Groundwater chemistry and health hazard risk valuation of fluoride and nitrate enhanced groundwater from a semi-urban region of South India.

Evaluation of groundwater chemistry and its related health hazard risk for humans is a prerequisite remedial measure. The semi-urban region in southern India was selected to measure the groundwater quality to know the human health risk valuation for different age groups of adults and children through oral intake and skin contact with elevated concentrations of fluoride ([Formula: see text]) and nitrate ([Formula: see text]) groundwater. Groundwater samples were collected from the semi-urban region for pre- and post-rainfall periods and resolute its major ion chemistry. The pH values showed the water is alkaline to neutral in nature. Total dissolved solid (TDS) ranged from 201 to 3612 mg/l and 154 to 3457 mg/l. However, [Formula: see text] concentration ranges from 0.28 to 5.48 mg/l and 0.21 to 4.43 mg/l; and NO3- ranges from 0.09 to 897.28 mg/l and 0.0 to 606.10 mg/l elevating the drinking water standards of [Formula: see text] in 32% and 38% samples and for [Formula: see text] about 62% and 38% during pre- and post-rainfall seasons, respectively. The fluoride-bearing minerals are the main sources of elevated concentrations of [Formula: see text] and excessive use of chemical fertilizers as the chief source of NO3- concentration in the aquifer regime. Water quality index (WQI) ranged from 18.3 to 233 and 12.97 to 219.14; 20% and 22% showed poor water quality for pre- and post-rainfall seasons with WQI ≥ 200. Piper plot suggests that 46% and 51% of samples signify carbonate water type ([Formula: see text]), and 32% and 28% of groundwater samples show ([Formula: see text]) type water for pre- and post-rainfall seasons respectively. Gibbs' plot suggests the dominance of water-rock interaction in the aquifer system. Further, the principal component analysis (PCA) revealed three and four components which explain 74.85% and 79.30% of the variance in pre- and post-rainfall seasons with positive loading of EC, TDS, Ca2+, Na+, Mg2+, K+, [Formula: see text], Cl-, and [Formula: see text] due to mineral weathering and water-rock interactions altering the chemistry for an elevated concentration of [Formula: see text] and [Formula: see text] in groundwater. Cluster analyses of chemical variables observed four clusters with a linkage distance of 5 to 25 with a linkage between different variables displaying predominant ion exchange, weathering of silicate and fluoride-rich minerals, salinization of the water, and a high value of [Formula: see text] concentration, resulting from fertilizers. The hazard quotient (HQ) through ingestion (HQing) and dermal (HQder) pathways of F- and NO3- was observed higher than its acceptable limit of 1.0 for different age groups indicating the non-carcinogenic effect on human health. Effective strategic measures like defluoridation, denitrification, safe drinking water supply, sanitary facilities, and rainwater harvesting structures are to be implemented in the area for improvement of human health conditions and also bring awareness to the local community about the health hazard effects of using high concentrated [Formula: see text] and [Formula: see text] water for daily uses.

Dhakate R ，More S ，Duvva LK ，Enjamuri S ... -  《-》

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.

Gugulothu S ，Subba Rao N ，Das R ，Duvva LK ，Dhakate R ... -  《-》

Evaluation of groundwater quality and human health risks from fluoride and nitrate in semi-arid region of northern India.

Singh G ，Rishi MS ，Herojeet R ，Kaur L ，Sharma K ... -  《-》

Groundwater fluoride and nitrate contamination and associated human health risk assessment in South Punjab, Pakistan.

