Groundwater Contamination Research Articles

Practical Remediation of Hg-Contaminated Groundwater by MoS2: Batch and Column Tests

Trace mercury contamination in groundwater poses a serious threat to ecological systems and human health. The kinetics and isotherms of MoS2 (MS) for Hg removal were studied in batch tests under an unfavorable high salinity and low mercury environment. Flower-like MS with nanosheets can effectively remove Hg in the groundwater matrix, with a shorter equilibrium time (3 h), superior removal efficiency (94.26%), excellent distribution coefficient (5.69 × 106 mL g−1), and higher maximum adsorption capacity (926.10 ± 165.25 mg g−1). Furthermore, the Adams-Bohart model (R2 = 0.9052–0.9416) can accurately describe the dynamic interception process of the initial stage (≤40 PVs), and the Yan model (R2 = 0.9765−0.9941) depicts the whole process (140 PVs) of MS in a fixed column well. A higher dosage of m, but lower C0 and νp facilitate the interception efficiency in column tests. Based on the characterizations of X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), which were used to simultaneously consider the species of Hg and the groundwater matrix, surface complexation, electrostatic attraction, ion exchange, and precipitation is a plausible interfacial adsorption mechanism of MS for mercury. The excellent performance demonstrates that MS with nanosheets is a promising candidate for the PRB remediation of trace Hg in saline groundwater.

Health risk assessment of toxic metals and DNA damage in somatic and germ cells by soil and groundwater of a major cement factory in Nigeria.

The waste generated from cement manufacturing is an important source of heavy metal contamination of groundwater and soil. This study investigated the concentration of toxic metals in the soil of a major cement factory and nearby groundwater. Ecological and carcinogenic risks of the metals were calculated. Potential reproductive toxicity and genotoxic effects of the samples were assessed in sex and somatic cells of male mice using sperm abnormalities and bone marrow micronucleus (MN) assays, respectively. Also, the serum ALP, ALT, AST, Total Testosterone (TT), Luteinizing Hormone (LH), and Follicle Stimulating Hormone (FSH); and liver SOD and CAT activities were measured in the treated mice. Cr, Cu, Ni, Zn, Mn, Cd, and Pb levels in the soil and groundwater exceeded the allowable maximum standard. Ingestion and dermal contact were the most probable routes of human exposure with children having about three times higher probability of exposure to the metals than the adults. Ni, Pb, and Cr presented carcinogenic risks in children and adults. In the MN result, nuclear abnormalities in the studied mice especially micronucleated polychromatic erythrocytes increased significantly (p < 0.05). Compared to the negative control, the ratio of PCE/NCE showed the cytotoxicity of the two samples. Data further showed a significant increase in the serum ALP, AST, and ALT while the liver CAT and SOD activities concomitantly decreased in the exposed mice. Sperm morphology result showed that the samples contained constituents capable of inducing reproductive toxicity in exposed organisms, with alterations to the concentrations of TT, LH, and FSH. Toxic metal constituents of the samples were believed to induce these reported reproductive toxicity and genotoxic effect. These results showed the environmental pollution caused by cement factory and the potential effects the pollutants might have on exposed eukaryotic organisms.

Numerical Simulation of Organic Pollution Migration in the Heterogeneous Aquifer and the Application of Chemotactic Bacteria for Remediation: A Case Study of a Chemical Contamination Site in Zhejiang Province, China

Groundwater pollution poses a significant threat to ecosystems and public safety. Traditional remediation methods have limitations, necessitating innovative approaches. This study integrates numerical modeling and bioremediation to address groundwater contamination in an industrial site. It explores the potential of chemotactic bacteria to enhance remediation efficiency. The research establishes groundwater pollutant transport models, analyzes flow fields, and assesses the distribution of various pollutants. The results demonstrate the effectiveness of chemotactic bacteria, particularly chemotactic bacteria that can rapidly adapt as the pollutant concentration decreases, the concentration of chemotactic bacteria in the low-permeability area has increased by 112%. This study provides insights into the practical application of bioremediation and the promising role of bacterial chemotaxis in treating contaminated groundwater.

