Groundwater characterization and non-carcinogenic and carcinogenic health risk assessment of nitrate exposure in the Mahanadi River Basin of India

Planetary boundaries transgressions: A review on the implications to public health

This literature review systematically examines the impacts of violating planetary boundaries from 2009 to 2023, emphasizing the implications for human health. Planetary boundaries define safe operational limits for Earth's systems, and their transgression poses significant threats to environmental stability and public health. This paper reviews extensive research on the health effects of breaches in these boundaries, including climate change, biodiversity loss, freshwater use, and aerosol loading. The review integrates findings from numerous studies, providing a critical overview of health impacts across various global regions. The analysis underscores the intricate links between planetary boundaries breaching impacts, highlighting urgent policy and governance challenges. The study's outcomes aim to inform policymakers, businesses, and communities, promoting sustainable development and resilience in the face of escalating global challenges.

Quality evaluation and health risk assessment of karst groundwater in Southwest China

Groundwater in karst regions is of immense value due to its vital support for regional ecosystems and residents' livelihoods. However, it is simultaneously threatened by multi-source pollution from agricultural non-point sources, industrial and domestic point sources, and mining activities. This study focuses on the Guangxi of China, which features typical karst topography, aiming to thoroughly assess the groundwater quality and related health risks in Guangxi, especially identifying the impacts of various key pollution sources on the groundwater environment. A total of 1912 groundwater samples were collected, covering an area of approximately 237,600 km2. The spatial distribution of pollutants was analysed using the Nemeroww index method and Kriging interpolation, while multivariate statistical and cluster analysis methods were employed to identify the main types of pollution sources. Furthermore, based on the human health risk assessment model of the U.S. Environmental Protection Agency (US EPA), a risk assessment was conducted for key pollutants. The results revealed widespread heavy metal contamination in Guangxi's groundwater, particularly with concentrations of Mn, As, Al, Pb reaching up to 9.4 mg/L, 2.483 mg/L, 37.95 mg/L, 4.761 mg/L, respectively, significantly exceeding China's national Class III groundwater quality standards. Cluster analysis indicated that mining and industrial activities are the primary sources of pollution. The health risk assessment demonstrated that these activities pose a significant risk to public health. The aim of this study is to provide a scientific basis for the protection of the groundwater environment in Guangxi and other karst areas, the formulation of pollution prevention and control strategies, and the optimization of urban and industrial land use layouts. Future research should focus on advanced isotopic and molecular biological techniques to trace pollution sources more precisely and evaluate the effectiveness of pollution control measures.

Groundwater pollution risk, health effects and sustainable management of halocarbons in typical industrial parks

As important chemical raw materials and organic solvents, halogenated hydrocarbons not only play an important role in economic development, but are also the main source of environmental pollution. This study proposed an improved groundwater risk assessment model system, aimed at identifying and treating contaminants at leak sites. Groundwater ubiquity score (GUS) was used to evaluate the leachability of organic pollutants. The entropy-weighted water quality index (EWQI) method was used to assess the comprehensive quality of groundwater at the site. An improved groundwater health risk assessment model was constructed to analyze the health risks of groundwater. The sources of organic pollutants were identified based on the positive matrix factorization (PMF) model. Self-organizing mapping (SOM) and the K-means algorithm were integrated to classify and manage pollution source areas. The results showed that groundwater in the study area was strongly affected by human activities. The pollution source was located in a factory near S05. Different organic pollutants were highly leachable and had high potential to contaminate surrounding groundwater. 1,2-dichloropropane and 1,2,3-trichloropropane caused the largest range of contamination. The groundwater pollution index in the study area was high, and 72% of the monitoring points were non-drinkable. Both the carcinogenic and non-carcinogenic indexes of groundwater far exceeded the international standard limits and had a great impact on human health. 1,2,3-trichloropropane and 1,2-dichloropropane were major non-carcinogenic risk factors. The leakage of pollutants and pesticide solvents were the main causes of groundwater pollution. Cluster areas III and II were areas with significant pollution impacts and needed to be monitored intensively. Most areas were cluster I, with relatively low risk. This study can provide technical support for groundwater pollution risk assessment and management in similar industrial parks.

