Global Groundwater Contamination: Sources, Risks, Solutions

Nina Johansson^*
*Correspondence: Nina Johansson, Department of Environmental Geotechnics, Lund University, Lund 223 63, Sweden, Email:

Introduction

Groundwater contamination poses a significant threat to global water resources and public health, necessitating comprehensive strategies for its assessment and remediation. One critical review emphasizes the synthesis of integrated approaches, combining geophysical, hydrogeological, and geochemical methods for accurate site characterization. This work also explores various conventional and advanced remediation technologies, such as bioremediation, phytoremediation, chemical oxidation, and membrane technologies, advocating for sustainable and cost-effective solutions tailored to specific contaminant types and site conditions. It further provides insights into modeling tools for predicting contaminant transport and fate, ultimately proposing a holistic framework for effective groundwater management [1].

Another study offers a global perspective on emerging contaminants (ECs) in groundwater, detailing their occurrence, fate, and associated health risks. This research delves into a wide spectrum of ECs, including pharmaceuticals, personal care products, pesticides, and industrial chemicals, attributing their pervasive presence to anthropogenic activities. It investigates factors influencing their transport and transformation within groundwater systems, like hydrogeology, redox conditions, and microbial activity. The assessment extends to potential ecological and human health risks, underscoring the urgency for enhanced monitoring and advanced treatment technologies to protect groundwater quality worldwide [2].

Research into heavy metal contamination in groundwater within industrial regions reveals critical insights into their sources, spatial distribution, and human health risks. Key heavy metals such as lead, cadmium, arsenic, and chromium are primarily linked to industrial discharges, mining operations, and agricultural runoff. By employing geostatistical methods and risk assessment models, researchers can pinpoint highly contaminated areas and quantify non-carcinogenic and carcinogenic risks to local populations through direct ingestion and dermal contact. These findings highlight the pressing need for stringent regulatory measures and effective remediation strategies to safeguard public health [3].

Agricultural activities are a significant contributor to groundwater pollution, particularly nitrate contamination. A review specifically examines mitigation strategies for reducing nitrate levels in agricultural groundwater. It outlines both source control measures, including optimized fertilizer application rates, timing, and types, along with improved irrigation management. In-situ treatment approaches, such as bioremediation using denitrifying bioreactors, are also discussed. The paper further explores the effectiveness of constructed wetlands and riparian buffers in intercepting nitrate runoff before it reaches groundwater, emphasizing a multi-pronged strategy combining best management practices with innovative technological solutions [4].

The emerging concern of microplastic contamination in groundwater is comprehensively assessed in another review, which covers their occurrence, potential sources, and transport mechanisms. Findings consolidate microplastic detection across various global groundwater systems, linking their presence to wastewater effluent, agricultural runoff from contaminated soils, and landfill leakage. The article meticulously describes how factors such as particle size, shape, density, and hydrogeological conditions influence microplastic migration through porous media, stressing the immediate need for standardized sampling, analytical methods, and further research into their ecological impacts and potential human health risks [5].

The persistent problem of per- and polyfluoroalkyl substances (PFAS) contamination in groundwater is also a major focus. One paper details their diverse sources, complex transport behavior, and significant remediation challenges, identifying industrial discharges, firefighting foams, and landfill leachate as primary culprits. The review elucidates how PFAS's unique chemical properties contribute to their high mobility and recalcitrance in groundwater, rendering conventional treatment methods ineffective. It critically evaluates current and emerging remediation technologies, including adsorption, advanced oxidation, and electrochemical methods, highlighting the demand for innovative and scalable solutions to tackle this pervasive class of contaminants [6].

A global review of pesticide contamination in groundwater provides a detailed assessment of their widespread occurrence, associated environmental and health risks, and various mitigation strategies. It categorizes prevalent pesticides, discussing their mobility and persistence as influenced by soil properties, hydrogeology, and chemical characteristics. The study evaluates the ecological impacts on aquatic life and potential human health risks via drinking water. It stresses the importance of integrated pest management, precision agriculture, and effective regulatory frameworks to minimize pesticide leaching and safeguard groundwater resources from agricultural pollution [7].

Beyond chemical pollutants, saltwater intrusion (SWI) in coastal aquifers represents another significant form of groundwater contamination, exacerbated by climate change and over-extraction. One article explores recent advancements in understanding and managing SWI, reviewing updated conceptual models and advanced numerical simulation techniques for predicting SWI dynamics. It discusses various monitoring technologies, such as geophysical methods and remote sensing, used for detecting and tracking the saline front. Furthermore, it evaluates the efficacy of different management and mitigation strategies, including artificial recharge, managed aquifer recharge, and subsurface barriers, to combat SWI and preserve vital freshwater resources [8].

