Groundwater Pollution Research Articles

Spatial variability, source identification, and partitioning of groundwater constituents in a typical lakeside plain on Yungui Plateau

The fragile ecological balance of lakeside plains on plateau makes groundwater hydrochemical composition highly susceptible to human disturbances. This research investigates a typical plain on Yunnan Plateau to quantitatively identify the potential sources of groundwater pollution in lakeside plains on plateau by combining receptor models with risk assessment models. Receptor models show there are three potential pollution sources for groundwater including water-rock interactions, agricultural pollution, and domestic sewage/manure discharge. Groundwater hydrochemical composition is predominantly shaped by natural water-rock interactions, accounting for an average of 50.12 % of the influence. This is followed by agricultural non-point source pollution, which contributes 10.79 %, and the discharge of domestic sewage and manure, which accounts for 10.61 %. Groundwater in the current plain could pose a minor non-carcinogenic risk for long-term drinking, with the total hazard index (THI) for adults varying between 0.015 and 1.089, and for children between 0.024 and 1.737. Notably, 4.35 % of groundwater samples have a THI exceeding the safe threshold of 1. NO3- (72 %) is the primary contributor to non-carcinogenic risks, accounting for 72 %, trailed by Mn (13 %), NH4+ (9 %), Fe (6 %) and NO2- (1 %). The non-carcinogenic risks are predominantly attributed to agricultural non-point source pollution (71.6 %) and the discharge of domestic sewage and manure (26.9 %). A conceptual model has been developed to encapsulate the dynamics of groundwater quality formation in lakeside plains on plateau. This research will aid residents in safeguarding against groundwater contamination and enhancing agricultural practices in present plain and similar lakeside plain worldwide.

Electrocatalytic arsenic removal: Unveiling selective capturing and conversion with a redox-active silica-lignosulfonate hybrid framework

Addressing the global challenge of arsenic groundwater pollution to ensure a safe water supply is crucial. Thus, we developed a versatile ferrocene (Fc) incorporated silica-lignosulphonate nano framework (Fc–Si–LS). This framework was precisely designed to target and transform the toxic arsenite (As+3) into a controllable form of arsenic (As+5). Results revealed that the unique Fc–Si–LS framework had significantly targeted As+3 and showed an impressive selective conversion (84 %) performance even at high concentrations (1 mM). Additionally, in real water application (As = 150 μg/L), the As+3 conversion rate remained effective (∼81.6 %). Remarkably, the synergy between Fc and Si–LS resulted in an exceptional adsorption capacity (106 mg/g) at 1.2 V, attaining a low energy consumption of only 0.072 kWh/m3. DFT simulations established a phenomenon that simultaneous selective capturing and conversion of arsenic requires a redox moiety integration on the catalyst surface to accept electrons from the selectively trapped As+3 to the electrode. Hence, this study highlighted the potential of precisely persuading Si–LS based redox-active nano frameworks in evolving energy effective solutions for arsenic removal from drinking water, thereby offering significant implications for sustainable water treatment technologies.

Unraveling the synergistic interplay of sulfur and wheat straw in heterotrophic-autotrophic denitrification for sustainable groundwater nitrate remediation

Nitrate pollution in groundwater is a global environmental issue that poses significant threats to human health and ecological security. This study focuses on elucidating the mechanisms of heterotrophic-autotrophic cooperative denitrification (HAD) by employing wheat straw and elemental sulfur as electron donors in varying proportions. The research initially underscores that heterotrophic denitrification (HD) accelerates the denitrification process due to its high-energy metabolism. However, as readily degradable organic matter diminished, reliance on more complex substrates such as lignocellulose posed a challenge to HD. This marks a pivotal transition towards autotrophic denitrification (AD), which, despite a slower initial rate, exhibits a more sustained denitrification performance. A low proportion of heterotrophic denitrification layer (e.g., 3:1) at the bottom facilitating efficient and sustainable denitrification. HD is capable of simultaneous removal of nitrates and nitrites, whereas AD demonstrates a higher affinity for nitrates, with nitrite accumulation reaching 100% at high influent nitrate concentrations (100 mg/L). HD not only provides the necessary alkaline environment for AD but also reduces sulfate production, whereas AD utilizes the residual organic carbon and ammonia produced by HD. The heterotrophic layer is characterized by a diverse community, whereas the autotrophic layer is predominantly composed of Thiobacillus. By delineating the interactive mechanisms and characteristics of HAD, this study highlights the importance of balancing heterotrophic and autotrophic activities for the effective remediation of groundwater nitrates.

