Assessment of groundwater fluoride and human health effects in a hard rock province of south India: Implications from Pollution Index Model (PIM) and Geographical Information System (GIS) techniques.

This research examines whether the groundwater in the Sivakasi Region of South India is suitable for consumption, and assesses the possible health hazards for various age demographics including infants, children, teenagers, and adults. A total of 77 groundwater samples were gathered, covering a total area of 580 km2 and analyzed for major and minor ions. The hydrogen ion concentration (pH) of the samples indicates neutral to marginally alkaline. The total dissolved solids (TDS) fluctuate from 255 to 2701 mg/l and electrical conductivity varies from 364 to 3540 µS/cm. A wide range of fluoride concentration was detected (0.1 to 3.2 mg/l) with nearly 38% groundwater samples surpassing the proposed limit (1.5 mg/l) suggested by the World Health Organization in 2017. Gibbs plot analysis suggested that most of the samples were influenced by geogenic factors, primarily rock weathering in this region. Correlation analysis showed that most of the samples were impacted by both natural and human sources. The pollution index of groundwater (PIG) fluctuated from 0.67 to 2.60 with approximately 30% and 53% of samples falling into insignificant and low pollution categories, respectively. Furthermore, 10% and 5% of total samples were characterized as moderate and high pollution levels, and 2% as very high pollution category. Spatial analysis using GIS revealed that 440.63 km2 were within safe fluoride levels according to the WHO standards, while 139.32 km2 were identified as risk zone. The principal component analysis (PCA1) showed strong positive loadings on EC (0.994), TDS (0.905), Mg2+ (0.910), Cl- (0.903) and HCO3- (0.923) indicating rock water interaction. PCA2 accounts the high positive factor loading on HCO3- (0.864) indicating ion exchange and mineral leaching. The PCA1 and PCA2 indicated that variables such as mineral leaching and rock water interaction are the major mechanisms contributing to the chemical signatures in groundwater, which may support for the elevated fluoride levels in certain areas. Risk assessments, including Hazard Quotient results showed that 71%, 61% 38%, and 34% of groundwater samples exceeded the permissible THI limit (THI > 1) for infants, children, teenagers, and adults, respectively. The study recommends implementing measures such as denitrification, defluorination, rainwater harvesting, and improved sanitation infrastructure to enhance the health conditions in the study region. Additionally, it suggests introducing educational programs in rural areas to create awareness about the health dangers due to consumption of water with high fluoride levels.

Exploring the potential of sulphur forms in Northeastern Indian coals: Implications in environmental remediation and heavy metal sensing.

The Sampar Coalfield in Northeastern India is a source of plentiful coal reserves, which are burnt for energy production and industrial applications, resulting in the release of pollutants such as sulphur , arsenic, and lead, which are hazardous to the environment and public health. In this work, samples from the Sampar coalfield have been analyzed to understand the origin, distribution, and various forms of sulphur and their ability to detect toxic heavy metals. The total sulphur concentration ranged from 4.31% to 6%, with organic sulphur being the predominant form at 69.21%, followed by pyritic sulphur at 16.49% and sulphate sulphur at 14.28%. With high sulphur content, this coal indicates a marine influence in the peat-forming swamps. The samples have also been examined for petrographic and elemental analysis, which have revealed the presence of vitrinite, liptinite, inertinite, carbon, hydrogen, nitrogen, oxygen, and mineral matter. In addition, the same coal sample has also been used for electrochemical sensing-based detection of toxic heavy metals like arsenic and lead, and the findings indicate an improved efficacy. These results are expected to have significant implications in the development of effective bio-based remediation strategies in the region to mitigate the harmful effects of coal-related pollution.

Characterization of lignite deposits of Barmer Basin, Rajasthan: insights from mineralogical and elemental analysis.

