Study of Nutrient Pollutants and Their Impacts on the Water Quality of the Mindu Reservoir at Morogoro Municipality

Abstract

The physical-chemical parameters characterization of Mindu Reservoir, whose 50% of its waters is being plagued byaquatic weeds, involved the analyses of water and sediment samples that were collected during the dry season. As thenutrients levels of Mindu waters were determined, phosphorous (TP - PO 43- ) levels were found to be high enough forsupporting eutrophication process. Likewise Nitrogen/Phosphorous ratios average of 8.51 ± 4.32 suggested a Redfieldbehavior of nutrients with nitrogen being a limiting one. The dominant clay minerals of the Mindu surficial sedimentswere found to be kaolin and illite, where as the Cation Exchange Capacity values were found to be high enough for thesorption of nutrients and pollutants. Both river inflows, overlay-flows and sediments forms the mode of transport ofnutrient, with the later behaving as sinks of nutrients through out the year. The evaporation, bio-geo-chemical andNitrogen fixation processes along with macrophyte productivity, support the hypotheses that physical-bio-geo-chemicalprocesses influences the spatial distribution of major ion in the Mindu Reservoir. These findings classify Mindu aseutrophic, calcium magnesium bicarbonate type. A detailed multidisciplinary study that involves more than one yearcycle was recommended, to capture inter seasonal variability, and for the modeling of the sequestration of nutrients invarious trophic levels.