Study on the carbon sequestration performance and barrier mechanism of biochar cement-based vertical cutoff walls for phenol pollution in groundwater

Study on the carbon sequestration performance and barrier mechanism of biochar cement-based vertical cutoff walls for phenol pollution in groundwater

Ecologically friendly remediation of groundwater sulfamethoxazole contamination: Biologically synergistic degradation by thermally modified activated carbon-activated peracetic acid in porous media

This study examines the efficacy and environmental impact of peracetic acid (PAA) activated by thermally modified activated carbon (AC600) for degrading antibiotics in actual groundwater. Laboratory-scale experiments evaluated the system's effects on contaminant degradation, ecological balance, and substance cycling in the hyporheic zone. Our findings demonstrated the effectiveness of the AC600/PAA system in removing sulfamethoxazole (SMX) from groundwater porous media. Additionally, the AC600/PAA system synergistically interacted with the in-situ microbiota of the hyporheic zone, producing more fragmented degradation products without increasing mixed toxicity. Bacterial abundance increased post-reaction, with notable alterations in the bacterial community and enhanced bacterial metabolism. Key genera such as Lysobacter thrived in the treated environment, playing critical roles in microbiota modification and SMX degradation. The pH remained stable before and after the reaction, while dissolved organic carbon content increased. Overall, our results highlight the promising potential of PAA activation by carbonaceous materials as a low-impact, ecologically friendly technology for in-situ remediation of organic pollutants in groundwater, characterized by high compatibility and biosynthesis.

How Pharmaceutical Residues Occur, Behave, and Affect the Soil Environment.

Many pharmaceuticals (PhMs), compounds for the treatment or prevention of diseases in humans and animals, have been identified as pollutants of emerging concern (PECs) due to their wide environmental distribution and potential adverse impact on nontarget organisms and populations. They are often found at significant levels in soils due to the continuous release of effluent and sludge from wastewater treatment plants (WWTPs), the release of which occurs much faster than the removal of PhMs. Although they are generally present at low environmental concentrations, conventional wastewater treatment cannot successfully remove PhMs from influent streams or biosolids. In addition, the soil application of animal manure can result in the pollution of soil, surface water, and groundwater with PhMs through surface runoff and leaching. In arid and semiarid regions, irrigation with reclaimed wastewater and the soil application of biosolids are usual agricultural practices, resulting in the distribution of a wide number of PhMs in agricultural soils. The ability to accurately study the fate of PhMs in soils is critical for careful risk evaluation associated with wastewater reuse or biosolid return to the environment. The behavior and fate of PhMs in soils are determined by a number of processes, including adsorption/desorption (accumulation) to soil colloids, biotic (biodegradation) and abiotic (chemical and photochemical degradation) degradation, and transfer (movement) through the soil profile. The sorption/desorption of PhMs in soils is the main determinant of the amount of organic chemicals taken up by plant roots. The magnitude of this process depends on several factors, such as crop type, the physicochemical properties of the compound, environmental properties, and soil-plant characteristics. PhMs are assumed to be readily bioavailable in soil solutions for uptake by plants, and such solutions act as carriers to transport PhMs into plants. Determining microbial responses under exposure conditions can assist in elucidating the impact of PhMs on soil microbial activity and community size. For all of the above reasons, soil remediation is critical when soil pollutants threaten the environment.

