Application of HMTL and novel IWQI models in rural groundwater quality assessment: a case study in Nigeria

A comparative hydrochemical assessment of groundwater quality for drinking and irrigation purposes using different statistical and ML models in lower gangetic alluvial plain, eastern India

Groundwater toxicity and water level depletion are serious concerns today. Assessing groundwater quality (GWQ) is crucial for effective planning and management due to increasing demands for drinking and irrigation water. Therefore, this study aims to analyze groundwater hydrochemistry, variability, and factors influencing quality for drinking and irrigation purposes using indices and models. For this purpose, 107 sampling sites were investigated considering 14 parameters. To assess the suitability of irrigation water, nine irrigation indices (magnesium hazard, sodium-adsorption-ratio, residual sodium-carbonate, residual sodium-bicarbonate, sodium percentage, potential salinity, Kelly's index, total hardness and permeability index) were applied. Shannon-entropy-based water quality index (SEWQI) and statistical techniques such as Pearson correlation, principal component analysis, and hierarchical cluster analysis were used assess to the selected parameters. Six machine learning models, both conventional and ensemble, (AdaBoost, DT, MLP, SVM, RF, and XGBoost) were employed for predictive analysis. The SEWQI reveals 38% samples are excellent to good, while 62% are poor to unsuitable, covering 5905.64 km2 area. Assessed irrigation indices confirm most samples are unsuitable. As per Gibbs and USSL diagrams, groundwater samples are primarily affected by rock dominance and suitable for irrigation despite high salinity and low sodium (C3S1 = 43.99%). Overall, the rock dominance zone is shaped by silicate and carbonate mineral dissolution and human activities, impacting GWQ. Hyperparameter optimization using the grid search method improves the performance accuracy of the XGBoost model with R2 of 0.999 and RMSE of 0.269. The results of this study can help implement appropriate management and monitoring strategies and provide insights into safe drinking water in the future.

A comprehensive evaluation of the contamination scenario and water quality in the gas fields of north-east region, Bangladesh

Gas fields generate a significant volume of produced water, disposed in the vicinity of gas fields in Bangladesh after processing. It may have a variety of effects on ecology and the environment. This study was conducted to assess the contamination scenario and quality of produced and discharged water from gas fields in northeastern Bangladesh. The physicochemical analyses for this study were performed using standard procedures. Based on the outcomes of the analyzed samples, the current research employs a variety of indexing and statistical approaches to investigate the overall status of the studied water. The physiochemical analysis revealed high electrical conductivity (EC), total dissolved solid (TDS), salinity, and Na contents in both produced and discharged water. No severe cases have been identified, certain metals, such as Fe, Ni, and Cd, have been detected at levels high enough to impact specific index values in some cases. The results of the weighted contamination index (WCI) indicated mild to considerable pollution in the gas field region. The average score of potential ecological risk (PER) reflects minimal ecological risk. The heavy metal toxicity load (HTML) reveals negligible metal pollution in the studied water. The agricultural risk indices displayed increased sodium concentrations and EC, resulting in salinity and sodium risks. The magnesium absorption ratio is within the allowable range. In addition, the average heavy metal pollution index (HMPI) value demonstrates that the produced and discharged water is unsuitable for drinking. The entropy-based water quality index (EWQI) is below the threshold limit (<100) for all samples, indicating satisfactory water quality. This study is an early effort to evaluate the quality of wastewater produced and discharged from gas fields in Bangladesh. The findings of this research will provide valuable insights for future researchers and regulators in effectively managing and mitigating pollution from wastewater.

The assessment of groundwater quality through the water quality and nitrate pollution indexes in northern Türkiye

Groundwater is contaminated by anthropogenic factors such as industry, domestic waste, and excessive fertilizers. Groundwater samples, which were obtained from 50 different wells in July 2020, were used in this study. Thirteen hydrochemical properties, including electrical conductivity (EC), pH, total dissolved solids (TDS), total hardness (TH), nitrate NO3-, anions, and cations were analyzed. Also, types of groundwater were investigated via the Piper diagram. The groundwater was also evaluated for irrigation suitability using the sodium percentage (Na%), sodium adsorption ratio (SAR), Kelly's index (KI), residual sodium carbonate (RSC), potential salinity, magnesium hazard (MR), and permeability index (PI). The samples were assessed for drinking the suitability using the water quality index (WQI) and the nitrate pollution index (NPI). Geographic information systems (GIS) were used to create spatial distribution maps of irrigation water quality indices, WQI, and NPI values. The results of major cations varied sodium 28.69-211.80 mg/L, calcium 78.74-258.89 magnesium 27.78-161.30 mg/L, and potasium 0.10-3.57 mg/L. The results from the study area showed that 62.70 of EC, 32.40% of PI, 20.09% of RSC, 51.55% of PS, and 49.36% of MR were inappropriate for irrigation purposes. The NPI data ranged from - 0.75 to 9.65, and 21.06% of the study areas were heavily polluted. The WQI showed that almost 62.90% of the experimental area was categorized as poor, very poor, and inappropriate for drinking water purposes, whereas 37.10% of the areas were categorized as good and excellent.

