Abstract
Hydrogeochemical controlling variables for the high rate of groundwater contamination in a shallow hard rock aquifer of the semi-arid region of Medchal District, Telangana State, South India, and its associated health risk to children and adults were studied in detail. A total of 56 groundwater samples were analysed for major ion chemistry in pre- and post-monsoon seasons in 2019 year. Spatial distribution, hydrochemical facies, water–rock interaction, health risk assessment, carcinogenic risk, and principal component analyses were carried out to assess the water quality. Spatial distribution of nitrate and fluoride concentrations, high values were observed in the northern, southern, central, and south-western parts of the region. In terms of NO3−, about 88% and 63% and for F− 45% and 32% of the groundwater samples are non-acceptable limits of nitrate 45 mg/l and fluoride 1.5 mg/l during pre- and post-monsoon seasons, respectively. Modified Gibb’s plot showed the majority of the area is dominated by rock dominance and evaporation mechanisms. Statistical analysis reveals that water chemistry is governed by weathering of feldspar minerals and the cation exchange reaction mechanism. The petro-graphical studies revealed the dominance of plagioclase, orthoclase, quartz, biotite, apatite, and hornblende minerals in the host rock. The factor analysis results reveal that the geogenic and anthropogenic activities contribute to groundwater chemistry. Health risk assessment was carried out by calculating the hazard quotient (HQ) on the basis of intake exposure of groundwater, as per the USEPA. Results were obtained for total hazard index value greater than 1 for adults and children, which causes non-cancerous health effects.
Highlights
Human beings rely heavily on natural resources
The allowable limit of pH is 6.5 to 8.5 (BIS 2012) for drinking water in the study region which is within the limits
About 41% and 32% of groundwater samples are a non-acceptable limit of M g+2 which is 30 mechanism of groundwater the plot of TDS (mg/L) prescribed for drinking water (BIS 2012)
Summary
Human beings rely heavily on natural resources. Fresh air and clean water, in particular, are essential for people to survive on this globe. Due to a lack of surface water, one-third of the world's population, in arid and semi-arid countries, relies on groundwater for their daily requirements, for drinking As a result of natural environmental changes and human activities such as agricultural and industrial activities, groundwater quality is gradually deteriorating, resulting in a water shortage crisis and a host of environmental challenges (Satyanarayana et al 2017; Toolabi et al 2021). Nitrate and fluoride levels are being harmed by poor groundwater quality around the world. Several researchers on water quality in terms of fluoride and nitrate have been undertaken in arid and semi-arid regions around the world in recent years (Satyanarayana et al 2017; Kadam et al 2020). Agricultural runoff, excessive fertilizer use, inadequate septic system construction, spilling city drains, slaughterhouses, dairy and poultry farming, manure systems, humanistic and animal wastes, and so on all have an impact on the elevated nitrate concentrations in groundwater
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