Sokoine University of Agriculture

Sources of salinity and urban pollution in the Quaternary sand aquifers of Dar es Salaam, Tanzania

Show simple item record Walraevens, Kristine Mjemah, Ibrahimu Chikira Mtoni, Yohana Camp, Marc Van 2022-12-17T09:43:50Z 2022-12-17T09:43:50Z 2014
dc.description Journal article en_US
dc.description.abstract Groundwater is globally important for human consumption, and changes in quality can have serious consequences. The study area is within a coastal aquifer where groundwater quality is influenced by various potential sources of salinity that determine the composition of water extracted from wells. Groundwater chemistry data from the aquifer have been acquired to determine the geochemical conditions and processes that occur in this area and assess their implications for aquifer susceptibility. Analysis of groundwater samples shows that the dominant watertype is mostly NaCl with pH < 7 in both aquifers (i.e. upper and lower) except for the shallow wells where CaHCO3 prevails with pHP7, and boreholes located near the Indian Ocean, where coral reef limestone deposits are located and the watertype evolves towards CaHCO3. In the lower aquifer, Cl is higher than in the upper aquifer. The origin of salinity in the area is strongly influenced by groundwater ascending from deep marine Miocene Spatangid Shales through faults, seawater incursion on the border of the Indian Ocean, and throughout, there is some salinity within the Quaternary aquifer, especially in intercalated deltaic clays in the fluviatile deposits, showing some marine influences. The seawater intrusion is linked to the strongly increasing groundwater exploitation since 1997. Another process that plays a major role to the concentration of major ions in the groundwater is calcite dissolution. Next to geogenic salinity and seawater intrusion, anthropogenic pollution as well is affecting groundwater quality in the aquifer. An important result of this study is the observation of high nitrate concentrations, that call for improved sanitation in the area, where domestic sewage with on-site sanitation (mainly pit latrines) also threatens the groundwater resource en_US
dc.language.iso en en_US
dc.publisher Elsevier en_US
dc.subject Quaternary aquifer en_US
dc.subject Hydrogeochemical processes en_US
dc.subject Geogenic salinity en_US
dc.subject Seawater intrusion en_US
dc.subject Pollution en_US
dc.subject Nitrate en_US
dc.title Sources of salinity and urban pollution in the Quaternary sand aquifers of Dar es Salaam, Tanzania en_US
dc.type Article en_US
dc.url en_US

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