Geospatial Distribution and Potential Noncarcinogenic Health Risk Assessment of Nitrate Contaminated Groundwater in Southern India: A Case Study

Integrated assessment of groundwater quality dynamics and Land use/land cover changes in rapidly urbanizing semi-arid region

Rapid urbanization worldwide, poses numerous environmental challenges between escalating land use land cover (LULC) changes and groundwater quality dynamics. The main objective of this study was to investigate the dynamics of groundwater quality and LULC changes in Sargodha district, Punjab, Pakistan. Groundwater hydrochemistry reveals acceptable pH levels (<8) but total dissolved solids (TDS), electrical conductivity (EC) and HCO3- showed dynamic fluctuations by exceeding WHO limits. Piper diagrams, indicated dominance by magnesium and bicarbonate types, underscoring the influence of natural processes and anthropogenic activities. Major ion relationships in 2010, 2015, and 2021 showed a high correlation (R2 > 0.85) between Na+ and Cl-, suggesting salinization. whereas, the poor correlation (<0.17) between Ca2+ and HCO3- does not support calcite dissolution as the primary process affecting groundwater composition. The examination of nitrate contamination in groundwater across the years 2010, 2015, and 2021 was found to be high in the municipal sewage zone, suggesting a prevailing issue of nitrate contamination attributed to urban activities. The Nitrate Pollution Index (NPI) reveals a concerning trend, with a higher proportion of samples classified under moderate to high pollution categories in 2015 and 2021 compared to 2010. The qualitative assessment of nitrate concentration on spatiotemporal scale showed lower values in 2010 while a consistent rise from 2015 to 2021 in north-east and western parts of district. Likewise, NPI was high in the north-eastern and south-western regions in 2010, then reduced in subsequent years, which may be attributed to effective waste management practices and alterations in agricultural practices. The health risk assessment of 2010 indicated Total Health Hazard Quotient (THQ) within the standard limit, while in 2015 and 2021, elevated health risk was observed. This study emphasizes the need to use multiple approaches to groundwater management for sustainable land use planning and regulations that prioritize groundwater quality conservation.

Assessment of hydrogeochemistry in groundwater using water quality index model and indices approaches

Groundwater resources around the world required periodic monitoring in order to ensure the safe and sustainable utilization for humans by keeping the good status of water quality. However, this could be a daunting task for developing countries due to the insufficient data in spatiotemporal resolution. Therefore, this research work aimed to assess groundwater quality in terms of drinking and irrigation purposes at the adjacent part of the Rooppur Nuclear Power Plant (RNPP) in Bangladesh. For the purposes of achieving the aim of this study, nine groundwater samples were collected seasonally (dry and wet season) and seventeen hydro-geochemical indicators were analyzed, including Temperature (Temp.), pH, electrical conductivity (EC), total dissolved solids (TDS), total alkalinity (TA), total hardness (TH), total organic carbon (TOC), bicarbonate (HCO3-), chloride (Cl-), phosphate (PO43-), sulfate (SO42-), nitrite (NO2-), nitrate (NO3-), sodium (Na+), potassium (K+), calcium (Ca2+) and magnesium (Mg2+). The present study utilized the Canadian Council of Ministers of the Environment water quality index (CCME-WQI) model to assess water quality for drinking purposes. In addition, nine indices including EC, TDS, TH, sodium adsorption ratio (SAR), percent sodium (Na%), permeability index (PI), Kelley's ratio (KR), magnesium hazard ratio (MHR), soluble sodium percentage (SSP), and Residual sodium carbonate (RSC) were used in this research for assessing the water quality for irrigation purposes. The computed mean CCME-WQI score found higher during the dry season (ranges 48 to 74) than the wet season (ranges 40 to 65). Moreover, CCME-WQI model ranked groundwater quality between the "poor" and "marginal" categories during the wet season implying unsuitable water for human consumption. Like CCME-WQI model, majority of the irrigation index also demonstrated suitable water for crop cultivation during dry season. The findings of this research indicate that it requires additional care to improve the monitoring programme for protecting groundwater quality in the RNPP area. Insightful information from this study might be useful as baseline for national strategic planners in order to protect groundwater resources during the any emergencies associated with RNPP.