Assessing Nitrate Leaching During Drought and Extreme Precipitation: Exploring Deep Vadose‐Zone Monitoring, Groundwater Observations, and Field Mass Balance

AbstractThe increasing concern over agricultural practices' impact on groundwater quality necessitates comprehensive studies to evaluate and compare monitoring strategies for nitrate leaching. This work addresses this imperative by examining three methodologies: deep vadose‐zone monitoring, shallow groundwater intensive monitoring, and field‐level mass balance. The primary objective of the study was to assess nitrate leaching from an intensively cropped processing tomato rotation field using three different methods. Additionally, this study focuses on contrasting conditions between the growing season (characterized by drought in some years) and the winter/rainy season (characterized by extreme precipitation in some years). Results indicate varying degrees of nitrate leaching across methods, with all approaches detecting leaching events during the growing season and off‐season precipitation. Despite uncertainties inherent in field‐level mass balance estimates, they align reasonably with intensive in‐situ monitoring results using the deep Vadose Monitoring System (VMS). Throughout two growing seasons and corresponding fall‐winter rainy periods, the VMS effectively tracked seasonal nitrogen leaching below the root zone, correlating with observed groundwater nitrate concentrations increases following extreme precipitation events. Nitrate leaching increased during heavy rainfall in the winter following dry summer periods observed across the deep vadose zone using two VMS systems. This underscores the importance of continuous monitoring and assessment in understanding nitrate dynamics and groundwater contamination risks. In conclusion, this study contributes to knowledge and ongoing research by providing insights into effective monitoring strategies for nitrate leaching into groundwater from intensive cropping systems.

Assessment of heavy metal contamination in groundwater of rural areas of Kurdistan Province Iran: A comprehensive study

This study focuses on the contamination of groundwater by heavy metals (HMs) in the Kurdistan Province of Iran, an area heavily reliant on these water resources, especially in rural regions. This research aimed to quantify the concentrations of 20 HMs in groundwater sources and assess the associated health risks, including both carcinogenic and non-carcinogenic effects, for different age groups. The study was conducted in 2024. We collected 155 groundwater samples from water resources of the villages in Kurdistan Province, west of Iran. The study encompassed comprehensive sampling of groundwater from various wells and springs throughout the province, which was subsequently subjected to thorough laboratory analysis utilizing Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) for the quantification of heavy metal (HM) concentrations. The highest concentrations of As, Co, Cu, and Mo were 7.90, 0.22, 2.48, and 1.68 μg/l, respectively. It was related to the cities of Qorveh, Sanandaj, Baneh, and Qorveh respectively. A Health Risk Assessment (HRA) was performed, indicating that, while the concentrations of most HMs were within the thresholds established by national and international standards, certain metals, such as arsenic and lithium, presented notable non-carcinogenic risks, especially to children. These metals were responsible for over 48 % of the cumulative hazard index (HI) across all ten cities evaluated. Furthermore, the HI for the adult demographic exceeded 1.0 (specifically 1.23) exclusively in Qorwe city. The study also identified a high carcinogenic risk associated with lead across the province, which has a carcinogenic risk of 7.3 × 10−03 in 10 studied cities, which is more than the guideline value of 10−04. The findings underscore the urgent need for continuous monitoring and the implementation of preventive measures to safeguard public health. The results provide crucial insights for policymakers and health authorities, facilitating informed decisions to mitigate the health risks posed by HM contamination in the region's groundwater.

