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.

Aquifer wise seasonal variations and spatial distribution of major ions with focus on fluoride contamination-Pandharkawada block, Yavatmal district, Maharashtra, India.

Seasonal variations in groundwater reveal lesser concentrations of major ions except NO3(-) during post-monsoon seasons in shallow aquifers as compared to deeper aquifers. The F(-) concentration from deeper aquifers is high in both seasons and shows a moderate positive relationship with weathering depth and is >5 mg/L in compound lava flow. Groundwater is mainly a Ca-HCO3 type in shallow aquifers and mixed type in deeper aquifers. Fluoride shows a positive correlation with pH, Na(+), HCO3(-) in shallow aquifers and an inverse correlation with Ca(2+) and HCO3(-) from deeper aquifers in both seasons. Approximately 45% of the samples are not suitable for drinking from both aquifers but suitable for irrigation purposes. Rock-water interaction, moderate alkalinity, sluggish movement, and higher residence time are the main causes for high F(-) in deeper aquifers as compared to shallow aquifers. As recommendations, drinking water requirement may be met from shallow aquifers/surface water and fluoride rich groundwater for other purposes. Most effective defluoridation techniques like ion exchange and reverse osmosis may be adopted along with integrated fluorosis mitigation measures and rooftop rainwater harvesting. Supplementary calcium and phosphorous rich food should be provided to children and creating awareness about safe drinking water habits, side effects of high F(-), and NO3(-) rich groundwater, improving oral hygiene conditions are other measures.

Major ion chemistry of shallow groundwater of a fast growing city of central India.

Nagpur City located in semiarid area of central India is a fast-growing industrial centre. In recent years, rapid development has created an increased demand for drinking water, which is increasingly being fulfilled by groundwater abstraction. The present study was undertaken to assess major ion chemistry of shallow groundwater to understand geochemical evolution of groundwater and water quality for promoting sustainable development and effective management of groundwater resources. A total of 47 water samples were collected from shallow aquifer of selected parts of the city and the water chemistry of various ions viz. Ca(2 +), Mg(2 +), Na(+), K(+), CO(3)(2-), HCO(3)(-), Cl(-), SO(4)(2-) and NO(3)(-) are carried out. The chemical relationships in Piper diagram identify Ca-HCO(3)-Cl and mixed Ca-Na-HCO(3)-Cl as most prevalent water types. Alkaline earth exceeds alkalis and weak acids exceed strong acids. Ionic ratios and Gibb's diagram suggest that silicate rock weathering and anthropogenic activities are the main processes that determine the ionic composition in the study area. The nitrate appeared as a major problem of safe drinking water in this region. We recorded highest nitrate concentration, i.e., 411 mg/l in one of the dug well. A comparison of groundwater quality in relation to drinking water quality standards revealed that about half of the shallow aquifer samples are not suitable for drinking.