Consumption of high fluoride (F-) and nitrate (NO3-) containing water may pose serious health hazards. One hundred sixty-one groundwater samples were collected from drinking wells in Khushab district, Punjab Province, Pakistan, to determine the causes of elevated F- and NO3- concentrations, and to estimate the human health risks posed by groundwater contamination. The results showed pH of the groundwater samples ranged from slightly neutral to alkaline, and Na+ and HCO3- ions dominated the groundwater. Piper diagram and bivariate plots indicated that the key factors regulating groundwater hydrochemistry were weathering of silicates, dissolution of evaporates, evaporation, cation exchange, and anthropogenic activities. The F- content of groundwater ranged from 0.06 to 7.9 mg/L, and 25.46% of groundwater samples contained high-level fluoride concentration (F-  > 1.5 mg/L), which exceeds the (WHO Guidelines for drinking-water quality: incorporating the first and second addenda, WHO, Geneva, 2022) guidelines of drinking-water quality. Inverse geochemical modeling indicates that weathering and dissolution of fluoride-rich minerals were the primary causes of F- in groundwater. High F- can be attributed to low concentration of calcium-containing minerals along the flow path. The concentrations of NO3- in groundwater varied from 0.1 to 70 mg/L; some samples are slightly exceeding the (WHO Guidelines for drinking-water quality: incorporating the first and second addenda, WHO, Geneva, 2022) guidelines for drinking-water quality. Elevated NO3- content was attributed to the anthropogenic activities revealed by PCA analysis. The high levels of nitrates found in the study region are a result of various human-caused factors, including leaks from septic systems, the use of nitrogen-rich fertilizers, and waste from households, farming operations, and livestock. The hazard quotient (HQ) and total hazard index (THI) of F- and NO3- showed high non-carcinogenic risk (> 1) via groundwater consumption, demonstrating a high potential risk to the local population. This study is significant because it is the most comprehensive examination of water quality, groundwater hydrogeochemistry, and health risk assessment in the Khushab district to date, and it will serve as a baseline for future studies. Some sustainable measures are urgent to reduce the F- and NO3- content in the groundwater.

Iqbal J ，Su C ，Wang M ，Abbas H ，Baloch MYJ ，Ghani J ，Ullah Z ，Huq ME ... -  《-》

Non-carcinogenic health risk assessment with source identification of nitrate and fluoride polluted groundwater of Wardha sub-basin, central India.

In order to understand the pollution status of groundwater with geochemical evolution and appraisal of its probable public health risk due to nitrate (NO3-) and fluoride (F-), a total of 93 groundwater samples were collected during pre-monsoon (May) period from Wardha sub-basin, central India. By employing Piper plot, transition from Ca-HCO3 type water (recharge waters) to Na-Cl (saline water) type water through mixed Ca-Na-HCO3, mixed Ca-Mg-Cl (reverse ion exchange waters) and Ca-Cl types (leachate waters), were observed. The Geogenic processes such as silicate, dolomite, halite and carbonate weathering along with calcite precipitation and ion exchange process were identified as major controlling factors for evolution and alteration of groundwater chemistry. The Saturation index highlighted that the groundwater in the area is oversaturated with respect to the mineral calcite and dolomite, and under saturated with gypsum, fluorite and halite. The high NO3- and F- concentration overpassing the permissible limit were found in 54.8% and 18.5% of samples. The plot of F- with Na+/Ca2+, Na+/Mg2+ and F-/Cl- established fluoride bearing rock weathering is responsible for F- contamination. Based on the cluster analysis, the groundwater was grouped into Cluster-I Ca-Na-HCO3 type (61.3%) and Cluster-II Na-Ca-HCO3-Cl type (30.1%). The total hazard index (HI) based on human health risk assessment (HHRA) model for cumulative NO3- and F- toxicity through oral and dermal pathways were computed as 100%, 97.85% and 96.77% for children, female and male populations respectively. The HQ(nitrate) > 1 through ingestion pathway were in 84.95%, 68.82% and 62.37%, and HQ(fluoride) > 1 in 83.87%, 62.37% and 43.01% of the groundwater samples were recorded for children, female and male population respectively. The risk assessment study highlighted very high toxicity and severe health impact of ingestion of contaminated groundwater on public health.

Nawale VP ，Malpe DB ，Marghade D ，Yenkie R ... -  《-》