The human health risk assessment and countermeasures study of groundwater quality

Karst water quality, source of pollution, and health risk assessment in China

Karst areas cover approximately 15 % of the world's non-frozen terrestrial surface area and contain lots of freshwater resources. Nearly one-third of China's territory comprises karst regions, where karst water plays an crucial role as the primary water source for local residents due to its good quality and abundance. However, being an open and semi-open ecosystem, the karst water system is highly vulnerable to external influences, including climate change and human activities, leading to a noticeable deterioration in water quality. By conducting a comprehensive literature review, this paper collects a large amount hydrochemical and isotope data related to karst water in China. The analysis of this data reveals significant disparity between karst water chemistry in North and South China, primarily stemming from distinct geological and climatic conditions. Karst waters are generally contaminated with sulfate, nitrate, heavy metals, and organic matter, all of which can cause harm to human health. The decline in karst water quality within China is mainly attributed to human activities, such as urban development, agricultural fertilizer, and industrial activities. The pollutants can directly or indirectly enter the karst water aquifers through various pathways, such as runoff and infiltration, thereby degrading the quality of karst water. This study reviews the chemical characteristics and pollution sources of karst water in China and assess human health risk of the nitrate in karst water, offering some insights for the future protection of karst water.

Curcumin mitigates sodium fluoride toxicity in Caenorhabditis elegans

Fluoride, a naturally occurring element found in water, soil, food, and atmospheric precipitation, can lead to fluorosis and various health issues when consumed excessively. However, the mechanism of fluorosis is still under investigation. This study utilizes Caenorhabditis elegans as a model organism to investigate the effects of fluoride exposure on biological systems and to explore the mechanisms by which curcumin mitigates fluoride-induced toxicity. Three groups were established: a blank control, a sodium fluoride (NaF) exposure group (concentration 5 mmol/L), and a curcumin intervention group (concentration 25 μmol/L). Physiological parameters, lipofuscin levels, intracellular reactive oxygen species (ROS) levels, mitochondrial membrane potential, and mitochondrial copy numbers were measured to assess the effects of fluoride toxicity and curcumin protection. RNA-seq and qRT-PCR were utilized to investigate the molecular mechanisms underlying fluoride-induced damage and curcumin's mitigating effects. Results indicated that fluoride-exposed nematodes displayed physiological abnormalities, increased ROS production, higher lipofuscin levels, altered mitochondrial membrane potential and mitochondrial copy number, and activated MAPK signaling pathway genes. Curcumin exhibited protective effects on these parameters, suggesting its potential in preventing fluoride-induced harm by modulating oxidative stress and preserving mitochondrial function. This research enhances our understanding of the mechanisms of fluoride toxicity and highlights the potential benefits of curcumin.

Assessment of hydrochemical characteristics, health risks and quality of groundwater for drinking and irrigation purposes in a mountainous region of Pakistan

Renowned for its agriculture, livestock, and mining, Zhob district, Pakistan, faces the urgent problem of declining groundwater quality due to natural and human-induced factors. This deterioration poses significant challenges for residents who rely on groundwater for drinking, domestic, and irrigation purposes. Therefore, this novel study aimed to carry out a comprehensive assessment of groundwater quality in Zhob district, considering various aspects such as hydrochemical characteristics, human health risks, and suitability for drinking and irrigation purposes. While previous studies may have focused on one or a few of these aspects, this study integrates multiple analyses to provide a holistic understanding of the groundwater quality situation in the region. Additionally, the study applies a range of common hydrochemical analysis methods (acid-base titration, flame atomic absorption spectrometry, and ion chromatography), drinking water quality index (WQI), irrigation indices, and health risk assessment models, using 19 water quality parameters. This multi-method approach enhances the robustness and accuracy of the assessment, providing valuable insights for decision-makers and stakeholders. The results revealed that means of the majority of water quality parameters, such as pH (7.64), electrical conductivity (830.13 μScm-1), total dissolved solids (562.83 mgL-1), as well as various anions, and cations, were in line with drinking water norms. However, the water quality index (WQI) predominantly indicated poor drinking water quality (range = 51-75) at 50% sites, followed by good quality (range = 26-50) at 37% of the sites, with 10% of the sites exhibiting very poor quality (range = 76-100). For irrigation purposes, indices such as sodium percent (mean = 31.37%), sodium adsorption ratio (mean = 0.98 meqL-1), residual sodium carbonate (- 3.15 meqL-1), Kelley's index (mean = 0.49), and permeability (mean = 49.11%) indicated suitability without immediate treatment. However, the magnesium hazard (mean = 46.11%) and potential salinity (mean = 3.93) demonstrated that prolonged application of groundwater for irrigation needs soil management to avoid soil compaction and salinity. Water samples exhibit characteristics of medium salinity and low alkalinity (C2S1) as well as high salinity and low alkalinity (C3S1) categories. The Gibbs diagram results revealed that rock weathering, including silicate weathering and cation exchange, is the primary factor governing the hydrochemistry of groundwater. The hydrochemical composition is dominated by mixed Ca-Mg-Cl, followed by Na-Cl and Mg-Cl types. Furthermore, the human health risk assessment highlighted that fluoride (F-) posed a higher risk compared with nitrate (NO3-). Additionally, ingestion was found to pose a higher risk to health compared to dermal contact, with children being particularly vulnerable. The average hazard index (HI) for children was 1.24, surpassing the allowable limit of 1, indicating detrimental health effects on this subpopulation. Conversely, average HI values for adult females (0.59) and adult males (0.44) were within safe levels, suggesting minimal concerns for these demographic groups. Overall, the study's interdisciplinary approach and depth of analysis make a significant contribution to understanding groundwater quality dynamics and associated risks in Zhob district, potentially informing future management and mitigation strategies.