A Comparative Study of the Effects of Dumpsites on Groundwater Quality in Uyo Metropolis of Akwa Ibom State

The study was conducted to compare the effects of dumpsites on groundwater quality in Uyo Metropolis of Akwa Ibom State. It aimed at examining the effect of dumpsites from physicochemical and heavy metal content of borehole water and determining the water quality rating of boreholes in the study areas. Three (3) dumpsites, namely Uyo Village Road Dumpsite (UVD), Atiku Road Dumpsite (ARD) and Ediene Uyo Dumpsite (EUD) were used for the study. The triangular sampling method was used to select three boreholes in each dumpsite area, giving a total of thirty-six (36) samples on replication for the three dumpsites and control. The water samples were collected in well-labeled pretreated 1-litre plastic bottles and were immediately transported to the laboratory for analysis. Data obtained were analyzed using descriptive statistics and means of significant parameters were separated using the Duncan multiple range test at 5% level of probability. The result showed that mean pH was 7.49 in control, significantly lower than 8.22–8.66 in the study areas. Electrical conductivity was 245.33–580.67 μs/cm with 335.00 μs/cm as control. Mean temperatures were 28.53–28.67 oC and 28.0 oC for control. Also, values obtained for turbidity were 3.47–4.21 and 3.47 in control. DO in control borehole water was 3.07 mg/l while that of dumpsites was 3.18–3.37 mg/l. The calculated water indices were 1871.92, 33492.86 and 32288.10 for UVD, ARD and EUD respectively. The findings revealed that mean values in water quality parameters like Magnesium, Dissolved Oxygen, Lead, Cadmium, Nickel and Zinc were above the permissible limit of the World Health Organization for drinking water, indicating higher evidence of groundwater pollution in the study area. The study generally showed that borehole water samples from the three dumpsites were unsuitable for drinking. Public awareness among borehole owners and users within the dumpsite environment on ground water contamination by dumpsites was recommended among others in the study area and the water should be treated before human consumption.

Non-target screening reveals 124 PFAS at an AFFF-impacted field site in Germany specified by novel systematic terminology.

The uncontrolled release of aqueous film-forming foam (AFFF) ingredients during a major fire incident in Reilingen, Germany, in 2008 led to significant soil and groundwater contamination. As the identity of fluorochemical surfactants in AFFF are often veiled due to company secrets, it is important to characterize AFFF contaminations and their impact on the environment comprehensively. In this study, we adapted a systematic approach combining a suitable extraction method with liquid chromatography high-resolution quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) for an extensive non-targeted analysis. Our analysis identified 124 per- and polyfluoroalkyl substances (PFAS) from 42 subclasses in the contaminated soil (confidence levels of identification between 1 and 3). Typical for AFFF-impacted field sites, these included anionic, cationic, and zwitterionic substances with perfluoroalkyl chains spanning from 3 to 14 carbon atoms. Furthermore, we identified 1 previously unreported substance, and detected 9 PFAS subclasses for the first time in soil. AFFFs have long been employed to extinguish large hydrocarbon fires, yet their environmental consequences remain a concern. This study sheds light on the complex composition of AFFFs at this particularly contaminated area, emphasizing the necessity for extensive contaminant characterization as sound basis for informed management strategies to mitigate their adverse effects. AFFF PFAS are often named differently in the literature, leading to inconsistency in terminology. To address this issue, we introduced partially new terminology for AFFF-related PFAS to establish consistent terminology, to facilitate communication of identified compounds, and to ensure that the chemical structure can be directly derived from acronyms.

Effect of chemical modification on hydraulic conductivity of stratified porous media

ABSTRACT Understanding hydraulic conductivity is essential in porous media as it dictates the capacity of fluids to permeate through these substances. This research investigated the impact of chemical modification using fly ash on hydraulic conductivity. The coefficient of hydraulic conductivity along the bedding plane at different angles of orientations was predicted by employing machine learning techniques such as gene expression programming (GEP), artificial neural networks (ANNs), and regression tree (RT), considering various influencing parameters. As the amount of fly ash in the porous medium rises, the hydraulic conductivity decreases. The statistical results demonstrate that the proposed ANN model effectively forecasted the horizontal hydraulic conductivity. It achieved the highest R2 value (0.989), the lowest mean absolute percentage error value (5.772), the lowest scatter index value (0.040), and the lowest Akaike Information Criterion value (−2,359.914) compared to the GEP, RT, and previously established approaches. Moreover, a novel equation has been proposed for determining horizontal hydraulic conductivity, which can be used for any stratified medium, distinguishing this work from previous ones. These findings can inform global practices in mitigating groundwater contamination, enhancing irrigation efficiency, and improving the design of subsurface fluid flow systems, making it a valuable contribution to both academic and practical applications worldwide.