Determination of high-risk factors and related spatially influencing variables of heavy metals in groundwater

Identifying high-risk factors (heavy metals (HMs) and pollution sources) by coupling receptor models and health risk assessment model (HRA) is a novel approach within the field of risk assessment. However, this coupled model ignores the contribution of spatial differentiation to high-risk factors, resulting in the assessment being subjective. Taking Dongting Plain (DTP) as an example, a coupling framework by jointly using the positive matrix factorization model (PMF), HRA, Monte Carlo simulation, and geo-detector was developed, aiming to identify high-risk factors in groundwater, and further explore key environmental variables influencing the spatial heterogeneity of high-risk factors. The results showed that at least 82.86 % of non-carcinogenic risks and 97.41 % of carcinogenic risks were unacceptable for people of all ages, especially infants and children. According to the relationships among HMs, pollution sources, and health risks, As and natural sources were defined as high-risk HMs and sources, respectively. The interactions among Holocene thickness, oxidation-reduction potential, and dissolved organic carbon emerged as the primary drivers of spatial variability in high-risk factors, with their combined explanatory power reaching up to 74%. This proposed framework provides a scientific reference for future studies and a practical reference for environmental authorities in developing effective pollution management measures.

Groundwater hydrochemical signatures, nitrate sources, and potential health risks in a typical karst catchment of North China using hydrochemistry and multiple stable isotopes

Nitrate pollution in aquatic ecosystems has received growing concern, particularly in fragile karst basins. In this study, hydrochemical compositions, multiple stable isotopes (δ2H-H2O, δ18Ο-Η2Ο, δ15Ν-ΝΟ3-, and δ18Ο-ΝΟ3-), and Bayesian stable isotope mixing model (MixSIAR) were applied to elucidate nitrate pollution sources in groundwater of the Yangzhuang Basin. The Durov diagram identified the dominant groundwater chemical face as Ca-HCO3 type. The NO3- concentration ranged from 10.89 to 90.45 mg/L (average 47.34 mg/L), showing an increasing trend from the upstream forest and grassland to the downstream agricultural dominant area. It is worth noting that 47.2% of groundwater samples exceeded the NO3- threshold value of 50 mg/L for drinking water recommended by the World Health Organization. The relationship between NO3-/Cl- and Cl- ratios suggested that most groundwater samples were located in nitrate mixed endmember from agricultural input, soil organic nitrogen, and manure & sewage. The Self-Organizing Map (SOM) and Pearson correlations analysis further indicated that the application of calcium fertilizer, sodium fertilizer, and livestock and poultry excrement in farmland elevated NO3- level in groundwater. The output results of the MixSIAR model showed that the primary sources of NO3- in groundwater were soil organic nitrogen (55.3%), followed by chemical fertilizers (28.5%), sewage & manure (12.7%), and atmospheric deposition (3.4%). Microbial nitrification was a dominant nitrogen conversion pathway elevating NO3- levels in groundwater, while the denitrification can be neglectable across the study area. The human health risk assessment (HHRA) model identified that about 88.9%, 77.8%, 72.2%, and 50.0% of groundwater samples posing nitrate's non-carcinogenic health hazards (HQ > 1) through oral intake for infants, children, females, and males, respectively. The findings of this study can offer useful biogeochemical information on nitrogen pollution in karst groundwater to support sustainable groundwater management in similar human-affected karst regions.

Human health risk of nitrate in groundwater of Tehran-Karaj plain, Iran

Groundwater pollution by nitrate has is a major concern in the Tehran-Karaj aquifer, Iran, where the wells provide up to 80% of the water supply for a population of more than 18 million-yet detailed human health risks associated with nitrate are unknown due to the lack of accessible data to adequately cover the aquifer in both place and time. Here, using a rich dataset measured annually in more than 75 wells, we mapped the non-carcinogenic risk of nitrate in the aquifer between 2007 and 2018, a window with the most extensive anthropogenic activities in this region. Nitrate concentration varied from ~ 6 to ~ 150 mg/L, around three times greater than the standard level for drinking use, i.e. 50 mg/L. Samples with a non-carcinogenic risk of nitrate, which mainly located in the eastern parts of the study region, threatened children's health, the most vulnerable age group, in almost all of the years during the study period. Our findings revealed that the number of samples with a positive risk of nitrate for adults decreased in the aquifer from 2007 (17 wells) to 2018 (6 wells). Although we hypothesized that unsustainable agricultural practices, the growing population, and increased industrial activities could have increased the nitrate level in the Tehran-Karaj aquifer, improved sanitation infrastructures helped to prevent the intensification of nitrate pollution in the aquifer during the study period. Our compilation of annually mapped non-carcinogenic risks of nitrate is beneficial for local authorities to understand the high-risk zones in the aquifer and for the formulation of policy actions to protect the human health of people who use groundwater for drinking and other purposes in this densely populated region.