The geochemistry of fly ash produced from the combustion of coal at thermal power plants presents a significant challenge for disposal and environmental impact due to its complex mineralogical and elemental composition. The objective of this study was to investigate the mineralogical and elemental distribution of thirty lignite samples from the Barmer Basin using advanced techniques such as X-ray diffraction (XRD), X-ray fluorescence spectrometry (XRF) and inductively coupled plasma mass spectrometry (ICP-MS). XRD analysis revealed the presence of minerals such as haematite (Fe2O3), nepheline, anhydrite, magnesite, andalusite, spinel and anatase. Other minor minerals included albite, siderite, periclase, calcite, mayenite, hauyne, pyrite, cristobalite, quartz, nosean and kaolinite. XRF analysis demonstrated that the most abundant elements in the Barmer Basin lignite ash were iron oxide (Fe2O3), sulphur oxide (SO3), calcium oxide (CaO), and quartz (SiO2) followed by minor traces of toxic oxides (SrO, V2O5, NiO, Cr2O3, Co2O3, CuO) that are known to have adverse effects on human health and the environment. The rare earth element (REE) composition showed higher concentrations of Tb, Dy, Ho, Er, Tm, Yb, Lu, Y and Sc at the Giral and lower concentrations at Sonari mine. The Barmer lignites recorded higher concentration of trace elements such as V, Cr, Co, Ni, Cu and Sr while lower concentration of Rb, Cs, Ba, Pb, As, Th and U were observed within optimal range. The study findings revealed the predominant mineral concentration, elemental makeup, trace elements and rare earth elements associated with lignite reserves in the Barmer Basin.

Heat capacity of microgram oxide samples by fast scanning calorimetry.

Quantitative scanning calorimetry on microgram-sized samples opens a broad, new range of opportunities for studying the thermodynamic properties of quantity-limited materials, including those produced under extreme conditions or found as rare accessory minerals in nature. We calibrated the Mettler Toledo Flash DSC 2+ calorimeter to obtain quantitative heat capacities in the range 200-350 °C, using samples weighing between 2 and 11.5 µg. Our technique is applied to a new set of oxide materials to which it has never been used before, without the need for melting, glass transitions, or phase transformations. Heat capacity data were obtained for silica in the high pressure stishovite (rutile) structure, dense post-stishovite glass, standard fused quartz, and for TiO2 rutile. These heat capacities agree within 5%-15% with the literature values reported for rutile, stishovite, and fused SiO2 glass. The heat capacity of post-stishovite glass, made by heating stishovite to 1000 °C, is a newly reported value. After accurate calibrations, measured heat capacities were then used to calculate masses for samples in the microgram range, a substantial improvement over measurement in conventional microbalances, which have uncertainties approaching 50%-100% for such small samples. Since the typical uncertainty of heat capacities measured on 10-100 mg samples in conventional differential scanning calorimetry is typically 7% (1%-5% with careful work), flash differential scanning calorimetry, using samples a factor of 1000 smaller, increases the uncertainty of heat capacity measurements by a factor of <3, opening the door for meaningful measurements on ultra-small, high-pressure samples and other quantity-limited materials.

Integrated hydrogeophysical and GIS based demarcation of groundwater potential and vulnerability zones in a hard rock and sedimentary terrain of Southern India.

This research has identified the groundwater potential and vulnerability zones in Tiruchirappalli district of Tamil Nadu, India. The Schlumberger electrode array has been used to conduct vertical electrical sounding (VES) at 95 sites with a maximum electrode spacing of 150 m. The study area comprises of hard rock and sedimentary formations. Geographical Information System (GIS) has been used to integrate the geoelectrical data and to prepare spatial variation maps for various parameters. Finally, groundwater potential and vulnerability zones have been demarcated, and these outputs have been validated using water level and nitrate data, respectively. The Dar-Zarrouk parameters such as longitudinal conductance (S), transverse unit resistance (T), and aquifer anisotropy (λ) have been used along with the spatial variation of resistivity and aquifer thickness to find out groundwater potential areas with the support of GIS. The thickness of topsoil, weathered zone and fractured zone are not uniform in the research area. Top soil plus weathered zone acts as a water table (phreatic) aquifer, which extends up to 38 m from the surface. Fractured zone extends up to 45 m, which acts as a kind of confined/semi-confined aquifer. Open and bore wells have been constructed to tap groundwater from the unconfined (water table) and confined/semi-confined aquifers, respectively. High to very high groundwater potential areas are associated with low resistivity, high thickness, low longitudinal conductance, high transverse unit resistance and high aquifer anisotropy areas. Very high groundwater potential areas are mostly confined to flood plain (alluvium) deposits in the central portion of the study area. High potential areas are noticed in the northern part, whereas low potential areas are noticed in the southern part. The areas with high longitudinal conductance indicate low permeable zones with less possibility of external pollution. Since agriculture is an important activity in the study region, this work will be useful to provide water supply for irrigation as well as for domestic needs.

