Assessment of physicochemical properties and heavy metals in water, sediment and fish (oreochromis niloticus) from the Upper Volta basin (stratum vii), Ghana

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2015-04-24
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Abstract
This study was carried out at the Upper Volta Basin (Stratum VII) to assess the levels of six (6) heavy metals, Arsenic, Lead, Copper, Cadmium, Zinc and Mercury in the water, sediments and fish as well as nutrients in the water (nitrates and phosphates) and sediments (nitrogen and phosphorus) from January to March, 2012. Three sampling locations, namely Korpedike (Upstream), Makango (Midstream) and Yeji (Downstream) were chosen to give adequate spatial coverage and obtain a comprehensive and representative assessment of the heavy metal as well as the nutrient levels of the study area. Physicochemical data gathered during the study at the three sampling locations were fairly similar over the sampling period with no significant spatial variations (p>0.05) in the assayed parameters. The nutrient levels were however variable with significant spatial variations in nitrate concentrations in the water with the highest concentration of 0.065 mgL -1 recorded at the Korpedike sampling location. The nutrients concentrations in the water were generally below the WHO (2011) Drinking Water Quality Standard for nitrate and phosphate. Nitrate values at some of the sampling stations however exceeded the guideline value for the protection of aquatic life of 0.05 mgL -1 . Concentration of metals in the water sediment and fish of the Basin were generally lower than their regulatory standards for their presence in the basin. Compared to the WHO (2002) Safety Reference Standards for Human Consumption, the fish samples from the three locations on the Volta Basin were considered wholesome for human consumption and are unlikely to cause harm to human consumers in these areas. Heavy metals in the water, sediment and fish from the Upper Volta Basin ranked in the order of; Upstream>Midstream>Downstream, indicating an influence of the artisanal mining on the Volta Basin.
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A thesis submitted to the Department of Theoretical and Applied biology, Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirement for the degree of Master of Science in Environmental Science,
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