This study was carried out to delineate the occurrence and spatial distribution of groundwater fluoride in a loess area of China and to determine the geochemical and anthropogenic factors that influence its concentration. Water quality was assessed for drinking purpose by comparing with the national and WHO drinking water guidelines, and the impacts of fluoride on human health were also quantified using the health risk assessment model recommended by the USEPA. The results demonstrate that groundwater in the study area is slightly alkaline in nature, and its quality is generally good except slightly excessive TDS, TH, Na+, F−, and nitrate at some local locations. High-fluoride groundwater is mainly distributed in the southeast part of the study area, which is in accordance with the groundwater flow direction in this area. Groundwater fluoride is mainly of natural origin and is dominantly controlled by natural factors such as pH, specific hydrochemical environment, ion exchange, and saturation state of minerals. Fluoride contributes the most to the total health risk in the present study. Children are at higher health risk than adults in this area. Establishing central water supply system and rainwater harvesting system are suggested to guarantee safe drinking water supply in this area.

Occurrence and Health Implication of Fluoride in Groundwater of Loess Aquifer in the Chinese Loess Plateau: A Case Study of Tongchuan, Northwest China

Fluoride contamination, health problems and remediation methods in Asian groundwater: A comprehensive review.

Fluoride contamination in the groundwater has got great attention in last few decades due to their toxicity, persistent capacity and accumulation in human bodies. There are several sources of fluoride in the environment and different pathways to enter in the drinking water resources, which is responsible for potential effect on human health. Presence of high concentration of fluoride ion in groundwater is a major issue and it makes the water unsuitable for drinking purpose. Availability of fluoride in groundwater indicates various geochemical processes and subsurface contamination of a particular area. Fluoride-bearing aquifers, geological factors, rate of weathering, ion-exchange reaction, residence time and leaching of subsurface contaminants are major responsible factors for availability of fluoride in groundwater. In India, several studies have reported that the groundwater of several states are contaminated with high fluoride. The undesirable level of fluoride in groundwater is one of the most natural groundwater quality problem, which affects large portion of arid and semiarid regions of India. Rajasthan, Andhra Pradesh, Telangana, Tamil Nadu, Gujarat, and West Bengal are the relatively high-fluoride-contaminated states in India. Chronic ingestion of high doses of fluoride-rich water leads to fluorosis on human and animal. Over 66 million Indian populations are at risk due to excess fluoride-contaminated water. Therefore, groundwater contamination subject to undesirable level of fluoride needs urgent attention to understand the role of geochemistry, hydrogeology and climatic factors along with anthropogenic inputs in fluoride pollution.

Groundwater fluoride contamination, probable release, and containment mechanisms: a review on Indian context.

Fluoride occurrence in groundwater systems at global scale and status of defluoridation – State of the art

For about the past eight decades, high concentrations of naturally occurring fluoride have been detected in groundwater in different parts of India The chronic consumption of fluoride in high concentrations is recognized to cause dental and skeletal fluorosis We have used the random forest machine-learning algorithm to model a data set of 12 600 groundwater fluoride concentrations from throughout India along with spatially continuous predictor variables of predominantly geology, climate, and soil parameters Despite only surface parameters being available to describe a subsurface phenomenon, this has produced a highly accurate prediction map of fluoride concentrations exceeding 15 mg/L at 1 km resolution throughout the country The most affected areas are the northwestern states/territories of Delhi, Gujarat, Haryana, Punjab, and Rajasthan and the southern states of Andhra Pradesh, Karnataka, Tamil Nadu, and Telangana The total number of people at risk of fluorosis due to fluoride in groundwater is pr

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Prediction Modeling and Mapping of Groundwater Fluoride Contamination throughout India

Fluoride contamination in water is a major problem across the globe, with health hazards such as dental and skeletal fluorosis. Most earlier studies are confined to local or regional scales. As the problem has serious socioeconomic implications, there is a need for a global perspective. Thus, here we review worldwide research for nearly a century on fluoride contamination in water. We investigated the distribution of fluoride contamination in water, its sources, mobilization and association. The major findings are: (1) Anomalous fluoride concentration in groundwater is mainly confined to arid and semiarid regions of Asia and North Africa. (2) The geogenic sources of fluoride in water are mainly fluorine-bearing minerals in rocks and sediments, whereas anthropogenic sources of fluoride in water are mainly pesticides and industrial waste. (3) Fluoride mobilization from geogenic sources is mainly controlled by alkalinity and temperature. (4) Fluoride occurrence in water is associated with ions such as sodium, arsenic chloride and bicarbonate. There are few associations of fluoride in water with calcium and magnesium.

