Assessment of nutrient retention of a wetland

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University of Dar es Salaam
Nateete wetland is dominated by cyperus papyrus and covers an area of about Ikm2. Nateete town lacks a treatment plant and the wetland is left as the only option. The study was done to assess the nutrient retention and loading to prevent overloading the system. The main objective was to assess the variation of water quality into, within and out of Nateete wetland and specifically to: determine the wastewater flow patterns; determine the nutrient retention capacity; estimate the nutrients loads into the wetland and assess plant biomass density and nutrient uptake by the dominant vegetation at selected locations in the wetland. Two access transects were cut in the wetland; Soil samples were taken at 10cm depth; water and plant were taken for analysis. Nitrogen, phosphorus, pH, Electrical Conductivity (EC) and temperature were measured. EC ranged between 530µs/cm and 113µs/cm. Nutrient loads were higher at the inlet (16.8g/s) than the outlet (3.24g/s) indicating retention by the wetland; however there was phosphorus release. Also the inflow was 0.86m3/s and the outflow 0.22m3/s. Plants stored highest nutrients (187,000ppm N and 33,400ppm P) compared to soil (82,506ppm N; 14,710ppm P) and water (36.8ppm N; 4.6ppm P). The below ground biomass was higher (1288.4kgDW/m2) than the above ground biomass (1019.7kgDW/m2). The wastewater is concentrated on the eastern side of the wetland. Plant uptake is a more important route of phosphorus removal in Nateete wetland. Harvesting papyrus can be an effective way of nutrient removal. Nateete wetland needs to be left in its natural state for better efficiency in nutrient retention. The microbiological processes of Nateete wetland need to be assessed as well.
Available in print form, East Africana Collection, Dr. Wilbert Chagula Library, Class mark (THS EAF QH195.E33K4)
Wetland, Wetland resources, Water quality, Kampala, Uganda
kanyiginya, V.(2008). Assessment of nutrient retention of a wetland, Master dissertation, University of Dar es Salaam.