Browsing by Author "Mnzava, Judica Lightness Joel"

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    The distribution, Chemistry and origin of the saline groundwater in Dar es Salaam area
    (University of Dar es Salaam, 1986) Mnzava, Judica Lightness Joel
    This study considers the evaluation of the distribution, chemistry and origin of saline groundwater of Dar Es Salaam area, on the eastern coast of Tanzania. For the purpose of the study, rock samples, rainwater samples and groundwater samples were collected throughout the study area in 1984. Analyses for salt content in rock samples, chloride content in rainwater and major ions dissolved in groundwater was done. From the results, salinity was observed in the rock samples in most of the boreholes sampled. Rainwater was found to contain an appreciable amount of chloride, (up to 28mg/l). The groundwater throughout the study area indicated a great variation in both distribution and chemistry of the salinity. The salinity was found to be largely due t excessive chloride concentrations, (.200mg/l). Other factors which exceeded the WHO maximum permissible levels are calcium, magnesium and pH observed at localised areas. It was observed that the excess chloride concentration is not related to any geological unit or to any trend pattern. The locally distribution of chloride and the great variation of salinity is suggested to be governed by salinity modification through diffusion, density current, flushing out, straight graphic disconformities and semi-pervious layers. The major origin of chloride based on the study material as a whole is suggested to be salts in marine stratification of probably pleistocene marine strata in which undoubtedly fossil remains of saline waters exist.