The hydrogeochemistry of the Ndavaya-Mrima area Coast Province Kenya

Abstract

The study involved hydrochemicql determination. occurrence and distribution analysis in a 554J.::.m~area between Ndavaya and Mrirna Hill in the Coast Province of Kenya bounded within the latitudes -+0,14'S; ..J.D:io's and longitudes 390,1O'E and 390 and J90,~1'E and lying to the Southwest of Kwale town. This study is aimed at determining the physio-chemical properties for the water resources in the :\davaya-\frima Ar ea. assess the extent of their contamination and identify the possible sources of pollution. Borehole, spring, river and water hole wat ers were sampled for analysis of both major constituents and trace elements. Temperature, pH. dissolved oxygen, electrical cond ucti vity, total clissol\'ed solids. total alkalinity, total hardness and total sus perided solids '.rere also determined. ,..•.nalytical techniques used in chemical analysis include atomic absorption s pectroscopyfor the determination of :\a T. :'C', Ca 2~ Cu 2\ Fe~~ ?lJ 2+.: U1c. Zn ~+;'on; specific ton electrode for fluoride ion measurement and X-:3:: fhnr':'scence [')1 the analysis of Fe2~ arid \In 2~ ions and trace metals. Tu rbidi.nent r y :H:d tit rirnet ric concent ration :T1CiPS and correlation coefficient analy sis were also used in ~he svnt hesis of the physio-chemical data. The grol.lndwaterflow in the :Idavaya-~.frimadr,=ais sre,::ttly influenced by topography, ~ithology arid ge810gical structures and is generally South-e2.steI'ly. The concentr anor, of the physical and chemical pa rarne te r s,determined s how a general increase from norr h ::0 south. Su1i)he.te anri silica ions are highly conce nt rated in the southern part of the study area wit h their contents decreasing in all directions away from this region. The grou nd water in the area ha ve relatively high salinities. moderate alkalinities and in some boreholes high hardness. Iron and bicarbonate ion contents in the water .- resources ar e r elat iv ely high while the surface water has 101\' fluoride concentration. Sodium and chloride ions [ire the most dominant cation and anion. respectively, wit