title: Lithological and hydrochemical controls on distribution and speciation of uranium in groundwaters of hard-rock granitic aquifers of Madurai District, Tamil Nadu (India).
abstract: Uranium is a radioactive element normally present in hexavalent form as U(VI) in solution and elevated levels in drinking water cause health hazards. Representative groundwater samples were collected from different litho-units in this region and were analyzed for total U and major and minor ions. Results indicate that the highest U concentration (113 µg l(-1)) was found in granitic terrains of this region and about 10 % of the samples exceed the permissible limit for drinking water. Among different species of U in aqueous media, carbonate complexes [UO2(CO3)(2)(2-)] are found to be dominant. Groundwater with higher U has higher pCO2 values, indicating weathering by bicarbonate ions resulting in preferential mobilization of U in groundwater. The major minerals uraninite and coffinite were found to be supersaturated and are likely to control the distribution of U in the study area. Nature of U in groundwater, the effects of lithology on hydrochemistry and factors controlling its distribution in hard rock aquifers of Madurai district are highlighted in this paper.
authors.affiliation: Department of Earth Sciences, Annamalai University, Annamalai Nagar, 608002, India.
authors.forename: C
authors.initials: C
authors.lastname: Thivya
authors.affiliation: Department of Earth Sciences, Annamalai University, Annamalai Nagar, 608002, India.
authors.forename: S
authors.initials: S
authors.lastname: Chidambaram
authors.affiliation: Isotope Production and Applications Division, Bhabha Atomic Research Centre, Mumbai, India.
authors.forename: Tirumalesh
authors.initials: T
authors.lastname: Keesari
authors.affiliation: Department of Applied Geology, Faculty of Engineering and Science, Curtin University, CDT 250, 98009, Miri, Sarawak, Malaysia. geoprasanna@gmail.com.
authors.forename: M V
authors.initials: MV
authors.lastname: Prasanna
authors.affiliation: Department of Earth Sciences, Annamalai University, Annamalai Nagar, 608002, India.
authors.forename: R
authors.initials: R
authors.lastname: Thilagavathi
authors.affiliation: Department of Earth Sciences, Annamalai University, Annamalai Nagar, 608002, India.
authors.forename: V S
authors.initials: VS
authors.lastname: Adithya
authors.affiliation: Department of Earth Sciences, Annamalai University, Annamalai Nagar, 608002, India.
authors.forename: C
authors.initials: C
authors.lastname: Singaraja
mesh_terms: D060587:Groundwater / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007194:India; D013696:Temperature; D014501:Uranium / Q000032:analysis*; D014875:Water Pollutants, Radioactive / Q000032:analysis*
chemical_list: D014875:Water Pollutants, Radioactive; D014501:Uranium
keywords: Hard-rock aquifer; Lithology; U-speciation; Uranium