Assessment of Nitrate Reduction by Microbes in Artificial Groundwater Medium

There are significant reasons for nitrate contamination in groundwater (Delhi, India): sewage, runoff from landfill sites, nitrogenous chemical fertilisers, and pesticides from agricultural lands. The highest recorded concentration of nitrate in Delhi’s groundwater is reported to be 1500 mg/l. Consumption of high nitrate through water may pose serious health problems in humans, especially children (below five years). The study’s primary objective was to isolate and identify nitrate-remediating microbes from the nitrate-contaminated site Okhla Barrage, located on the Yamuna River in Delhi, India. A total of 11 different strains were isolated from this site. Among these four strains exhibited 40%–50% remediation efficiency at a nitrate concentration of 1000 mg/l. Molecular characterisation revealed that these four strains, Enterobacter aerogenes, E. coli K12, &lt;i&gt;Klebsiella oxytoca&lt;/i&gt; and &lt;i&gt;Lelliottia amnigena&lt;/i&gt;, belong to the Enterobacteriaceae family. This study assessed the nitrate remediation potential of isolated microbes in groundwater with 1000 and 1500 mg/l nitrate concentrations. By using a 2% inoculum, the microbes were incubated anaerobically at room temperature for ten days. Nitrate concentrations were monitored every 48 hours. &lt;i&gt;Lelliottia&lt;/i&gt;, &lt;i&gt;E. coli&lt;/i&gt;, and &lt;i&gt;Enterobacter&lt;/i&gt; reduced nitrate (1500 mg/l) by approximately 42%, 24%, and 29%, respectively, while &lt;i&gt;K. oxytoca&lt;/i&gt; showed minimal reduction. &lt;i&gt;L. amnigena&lt;/i&gt; exhibited superior nitrate removal efficiency compared to other strains. According to the reported data, these strains are known to reduce nitrate concentrations of 620 mg/l. However, our findings demonstrate a remarkable nitrate remediation capacity of 1500 mg/l, showcasing a novel contribution to this study. Further detailed analysis for condition optimisation and association of microbe-microbe could be more helpful.

Assessing Nitrogen Fertilization in Processing Pepper: Critical Nitrogen Curve, Yield Response, and Crop Development

Groundwater pollution in intensive horticultural areas is becoming an increasingly important problem. Over-fertilization of these crops, combined with poor irrigation management, leads to groundwater contamination through leaching. Previous research on the effect of N on sweet peppers grown in greenhouses is abundant, but data on outdoor cultivation, especially considering variety and site influences, are lacking. Therefore, this study evaluates nitrogen (N) fertilization in open-field processing-pepper crop in Extremadura, Spain to mitigate this environmental impact. Field trials were conducted in 2020, 2021, and 2022 to determine the optimum N fertilizer rate for processing peppers, with the aim of reducing environmental impacts such as nitrate leaching while maintaining crop yields. The trial consisted of applying different N doses, 0, 60, 120, and 180 kg N/ha in 2020 and 2021 and 0, 100, and 300 kg N/ha in 2022. There were four replications of each treatment, arranged in randomized blocks. Measurements included crop yield, biomass, intercepted photosynthetically active radiation (PAR), and canopy cover. The study also developed a critical nitrogen curve (CNC) to determine the minimum N concentration required for optimal growth. The commercial yield results showed that there were no significant differences between the two treatments with higher N inputs in the three years; therefore, the application of more than 120 kg N/ha did not significantly increase yield. Nitrogen-free treatments resulted in earlier fruit maturity, concentrating the harvest and reducing waste. In addition, excessive N application led to environmental problems such as groundwater contamination due to nitrate leaching. The study concludes that outdoor pepper crops in this region can achieve optimal yields with lower N rates (around 120 kg N/ha) compared to current practices, taking into account that initial soil N values were higher than 100 kg N/ha, thereby reducing environmental risks and fertilizer costs. It also established relationships between biomass, canopy cover, and N uptake to improve fertilization strategies. These data support future crop modeling and sustainable fertilization practices.

