Geohydrochemical and fluoride contamination studies of groundwater of northern part of garhwa district Jharkhand

Abstract

The present geohydrological and fluoride contamination studies have been undertaken in Northern part of Garhwa District which includes six blocks. newline The area under investigation lies between 24000 and 24032 North Latitude and 83022 and 84000 East longitude. The average elevation of Garhwa district is about 1200 ft above the MSL. newline Geologically the area falls in the Precambrian terrain of Chotanagpur plateau covered by rocks of Precambrian, Vindhyan and Gondwana ages. The important rock types include granites, granite gneisses, crystalline limestone, dolerite, metadolerite and sandstone. newline The groundwater in the study area is mostly alkaline in nature and is suitable for drinking. Only about 6 % waters in pre monsoon and 15 % in post monsoon are slightly acidic. TDS is almost well within the tolerance limit in most places during pre and post monsoon. newlineThe study of concentration of toxic metals such as Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn in the selected 30 groundwaters samples of the study area reveals that most of the metals are well within the permissible limits. newlineFluoride in the groundwater is mostly geogenic and has come from minerals containing fluoride such as apatite, fluorspar, cryolite, amphibole, micas etc. The concentration of fluoride in the groundwater of the study area ranges from 0.2 mg/l to 5mg/l during pre-monsoon season and 0.1 mg/l to 4.9 mg/l during post monsoon season. The fluoride concentration above the permissible limit of 1.5 mg/l. newlineRecommendations has been made to prevent adverse effect of fluoride which include (a) identification of fluoride contaminated wells and using alternate source of drinking water, (b) regularly monitoring of drinking water sources. (c) affordable defluoridation methods such as use of alum salt, mud pots, bleaching powder and other low cost absorbents which is capable to remove fluoride to some extent. (d) The Nalgonda Technique, which is economical and effective household defluoridation technique has also been suggested. newline newline