Ozone Plasma Nanobubble (OPN) Reactor Combined with Coagulation-Flocculation Process: A Promising Technology for Leachate Treatment

According to World Bank data, approximately 2.01 billion tons of urban waste is produced annually, with approximately 33% of waste being improperly managed, leading to concentrated and toxic leachate. This poses a global challenge due to its varied characteristics influenced by climate, landfill age, and waste composition, resulting in groundwater and surface water pollution with severe impacts on human health, ecosystems, and biodiversity, necessitating stringent treatment measures. To address this, a study integrated coagulation-flocculation and advanced oxidation processes (AOPs) using a dielectric barrier discharge (DBD) ozone plasma nanobubble (OPN) reactor to degrade leachate. Gas flow rate, plasma voltage, and gas sources are variated. This research uses O2 or air as a gas source that produces plasma. The leachate is fed into the DBD reactor, so the bubble will burst and produce further ROS. Optimal results were observed after 60 min, with oxygen gas feed reducing total suspended solids (TSS), chemical oxygen demand (COD), and biological oxygen demand (BOD) by 100, 93.93, and 74.12%, respectively, alongside a decrease in pH. This study indicates the promising potential of this technology for leachate treatment and demonstrates the potential for nitrate production using both types of gas feed.

A thermodynamics-based coupled model for multi-phase flowback in deformable dual-porosity shale gas reservoirs

Over the past decades, there has been growing interest in modelling multi-phase flowback in shale gas reservoirs during hydraulic fracturing, primarily due to the significant risk of groundwater pollution. However, the lack of fully coupled simulations and a unified theoretical model has hindered the study of coupled adsorptive hydro-mechanical behaviour and its influence on fluid flowback prediction. In this paper, we have extended the non-equilibrium thermodynamics-based Mixture Coupling Theory to derive the constitutive relationship and governing equation for adsorptive multi-phase fluid flows in deformable dual-porosity media. Helmholtz free energy density has been used to establish the relationship between solids and fluids. The interaction of adsorptive fluids in the pore and fracture space has been fully considered, leading to a new form of constitutive equation, which obtained the molecular adsorptive effect on the rock by introducing adsorption entropy production. The proposed governing equations determine the fully coupled evolution of solid deformation and multi-phase flow, with the consideration of adsorption as well as pore and fracture porosity change. Numerical simulation is then performed to study the flowback of a real shale gas well and the influence of coupled behaviour on model prediction. The simulation shows that the flowback flux is mainly by the fracture (more than 99.9 %) and the overall cumulative volume is 2427.1 m3 within 225 h which accounts for about 5.3 % of the total injected fracturing fluid, and the sensitivity analysis reveals that the manual fracture porosity is the most sensitive factor to the cumulative flowback. This work provides new insights into the flowback process of shale reservoirs in a fully coupled view and the proposed theoretical tool should contribute to the modelling of other adsorptive multi-phase flow problem in deformable dual-porosity media such as carbon storage and coalbed methane production.

Assessment of Groundwater Vulnerability to Pollution in the Metro Hilir Watershed Using the SINTACS Method

Abstract Assessment of groundwater vulnerability in the Metro Hilir watershed is necessary because most people use well water to meet basic needs. Identification and spatial analysis are the first steps to determine the potential for groundwater pollution in the area. The SINTACS method was used to assess the intrinsic vulnerability of groundwater using the parameters of groundwater table depth, effective infiltration, material in the unsaturated zone, soil texture type, aquifer media, hydraulic conductivity, and slope. Data processing was carried out by using Geographic Information System (GIS) techniques. Weight scenarios was used based on the hydrological conditions of the study area, namely “Normal Impact” and “Drainage/seepage”. The SINTACS index results was classified into several levels of vulnerability. The high vulnerability class is spread across the east to the south side, while the low vulnerability class is more dominant in the western area. The results of Sensitivity Analysis using the Map Removal technique showed that in both scenarios, soil texture parameters have the highest variation index value of 1.73% in the “Normal Impact” scenario and 2.13% in the “Drainage/Seepage” scenario. Parameters with high variation index values have a sensitive influence on vulnerability class values.