Hydrogeochemical characterization, quality assessment, and potential nitrate health risk of shallow groundwater in Dongwen River Basin, North China

Assessing groundwater geochemical formation processes and pollution circumstances is significant for sustainable watershed management. In the present study, 58 shallow groundwater samples were taken from the Dongwen River Basin (DRB) to comprehensively assess the hydrochemical sources, groundwater quality status, and potential risks of NO3- to human health. Based on the Box and Whisker plot, the cation's concentration followed the order of Ca2+  > Mg2+  > Na+  > K+, while anions' mean levels were HCO3-  > SO42-  > NO3-  > Cl-. The NO3- level in groundwater samples fluctuated between 4.2 and 301.3 mg/L, with 67.2% of samples beyond the World Health Organization (WHO) criteria (50 mg/L) for drinking. The Piper diagram indicated the hydrochemical type of groundwater and surface water were characterized as Ca·Mg-HCO3 type. Combining ionic ratio analysis with principal component analysis (PCA) results, agricultural activities contributed a significant effect on groundwater NO3-, with soil nitrogen input and manure/sewage inputs also potential sources. However, geogenic processes (e.g., carbonates and evaporite dissolution/precipitation) controlled other ion compositions in the study area. The groundwater samples with higher NO3- values were mainly found in river valley regions with intense anthropogenic activities. The entropy weight water quality index (EWQI) model identified that the groundwater quality rank ranged from excellent (70.7%) and good (25.9%) to medium (3.4%). However, the hazard quotient (HQ) used in the human health risk assessment (HHRA) model showed that above 91.38% of groundwater samples have a NO3- non-carcinogenic health risk for infants, 84.48% for children, 82.76% for females, and 72.41% for males. The findings of this study could provide a scientific basis for the rational development and usage of groundwater resources as well as for the preservation of the inhabitants' health in DRB.

Using unsupervised machine learning models to drive groundwater chemistry and associated health risks in Indo-Bangla Sundarban region

Groundwater is an essential resource in the Sundarban regions of India and Bangladesh, but its quality is deteriorating due to anthropogenic impacts. However, the integrated factors affecting groundwater chemistry, source distribution, and health risk are poorly understood along the Indo-Bangla coastal border. The goal of this study is to assess groundwater chemistry, associated driving factors, source contributions, and potential non-carcinogenic health risks (PN-CHR) using unsupervised machine learning models such as a self-organizing map (SOM), positive matrix factorization (PMF), ion ratios, and Monte Carlo simulation. For the Sundarban part of Bangladesh, the SOM clustering approach yielded six clusters, while it yielded five for the Indian Sundarbans. The SOM results showed high correlations among Ca2+, Mg2+, and K+, indicating a common origin. In the Bangladesh Sundarbans, mixed water predominated in all clusters except for cluster 3, whereas in the Indian Sundarbans, Cl--Na+ and mixed water dominated in clusters 1 and 2, and both water types dominated the remaining clusters. Coupling of SOM, PMF, and ionic ratios identified rock weathering as a driving factor for groundwater chemistry. Clusters 1 and 3 were found to be influenced by mineral dissolution and geogenic inputs (overall contribution of 47.7%), while agricultural and industrial effluents dominated clusters 4 and 5 (contribution of 52.7%) in the Bangladesh Sundarbans. Industrial effluents and agricultural activities were associated with clusters 3, 4, and 5 (contributions of 29.5% and 25.4%, respectively) and geogenic sources (contributions of 23 and 22.1% in clusters 1 and 2) in Indian Sundarbans. The probabilistic health risk assessment showed that NO3- poses a higher PN-CHR risk to human health than F- and As, and that potential risk to children is more evident in the Bangladesh Sundarban area than in the Indian Sundarbans. Local authorities must take urgent action to control NO3- emissions in the Indo-Bangla Sundarbans region.