Microbial contamination in groundwater also poses considerable risks. A global overview addresses its prevalent sources, advanced detection methods, and significant health implications, identifying leaky septic systems, agricultural runoff, and inadequate wastewater treatment as primary contributors of pathogenic bacteria and viruses. The article reviews conventional and molecular techniques for pathogen detection, emphasizing the necessity for rapid and accurate methods. It highlights serious public health risks, including waterborne diseases, advocating for integrated water management, improved sanitation infrastructure, and regular monitoring to ensure safe drinking water supplies [9].

Finally, radionuclide contamination in groundwater is examined, focusing on its diverse sources, complex transport mechanisms, and associated radiological health risks. This paper discusses natural sources, like uranium and thorium series, alongside anthropogenic sources, such as nuclear power plants, mining activities, and waste disposal sites. It details factors influencing radionuclide mobility in groundwater, including pH, redox conditions, and the presence of complexing agents. Methodologies for risk assessment and monitoring are also covered, emphasizing the crucial understanding of radionuclide behavior for effective environmental protection and safe management of contaminated sites [10].

Description

Groundwater, a vital natural resource, faces pervasive contamination threats from a wide array of pollutants. Integrated approaches are essential for effectively assessing and remediating contaminated sites, combining geophysical, hydrogeological, and geochemical methods for precise characterization. This holistic framework supports sustainable and cost-effective remediation solutions, which may include bioremediation, phytoremediation, chemical oxidation, and membrane technologies, all tailored to specific contaminant types and site conditions [1]. Understanding contaminant transport and fate also relies heavily on advanced modeling tools, crucial for proactive management of groundwater resources [1].

The landscape of groundwater contamination is increasingly shaped by emerging contaminants (ECs), such as pharmaceuticals, personal care products, pesticides, and industrial chemicals. These ECs are globally pervasive due to anthropogenic activities, with their transport and transformation influenced by hydrogeology, redox conditions, and microbial activity. Their presence poses significant ecological and human health risks, demanding improved monitoring strategies and advanced treatment technologies [2]. In industrial regions, heavy metals like lead, cadmium, arsenic, and chromium are major concerns, primarily originating from industrial discharges, mining operations, and agricultural runoff. Geostatistical methods and risk assessment models are instrumental in identifying high-contamination areas and quantifying non-carcinogenic and carcinogenic risks to local populations, underlining the urgent need for stringent regulatory measures and effective remediation strategies [3]. Furthermore, the persistent problem of per- and polyfluoroalkyl substances (PFAS) in groundwater stems from industrial discharges, firefighting foams, and landfill leachate. The unique chemical properties of PFAS lead to their high mobility and recalcitrance, making conventional treatments ineffective and highlighting the necessity for innovative solutions like adsorption, advanced oxidation, and electrochemical methods [6].

Agricultural practices are a leading source of specific groundwater pollutants, particularly nitrates and pesticides. Mitigation strategies for nitrate contamination include optimized fertilizer application rates and improved irrigation management, alongside in-situ treatment options like denitrifying bioreactors. Constructed wetlands and riparian buffers also play a crucial role in intercepting nitrate runoff [4]. Similarly, pesticide contamination is a global concern, with their mobility and persistence influenced by soil properties and hydrogeology. Assessing their ecological impacts and human health risks necessitates integrated pest management, precision agriculture, and robust regulatory frameworks to prevent leaching [7]. Beyond these, microplastic contamination is an emerging issue, with widespread occurrence linked to wastewater effluent, agricultural runoff, and landfill leakage. Factors like particle size, shape, density, and hydrogeological conditions govern microplastic migration, emphasizing the need for standardized sampling and analytical methods, plus further research into their environmental and health implications [5].

Groundwater can also be affected by natural phenomena and microbial pathogens. Saltwater intrusion (SWI) in coastal aquifers is a significant issue, exacerbated by climate change and over-extraction. Advances in conceptual models, numerical simulations, and monitoring technologies like geophysical methods are crucial for predicting and tracking SWI dynamics. Effective management involves strategies such as artificial recharge, managed aquifer recharge, and subsurface barriers to preserve freshwater resources [8]. Microbial contamination, primarily from leaky septic systems, agricultural runoff, and inadequate wastewater treatment, introduces pathogenic bacteria and viruses. Rapid and accurate detection methods, both conventional and molecular, are vital. This contamination poses serious public health risks, including waterborne diseases, advocating for integrated water management, improved sanitation infrastructure, and regular monitoring [9]. Finally, radionuclide contamination originates from natural sources like uranium and thorium series, as well as anthropogenic activities such as nuclear power plants and mining. Factors like pH and redox conditions influence radionuclide mobility, making comprehensive risk assessment and monitoring essential for environmental protection and safe site management [10].

