Groundwater fluoride contamination in Coimbatore district: a geochemical characterization, multivariate analysis, and human health risk perspective

In this paper, fluoride geochemistry and health risk of groundwater in Coimbatore district is studied. The order of dominance of ions were HCO3 > Cl > SO4 > CO3 and Na > Ca > Mg > K. Alkaline groundwater and the dominance of HCO3 and Na is favourable for the fluoride enrichment. Around 46% of the samples, N–NE regions, have F− higher than permissible limit of 1.5 mg/L. Pink granites, charnockite and gneisses in lithology is the possible origin of F−. However, NO3 vs F plot shows positive trend in some samples, indicating anthropogenic inputs of F−. Correlation plots of F− was trending positive with pH, HCO3 and Na and but negative for Ca, indicating the control of these ions in F− mobility. This result is supported by undersaturation of fluorite and supersaturation of carbonates. Four significant principal components were derived, which have explained 87% of the total variation. PC1 has high factor loadings for EC, Ca, Mg Na, Cl, SO4, NO3 indicating both natural and anthropogenic influences. PC2, PC3 and PC4 have higher loading for pH and HCO3, K and HCO3 and F−, respectively, indicating geogenic factors in the F− enrichment. Human health risk assessment (HHRA) by ingestion and dermal pathways were calculated using Hazard Quotient HQ and Hazard Index (HI). 27% of males, 36% of females and 39% of the children have HI > 1, posing noncarcinogenic risks

GIS-based mapping of water-level fluctuations (WLF) and its impact on groundwater in an Agrarian District in Tamil Nadu, India

This study describes the results of groundwater table variation in Thanjavur District before and after the monsoon seasons. Groundwater-level data acquired by the field measurement and the elevation data have been obtained from the topographic survey. Groundwater is the major source for different sectors in this region, and the major portion was used for irrigation. The impacts of geology, soil types, topographic elevation, land-use changes were critically analyzed and identified that these factors are controlling the infiltration capacity. The maximum fluctuation in the water table was 2 m below the ground level; still, 50% of the study area is under threat of overexploitation. This is projecting to a severe shortage in water supply soon. Groundwater quality is threatening by the saline intrusion in the coastal region, and the irrigation return flows inland. The spatial variation maps were useful in visualizing the seasonal water level and fluctuation in Thanjavur. A proper monitoring system, efficient irrigation practices, and effective groundwater recharge structures are recommended

Physicochemical parameters and their sources in groundwater in the Thirupathur region, Tamil Nadu, South India

This study reports physicochemical characteristics and their sources in groundwater in Thirupathur region in Tamil Nadu, India. For this purpose, groundwater samples were collected and analysed using standard methods. A wide seasonal variation was showed for the majority of the samples; higher concentration was observed in the pre-monsoon season. Concentration of fluoride was quite alarming in many locations. Groundwater is found to be dominated by Na+, Ca+, HCO3 and Cl−. Gibbs plot showed the dominance of rock–water interaction. Geology of the area in comparison with the results obtained in the chemical cross plots showed the dominance of silicate weathering, with a minor contribution from the cation exchange. Other processes such as evaporation dissolution of carbonate and gypsum were proved to be ineffective. However, dissolution of fluoride minerals present in the geological formation is the major source of fluoride in groundwater

Groundwater fluoride contamination in Coimbatore district: a geochemical characterization, multivariate analysis, and human health risk perspective

In this paper, fluoride geochemistry and health risk of groundwater in Coimbatore district is studied. The order of dominance of ions were HCO3 > Cl > SO4 > CO3 and Na > Ca > Mg > K. Alkaline groundwater and the dominance of HCO3 and Na is favourable for the fluoride enrichment. Around 46% of the samples, N–NE regions, have F− higher than permissible limit of 1.5 mg/L. Pink granites, charnockite and gneisses in lithology is the possible origin of F−. However, NO3 vs F plot shows positive trend in some samples, indicating anthropogenic inputs of F−. Correlation plots of F− was trending positive with pH, HCO3 and Na and but negative for Ca, indicating the control of these ions in F− mobility. This result is supported by undersaturation of fluorite and supersaturation of carbonates. Four significant principal components were derived, which have explained 87% of the total variation. PC1 has high factor loadings for EC, Ca, Mg Na, Cl, SO4, NO3 indicating both natural and anthropogenic influences. PC2, PC3 and PC4 have higher loading for pH and HCO3, K and HCO3 and F−, respectively, indicating geogenic factors in the F− enrichment. Human health risk assessment (HHRA) by ingestion and dermal pathways were calculated using Hazard Quotient HQ and Hazard Index (HI). 27% of males, 36% of females and 39% of the children have HI > 1, posing noncarcinogenic risks.Freie Universität Berlin (1008

Nutrient chemistry and seasonal variation in the groundwater quality of a Riverine Island on the west coast of Kerala, India

This study attempted to evaluate the groundwater quality, with a special emphasis on nutrients, of a riverine coastal island near Kodungallur, Kerala. Water quality parameters were analyzed in the collected samples over pre- and post-monsoon seasons. A considerable variation in groundwater chemistry was observed in the two periods. During pre-monsoon season, many wells were contaminated with TDS, Cl, Fe, Ca and Mg in certain locations. Whereas, post-monsoon water was relatively fresh, indicating the dilution process as well as aquifer recharge by the monsoon rain and consequent regression of saline water. A higher concentration of Fe was observed in the pre-monsoon season (41%) than in the post-monsoon season (24%). Nitrate and phosphates were analyzed to assess the nutrients and the observed concentration was below their corresponding permissible limits. Results show that overexploitation of the aquifer as well as the decreased flow of the River Periyar during the pre-monsoon period increased the threat from seawater intrusion and groundwater contamination. An interesting groundwater recharge mechanism locally known as backwashing—the diversion of rainwater from rooftops to dug wells—is being practiced in the study area and has been found to be effective in raising water levels and improving water quality