Investigation into factors controlling groundwater evolution in mining areas with an integrated approach

The study of groundwater evolution is of great significance for water resource protection and management, groundwater pollution control, and ecological environment protection. Experts and scholars have found that the hydrochemical processes and evolutionary patterns of groundwater are determined by both natural processes and human activities. However, there is relatively little research on the evolution of groundwater in mining areas where human activities have a significant impact. Therefore, to study the main controlling factors affecting the hydrogeochemical evolution of groundwater in mining areas, this paper proposes a method combining mixed ratio calculation and multivariate statistical analysis. Firstly, a total of 40 groundwater samples are classified into six clusters via hierarchical cluster analysis. By comprehensively analyzing the spatial location of the samples, it was found that there was no obvious distribution pattern of groundwater in space. Furthermore, the rationality of the cluster analysis is evaluated via principal component analysis. Next, hydrochemical and isotopic analyses were conducted to determine the source of groundwater in the mining area, and a three terminal element mixing model was established to identify the source of pollutants and calculate the terminal element mixing ratio. The research results indicate that groundwater in mining areas is formed by a mixture of shallow bedrock fissure water, deep bedrock fissure water, and rainwater, and the mixing effect is the main factor affecting the evolution of groundwater in mining areas, with a more significant impact than the depth of groundwater circulation. In addition, different types and degrees of water–rock interaction in different regions have altered the hydrochemical characteristics of groundwater in mining areas, such as the dissolution of multiple minerals, cation exchange, and common ion effects. Based on the above analysis results, a water circulation model for the mining area has been established. The findings of this study not only contribute to the protection of shallow fissure groundwater in the study area, but also provide a basis for investigating the groundwater evolution patterns in other metal mines.

Study of the extent of groundwater pollution with sewage water in the farms surrounding the well (laqoun) from the chemical and microbiological perspective in the Anjila - Janzour area"

This study was conducted in the Anjila-Janzour area west of Tripoli, with the aim of studying the extent of groundwater pollution with sewage, whether sewage, agricultural or industrial, where (28) samples were taken from groundwater wells of a number of farms near and far from the well (Al-Laquon), where the nearest farm was 550 meters away from the well, and the farthest farm was 4 kilometers away, and chemical and microbiological analyses and heavy elements analysis were conducted for all samples, and through the results obtained, the concentrations (pH) were within the permissible limit (6 - 8), while the total dissolved salts (TDS) were mostly more than the permissible limit, which is (ppm 1000) according to the specification adopted in the study [2], and from the chemical point of view, it was found that there was a variation in the concentrations of both iron (Fe) and copper (Cu), and all results were within the permissible limits, which is (ppm 0.31.0 ppm -), as for the elements sodium (Na) and chloride (Cl), there was pollution and the results were more than the permissible limit (ppm 200 - 250 ppm) respectively, and it was also found that there was an increase in the concentration of nitrates (No₃) and it was more than the permissible limit (45 ppm) ,As for the microbiological aspect, it was proven that there was microbial pollution with E.coli bacteria in the groundwater samples of most farms, and this indicates the presence of sewage leakage into the groundwater wells. As for the analyses of heavy elements, pollution with lead (Pb) and cadmium (Cd) was found in most samples.Through the results of this study, it can be said that most of the farms in the study area suffer from microbial contamination with E.coli bacteria due to the presence of the cesspool (lagoon), and chemical contamination with some elements such as sodium (Na) and chloride (Cl) was also found, and nitrate contamination (No₃) was also found due to the excessive use of pesticides for nitrogen fertilizers, and also it was proven through the analysis that there is contamination with heavy elements (Pb - Cd) and the reason is likely to be the presence of some industrial activities in the study area. Keywords: Microbiology, Heavy Elements, Cemetery (lagoon), Wastewater, Groundwater Wells, Water Pollution.

