School of Natural and Social Sciences (SNSS)

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Browsing School of Natural and Social Sciences (SNSS) by Author "ALI, Neema Ashkina"

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    Characterization and Identification of Salinity Sources in Groundwater of Some Areas of Zanzibar
    (SUZA, 2022-12-01) ALI, Neema Ashkina
    The coastal areas of Zanzibar are mostly vulnerable to elevated groundwater salinization. The groundwater salinity could be associated with cardiovascular diseases and gestational hypertension. The current study was aimed to characterize and identify the groundwater salinity sources at urban Unguja selected areas. These areas were Mjimkongwe, Chukwani, Magomeni and Bububu. The samples of groundwater were collected in 500 ml new plastic bottles. The chemical analysis was performed using Atomic Absorption Spectroscopy (AAS) for Na+ , K+ and Al3+ , UV- spectrophotometer for SO4 2- , Iron meter for NO3 -and F- where by titration for Mg2+, Ca2+, HCO3 - and Cl- . Fourth (40) samples of groundwater were analyzed for salinity, temperature, pH, DO, EC together with cations and anions that mentioned above. Groundwater types through piper diagram were determined as Na-HCO3, Na-Cl, Ca-HCO3, Mg-HCO3, and Ca-Cl whereby more than 45% of all water samples were belongs to Na-Cl water types. Electrical conductivity (EC) values varied from 334μS/cm to 12631μS/cm with an average of 1856.86μS/cm. The concentration of chloride ions was between 56.73mg/L to 3091mg/L with its average of 360.88mg/L. Also high nitrate concentrations were found at Magomeni and Mjimkongwe with its mean values of 179.21mg/L and 135.61mg/L respectively. Na/Cl ratio values of Mjimkongwe and Chukwani were closely related to that of seawater (0.86). In addition, the existence of strong correlation of Cl with EC and Na 0.982 and 0.996 respectively. Seawater intrusion is mostly occurred in the groundwater samples from Mjimkongwe and Chukwani. Hence, the origin of groundwater salinization in the study area was recognized to seawater intrusion and nitrate contamination. The results from this research showed that significant quantities required to raising awareness about the health risks. Therefore, it is important to develop inexpensive methods to produce water resources with low salt content in order to control this emerging threat to consumer