The water quality of Birim river in South-East Ghana

Abstract

A limo-chemical characterization and water quality assessment of Birim River Catchment identified mining and domestic activities as the main pollution sources. The concentrations of a range of elements and ions in the river waters were measured over a of 12-month period. The river waters were well oxygenated due to their turbulence with resultant diffusion action, and 72.2% of the waters had dissolved oxygen (DO) above the natural background level range of 5.0 - 7.0 mg L . Evidence of high nutrient loads recorded in the basin was as a result of influences from domestic, agricultural and industrial activities, as well as biogeo-chemical reactions in the soil. The seasonal variations of the nutrients were higher in the rainy season than in the dry season. The waters of the Birim basin showed an overall ionic dominance pattern of Ca > Mg and HCO, > CI > SO,, typical of freshwater systems, due to the dominance of Ca and HCO,. Calcium and magnesium showed a strong linear correlation r= 0.95 significant at P <0.001, an indication of strong weathering pattern in the Birim catchment. Variations of chlorides and suspended solids were high in the rainy season. BOD loads were high in the lower reaches, an indication of industrial, domestic and commercial discharges. 84.2% of the measured Mn values exceeded the background level of 0.1 mg Li' as a result of mining activities and other anthropogenic point sources.