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Fluoride-bearing groundwater in Gummanampadu Sub-basin, Guntur District, Andhra Pradesh, India |
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| Authors: | N Subba Rao A Subrahmanyam G Babu Rao |
| Institution: | 1. Department of Geology, Andhra University, Visakhapatnam, 530 003, Andhra Pradesh, India 2. Department of Geology, Hindu College, Guntur, 522 003, Andhra Pradesh, India 4. Department of Civil Engineering, Malineni Perumallu Educational Society Groups of Engineering College, Pulladigunta, 522 017, Andhra Pradesh, India 3. Department of Geology, Acharya Nagarjuna University, Nagarjunanagar, 522 510, Andhra Pradesh, India |
| Abstract: | The functional factors responsible for fluoride (F?)-bearing groundwater used for drinking as well as for cooking in the area of Gummanampadu Sub-basin, Guntur District, Andhra Pradesh, India are discussed. The study area is a part of an Archean Gneissic Complex, consisting of banded-biotite-hornblende-gneisses, over which the Proterozoic Cumbhum quartzites, shales, phyllites, and dolomitic limestones occur. The chemistry of groundwater is dominated by carbonates (HCO3 ? and CO3 2?) at a higher pH. This results in a higher total alkalinity over total hardness, causing an excess alkalinity. Sodium ion is dominated among the cations (Ca2+, Mg2+, and K+). The concentration of F? (2.1–3.7 mg/L) is higher than that of desirable national limit (1.2 mg/L) prescribed for drinking purpose. A significant positive correlation exists between F? and pH as well as that between F? and HCO3 ? + CO3 2?. This indicates that the alkaline condition is the prime conducive factor for dissolving F?-bearing minerals more effectively leading to a higher concentration of F? in the groundwater. Furthermore, a positive chloro-alkaline index reflects the ion exchange, and an oversaturation with respect to CaCO3 indicates the evaporation. In addition, a negative relation between the well depth and F? shows the effect of solubility and/or leaching of salts in different depth levels. These factors regulate the concentration of F? in the groundwater. On the other hand, a positive correlation of F? with SO4 2? as well as with K+ shows the human land use activities (namely, use of chemical fertilizers, disposal of domestic wastes, etc.), which add F? to the groundwater. A significant number of the residents of the study area suffer from the health disorders related to fluorosis, which is a consequence of higher concentration of F? in the drinking water. Thus, this study emphasizes the need for supply of safe drinking water, nutritional diet, rainwater-harvesting structures, and public education to realize “health for all” motto of World Health Organization. |
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