Affiliations: Department of Chemical Sciences, Tezpur University
Tezpur-784 028, Assam, India | Defence Research Laboratory, DRDO Tezpur-784 001,
Assam, India | Kaliabor College, Kunworitol, Nagaon, Assam,
India
Abstract: Fluoride contamination of groundwater of the central region of the
state of Assam, India, has been studied. The study area includes five
districts, viz., Karbi Anglong, North Cachar Hills, Nagaon, Morigaon and
Golaghat. A total of 388 groundwater samples have been analyzed for fluoride
contamination and 25 of them have been analyzed for fluoride as well as other
related parameters. High fluoride contamination has been observed in the
groundwater of areas having ancient alluvial red soil and Precambrian
metamorphic rock complex basement in the Kapili-Jamuna sub-basin, viz., the
plains of Diphu and Hojai subdivisions of Karbi Anglong and Nagaon districts,
respectively. Moderate fluoride has been found in groundwater of some places in
Morigaon and Golaghat districts also. Besides fluoride, presence of high
concentrations of SO_4^{2-}, much above the guideline
values, have also been recorded in some samples. The fluoride contents, as a
whole, have poor positive correlation with Na^+,
K^+, pH and depth of source, and poor negative correlation
with Mg^{2+}, Ca^{2+} and total hardness
with cumulative data spread over entire area of study. The observed poor
correlation has been attributed to the diversity of the study area. However,
fluoride showed fairly good positive correlation with depth of sources when
plotted separately for different localities.
Keywords: Fluoride, groundwater, water pollution, central Assam, India
