Heavy metal pollution in Southeastern Nigeria’s Enugu area presents a severe environmental and public health hazard, with specific locations such as Emene Industrial Area, Ngwo Mechanic Village, and Abakpa experiencing particularly high contamination levels. The primary contaminants—lead, cadmium, arsenic, mercury, and chromium—originate from industrial operations, mining activities, and unregulated waste disposal. In Emene Industrial Area, soil and water samples reveal arsenic and manganese levels significantly above safety thresholds, impacting local residents, especially children and pregnant women. Ngwo Mechanic Village exhibits dangerously high concentrations of lead and chromium due to persistent automobile emissions and industrial effluents, leading to respiratory and neurological health risks for workers and nearby communities. Additionally, agricultural zones like Abakpa are impacted by cadmium from fertilizers, resulting in contamination of crops and local water sources, which poses long-term health risks to consumers. This review examines the sources, pathways, and adverse health effects of heavy metal pollution across these high-risk locations in Enugu, while also recommending mitigation strategies, including stricter environmental regulations, sustainable agricultural practices, and community education to reduce exposure and protect public health.

Groundwater is the primary source of potable and irrigation water in Gashua, Northeastern Nigeria, where arid climatic conditions limit surface water availability. Unlike previous studies in the Chad Basin that focused on limited chemical parameters, this study applies integrated geospatial modelling and multivariate statistics to delineate hydrochemical facies and anthropogenic hotspots in a semi-arid aquifer. Twenty-five groundwater samples were analyzed for pH, electrical conductivity, total dissolved solids, total hardness, major cations (Ca²⁺, Mg²⁺, Na⁺, K⁺), and anions (Cl⁻, SO₄²⁻, NO₃⁻, HCO₃⁻). Results showed pH values from 5.7 to 7.9, EC between 415 and 1464 µS/cm, and TDS from 265.6 to 937.0 mg/L. 80% (20/25) of the samples exceeded the Nigerian Standard for Drinking Water Quality (NSDWQ) limit for hardness. Piper and Durov diagrams revealed Ca²⁺–Mg²⁺–Cl⁻–SO₄²⁻ and Ca²⁺–Mg²⁺–HCO₃⁻ facies, reflecting carbonate and sulphate dissolution, cation exchange, and evaporative concentration. Spatial analysis delineated recharge zones in the north and discharge zones in the south, with higher salinity and nitrate levels in peri-urban areas. Nitrate ranged from 10.8 to 88 mg/L, with one sample exceeding the World Health Organization (WHO) limit of 50 mg/L; sampling was conducted during the dry season. Principal Component Analysis (PCA) explained 79% of total variance and identified mineralization, pH buffering, and nitrate pollution as key processes. Hierarchical Cluster Analysis (HCA) classified wells into recharge, transitional, and discharge zones. Irrigation suitability assessed by SAR, Na⁺%, PI, KR, and MH confirmed that most samples are suitable, though moderate salinity (C2S1) and isolated sodicity risks highlight the need for site-specific management. These findings emphasize the vulnerability of groundwater to both natural geochemical evolution and human activities. The integrated hydrogeochemical and multivariate approach provides actionable implications: protecting recharge areas in the north, routine surveillance of southern salinity and nitrate hotspots, and tailored farmer advisories for irrigation practices. Such measures are critical for sustainable aquifer management in arid regions.

Groundwater recharge, the downward movement of water through soil to replenish aquifers is a critical process underpinning global freshwater availability. Accurate estimation of recharge rates is essential for sustainable groundwater management, particularly in regions facing water scarcity, over-extraction, and environmental degradation. This review synthesizes seven principal methods used to estimate groundwater recharge: lysimeters, the water balance method, groundwater table fluctuation (GTF) method, stable isotopes, chloride mass balance (CMB), drip tests in karst aquifers, and unsaturated zone modelling. Each method is evaluated based on its theoretical framework, field applicability, data requirements, accuracy, advantages, limitations, and representative case studies. Lysimeters offer precise, site-specific measurements but are costly and limited in spatial scope. The water balance method is scalable and widely used but sensitive to input data quality. The GTF method is cost-effective in unconfined aquifers but depends on reliable specific yield values. Isotopic and chloride tracers provide insight into recharge pathways and sources, particularly in arid and semi-arid zones, though they may be affected by anthropogenic inputs. Drip tests effectively characterize recharge dynamics in complex karst systems, while unsaturated zone models simulate recharge processes in detail under varying climatic and land-use conditions. The review emphasizes the applicability of these methods across various climatic and geological contexts, including arid, semi-arid, and humid regions. Research gaps, including scalability and data limitations, highlight the need for integrated approaches and advanced monitoring techniques. Comparative analysis suggests that no single method suffices across all contexts; instead, combining techniques tailored to specific hydrogeological and climatic settings yields more robust estimates. This review highlights the importance of method integration and site-specific considerations to improve recharge assessments, support informed water policy, and guide sustainable groundwater development.

This research aimed at assessing the quality of groundwater for safe drinking in the western part of BUK's new campus and its environs, Kano state. In achieving the aim, a total of ten (10); five (5) boreholes and five (5) hand-dugged wells were selected at random across the area, taking into consideration the fact that thousands of staff and students depend on these sources. Water from each of the selected wells was sampled in a sterilized 500 mL plastic container and taken to the laboratory for analysis. Fourteen relevant parameters on the test of water quality were taken into consideration. Analysis of physical parameters was made in-situ using a PC400 portable pH/COND/EC/Temp meter. The result reveals that electrical conductivity is the only parameter with a mean concentration of 437.9 mg/L higher than the maximum permissible limit of 400 mg/L sets by the World Health Organization, 2011. The mean values of other physical parameters are within the standards. Chemical parameters analysis reveals that chloride (335.5 mg/L), calcium (781.3 mg/L), sodium (62.5 mg/L) and magnesium (115.9 mg/L) are the parameters with concentrations higher than the maximum permissible levels of 250 mg/L, 100 mg/l, 50 mg/L and 50mg/L respectively, all in Tudun Malumai area. Therefore, with the exception of this area, all other sources investigated are safe for drinking by meeting the standard requirements. The high concentration of chloride in the Tudun Malumai area is attributed to the use of inorganic fertilizers and animal feeding. Distillation, one of the oldest, and yet still very effective method of purifying water sources is highly recommended.