Nitrate contamination and associated health risks of the Benslimane groundwater, Morocco

Consumption of polluted water has harmful impacts on human health. This study examined the quality of groundwater in the Benslimane area for drinking purposes based on the Water quality index (WQI), Nitrate pollution index (NPI), and Total risk quotient (THQ) for different age groups. A total of 120 groundwater samples were collected for physicochemical analyses. The results showed WQI values ranging from 157.7 to 472.7 and an average of 279.4, with a total absence of water of excellent or good quality, and about 62.5% of the groundwater samples were of very poor quality for consumption. Nitrate concentrations ranged from 1 to 270 mg/L with an average of 64 mg/L, and 56.7% had values above the World Health Organization safety level of 50 mg/L. The NPI showed that 78.3% of the sampled sites showed very high pollution as a result of intense anthropogenic activities. High contamination is observed in the north and east of the region for arboriculture, grapes, maize, and vegetables as opposed to cereals. The health risk associated with nitrates, based on oral exposure, was much higher than dermal contact. The total risk quotient for both pathways was 0.02 to 6.58, 0.02 to 6.12, 0.06 to 17.06, and 0.05 to 13.35 for women, men, children, and infants, respectively. A total of 65, 63.3, 82.0, and 78.3% of groundwater samples presented a non-cancer health risk for women, men, children, and infants, respectively. Therefore, this study can help identify contaminated areas in order to track corrective safety measures to control groundwater quality in the region and improve sanitary conditions.

Hydrochemical characterization of groundwater quality using chemometric analysis and water quality indices in the foothills of Himalayas

Groundwater pollution of the watershed is mainly influenced by the multifaceted interactions of natural and anthropogenic process. To analyse the spatial-temporal variation and pollution source identification and apportionment, the dataset was subjected to a globally acknowledged coherent technique using water quality indices and chemometric techniques (principal component analysis (PCA) and cluster analysis. The bulk of the samples tested were below the BIS's permissible levels. Groundwater samples from the pre- and post-monsoon seasons mostly contained the anions HCO- 3 > Cl- > SO2- 4 > NO- 3, while the primary cations were Ca2+ > Mg2+ > Na+ > K+. Groundwater was alkaline and hard at most of the sites. According to hydro-geochemical facies and relationships, Piper diagrams, and principal component analysis, weathering, dissolution, leaching, ion exchange, and evaporation were the key mechanisms influencing groundwater quality. The hydrochemical facies classified the groundwater samples into the Ca-Mg-HCO3 type. For all the sampling locations, PIG was determined to be 0.43, 0.52, 0.47, 0.48, 1.00, and 0.70; respectively. The majority of the test locations fell into the low to medium contamination zone, as determined by the groundwater pollution index (PIG) and contamination index. Three principal components, which together account for 93.8% of the total variance, were identified via PCA. The study's findings confirm the value of these statistical techniques in interpreting and understanding large datasets and offering reliable information to reduce the time and expense of programmes for monitoring and evaluating water quality.

Estimating adults and children's potential health risks to heavy metals in water through ingestion and dermal contact in a rural area, Northern Tunisia