Geochemical, mineralogical and toxicological characteristics of coal fly ash and its environmental impacts.

Coal and coal-based products (by-products), along with other fossil fuels should be used with caution because of their impact on human health and the global climate. In the light of the environmental impact these fossil fuels cause, it's essential to understand the elemental configuration of coal-derived samples and their impact on the ecosystem. Some reports in past have described, geochemical and mineralogical physiognomies of fly-ash and their impact on the environment. However, a comprehensive investigation of various aspects of fly ash like geochemistry, mineralogy, morphology, and toxicological effects has been very sparse and the present study reports the above aspects. The ICP-OES studies confirm the presence of various elements (Al, Ca, Fe, Mg, Na, P, S, Si, and Ti) in the samples. The XRD analysis exposed the presence of minerals like Quartz, H-Hematite, Anatase, Muscovite, and Rutile, in addition to the various phases such as amorphous and crystalline in the fly-ash. Specific samples also possessed Ilmenite which is uncommon in many other samples. Chromium and lead, the well-known heavy metals to cause soil and water pollution in the neighbourhood were found to be existing in higher concentrations in the fly-ash samples, whereas cadmium was found to be the least among the toxic elements found in the samples. The samples were subjected to FE-SEM analysis, which reveals the presence of irregularly shaped minerals and unburnt carbon known to reduce the burning efficiency of coal, especially in power plants. Toxicology studies reported in the work suggested that fly-ash is toxic to the environment at higher concentrations than at lower concentrations.

Environmental chemistry, toxicity and health risk assessment of groundwater: Environmental persistence and management strategies.

Groundwater is a significant supply of freshwater for the world's population, being used for residence, agricultural, and industrial purposes. One-third of the world's population relies on groundwater for drinking applications. Groundwater pollution is a global issue with serious consequences for human health and the environment. It needs a thorough understanding because access to safe drinking water is a basic human right. However, groundwater quality is being threatened by urbanisation, agricultural activities, industrial activities, and climate change, among others. Pollutants like hydrocarbons, toxic metals, pesticides, microplastics, nanoparticles and other emerging contaminants mean a risk to human health and sustainable socioeconomic development. To ensure sustained groundwater usage to assess, monitor, and regulate groundwater quality issues is essential. Excess withdrawal alters groundwater flow together with contaminants like uranium, radon, radium, salinity, arsenic and fluoride, resulting in mediocre water quality. Consequently, chemical and biological contaminants owing to domestic, industrial, and agricultural practices alter water quality and threaten human health. Controlling and management of groundwater pollution and related health risks require developing vulnerability, hazard, and risk maps.

Provincial and seasonal influences on heavy metals in the Noyyal River of South India and their human health hazards.

This study was carried out to evaluate the heavy metals (Lead (Pb), Nickel (Ni), Chromium (Cr), Copper (Cu), Cadmium (Cd) and Zinc (Zn)) pollution in the Noyyal River of South India by collecting 130 river water samples (65 each in pre- and post-monsoon). The heavy metals were measured using Atomic Absorption Spectrophotometer (AAS). The data were used to calculate the associated health hazards for the inhabitants consume river water. Correlation analyses and average concentration of heavy metals denoted that post-monsoon metal concentrations were lesser compared to the pre-monsoon due to dilution effect. Modified Contamination Degree (MCD) indicated that 45% of pre-monsoon and 25% of post-monsoon samples were classified under extremely polluted category. Heavy metal pollution index (HPI) showed that all the regions fall under highly polluted category except 'Region I' where 20% of samples were under safe category during the pre-monsoon, whereas 9%,28%, 17% and 26% of samples in Regions I, II, III and IV were highly polluted during the post-monsoon season, respectively. Ecological Risk Index (ERI) revealed that high risks attained in Regions II (78%) and III (82%) during pre-monsoon, and reduced risks found in Regions II (28%) and III (45%) during post-monsoon season due to dilution by monsoon rainfall. Non-carcinogenic risks as inferred by the Hazard Index (HI) indicated that 78% and 52% of samples for infants, 75% and 49% of samples for teens and 71% and 45% of samples for adults exceeded the threshold limits of USEPA (HI > 1) and possessed risks during pre- and post-monsoon, respectively. The cancer risk assessment based on ingestion of heavy metals indicated that the order of risk is Ni > Cr > Cu. The HI for infants and teens was notably high to that of adults in both the seasons. This study will be useful to develop effective strategies for improving river water quality and to reduce human health hazards.