Worldwide contamination of water by fluoride

Concentration of fluoride in groundwater of India: A systematic review, meta-analysis and risk assessment

The Yamuna flood plains spread across the northern part of Indian subcontinent is home to millions of people. The ever-growing population in these plains make it difficult to sustain the demand of freshwater resources. However, the productive aquifers of flood plains could provide solution for these issues. In this context, it is necessary to understand the aquifer characteristics. Thus, the paper attempts to characterize the aquifer in Palla area of the flood plain using integrated approach. Besides, grain size analysis and site-litholog study, the nature of aquifer material was also ascertained from bulk mineralogy of the sediments using X-Ray Diffraction. The aquifer parameters were estimated with help of long duration pumping test data. Moreover, the effect of pumping on salinity variation and hydrochemical facies evolution was also examined. The sand dominant, unconfined aquifer was estimated to have horizontal hydraulic conductivity in the range of 25 m/day and vertical hydraulic conductivity of 6–7 m /day. While the specific yield of the aquifer was estimated in the range of 0.07–0.08. It is observed that under conducive active flood plain environment, the given sand mineralogy at the site does not allow salinity increase in groundwater even after more than a decade of groundwater pumping. In fact, over years, hydrochemical facies have evolved towards Bicarbonate type. These things put together make the active flood plain aquifer a sustainable groundwater resource.

Hydrogeological characterization of aquifer in palla flood plain of Delhi using integrated approach

The Khammam Schist Belt (KSB), southeastern India, represents a part of the collision zone that is sandwiched between the Eastern Dharwar Craton to the west and the Eastern Ghats Mobile Belt (EGMB) to the east. Quartzofeldspathic gneisses of the EGMB and garnet–kyanite metapelites of the KSB have been investigated to characterize P–T–t evolution of the Khammam region. Pseudosection modeling reveals that the melt-bearing quartzofeldspathic gneiss experienced peak and post-peak metamorphism at P–T conditions of 7.9–8.1 kbar/790–810 °C and ~ 7.0 kbar/740–750 °C, respectively. In contrast, metapelite witnessed peak metamorphism at 7.4–7.8 kbar/600–640 °C, followed by post-peak retrogression at 6.1–6.6 kbar/590–625 °C. U–Th–(total) Pb monazite ages from the gneiss constrain the peak and retrograde metamorphic episodes at 1.63–1.53 Ga and 1.48–1.38 Ga, while those in the metapelites were determined at 1.25–1.20 Ga and 1.18–1.10 Ga, respectively. These P–T–t estimates indicate that the KSB, Vinjamuru, and Ongole domains evolved distinctly during Late Paleoproterozoic–Late Mesoproterozoic. The younger ages (0.90–0.81 Ga) were ascribed to the formation of the Eastern Indian Tectonic Zone, implying its extension beyond the western margin of the EGMB. Besides, the distinct Neoarchean ages (2.79–2.45 Ga) are related to the Archean protolith of the quartzofeldspathic gneisses, which were likely derived from the Archean crust of the Napier–Rayner Complex. This tectonothermal restoration is new and characterizes the Khammam region as the hot and composite collision zone with protracted geological history. (250 words)

Tectonothermal evolution of a collisional orogen in the Khammam region, southeastern India: insights from structures, phase equilibria modeling and U–Th–(total) Pb monazite geochronology

Sachin Kumar Thakur

Papers

Worldwide contamination of water by fluoride

Concentration of fluoride in groundwater of India: A systematic review, meta-analysis and risk assessment

Hydrogeological characterization of aquifer in palla flood plain of Delhi using integrated approach

Tectonothermal evolution of a collisional orogen in the Khammam region, southeastern India: insights from structures, phase equilibria modeling and U–Th–(total) Pb monazite geochronology