Clays as Micro-Electrodes in Environmental Detoxification

AbstractIn-situ reduction of contamination in soil and groundwater is an ongoing challenge that often requires a multi-pronged approach for effective and efficient clean-up. Spontaneous or assisted electrochemical reactions that break down certain pollutants held on clay surfaces can render natural clays a unique and powerful ally in environmental mitigation of contaminated soils. Application of a low-level DC electric field (mV/cm) has been shown to facilitate transformation of some compounds and ionic species through redox reactions in addition to transporting them through the pores in wet clay soils. Results from previous tests suggest that the natural electrochemical processes that promote pollutant sloughing or chemical breakdown can be enhanced for targeted treatment by applying low-level electric field to the contaminated soil with clay content. The central idea of this hypothesis is that clay, due to its surface charge and electrostatic interaction with adjacent pore fluid, acts as a “micro-electrode” through the diffused double layer (DDL) interactions when subjected to an external electric field. This hypothesis, proven viable, may unlock potential ability of natural clays to generate beneficial reactions for detoxification of contaminated sub-surfaces. Evidence from past laboratory experiments accompanied by a proposed electrical model of clay behaving as a micro-electrode are presented in this paper. The laboratory experiment results support the proposed electrical model.

Statistical Mapping of PFOA and PFOS in Groundwater throughout the Contiguous United States.

Per-and polyfluoroalkyl substances (PFAS) are synthetic chemicals that are increasingly being detected in groundwater. The negative health consequences associated with human exposure to PFAS make it essential to quantify the distribution of PFAS in groundwater systems. Mapping PFAS distributions is particularly challenging because a national patchwork of testing and reporting requirements has resulted in sparse and spatially biased data. In this analysis, an inhomogeneous Poisson process (IPP) modeling approach is adopted from ecological statistics to continuously map PFAS distributions in groundwater across the contiguous United States. The model is trained on a unique data set of 8910 PFAS groundwater measurements, using combined concentrations of two PFAS analytes. The IPP model predictions are compared with results from random forest models to highlight the robustness of this statistical modeling approach on sparse data sets. This analysis provides a new approach to not only map PFAS contamination in groundwater but also prioritize future sampling efforts.

Development of modified MgO/biochar composite for chemical adsorption enhancement to cleanup fluoride-contaminated groundwater

Fluoride contamination in groundwater has become a global environmental issue. Magnesium oxide (MgO) has demonstrated effectiveness as an adsorbent in treating fluoride pollution in groundwater. However, its use in powder and fine granular form often results in losses during the adsorption process, posing challenges for post-treatment recovery and potentially causing secondary environmental pollution. In this study, two novel fluoride adsorbents [rice husk (RH) and spent coffee grounds (SCG)-based magnesium oxide (MgO) biochar composites (MgO/RH and MgO/SCG)] were developed to cleanup fluoride-polluted groundwater. During the adsorbent synthesis process, RH and SCG biochar were pyrolyzed at 500 °C and modified by calcination using MgO. Both MgO/RH and MgO/SCG surfaces exhibited abundant pore structures and formed MgO crystal phases. Batch experiments results show that when the MgO/RH and MgO/SCG material dosages were 1 g/L, fluoride removal rates reached 80% and 86% respectively. The isotherms and kinetics of fluoride adsorption with MgO/RH and MgO/SCG followed the Langmuir isotherm equation and pseudo-second-order kinetic model. The maximum fluoride adsorption capacities of MgO/RH and MgO/SCG were 63.47 mg/g and 141.98 mg/g, respectively, indicating these materials used mono-layer adsorption mechanism for fluoride adsorption. The addition of MgO into the pores of porous adsorbent materials effectively increased their reactive sites and enhanced the adsorption performance of carbon materials. Particularly, SCG biochar had a richer pore structure than RH biochar, providing a larger contact surface area, facilitating the effective dispersion and doping of MgO into the pores. Therefore, MgO/SCG composite exhibited excellent fluoride adsorption properties in water, indicating the potential for developing a new type of MgO-modified SCG adsorbent material with green prospects. This composite effectively mitigated fluoride contamination, reducing the fluoride concentration in groundwater. Both RH and SCG are agricultural and food waste by-products, thus offering the opportunity to significantly reduce production, operation, and maintenance costs.