High concentrations of heavy metals (HMs) in water (e.g., As, Cr, and Cd) are harmful to human health, especially to children. HMs' (As, Cd, Mn, Fe, Cu, Hg, Zn, Cr, and Se) values have been determined from the water of the Guenniche plain (Tunisia); then the carcinogenic risk (CR) and non-carcinogenic Risk (N-CR) were estimated through ingestion and dermal contact for adults and children. The analysis results show that the Hg, As, and Cd in 50% of the ephemeral streams (ESs) exceeded one of the WHO and NT guidelines for safe water, as is the case with Hg and Cd in 25% of the shallow groundwater wells (SGW). In all samples, the N-CR of all HMs, and the CR due to the dermal contact controlled by As, for both age brackets, are deemed to fall far short of the threshold set by USEPA. The CR due to the ingestion pathway caused by As, Cr, and Cd contamination indicates a "high" to "very high" risk on its users in roughly 50% of all the samples (ESs and SGW) for both age brackets by exceeding 10^-5. Overall, the SGW samples close to the floodplain area of the ESs pose a real CR to both age groups, which is more serious for children. Therefore, the SGW are not recommended for drinking use, with an urgent call for a solution by the policy-makers to improve the water quality of the region.

Evaluation of non-carcinogenic causing health risks (NCHR) associated with exposure of fluoride and nitrate contaminated groundwater from a semi-arid region of south India

Groundwater is the foremost resource for drinking water supply in arid and semi-arid regions of the world, and also intake of contaminated drinking water is the major source for creating a several health risk for humans. To estimate the groundwater suitability for drinking and also to measure the non-carcinogenic health risk for infants, children, and adults, a total of 35 groundwater samples were collected from the semi-arid region of India and analyzed major ions including fluoride and nitrate. The results revealed that the concentration of fluoride ranges from 0.6 to 3.6 mg/L and is about 2.4 times higher than the maximum allowable limit of 1.5 mg/L for drinking water purposes. And nitrate contents varied from 17 to 120 mg/L in which 54.29% of the groundwater samples exceeded the recommended limit of 50 mg/L. The estimated individual non-carcinogenic health risk (INCHR) frequency is evidently displayed that intake of higher concentration of nitrate creates the greater detrimental health effects than fluoride. The contribution of individual non-carcinogenic health risk (INCHR) of nitrate is greater detrimental health effects than the fluoride. The results of total non-carcinogenic health risk (TNCHR) reflect the infants and also children were found to be more susceptible towards fluoride and nitrate-associated health risks in the investigated region. Fluoride-bearing minerals and different anthropogenic sources such as septic tank leakages, nitrogen fertilizers, domestic, agricultural, and animal wastes played a vital role in groundwater pollution and thereby non-carcinogenic human health risks. Therefore, a proper sustainable future plan is most important to mitigate the fluoride and nitrate contamination in the groundwater of the study region.

Judging the sources of inferior groundwater quality and health risk problems through intake of groundwater nitrate and fluoride from a rural part of Telangana, India

Evaluation of groundwater quality and related health hazards is a prerequisite for taking preventive measures. The rural region of Telangana, India, has been selected for the present study to assess the sources and origins of inferior groundwater quality and to understand the human health risk zones for adults and children due to the consumption of nitrate ([Formula: see text])- and fluoride (F^-)-contaminated groundwater for drinking purposes. Groundwater samples collected from the study region were determined for various chemical parameters. Groundwater quality was dominated by Na⁺ and [Formula: see text] ions. Piper's diagram and bivariate plots indicated the carbonate water type and silicate weathering as a main factor and man-made contamination as a secondary factor controlling groundwater chemistry; hence, the groundwater quality in the study region is low. According to the Groundwater Quality Index (GQI) classification, 48.3% and 51.7% of the total study region are excellent (GQI: < 50) and good (GQI: 50 to 100) water quality types, respectively, for drinking purposes. However, [Formula: see text] ranged from 0.04 to 585 mg/L, exceeding the drinking water quality limit of 45 mg/L in 34% of the groundwater samples due to the effects of nitrogen fertilizers. This was supported by the relationship of [Formula: see text] with TDS, Na⁺, and Cl^-. The F^- content was from 0.22 to 5.41 mg/L, which exceeds the standard drinking water quality limit of 1.5 mg/L in 25% of the groundwater samples. The relationship of F^- with pH, Ca²⁺, Na⁺, and [Formula: see text] supports the weathering and dissolution of fluoride-rich minerals for high F^- content in groundwater. They were further supported by a principal component analysis. The Health Risk Index (HRI) values ranged from 0.20 to 20.10 and 0.36 to 30.90 with a mean of 2.82 and 4.34 for adults and children, respectively. The mean intensity of HRI (> 1.0) was 1.37 times higher in children (5.70) than in adults (4.16) due to the differences in weight size and exposure time. With an acceptable limit of more than 1.0, the study divided the region into Northern Safe Health Zone (33.3% for adults and 28.1% for children) and Southern Unsafe Health Zone (66.7% for adults and 71.9% for children) based on the intensity of agricultural activity. Therefore, effective strategic measures such as safe drinking water, denitrification, defluoridation, rainwater harvesting techniques, sanitary facilities, and chemical fertilizer restrictions are recommended to improve human health and protect groundwater resources.