Bioavailability and health risk of pollutants around a controlled landfill in Morocco: Synergistic effects of landfilling and intensive agriculture

Toxic contamination of agricultural soils by trace metal(oid)s can pose detrimental effects on human health and agroecological systems. In this view, the current research explored total and available metal(oid)s in surface soils and assessed the associated hazards using pollution indices, PMF modeling, PCA, and Montecarlo probabilistic human risk assessment with 10,000 repetitions. The mean concentrations of Cd, Pb, As, Cr, Ni, Cu, Zn, and Fe were 0.89, 24.86, 1.81, 19.10, 25.44, 7.98, 49.12 and 6183.32 mg kg-1 dry weight, respectively. These findings highlighted that the concentration of pollutants exceeded the values measured in the geochemical background. Soil enrichment by heavy metal (oid)s was confirmed by analyzing available fractions using DTPA ,CaCl2 and enrichment factor (EF). Additionally, pollution indicators (Igeo, PLI, and PERI) displayed significant contamination levels, with a higher ecological risk. Matrix Factorization (PMF) receptor and multivariate statistical analysis reflected that anthropogenic activities, particularly landfilling and agricultural practices were the main causes of the contamination. Furthermore, probabilistic and deterministic human risk assessments showed that carcinogenic risks exceeded the threshold values (10-4) set by the USEPA. Consequently, it is crucial to implement continuous monitoring and supervision of landfill sites to prevent additional pollution. These measures should be integrated into the management plans for waste management.

Hydrochemical characterizations and groundwater quality assessment in the coastal region of the Jiaodong peninsula, North China

Groundwater resources constitute a primary water source in the coastal region of Jiaodong Peninsula (CRJP), serving as an essential foundation for socio-economic development and municipal water supply. This study sought to evaluate the hydrogeochemical properties of the CRJP's groundwater using 73 samples collected in 2017, comprehensively analyzing the chemical composition and environmental factors using mathematical statistics and hydrochemical techniques. The results demonstrate that groundwater in the CRJP possesses TDS values ranging from 262 to 28,160 mg/L, with a pH ranging between 6.4 and 8.5, characterizing a weakly alkaline water system. The cation order in groundwater is Na+ > Ca2+ > Mg2+ > K+, while the anionic sequence comprises Cl- > HCO3- > SO42- > NO3-. According to the Piper diagram, groundwater samples predominantly clustered into SO4·Cl-Ca·Mg and SO4·Cl-Na types. Additionally, significant spatial variations exist in the primary chemical components of groundwater. Hydrogeochemical characteristics within the region are influenced both by natural and human activities; natural elements include weathering of silicate rocks, gypsum and carbonate minerals dissolution, while human practices comprise industrial and mining activities, agricultural practices, and domestic waste discharge. The results from a health risk assessment show that non-carcinogenic risks posed by nitrate intake via drinking water are considerably high for infants in comparison to adults, teenagers, and children. Furthermore, certain regions within the CRJP show notable seawater intrusion effects on groundwater studied.

Hydrochemical investigation of groundwater in a trans-Himalayan region of Ladakh, India, using geochemical modelling and entropy technique

Evaluating the hydrogeochemistry and groundwater quality status is vital to understand the sources and extent of groundwater contamination. Chemometric analysis, geochemical modelling and entropy technique were explored to delineate the hydrogeochemistry of groundwater in the trans-Himalayan region. Analysis of hydrochemical facies revealed that 57.14, 39.29, and 3.57% of samples were Ca-Mg-HCO3-, Ca-Mg-Cl- and Mg-HCO3- water types, respectively. Gibbs diagrams illustrate the effects of the dissolution of carbonates and silicates during weathering on groundwater hydrogeochemistry. The PHREEQC modelling depicted that most of the secondary minerals are supersaturated except for halite, sylvite, and magnetite which are undersaturated and in equilibrium with nature. Multivariate statistical techniques, including principal component analysis, were applied for source apportionment indicating that the hydrochemistry of the groundwater was mainly controlled by geogenic sources (rock-water interaction) along with secondary pollution through increased anthropogenic sources. Heavy metal accumulation in groundwater depicted the order of Cd > Cr > Mn > Fe > Cu > Ni > Zn. EWQI analysis revealed that none of the samples fell into excellent and good categories. In total, 92.86% of groundwater samples were in an average category while the rest of the samples (7.14%) were unfit for drinking. This study will provide baseline data and a scientific framework which can be used in source apportionment studies, predictive modelling and efficient management of water resources.