Groundwater Contamination by Heavy Metals in Malaysia: Sources, Transport, and Remediation Strategies

Groundwater contamination by heavy metals is a pressing environmental concern, particularly in regions highly dependent on groundwater as a freshwater source. While Malaysia primarily relies on river water, certain states and islands depend on groundwater for their supply. Research on heavy metal contamination in Malaysia’s groundwater remains limited, making it crucial to study the distribution and mobility of contaminants to develop appropriate remediation strategies. In addition to natural sources, anthropogenic activities such as landfills, mining, and the use of fertilizers contribute significantly to heavy metal pollution in groundwater. Factors like rainfall, fluctuating groundwater levels, and low soil pH can exacerbate heavy metal leaching into aquifers. Various models and techniques, including 2D resistivity imaging and MODFLOW, are used to assess groundwater flow and contaminant transport. These models suggest that contaminant concentrations decrease with increased depth and radial distance from pollution sources such as landfills and mining areas. The health risks associated with heavy metal exposure through groundwater consumption are significant, necessitating effective remediation strategies. Phytoremediation is an economical solution for groundwater containing low concentrations of heavy metals, while permeable reactive barriers may be suitable for more complex cases, pending detailed site investigation. This review aims to examine the current state of knowledge on heavy metal contamination in Malaysia’s groundwater, focusing on sources, distribution patterns, and movement of pollutants. It also seeks to evaluate existing remediation methods, including phytoremediation and permeable reactive barriers, while identifying gaps in research, particularly concerning risk assessments and heavy metal speciation.

Evaluation of the Effectiveness of Existing Preventive Fire-Fighting Measures in the City of Douala, Cameroon, to Improve Decision-Making and Public Safety

The storage of hydrocarbons in urban areas poses significant risks to local populations, including the potential for fire, explosion, groundwater contamination, and air pollution. The objective of this study is to evaluate the efficacy of current fire prevention and suppression strategies in the city of Douala. The study will be approached by first identifying, geolocating, and characterizing urban firefighting equipment. Subsequently, a proposal will be put forth for a response system to safeguard the city in the event of a catastrophic fire at a service station. In order to achieve this objective, the current regulatory framework governing the location of FH facilities was subjected to a thorough examination. Subsequently, pivotal compliance factors were identified, operationalized, and an audit checklist was formulated. A safety questionnaire was utilized to assess the equipment within service stations. GPS technology was employed to record the GPS coordinates of the FHs. GIS10.3.1 software was utilized to evaluate the BI distribution model. The data obtained from the questionnaires were analyzed using SPSS20.0 software, which revealed that the 142 BIs studied were essentially randomly distributed across the following neighborhoods. The results of the election yielded the following results: Bonamoussadi 27 (19%), Bonandjo 19 (13%), Bali 02 (1%), Deido 09 (6%), Akwa Nord 03 (2%), Bonamoussadi 18 (12%), Makepe 18 (12%), and B. The remaining 5% is distributed among the following: Assa, Bepanda, Cité-Sic, Ndogbong, Cité des Palmiers, Bonaberi, and New-Bell. Of the 142 FH identified, 30 (21.12%) lack water, and 4 (2.81%) have a flow rate of less than 30 m³/h with a dynamic pressure of less than 1 bar. Seventeen (11.97%) are inaccessible; 79 (55.63%) are operational; five (3.52%) are challenging to operate; and seven (4.92%) are situated within a private enclosure. The response time of the fire department is inadequate for all stations situated more than 3 km from their base in Ngondi-Douala. Only 17 (11.52%) of the stations are situated at distances of less than 5.83 km, which is conducive to efficient intervention. In contrast, 134 (88.74%) of the stations are located at distances of 5.83 km or more from the fire department base, which is not conducive to efficient intervention. The results indicate that the BIs are situated at considerable distances from the stations. Notably, the Total Laquitinie station is the sole city station with a FH located at its entrance. The database developed in this study could serve as a valuable resource for policymakers to inform appropriate action.