Assessment of the hydrochemistry, water quality, and human health risk of groundwater in the northwest of Nansi Lake Catchment, north China

In this study, the formation mechanism and water quality of groundwater in the northwest of Nansi Lake Catchment (NNLC) were analyzed through mathematical statistics, hydrochemical analysis and entropy weighted water quality index (EWQI), and the human health risk of nitrate was also evaluated. To this end, 89 wells in the NNLC were sampled, and the groundwater samples were divided into three groups (I, II, and III) according to cluster analysis results and spatial distribution. The main results are as follows: Topographically, Groups I, II, and III correspond to the alluvial plains, apron plain, and low hills and its front margin, respectively. According to the Piper diagram, the hydrochemical types of Groups I and II groundwater are Na-SO₄·Cl and Ca·Mg-HCO₃, respectively, and that of Group III is more concentrated, mostly corresponding to the Ca-HCO₃ type. Hydrochemical analysis indicated that the development of groundwater hydrochemistry is mainly attributable to water-rock interactions, with the primary process being the dissolution of minerals such as calcite, dolomite, gypsum, and albite. Evaporation exhibited an increasing trend from the northeast to the southwest. Groups I and III presented obvious effects of human activities, with Group I showing sulfate pollution and Group III mainly showing nitrate pollution. Analysis of the characteristics and causes of the groundwater hydrochemistry revealed the proposed approach has excellent performance for classification in areas with complex hydrogeological conditions. The results of EWQI showed that the overall water quality was good, following the order Group III > Group II > Group I. The overall human health risk of nitrate in groundwater was low, but the risk was slightly higher for children than for adults. Therefore, the effects of nitrate contamination should be considered when exploiting hilly and peri-urban groundwater for drinking water.

Source apportionment and health risk assessment of nitrate in foothill aquifers of Western Ghats, South India

The present research reports the level of nitrate (NO₃^-), associated health risks and possible sources of contamination in groundwater from south India. Many samples (32%) are above or approaching the recommended level of NO₃^- for safe drinking water. The correlation analysis indicates different sources of NO₃^- contamination in different regions rather than a common origin. The isotopic measurements provide information about potential nitrogen sources contributing NO₃^- to the groundwater. Based on isotope analysis, the sources of NO₃^- in the groundwater of this region are likely to be from (a) septic sewage (b) organic nitrogen (animal and livestock excreta) (c) sewage (domestic & chemical fertilizers). Among the sample analyzed sewage, manure and septic sewage contribute 46%, 23% and 31% NO₃^- to groundwater. The HQ > 1 indicates non-carcinogenic health risk due to consumption of high NO₃^- in drinking water. Among the studied age groups, infants are exposed to higher risk than children and adults. Results indicate that groundwater of this region is polluted with NO₃^- due to anthropogenic activities. Continuous consumption of such water may pose serious health risk to the residents.