Groundwater pollution by nitrate and salinization in Morocco: a comprehensive review

ABSTRACT Groundwater plays a critical role in supporting a wide range of human activities. However, it faces substantial challenges due to the growing demand for water and reduced precipitation resulting from climate change. Various studies have revealed the high vulnerability of Morocco's groundwater to contamination from multiple anthropogenic sources. This review focuses on assessing nitrate and salinization pollution in Moroccan groundwater, with a specific emphasis on the Gharb region. A comprehensive analysis of research conducted from 2010 to 2023, using reputable databases, underscores the pressing need to address groundwater pollution in Morocco, especially in the Gharb region. The results highlight the significant challenges faced by Morocco's groundwater resources. Agricultural practices and poorly designed irrigation systems are identified as primary contributors to nitrate contamination. Additionally, salinization in the region is influenced by factors such as seawater intrusion, hydrogeological characteristics, and irrigation practices. An integrated approach, combining laboratory analysis, remote sensing, geospatial tools, modeling, and geographic information systems technology, has proven to be effective in addressing the complex issues of assessing groundwater pollution due to nitrate and salinization. This survey presents a comprehensive framework for future research and decision-making processes aimed at achieving sustainable water resource management, preserving the groundwater heritage and safeguarding public health.

Primary Study on Influence of Conventional Hydrochemical Components on Suspension of Endogenous Fine Loess Particles in Groundwater over Loess Regions

To ascertain the effects of conventional hydrochemical components on the presence of endogenous fine loess particles (EFLPs) in groundwater over loess regions, Na+, NO3− and Cu2+, as conventional hydrochemical components, were employed in batch tests with EFLPs from a typical loess as aquifer media in Guanzhong Plain, China. The results showed that EFLPs had high zeta potential (ζ) and remained suspended over 40 h, indicating their good dispersity and potential to be suspended in groundwater. ζ was employed to replace electrostatic repulsion in the DLVO equation to determine the critical coagulation concentrations for Cu(NO3)2 and NaF as 0.1 mmol/L and 50 mmol/L for 1.1 µm D50 EFLPs, which were almost consistent with the batch test results and greater than those in the groundwater, respectively, further implying that EFLPs are likely to be suspended in groundwater. The multi-factor tests showed that the key factors including particle size, hydro-chemical component and concentration interacted with each other and their relative magnitudes varied in the test processes, where the effects of concentration strengthened while those of the component weakened. So, hydrogeochemical conditions were beneficial to the suspension of EFLPs and the benefit got strong along the groundwater flow path, which is conducive to the cotransport of EFLPs with pollutants in groundwater over loess regions.

Synthesis of gamma aluminum oxide nano-powder for adsorptive removal of nitrate from aqueous solutions

Nitrate pollution of surface and groundwater could be a worldwide issue resulting in the threat to the environment and public health. The removal of nitrate from water was carried out using gamma aluminum oxide (γ-Al2O3) nano powder. The nano powder was synthesized from aluminum oxide powder using the aqueous-based reflux method and applied for nitrate removal. The surface properties of the activated γ-Al2O3 were characterized using FTIR, XRD, and BET surface area analysis. Analysis of variance (ANOVA) was used to analyze nitrate removal to determine the appropriate regression model, which was found to be the quadratic model with a coefficient of determination (R2 = 0.99). The adsorption process was observed to be dependent on initial nitrate concentration, adsorbent dose, and time. The optimized nitrate removal efficiencies were 97.01% using a dose of 2.26 gL−1, an initial nitrate concentration of 10 mgL−1, and a contact time of 45 min. Additionally, the kinetics of nitrate ion adsorption was discussed based on pseudo-first order and pseudo-second order kinetic models. The experimental data fitted well with the pseudo-second order kinetic model, indicating that the adsorption mechanism is chemisorption. The equilibrium adsorption of nitrate experimental data followed the both Freundlich and Langmuir isotherm (R2 = 0.95), implying a homogeneous nature of the γ-Al2O3 surface sites. These results suggest further consideration of the practical application of γ-Al2O3 for nitrate treatment for domestic purposes.

