Nutrient concentrations in the surface sediments of Lake Chivero, Zimbabwe: A shallow, hypereutrophic, subtropical artificial lake

Abstract

AbstractA lake‐wide survey in Lake Chivero, Zimbabwe, was performed to (i) examine the spatial distribution of three sediment grain sizes; (ii) determine their nutrient concentrations; and (iii) analyse the relationships between the measured surface sediment variables in the three sediment grain sizes. The results of this study indicated sand, silt and mud sediments occupied about 24, 22 and 54%, respectively, of the lake area. All the measured physicochemical variables varied significantly among the three sediment grain sizes (P < 0.05, anova). High values for pH, dissolved oxygen and NO3 were observed in the sand sediments, while water depth, electrical conductivity, soluble reactive phosphorus, NH4, total phosphorus, total nitrogen and total organic carbon were observed in the mud sediments. In the silt sediments, most measured variables showed intermediate values. Intervariable correlation indicated varied correlation patterns among the three sediment grain sizes. Information generated in this study is essential for an accurate delineation of the spatial extent of nutrient and contaminant distribution in the sediment of Lake Chivero and will facilitate the ability of lake managers to derive a comprehensive nutrient budget of the lake as a means of establishing realistic target conditions for lake restoration.