Chemistry
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Browsing Chemistry by Author "Kolawole, G.A"
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- ItemEstablishment of the relationship between the sediments mineral composition and groundwater quality of the primary aquifers in the Maputaland coastal plain(2010) Mkhwanazi, Millicent N.; Kolawole, G.A; Kelbe, B.The Maputaland coastal plain has the largest primary aquifers in South Africa. It has highly permeable sediments that promote rapid recharge to the aquifers and strong interactions with wetlands in the region. The hydrochemical study of the Richards Bay aquifers suggested that there is rising levels of dissolved minerals in the Science Center aquifer. This study was designed to determine the relationship between sediment mineral composition and the groundwater quality of the selected primary aquifers of the Maputaland coastal plain. The aquifers of interest were classified into Cretaceous, Miocene, Pleistocene and Holocene Units, depending principally on a specific type of rock Formation penetrated during the drilling process. The sediments of the aquifers were classified into the Kwambonambi, Sibaya, Kosi Bay, Port Durnford, Uloa and St Lucia Formations, according to the established lithological Units, using the grain size, texture and colours of the sediments. Water samples taken from the boreholes were assumed to represent all aquifers intersected during the drilling process. Maputaland aquifers are low in potassium, sulphate and magnesium ions. Sodium and chloride ions remain unevenly distributed throughout the entire selected Maputaland coastal plain aquifers. The Miocene Unit is characterized by two chemical signatures, calcium and bicarbonate ions dominance and sodium, calcium and bicarbonate ions dominance. The Pleistocene Unit is characterized by three chemical signatures, sodium and bicarbonate ions dominance, calcium and bicarbonate ions dominance and sodium and chloride ions dominance. The Holocene Unit is characterized by two chemical signatures, sodium and chloride ions dominance and calcium and bicarbonate ions dominance. The Richards Bay sediments of the shallow Units are predominantly acidic with high clay minerals, while the deep Units are mostly neutral or alkaline. It was concluded that the sediments in the shallow aquifers are acidic due to high rainfalls that leaches calcium and carbonate ions from the sediments resulting in weathering of the sediments to high clay minerals. Sodium and chloride ions were assumed to be contributed by marine sediment deposits, coastal-influence precipitation or direct recharge from surface water resources. These ions are exchanging sites with calcium and bicarbonate ions resulting in sodium and chloride ions dominance. Although the groundwater quality of the Maputaland region has elevated total dissolved solids with unevenly distributed sodium and chloride ions, low calcium and bicarbonate ions in the shallow aquifers, the chemical composition of the groundwater is still suitable for potable purposes, except in areas where the pH is low with elevated dissolved ferrous, fluoride, aluminium and manganese ions.