distribution using a low‐dimensional latent representation. Then, surrogate models are developed based on the deep neural networks to perform uncertainty quantification of pressure heads and solute concentrations at locations of pre‐designed candidate monitoring stations. The monitoring stations are then ranked using the greedy search algorithm based on the maximum information minimum redundancy (MIMR) criterion. In order to depict the importance of each candidate monitoring location, the hotspot maps of the selection probability (Ps) are derived from MIMR repetition results. Comprehensive monitoring networks derived from the hotspot maps are then conducted as the final monitoring stations to improve monitoring information compared to MIMR results. Additionally, nine entropy quantization strategies are compared to evaluate their effects on monitoring network optimization results. Results indicate that caution should be taken when selecting entropy quantization strategies to achieve the accuracy required for model calibration and to improve the efficiency of monitoring optimization. Considering high‐dimensional uncertainties associated with aquifer parameters, the developed framework can provide important insights for monitoring network designs in various earth observational projects.

Reconstructing sedimentary processes in a Permian channel–lobe transition zone: an outcrop study in the Karoo Basin, South Africa

AbstractTurbidity currents commonly bypass sediment in submarine channels on the continental slope, and deposit sediment lobes farther down-dip on the flat and unconfined abyssal plain. Seafloor and outcrop data have shown that the transition from bypass to deposition usually occurs over complex zones referred to as channel–lobe transition zones (CLTZs). Recognition of these zones in cores and outcrop remains challenging due to a lack of characteristic sedimentary facies and structures. This paper focuses on Unit E of the Permian Fort Brown Formation in the Karoo Basin, South Africa, in the Slagtersfontein outcrop complex, which has previously been interpreted as a CLTZ. This study integrates thin-section micrographs, sedimentary facies, bed-set and stratigraphic architecture, and palaeoflow directions to achieve a multiscale analysis of CLTZ features. A novel process-based facies scheme is developed to evaluate deposits in terms of the depositional or erosional tendencies of the flows that formed them. This scheme allows bypass to be distinguished from depositional zones by the spatial distribution of certain sediment facies. Areas of net sediment bypass were predominantly marked by erosive sediment facies and a larger variability in palaeoflow direction while depositional areas showed a lower variability in palaeoflow directions. Metre-scale structures in the bypass-dominated area reveal seafloor erosion and scour formation. Field relations suggest the presence of a ∼500 m long mega-scour in the CLTZ. The characteristic structures documented here are applicable for identifying CLTZs in sparse datasets such as outcrops with limited palaeogeographical context and sediment cores obtained from subsurface systems.

Physiological studies on eggplant (Solanum melongena) grown under drought conditions

Field experiment was conducted during the two growing seasons of 2019 and 2021, at Dokki region, El-Giza Governorate, Egypt, in order to investigate the effect of deficit irrigation (DI) treatments: 100% (control), 70% and 50% of ETo (Reference evapotranspiration) and two irrigation systems: Surface drip irrigation (SDI) and Subsurface irrigation (SSI)porous pipe (20.0cm soil depth) on vegetative growth, chemical constituents, fruit yield and quality of eggplant plants (Cultivars : “Classic” “Swad Eleil”). Results revealed that, DI treatments significantly decreased the vegetative growth, total yield ,marketable yield, leaf relative water content (LRWC) and membrane stability index (MSI) of eggplant plants, compared to control treatment (100% ETₒ). While, water stress treatments improved leaves proline content, alkaloids and irrigation water use efficiency (IWUE). Using SSI (porous pipe) system significantly increased plant height, fresh weight, total yield, marketable fruit yield of eggplant, LRWC and MSI, “Classic” cv had the highest total yield and total marketable yield under the subsurface irrigation system compared to “Swad El-Layl”cv. Regarding, the effect of interaction between DI treatments and irrigation systems, the results illustrated that application of irrigation water with 100% ET0 by SSI system produced the highest significant values of vegetative growth, fruit yield.

Biotransformation of 8:2 Fluorotelomer Alcohol in Soil from Aqueous Film-Forming Foams (AFFFs)-Impacted Sites under Nitrate-, Sulfate-, and Iron-Reducing Conditions

The environmental fate of per- and polyfluoroalkyl substances (PFAS) in aqueous film-forming foams (AFFFs) remains largely unknown, especially under the conditions representative of natural subsurface systems. In this study, the biotransformation of 8:2 fluorotelomer alcohol (8:2 FTOH), a component of new-generation AFFF formulations and a byproduct in fluorotelomer-based AFFFs, was investigated under nitrate-, iron-, and sulfate-reducing conditions in microcosms prepared with AFFF-impacted soils. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) and high-resolution mass spectrometry (HRMS) were employed to identify biotransformation products. The biotransformation was much slower under sulfate- and iron-reducing conditions with >60 mol % of initial 8:2 FTOH remaining after ∼400 days compared to a half-life ranging from 12.5 to 36.5 days under nitrate-reducing conditions. Transformation products 8:2 fluorotelomer saturated and unsaturated carboxylic acids (8:2 FTCA and 8:2 FTUA) were detected under all redox conditions, while 7:2 secondary fluorotelomer alcohol (7:2 sFTOH) and perfluorooctanoic acid (PFOA) were only observed as transformation products under nitrate-reducing conditions. In addition, 1H-perfluoroheptane (F(CF2)6CF2H) and 3-F-7:3 acid (F(CF2)7CFHCH2COOH) were identified for the first time during 8:2 FTOH biotransformation. Comprehensive biotransformation pathways for 8:2 FTOH are presented, which highlight the importance of accounting for redox condition and the related microbial community in the assessment of PFAS transformations in natural environments.

Modeling and simulation of trifluralin herbicide movement due to its application on soils by chemigation

The Trifluralin (TFN) is a pre-emergent herbicide which is widely used in agriculture. Usually, this pesticide is directly applied to the soil, where it can remain for long periods or can be transported. In this sense, knowing the dynamics of an herbicide soil transport is essential to avoid environmental contamination problems and risks to human health. Thus, this study aims to model and simulate TFN movement on soils with two different textures, a sandy loam and clay loam soil. It was considered that the herbicide was applied via chemigation trough a subsurface drip irrigation system, under a non-steady regime. Therefore, the transport parameters of TFN in these soils and physical-hydric characteristics of these were used, while the physical environment modeling were conducted using the Hydrus 2D software. The results showed that both in sandy and clayey soils, the TFN tends to be retained by the soil, close to where it was applied, not exceeding a layer greater than 2.5 mm outside the dripper radius, even in more favorable conditions such as the presence of irrigation. Finally, it could be concluded that this herbicide movement in the soil is of low potential, due to this product high solid-liquid partition coefficient (Kd), even in sandy soil, which has low cation exchange capacity (CEC).