A Comparison of Order-Disorder in Several Families of Cubic Oxides.

Order-disorder on both cation and oxygen sites is a hallmark of fluorite-derived structures, including pyrochlores. Ordering can occur on long- and short-range scales and can result in persistent metastable states. In various cubic oxide systems, different types of disorder are seen. The purpose of this paper is to review and compare the types and energetics of order-disorder phenomena in several families of cubic oxides having pyrochlore, weberite, defect fluorite, perovskite, rocksalt, and spinel structures. The goal is to better understand how structure, composition, and thermodynamic parameters (enthalpy and entropy) determine the feasibility of different competing ordering processes and structures in these diverse systems.

Effects of COVID-19 pandemic lockdown on microbial and metals contaminations in a part of Thirumanimuthar River, South India: A comparative health hazard perspective.

Twenty-two water samples from the Thirumanimuthar River course in southern India were collected before COVID-19 lockdown and during COVID-19 lockdown periods and were analyzed for microbiological parameters (fecal coliform bacteria, total coliform bacteria, Escherichia coli, and fecal streptococci) and heavy metals (Fe, Mn, Zn, Cu, Cd, Ni, Pb and Cr). The lockdown has decreased microbial populations and heavy metals. Fe, Cu, Cd, Ni, Pb and Cr exceeded the drinking water limits, respectively, in 77%, 45%, 27%, 18%, 9% and 91% of the pre-lockdown samples. During the lockdown period, Fe, Cu and Cd concentrations in 23% and Cr in 50% of the samples exceeded the limits. Heavy Metal Pollution Index (PI) expressed that 27%, 64% and 9% of the pre-lockdown samples represented 'low', 'medium' and 'high' pollution categories, respectively, but 68% and 32% of the lockdown period samples represented 'low' and 'medium' categories, respectively. The Metal Index (MI) exposed that all samples of pre-lockdown were under the seriously affected category, whereas 54% and 46% of lockdown samples were under strongly and seriously affected categories, respectively. Health risk evaluation predicted that 95%, 91% and 86% of pre-lockdown samples and 45%, 36% and 33% of lockdown period samples were at risk among children, teenagers and adults, respectively. As there is no integrated study on river water quality of COVID-19 lockdown this work is uniquely carried out by combining heavy metal pollution, microbial contamination and human health risk evaluation.

Investigation of health risks related with multipath entry of groundwater nitrate using Sobol sensitivity indicators in an urban-industrial sector of south India.

In the present study, we used a variance decomposition based global sensitivity index to evaluate the sensitivity of input variables and their contribution for non-carcinogenic health risks via intake and dermal pathways. Groundwater samples were collected from an industrial sector (Tiruppur region) of south India during the month of January 2020. These samples were analysed for nitrate, which varied from 10 to 290 mg L-1 having the mean of 87 mg L-1. Nearly 58% of the samples surpassed the permissible limit (45 mg L-1) defined by the World Health Organization. Total hazard index (THI) ranged from 0.29 to 8.52 for children, 0.28 to 8.26 for women, and 0.24 to 6.99 for men. The first-order effect (FOE) and second-order effect (SOE) were derived for the three different age groups using Sobol sensitivity approach. The FOE scores showed that nitrate concentration in groundwater is the most sensitive parameter followed by exposure frequency for children, men and women via oral pathway. The SOE scores showed that nitrate concentration along with ingestion rate had greater sensitiveness in the oral input model. The higher SOE was obtained for the interaction of nitrate with skin surface area for children via dermal pathway, but it was not significant for women and men. These results suggest that epidemiology due to nitrate risk should be studied taking into account of concentration of nitrate, exposure frequency, fraction of contact and body weight. Additionally, ingestion rate and skin surface area were considered for the assessment of health risks for children.