Determining the Effective Meteorological Parameters on Potato Yield in Niğde Province and Yield Prediction with Machine Learning and Deep Learning Models

In this study, we explore the impact of meteorological parameters on potato yield in Nigde province, a key agricultural region in Turkey for potato production. Understanding the relationship between weather conditions and crop yield is crucial for optimizing agricultural practices and ensuring food security, especially in regions susceptible to climate variability. The study includes all meteorological parameters observed and recorded in Nigde Directorate of Meteorology, covering the period between 1990 and 2023. Through the analysis of historical weather data and potato yield records, we aim to identify the most influential meteorological factors affecting potato production. Then, artificial intelligence techniques such as Random Forest, Gradient Boost, Convolutional Neural Networks and Recurrent Neural Networks are utilized to predict the potato yield in order to provide valuable insights into how different weather patterns influence crop performance. The findings suggest that potato yield is correlated with meteorological parameters to some degree and AI techniques can predict the potato yield but lacks the precision. The reason is that potato production in Nigde is mostly done with irrigation. However, this further increases the risk that could result from the changes in groundwater levels and pollution in irrigation ponds for agricultural practices in Nigde.

Chemical elements migration in underground waters of mining territory

Relevance. The need to study the forms of migration of chemical elements in the groundwater of flooded copper pyrite mines in order to correctly understand and predict their transfer and distribution in hydrogeochemical fields. Ground and surface waters are a complex mixture of substances in which, depending on pH, Eh and t °С, phase transitions are formed with subsequent dissolution or precipitation of minerals. To solve these problems, numerical hydrogeomigration modeling is used, including physicochemical, which allows drawing conclusions about the scale of pollution and the localization of such areas for subsequent development of measures to improve the state of the hydrosphere. Aim. To determine the forms of metal migration in groundwater and to calculate water saturation indices in relation to minerals. Objects. Groundwater in the territory of the closed Levikha copper pyrite mine. Methods. Laboratory studies of groundwater were carried out using flame emission spectrometry, flame atomic absorption, photometric method with Nessler's reagent, titrimetric, mercumetric and potentiometric methods; mass spectrometry with ionization in inductively coupled plasma and gravimetric method. Physical and chemical modeling using the software product Visual MINTEQ 3.1. Results. According to the results of processing chemical analyzes and physical and chemical modeling, all tested wells are divided into groups: 1) wells no. 1, 2, 3 and 6, located within the former mining allotment (near the Levikha XIV mine, a man-made reservoir, the Levikha II mine and a neutralization station); 2) represented by water in wells no. 4 near the shaft of the mine Tsentralnaya and no. 5 near the dump Yuzhny; 3) well no. 7, located near the mouth of the Levikha river. Saturation indices and forms of migration of components in the aquatic environment make it possible to identify the scale of pollution and the localization of such areas. Thus, with the current pumping system, there is no large-scale pollution of groundwater at the Levikha mine. It is localized in the area of the Tsentralny mine shaft (well no. 4) and the Yuzhny dump (well no. 5).

Assessment of Spatial Variation in Terrain Parameters Impacting Surface and Groundwater Quality for Sustainable Geo-Environmental Management

Soil and water conservation measures crucial for quality enhancement should focus on terrain-specific challenges. Evaluating groundwater resources from wells in the area is essential to ascertain their appropriateness for different applications. In semiarid tropical regions, the risk of inland salinity can escalate under extreme conditions like droughts and reduced monsoonal rainfall. During droughts, the groundwater table declines, leading to deterioration in groundwater quality, making it unsuitable for consumption, industrial processes, and arboriculture. In this scenario, analysing the spatial variation in water quality parameters becomes crucial for safeguarding environmental geology and effectively managing the geo-environment of impacted regions. Unfavourable geo-environmental conditions can be mitigated by reducing surface and groundwater pollution, sheet erosion, landslides, and land subsidence. Examining the variation in groundwater quality across both spatial and temporal dimensions is necessary to recommend treatments that make groundwater suitable for various uses, including potable purposes. The spatial as well as temporal variations of different water quality parameters, determined through a composite water quality index, can inform land use alterations, resource exploitation without unacceptable consequences, and artificial recharge measures that do not pollute the geo-environment. Enhancing the sustainability of the geo-environment can be achieved by investigating and prioritizing conservation measures and practices. Employing temporal remote sensing alongside related datasets facilitates the assessment of delineated watersheds within the region through the Analytical Hierarchy Process (AHP) Model. This approach is essential for prioritizing watersheds and formulating strategic action plans to sustain a balanced geo-environment.