Hydrogeochemical assessment and health-related risks due to toxic element ingestion and dermal contact within the Nnewi-Awka urban areas, Nigeria

Awka and Nnewi metropolises are known for intensive socioeconomic activities that could predispose the available groundwater to pollution. In this paper, an integrated investigation of the drinking water quality and associated human health risks of contaminated groundwater was carried out using geochemical models, numerical water quality models, and the HHRISK code. Physicochemical analysis revealed that the groundwater pH is acidic. Predicted results from PHREEQC model showed that most of the major chemical and trace elements occurred as free mobile ions while a few were bounded to their various hydrated, oxides and carbonate phases. This may have limited their concentration in the groundwater; implying that apart from anthropogenic influx, the metals and their species also occur in the groundwater as a result of geogenic processes. The PHREEQC-based insights were also supported by joint multivariate statistical analyses. Groundwater quality index, pollution index of groundwater, heavy metal toxicity load, and heavy metal evaluation index revealed that 60-70% of the groundwater samples within the two metropolises are unsuitable for drinking as a result of anthropogenic influx, with Pb and Cd identified as the priority elements influencing the water quality. The HHRISK code evaluated the ingestion and dermal exposure pathway of the consumption of contaminated water for children and adult. Results revealed that groundwater from both areas poses a very high chronic and carcinogenic risk from ingestion than dermal contact with the children population showing greater vulnerability. Aggregated and cumulative HHRISK coefficients identified Cd, Pb, and Cu, to have the highest health impact on the groundwater quality of both areas; with residents around Awka appearing to be at greater risks. There is, therefore, an urgent need for the adoption of a state-of-the-art waste management and water treatment strategies to ensure safe drinking water for the public.

Evaluation of oral and dermal health risk exposures of contaminants in groundwater resources for nine age groups in two densely populated districts, Nigeria

Human health and the sustainability of the socioeconomic system are directly related to water quality. As anthropogenic activity becomes more intense, pollutants, particularly potentially harmful elements (PHEs), penetrate water systems and degrade water quality. The purpose of this study was to evaluate the safety of using groundwater for domestic and drinking purposes through oral and dermal exposure routes, as well as the potential health risks posed to humans in the Nnewi and Awka regions of Nigeria. The research involved the application of a combination of the National Sanitation Foundation Water Quality Index (NSFWQI), HERisk code, and hierarchical dendrograms. Additionally, we utilized the regulatory guidelines established by the World Health Organization and the Standard Organization of Nigeria to compare the elemental compositions of the samples. The physicochemical parameters and NSFWQI evaluation revealed that the majority of the samples were PHE-polluted. Based on the HERisk code, it was discovered that in both the Nnewi and Awka regions, risk levels are higher for people aged 1 to <11 and >65 than for people aged 16 to <65. Overall, it was shown that all age categories appeared to be more vulnerable to risks due to the consumption than absorption of PHEs, with Cd > Pb > Cu > Fe for Nnewi and Pb > Cd > Cu > Fe for water samples from Awka. Summarily, groups of middle age are less susceptible to possible health issues than children and elderly individuals. Hierarchical dendrograms and correlation analysis showed the spatio-temporal implications of the drinking groundwater quality and human health risks in the area. This research could help local government agencies make informed decisions on how to effectively safeguard the groundwater environment while also utilizing the groundwater resources sustainably.

Assessment of metal concentrations from recreational rivers in a tropical region (Jengka, Malaysia)

A recreational river may be exposed to some extent of metal pollution. Two rivers, namely Sungai Weh and Sungai Jempul, were selected for this study, as both areas offer recreational activities for residents in Jengka, Pahang, Malaysia. This study examines the concentration of selected metals (Fe, Mn, and Pb), elucidates the possible sources, evaluates the toxicity loads, and estimates the potential health risk. Metal concentrations were analysed using inductively coupled plasma optical emission spectrometry (ICP-OES). The concentrations were found in the sequence of Fe > Pb > Mn. Hierarchical cluster analysis (HCA) suggested that the metals’ origins included both anthropogenic activities and natural sources. About 16.66% of Pb should be removed from the river water to ensure safety, based on the heavy metal toxicity load calculation (HMTL). Children are more vulnerable to non-cancer and cancer risks than adults. The findings indicate that comprehensive monitoring of water quality parameters and thorough exposure assessment should be performed.