Chromium contamination in groundwater and Sobol sensitivity model based human health risk evaluation from leather tanning industrial region of South India.

The present investigation was conducted to find the possible chromium contamination in groundwater and the related health risks in a leather industrial region of south India using Sobol sensitivity modeling. Thirty-five groundwater samples were sampled from the field sites and were analyzed for pH, TDS (Total Dissolved Solids), EC (Electrical Conductivity), F- (Fluoride), NO3- (Nitrate) and Cr (Chromium). The concentration of nitrate varied from 3 to 81 mg/L with a mean of 48.6 mg/L. About 57% (n = 20) of the wells surpassed the drinkable limit (45 mg/L) for NO3- as per World Health Organization (WHO). The fluoride ion ranged from 0.1 to 2.7 mg/L with a mean of 1.5 mg/L. Around 51% (n = 18) of the samples crossed the recommended limit of WHO for F- (1.5 mg/L). The chromium varied from 0.01 to 0.19 mg/L in groundwater with a mean of 0.1 mg/L. About 66% (n = 23) of the samples overshoot the permissible limit of WHO standards (0.05 mg/L) for Cr. The spatial distribution map of chromium in the groundwater showed that 271.76 km2 area is under risk. Based on total hazard index (THI), 66%, 46%, and 43% of the groundwater samples surpassed the allowable limit (THI > 1) for children, women and men, correspondingly. Children pose severe health risks than women and men in this region. Using Sobol sensitivity indices, three different categories of risk effects were assessed: first order effect (FOE), total effect (TE) and second order effect (SOE). In the oral sensitivity model, concentration of Cr (Cw) in water and ingestion rate (IR) had the dominant role, whereas in the dermal model, skin surface area (SA) and contact fraction by skin (F) had vital role in addition to the concentration (Cw). Further, the outcome of this study insists the responsibilities of industrial, municipal and agricultural sectors to keep the environment pollution free and to ensure the supply of potable water to the people.

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.

Groundwater Pollution and Human Health Risks in an Industrialized Region of Southern India: Impacts of the COVID-19 Lockdown and the Monsoon Seasonal Cycles.

Samples of groundwater were collected during a post-monsoon period (January) and a pre-monsoon period (May) in 2020 from 30 locations in the rapidly developing industrial and residential area of the Coimbatore region in southern India. These sampling periods coincided with times before and during the lockdown in industrial activity and reduced agricultural activity that occurred in the region due to the COVID-19 pandemic. This provided a unique opportunity to evaluate the effects of reduced anthropogenic activity on groundwater quality. Approximately 17% of the wells affected by high fluoride concentrations in the post-monsoon period returned to levels suitable for human consumption in samples collected in the pre-monsoon period. This was probably due to ion exchange processes, infiltration of rainwater during the seasonal monsoon that diluted concentrations of ions including geogenic fluoride, as well as a reduction in anthropogenic inputs during the lockdown. The total hazard index for fluoride in the post-monsoon samples calculated for children, adult women, and adult men indicated that 73%, 60%, and 50% of the groundwater samples, respectively, had fluoride levels higher than the permissible limit. In this study, nitrate pollution declined by 33.4% by the pre-monsoon period relative to the post-monsoon period. The chemical facies of groundwater reverted from the Na-HCO3-Cl and Na-Cl to the Ca-HCO3 type in pre-monsoon samples. Various geogenic indicators like molar ratios, inter-ionic relations along with graphical tools demonstrated that plagioclase mineral weathering, carbonate dissolution, reverse ion exchange, and anthropogenic inputs are influencing the groundwater chemistry of this region. These findings were further supported by the saturation index assessed for the post- and pre-monsoon samples. COVID-19 lockdown considerably reduced groundwater pollution by Na+, K+, Cl-, NO3¯, and F- ions due to shutdown of industries and reduced agricultural activities. Further groundwater quality improvement during lockdown period there is evidence that the COVID-19 lockdown by increased HCO3¯ ion concentration. Overall results illustrate the positive benefits to groundwater quality that could occur as a result of measures to control anthropogenic inputs of pollutants.