Overall, the diverse challenges of groundwater contamination, ranging from chemical pollutants and emerging contaminants to natural processes and microbial threats, underscore the critical importance of a multi-faceted approach. Addressing these issues effectively requires not only advanced scientific understanding of contaminant behavior and transport but also the implementation of innovative remediation technologies, stringent regulatory oversight, and proactive management strategies across agricultural, industrial, and urban sectors. The long-term protection of groundwater resources globally hinges on continued research, collaborative efforts, and public awareness regarding these vital water supplies.

Conclusion

Groundwater contamination is a complex global issue, driven by a range of pollutants from both anthropogenic and natural sources. Research highlights the necessity of integrated approaches for assessing and remediating contaminated sites, combining geophysical, hydrogeological, and geochemical methods for accurate characterization. Various studies underscore the pervasive nature of emerging contaminants like pharmaceuticals, microplastics, and PFAS, detailing their sources from industrial discharges, wastewater, and agriculture, as well as their challenging transport and remediation. Heavy metals, nitrates, and pesticides are also significant concerns, stemming primarily from industrial activities and agricultural runoff, with studies evaluating their spatial distribution, health risks, and mitigation strategies. Beyond chemical pollutants, natural processes like saltwater intrusion in coastal aquifers, exacerbated by climate change, and microbial contamination from inadequate sanitation or agricultural runoff, pose distinct threats. Radionuclide contamination from natural deposits and human activities is also a concern, with complex transport mechanisms and radiological risks requiring careful assessment. The collective findings advocate for enhanced monitoring, advanced treatment technologies, and robust regulatory frameworks. Emphasizing sustainable, cost-effective, and tailored solutions, these studies collectively call for a holistic management approach to effectively safeguard groundwater quality and protect public health worldwide.

Acknowledgement

None.

Conflict of Interest

None.

References

1. Muhammad I, Muhammad A, Muhammad A. "Integrated approaches for assessing and remediating groundwater contamination: A critical review".Sci Total Environ 855 (2023):158784.

Indexed at, Google Scholar, Crossref

2. Jing Z, Xiaoqiang L, Yang L. "Occurrence, fate, and health risks of emerging contaminants in groundwater: A global perspective".Environ Pollut 341 (2024):122904.

Indexed at, Google Scholar, Crossref

3. Kai L, Wei D, Yanyan J. "Sources, distribution, and health risk assessment of heavy metal contamination in groundwater of a typical industrial area".Ecotoxicol Environ Saf 236 (2022):113495.

Indexed at, Google Scholar, Crossref

4. Yanan S, Wenxue L, Weijun Y. "Mitigation strategies for nitrate contamination in agricultural groundwater: A review".J Environ Manage 325 (2023):116492.

Indexed at, Google Scholar, Crossref

5. Jinhu H, Jian X, Jianying S. "Microplastic contamination in groundwater: A review of occurrence, sources, and transport".Sci Total Environ 792 (2021):148507.

Indexed at, Google Scholar, Crossref

6. Junya Z, Yifeng N, Bin C. "Per- and polyfluoroalkyl substances (PFAS) in groundwater: Sources, transport, and remediation challenges".Environ Res 236 (2023):116666.

Indexed at, Google Scholar, Crossref

7. Sajjad A, Muhammad R, Muhammad A. "Assessment of pesticide contamination in groundwater: A global review on occurrence, risks, and mitigation".Sci Total Environ 824 (2022):153721.

Indexed at, Google Scholar, Crossref

8. Alessandro LR, Matteo V, Salvatore C. "Recent advancements in understanding and managing saltwater intrusion in coastal aquifers".Water Resour Manage 35 (2021):4797-4813.

Indexed at, Google Scholar, Crossref

9. Muhammad A, Muhammad A, Muhammad S. "Microbial contamination of groundwater: A global perspective on sources, detection, and health implications".Environ Sci Pollut Res 27 (2020):41253-41267.

Indexed at, Google Scholar, Crossref

10. Yonggang J, Jianmin L, Hongwei Z. "Radionuclide contamination in groundwater: Sources, transport, and risk assessment".J Environ Radioact 208-209 (2019):105995.

Indexed at, Google Scholar, Crossref