Co-tracing of groundwater emerging and conventional contaminants in karst area of Southwest China: Distribution, source, and source-specific health risks

Groundwater pollution, especially the co-contamination of emerging contaminants (ECs) and conventional contaminants, is increasingly recognized as a critical global concern. Karst aquifers are found throughout the world, providing critical water sources and sustaining rivers and ecosystems, and are particularly vulnerable to pollution. In this study, the characteristics of the contamination, potential sources, and source-specific health risks related to ECs and trace elements (TEs) in groundwater were investigated in Guiyang (a typical karst city in southwest China). The distribution of TEs followed a descending pattern from urban to suburban to rural areas. Interestingly, the median concentrations (217 ng/L) of Caffeine (CAF) in rural areas surpassed those in urban areas (145 ng/L) and even exceeded these in densely populated areas. Additionally, ECs and TEs in groundwater are significantly influenced by population density and land use types within a 1000-meter buffer zone around the sampling sites. Hierarchical cluster analysis and positive matrix factorization suggested that five principal sources of contamination were identified: domestic wastewater (29.7 %), industrial production (25.2 %), agricultural activities (16.3 %), natural and industrial sources (14.9 %), and pharmaceuticals (13.9 %). Monte Carlo simulations revealed that the non-carcinogenic risks to children in urban areas are significant, with 30.0 % of these risks exceeding the safety threshold. Source-specific health risk assessments indicated that industrial production is the primary source of risk. Furthermore, this study introduces a co-tracing method to trace the sources of groundwater contamination in karst systems. The co-tracing method based on the ECs and TEs allows for a deeper understanding of contaminant transfer and its fate in karst groundwater.

Sewage sludge as soil amendment in arid soils - A trace metal, nutrient and trace organics perspective

Sewage sludge management has emerged as a critical environmental challenge due to the large volumes generated globally. Valorization techniques, including energy production and agricultural applications, offer sustainable solutions, particularly in regions with low soil fertility. The sewage sludge utilization in the Middle East region is low. This paper presents a pragmatic risk-based assessment using the risk-based corrective action approach to evaluate sludge application in desert soils. This methodology focuses on the source-pathway-receptor interaction and assesses the likelihood of contaminants posing a real threat. In arid desert regions like Kuwait, where soil organic content and moisture are extremely low, the application of sewage sludge presents a feasible option to enhance soil quality and valorize unutilized sludge dumps which pose significant environmental concerns but are left to desiccate in the absence of any environmental regulation towards its utilization and due to religious apprehensions. Since the sludge characterization is not well detailed a brief review of the available data was included to establish the bounds of various organic, metal and nutrients that were used for generating the model. This study examines the changes in the physico-chemical properties of desert soils following sludge application, focusing on the likely fate of trace metals and organic contaminants. The alkaline desert soils of Kuwait, with a pH range of 7.7–8.9, are particularly suitable for sludge application due to the low mobility of metals in alkaline conditions. Additionally, sludge application lowers soil pH, improving conditions for plant growth. The region's deeper water table and scant annual precipitation (<0.15 m) further reduce the risk of groundwater contamination and deeper soil profile contamination. The presence of organic content, nitrates, Zn, and Cu in sludge can promote native vegetation growth. However, trace organic contaminants, including PAHs, PCBs, and pharmaceuticals, pose a potential risk to soil contamination, but since the geological section shows intervening impervious layers the contamination is going to be localized, even if there is sufficient leachable fraction. Given the minimal risk of contamination under the unique conditions of arid regions, this approach highlights the potential for eco-friendly sludge valorization, that will improve vegetation cover and arrest the suspended particulate suspension. However, before the large-scale implementation of this modelled concept, a detailed experimental study on the pilot scale or lysimeters is recommended to assess the long-term impacts of sludge application and to obtain data that can inform policy guidelines for sustainable sludge management in desert environments.

