The mineralogy of fluoride mobilisation to groundwater from the peninsular granite, Andhra Pradesh, India.
Doctoral thesis, UCL (University College London).
This thesis investigates the mineralogical sources of fluoride (F) in groundwater in two gneissic granite bedrock aquifers in Andhra Pradesh, India, with the aim of developing a conceptual framework for describing the mechanisms of F release from mineralogical sources to groundwater. This included an enquiry into the spatial variation and relative importance of the mineralogical F sources, the effect of weathering and regolith development on F distribution, and the processes of waterrock interaction concerning F. The two catchments (Maheshwaram and Wailpally) are underlain by Pre-Cambrian gneissic granite, with groundwater F concentrations often exceeding the WHO guideline limit for F in drinking water (1.5 mg/l). Samples of fresh and weathered rock were collected and analysed using optical petrology, point counting, X-ray diffraction, electron microprobe and whole rock chemical analysis, the results of which were used to develop mass balances of F occurrence through the weathering profile. The availability of fluorine for release to groundwater was investigated through batch leaching experiments. Results indicate the principal F-bearing rocks to be porphyritic granites in both catchments, with apatite, biotite, fluorite, amphiboles and titanite as the principal Fbearing minerals overall. The relative availability of F for release to groundwater (as indicated by batch leaching experiments) does not directly relate to sample total F content. Weathered samples, with typically low total F content and few F-bearing minerals may provide a source of F to groundwater through the leaching of relatively mobile and water soluble F. High F leached from calcrete samples and mafic vein samples in Wailpally may be important sources of F to groundwater where present. Generalisations of F distribution and release to groundwater at both a catchment scale and local scale are represented by a series of conceptual models, and a semiquantitative analysis of F-loss through long term weathering presented.
|Title:||The mineralogy of fluoride mobilisation to groundwater from the peninsular granite, Andhra Pradesh, India|
|Open access status:||An open access version is available from UCL Discovery|
|Additional information:||Copyright restricted material has been removed from the e-thesis. In Chapter 1: pages 20, 25; in Chapter 2: pages 35, 44, 45, 47, 52, 54, in Chapter 3: pages 60, 61, 63, 64, 67, 68, 69, 70, 74, 75, 76, 77; in Chapter 4: pages 85, 87, 93, 103; in Chapter 7: pages 264, 268, 270, 271, 276; in Appendix 1: pages 322, 324|
|UCL classification:||UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Earth Sciences|
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