Assessment of Seawater Intrusion in Coastal Aquifers Using Multivariate Statistical Analyses and Hydrochemical Facies Evolution-Based Model

Groundwater (GW) studies have been conducted worldwide with regard to several pressures, including climate change, seawater intrusion, and water overexploitation. GW quality is a very important sector for several countries in the world, in particular for Tunisia. The shallow coastal aquifer of Sfax (located in Tunisia) was found to be under the combined conditions of continuous drop in GW and further deterioration of the groundwater quality (GWQ). This study was conducted to identify the processes that control GWQ mainly in relation to mineralization sources in the shallow Sfax coastal aquifer. To perform this task, 37 wells are considered. Data include 10 physico-chemical properties of groundwater analyzed in water samples: pH, EC, calcium (Ca), sodium (Na), magnesium (Mg), potassium (K), chloride (Cl), sulfate (SO₄), bicarbonate (HCO₃), and nitrate (NO₃), i.e., investigation was based on a database of 370 observations. Principal component analysis (PCA) and hydrochemical facies evolution (HFE) were conducted to extract the main factors affecting GW chemistry. The results obtained using the PCA model show that GWQ is mainly controlled by either natural factors (rock-water interactions) or anthropogenic ones (agricultural and domestic activities). Indeed, the GW overexploitation generated not only the GWQ degradation but also the SWI. The inverse distance weighted (IDW) method, integrated in a geographic information system (GIS), is employed to achieve spatial mapping of seawater intrusion locations. Hydrochemical facies evolution (HFE) results corroborate the seawater intrusion and its spatial distribution. Furthermore, the mixing ratio showed that Jebeniana and Chaffar-Mahares localities are characterized by high SWI hazard. This research should be done to better manage GW resources and help to develop a suitable plan for the exploitation and protection of water resources.

Investigating Health Context: Using Geospatial Big Data Ecosystem (Preprint)

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Seasonal variation in groundwater quality and beneficial use for drinking, irrigation, and industrial purposes from Deccan Basaltic Region, Western India

Sustainable management of groundwater resources requires detailed basin-wide water assessments. Semi-urbanized areas surrounding metropolitan cities in the western part of India were assessed for their suitability for domestic, irrigation, and industrial purposes. These study areas reflect rapid urban growth with residential complexes, combined with agricultural, horticultural, and industrial uses. Therefore, 68 representative groundwater samples were collected during the pre-monsoon (PRM) and post-monsoon (POM) seasons of 2015 and analyzed for major ions. According to the World Health Organization (WHO) drinking standards, parameters like EC, TDS, TH, HCO3, Ca, and Mg were found to exceed the desirable maximum limits, and the B and F content exceeded the permissible limits. The drinking suitability was studied using the modified water quality index (MWQI). The irrigation suitability was assessed using indices such as sodium adsorption ratio (SAR), percent sodium (%Na), and permeability index (PI). The industrial suitability was evaluated based on Langelier saturation index (LSI), saturation index (SI), Ryznar stability index (RSI), etc. MWQI results corroborate that 52.94 and 70% samples fall in no pollution category, and 47% and 30% samples were identified to be in the moderate category of pollution in the PRM season and POM season, respectively. The spatial variation maps of LSI, SI, RSI, Puckorius scaling index (PSI) and Larson-Skold index (LaI) show that the majority of the samples in the PRM season have low to insignificant scaling and corrosive potentials as compared to POM samples. The study results provide reliable information for water reserve managers to prepare the sustainable and more accurate basin management plans.

Sources and Consequences of Groundwater Contamination

Groundwater contamination is a global problem that has a significant impact on human health and ecological services. Studies reported in this special issue focus on contaminants in groundwater of geogenic and anthropogenic origin distributed over a wide geographic range, with contributions from researchers studying groundwater contamination in India, China, Pakistan, Turkey, Ethiopia, and Nigeria. Thus, this special issue reports on the latest research conducted in the eastern hemisphere on the sources and scale of groundwater contamination and the consequences for human health and the environment, as well as technologies for removing selected contaminants from groundwater. In this article, the state of the science on groundwater contamination is reviewed, and the papers published in this special issue are summarized in terms of their contributions to the literature. Finally, some key issues for advancing research on groundwater contamination are proposed.