Spatio-temporal variation of groundwater pollution in urban wetlands and management strategies for zoning

Groundwater is an important resource to maintain the sustainable development of urban wetlands. The Jixi National Wetland Park (JNWP) was studied to realize the refined prevention and control of groundwater. The self-organizing map-K-means algorithm (SOM-KM), improved water quality index (IWQI), health risk assessment model and forward model were used comprehensively to evaluate the groundwater status and solute sources in different periods. The results showed that the groundwater chemical type in most areas was the HCO₃-Ca type. Groundwater chemistry data from different periods were clustered into five groups. Groups 1 and 5 are affected by agricultural and industrial activities, respectively. The IWQI value in the normal period was higher in most areas due to the influence of spring ploughing. The east side of the JNWP was disturbed by human activities, and the quality of drinking water continued to deteriorate from the wet period to the dry period. 64.29% of the monitoring points showed good irrigation suitability. The health risk assessment model showed that the health risk was the largest in the dry period and the smallest in the wet period. The main factors causing health risks in the wet period and other periods were NO₃^- and F^-, respectively. The overall cancer risk was within acceptable limits. The forward model and ion ratio analysis showed that the weathering of carbonate rocks was the main factor affecting the evolution of groundwater chemistry, accounting for 67.16%. The high-risk areas of pollution were mainly concentrated in the east of the JNWP. K⁺ and Cl^- were the key monitoring ions in the risk-free zone and potential risk zone, respectively. The research can be used to help decision-makers carry out fine zoning control of groundwater.

Estimation of Polycyclic Aromatic Hydrocarbons in Groundwater from Campania Plain: Spatial Distribution, Source Attribution and Health Cancer Risk Evaluation

The aim of this study was to evaluate the concentrations of polycyclic aromatic hydrocarbons (PAHs) in 1168 groundwater samples of the Campania Plain (Southern Italy), taken using a municipal environmental pressure index (MIEP), and to analyze the distribution of these compounds to determine source PAHs using ratios of isomers diagnostic. Lastly, this study also aimed to estimate the potential health cancer risk in groundwaters. The data indicated that the highest concentration of PAHs was found in groundwater from Caserta Province and the contents of BghiP, Phe, and Nap were detected in the samples. The spatial distribution of these pollutants was evaluated using the Jenks method; moreover, the data indicated that incremental lifetime cancer risk ILCR_ingestion ranged from 7.31 × 10^-20 to 4.96 × 10^-19, while ILCR_dermal ranged from 4.32 × 10^-11 to 2.93 × 10^-10. These research findings may provide information about the Campania Plain's groundwater quality and aid in the development of preventative measures to lessen PAH contamination in groundwater.

Evaluation of quality and risk to human health of groundwater in a coastal coal-bearing graben basin, North China

Water quality assessments are essential for ensuring human and ecosystem health. This study conducted a water quality assessment on a typical coastal coal-bearing graben basin. Suitability of groundwater quality of the basin for drinking and agricultural irrigation was assessed. Hazards posed to human health by groundwater nitrate were assessed using the objective combined weight water quality index, percent sodium, sodium adsorption ratio, and health risk assessment model. The results indicated groundwater of the basin to be weakly alkaline hard-fresh or hard-brackish, and mean values of pH, total dissolved solids, and total hardness of 7.6, 1464.5 mg/L, and 794.1 mg/L, respectively. The ranks of groundwater cations and anions by abundance were Ca²⁺>Na⁺>Mg²⁺>K⁺ and HCO₃^->NO₃^->Cl^->SO₄^2->F^-, respectively. The main groundwater type was Cl-Ca, followed by HCO₃-Ca. The results of the water quality evaluation indicated that most groundwater in the study area is of a medium quality (38%), followed by poor (33%), and extremely poor (26%). Groundwater quality gradually worsened from inland to the coast. Groundwater of the basin was generally suitable for agricultural irrigation. Groundwater nitrate posed a hazard to over 60% of the exposed population, with infants most at risk, followed by children, adult females, and adult males.