Health risk cause of water around landfill in hilly area and prevention and control countermeasures

Evaluating the health risks of the groundwater and surface water in landfill areas is of great significance to the health and safety of local residents. The current practice of health risk assessment is based only on the analysis results of groundwater and surface water samples, which reflect the current situation of water security in landfill areas. However, due to the neglect of risk causes analysis, thus a health risk assessment is insufficient to provide rigorous scientific countermeasures for risk prevention and control. The health risks caused by groundwater and surface water is mainly controlled by the water quality, which is comprehensively controlled by the conditions of its formation and evolution. When a landfill site is located in a hilly area, the environmental characteristics, causes, main controlling factors, and evolution processes of the surface water and groundwater in different parts of the catchment are significantly different. This study used a municipal solid waste landfill area in a hilly area as an example and defined the causes and main controlling factors of regional health risks caused by water based on an analysis of the characteristics of natural and anthropogenic factors affecting the groundwater and surface water. Then, prevention and control countermeasures were proposed for health risks caused by water in different parts of the landfill area. This study provides a method for the causes analysis and prevention and control countermeasures of health risks caused by water in municipal solid waste landfills in hilly areas.

Microbial community structural response to variations in physicochemical features of different aquifers

Introduction

The community structure of groundwater microorganisms has a significant impact on groundwater quality. However, the relationships between the microbial communities and environmental variables in groundwater of different recharge and disturbance types are not fully understood.

Methods

In this study, measurements of groundwater physicochemical parameters and 16S rDNA high-throughput sequencing technology were used to assess the interactions between hydrogeochemical conditions and microbial diversity in Longkou coastal aquifer (LK), Cele arid zone aquifer (CL), and Wuhan riverside hyporheic zone aquifer (WH). Redundancy analysis indicated that the primary chemical parameters affecting the microbial community composition were NO3 -, Cl-, and HCO3 -.

Results

The species and quantity of microorganisms in the river-groundwater interaction area were considerably higher than those in areas with high salinity [Shannon: WH (6.28) > LK (4.11) > CL (3.96); Chao1: WH (4,868) > CL (1510) > LK (1,222)]. Molecular ecological network analysis demonstrated that the change in microbial interactions caused by evaporation was less than that caused by seawater invasion under high-salinity conditions [(nodes, links): LK (71,192) > CL (51,198)], whereas the scale and nodes of the microbial network were greatly expanded under low-salinity conditions [(nodes, links): WH (279,694)]. Microbial community analysis revealed that distinct differences existed in the classification levels of the different dominant microorganism species in the three aquifers.

Discussion

Environmental physical and chemical conditions selected the dominant species according to microbial functions. Gallionellaceae, which is associated with iron oxidation, dominated in the arid zones, while Rhodocyclaceae, which is related to denitrification, led in the coastal zones, and Desulfurivibrio, which is related to sulfur conversion, prevailed in the hyporheic zones. Therefore, dominant local bacterial communities can be used as indicators of local environmental conditions.