Assessment of the water and mass balance in the landfill body by modelling using the example of the Dubna city landfill

To predict the migration of pollutants in groundwater from the landfill site, it is necessary to know the infiltration rate and the concentration of pollutants in the moisture entering the groundwater level below the landfill. It is shown that the HELP program for calculating moisture transport in the unsaturated zone can be used to estimate the infiltration rate by the example of the municipal solid waste in Dubna, To estimate chloride ion concentration in the leachate entering the groundwater level, the VS2DT program for calculating the transport of pollutants with moisture in the unsaturated zone can be used. It is shown how uncertainty and insufficiency of information about the landfill site affects the estimation of these parameters, in what cases it is possible to use information about a similar dump, how test calculations help to verify hypotheses of formation of groundwater pollution under the landfill. The ranges of infiltration rate and chloride ion concentrations in moisture entering the groundwater level under the landfill body obtained as a result of calculations of the water and mass balance of the landfill in Dubna were further used to calculate the chloride ion transport in groundwater.

Three-dimensional solute transport in finite and curved porous media with surface input sources

In this paper, an analytical solution for three-dimensional solute transport in porous media between two curved surfaces is investigated. It is assumed that the groundwater velocity and dispersion coefficient vary with time and position. Groundwater velocity is not considered to be horizontal. The components of dispersion coefficient along the axes are considered to be proportional to the square of corresponding the position variable. The dispersion coefficient components along axes are proportional to the corresponding component of groundwater velocity in temporal aspects while former is squarely proportional to letter one in position components. It is assumed that the sources originate from two curved surfaces. The nature of the source on the two surfaces is the same, but there may be a variation in potential. Initially, the aquifer's domain is supposed to be uniformly polluted. The Laplace Integral Transformation Technique (LITT) is used to obtain analytical solutions. Numerical examples are given to demonstrate the effects of various factors on the solute concentration profile in a system where advection and dispersion play important roles.In addition, the sub-case of horizontal flow is also discussed. The model is extremely useful in analyzing and dealing with widespread surface sources of groundwater pollution in simulated agricultural fields or urban dumping areas.

Vertical migration and leaching behavior of antibiotic resistance genes in soil during rainfall: Impact by long-term fertilization

The vertical migration and leaching behavior of antibiotic resistance genes (ARGs) during rainfall in soils subjected to long-term fertilization remain largely unclear. In this study, ARGs in vertical profiles (0−60 cm) and leachates from three soils (acidic, neutral, and calcareous) in a long-term (13 years) field fertilization experiment were monitored by high-throughput quantitative PCR after each rainfall event throughout an entire year. The results showed that, compared with unfertilized soils, long-term manure fertilization mainly promoted the vertical migration and leaching of aminoglycoside, beta-lactam, and multidrug resistance genes in the soil profiles. As a result, the annual cumulative loads of ARGs in leachates from the three soils with long-term manure fertilization were significantly increased compared to the controls and were in the order of acidic soil > neutral soil > calcareous soil. SourceTracker analyses revealed that manured soil was the predominant source of the ARGs in the soil leachate samples. Pseudomonas, Anaeromyxobacter, IMCC26256, and MND1 were identified as the dominant potential hosts responsible for the vertical migration and leaching of ARGs in the three soils. PiecewiseSEM analysis further showed that long-term manure fertilization affected the vertical migration of ARGs during rainfall mainly by altering soil properties (i.e., pH, soil organic carbon, and sand). Our results suggest that the ARGs in soils with long-term manure fertilization are a significant potential source of ARG pollution in groundwater, and the measures should be taken to mitigate the vertical migration and leaching of ARGs during rainfall.