Assessment of Groundwater Quality Parameters in Northern Region of Zanzibar Island

Abstract

The water quality is one of the poignant issues in many countries. The exploitation of water from groundwater aquifers has become a common practice in different areas of Zanzibar Island. Vulnerability of water to contaminants due to natural and anthropogenic sources is not unusual. Therefore, the primary objective of this manuscript is to study the groundwater quality parameters in the water sources of Northern region of Zanzibar Island. In June 2014, water samples were collected from fourteen wells for bio-chemical analysis. The chemical parameters were analyzed by ICP-OES, while the microbial analysis was done following Bergey‟s Manual of Determinative Bacteriology. Some of the analyzed parameters (Co, Be, Cd, Al, Fe and Mn) were not detected. Their concentrations were below detection limit (˂ DL). The ranges of concentration for other parameters were; Li: ˂ DL - 0.0433 mgL-1; As: ˂ DL - 0.0026 mgL-1; Ca: 25.86 - 363.25 mgL -1 ; Cr (III) : 0.0156 - 0.0382 mgL -1 ; Mg: 1.784 - 59.82 mgL -1 ; Na: 13.03 - 166.5 mgL -1 ; Ni: 0.0008 - 0.0251 mgL -1 ; Sr: 0.019 - 0.22 mgL-1; Cu: 0.0007 - 0.0072 mgL-1; Pb: ˂ DL - 0.0054 mgL-1; Se ˂ DL - 0.0006 mgL-1. Tl: ˂ DL - 0.0072 mgL -1 ; V: ˂ DL - 0.0063 mgL -1 ; and Zn: ˂ DL - 0.0605 mgL -1 . Microbial analysis reveals that some of water samples contained bacterial contamination. Chemical analysis shows that some of the parameters are beyond the WHO or USEPA guidelines. Thus, consumption of water from groundwater sources without awareness of its quality might cause serious ill effects. Therefore, there is a need of attention for the water regulatory agencies and other stakeholders to undertake regular and in-depth assessments of groundwater quality to protect public health.