COVID-19 lockdown impacts on heavy metals and microbes in shallow groundwater and expected health risks in an industrial city of South India.

In this investigation, the positive impact of COVID-19 lockdown on heavy metals concentration and biological parameters in the shallow groundwater samples of Coimbatore city of South India was ascertained. The groundwater samples (n=15) were obtained from shallow open wells during before lockdown (24-25 February 2020) and after lockdown (2-3 June 2020) periods. These samples were analysed for heavy metals (Fe, Mn, Ni, Cr and Pb) and biological parameters (E. coli, Fecal coliforms, Fecal streptococci and Total coliforms). Fe concentration was within the permissible limit but, the concentrations of Mn, Ni, Cr and Pb were above the allowable limits for drinking uses as per the WHO. However, after lockdown the number of samples crossing the cutoff limit had considerably decreased (Mn: from 2 to 0 mg/L; Ni: from 13 to 10 mg/L; Cr: 7 to 5 mg/L and Pb: from 13 to 8 mg/L). The heavy metal pollution index (HPI) revealed that 176.75 km2 (67.4%) and 85.35 km2 (32.6%) areas fell under unsuitable and very poor categories, respectively, during the pre-lockdown period, whereas 138.23 km2 (52.6%), 118.98 km2 (45.3%) and 4.89 km2 (2.1%) areas fell under very poor, poor and good categories, respectively, during the post-lockdown period. Similarly, Total coliform, Fecal coliform and E. coli had decreased distinctly due to the pandemic lockdown. Therefore, the shutdown of small and large-scale industries during the lockdown period had improved the groundwater quality. The health risk assessment showed that 93%, 87% and 80% of pre-lockdown samples, and 87%, 80% and 73% of post-lockdown samples possessed non-carcinogenic risks (HI > 1) for children, female and male categories, respectively.

Groundwater quality evolution based on geochemical modeling and aptness testing for ingestion using entropy water quality and total hazard indexes in an urban-industrial area (Tiruppur) of Southern India.

This study used geochemical modeling to understand the chemical evolution of groundwater, entropy water quality index to assess the aptness of groundwater for human consumption, and total hazard index to determine the possible non-carcinogenic risks among children, women, and men in an urban-industrial area (Tiruppur region) of southern India. For the above purposes, 40 groundwater samples were collected from tube and dug wells, and they were tested for various physicochemical parameters. Fluoride and nitrate levels ranged from 0.10 to 2.70 mg/l and 10 to 290 mg/l, respectively. Nearly, 50% of the fluoride samples and 58% of the nitrate samples exceeded the WHO limits of 1.5 and 45 mg/l, respectively. The majority of the groundwater samples (22.5%) represented Ca2+-Na+-Cl- water type while the remaining samples exhibited mixed water types. Approximately, 85% of the samples indicated high levels of salinization since they had Revelle index > 0.5 meq/l. The saturation index (SI) revealed that mineral weathering; dissolution of halite, gypsum, and anhydrite; and precipitation of calcite and dolomite contributed to groundwater chemistry. Based on the entropy water quality index (EWQI), none of the groundwater samples was characterized as excellent or good water quality while 57.5% of the samples had medium water quality, and 32.5% and 10% of the samples exhibited poor and extremely poor water qualities, respectively. The last two categories are designated as unfit for consumption. The cumulative health risk (nitrate and fluoride together) ranged from 0.97 to 11.16 for children, 0.60 to 10.54 for women, and 0.39 to 6.92 for men. These values represent health risks among 88%, 80%, and 73% of the groundwater samples for children, women, and men, respectively. Therefore, proper measures should to be done to reduce the health risks associated with high nitrate and fluoride in the groundwater of the study area, which is used for drinking purposes.