Environmental Impact of Synthetic Dyes on Groundwater in Malaysia: Sources, Distribution, Transport Mechanisms, and Mitigation Strategies

Synthetic dyes, extracted from natural sources like insects, plants, coal, and ochre, have become prevalent due to their advantages over natural dyes. However, their production has led to increased environmental pollution, particularly in groundwater. Groundwater contamination from synthetic dyes occurs through advection, dispersion, and retardation. This review aims to highlight the environmental impacts of synthetic dyes on groundwater, elucidate the mechanisms of dye transport, and propose effective strategies for monitoring and mitigating contamination. Urban runoff carries dyes from surfaces such as roofs, parking lots, and roads into stormwater systems, while agricultural runoff transports dyes from products like soil conditioners, fertilizers, and seed coatings into water bodies. In groundwater, dyes move through the aquifer via advection, dispersion, and retardation, all influenced by groundwater flow and geological conditions. The advection process involves the bulk movement of groundwater carrying dissolved dyes, while dispersion causes dyes to spread and dilute over time and distance. Retardation, which involves the adsorption of dye molecules onto soil particles, slows dye movement, prolonging their presence in groundwater. Understanding the sources, distribution, and movement of synthetic dyes in groundwater is crucial for developing strategies to protect water resources and reduce environmental and health impacts. The extensive use of dyes in industrial and domestic activities necessitates comprehensive monitoring and management to ensure sustainable groundwater quality.

Groundwater fluoride contamination, sources, hotspots, health hazards, and sustainable containment measures: A systematic review of the Ghanaian context

Groundwater quality is globally threatened by geogenic and human activities. These activities release high levels of potentially toxic elements, such as fluoride (F−), which pose significant threats to human health. This has become a global issue, especially in developing countries such as Ghana. Despite efforts to address this issue, knowledge gaps still need to be addressed to ensure safe and healthy drinking water for all Ghanaians. Moreover, Ghana has been reported to be a fluorosis-endemic country but the sources and exact hotspots of F− enrichment in the aquifers on a countrywide scale are lacking in the available literature. Understanding the quality of water used for diverse purposes in Ghana is necessary to achieve the United Nations Sustainable Development Goals like good health and well-being (SDG 3) and clean water and sanitation (SDG 6), among others. Therefore, this study synthesized all previous studies on groundwater F− contamination in Ghana, to identify the sources of F− enrichment in groundwater, delineate the hotspots for fluorosis, assess the associated human health risks, identify the best sustainable defluoridation methods, and recommend policy intervention for high groundwater F− threat to aquifers in Ghana. In the Ghanaian context, F− contamination in groundwater is largely from geogenic sources like the weathering of fluoride-bearing rocks (granitoids and carbonate sedimentary lithologies) from the Birimian and Voltaian Supergroups and the dissolution of fluoride-rich minerals (fluorapatite, amphiboles, fluorite, biotite, and muscovite). Hotspots for high groundwater F− in Ghana are mainly restricted to the Upper East Region (0.10–5.00 mg/L), North East Region (0.01–13.29 mg/L), Northern Region (0.1–11.6 mg/L), and the White Volta River Basin (0.04–3.79 mg/L). The mean and maximum values of F− in these hotspots exceed the maximum permissible level (1.5 mg/L) set by the World Health Organization and Ghana Standards Authority. Most people in these areas suffer from dental fluorosis. Therefore, affordable and sustainable defluoridation technologies as well as community-based initiatives are recommended to deal with this menace.

Investigating Heavy Metal Contamination in Groundwater of Agricultural Areas: The Case Study of Shekhan, Duhok, Iraq

Investigating Heavy Metal Contamination in Groundwater of Agricultural Areas: The Case Study of Shekhan, Duhok, Iraq