Seasonal physicochemical variation in the Nabugabo wetland

Abstract

The study determined physicochemical characteristics of Lake Nabugabo wetland during a wet and a dry season to evaluate season variation in water quality. Standard (APHA 1992) and HACH methods wereused to determine the physicochemical parameters for a period of one seasonal cycle. Results were pH 3.8 (3.0-4.2); temperature 23.0 (19.4 – 26.4) 0C; conductivity 20.5(15.6-30.45) ìScm-1; total dissolved solids 11.4(4.1-14.2) mgl-1;dissolved oxygen 3.9(0.0 -5.3) mgl-1; Ca++ 3.0 (0.2-4.3) mgl-1; Mg++ 2.1(0.06-2.5) mgl-1; K+ 0.9 (0.8-1.1) mgl-1; Na+ 2.9 (2.1-3.2) mgl-1; total phosphorus 0.3 (0.07-1.3) mgl-1; soluble reactive phosphate 0.002 (0.004-0.06) mgl-1; total nitrogen 0.8 (0.5-1.8) mgl-1; nitrate-nitrogen 0.01(0.001-0.12) mgl-1; ammonianitrogen0.46 (0.1-2.2) mgl-1. Nitrate-nitrogen and dissolved oxygen varied significantly (P0.05) variation with season. The wetland hydroperiods were 0.83 north of Lake Nabugabo and 0.58 south of the Lake. Seasonal variations of nitrogenand phosphorus concentrations were strongly linked to rainfall and hydroperiods. The study showed that the wetland water quality varies with season which is important for designing temporal sampling strategy and the understanding of wetland influence on adjacent open water bodies.