Jane Oremo^{1, 2,}, Francis Orata^{1, 2}, Joseph Owino^{1, 2}, William Shivoga^{2, 3}

Surface water contamination has become one of the main environmental issues of concern and a challenge to the world population, especially in the developing world, that face potable or usable water security. In this study concentrations of available nutrients (PO₄^3- and NO₃^-) in sediments and water along River Isiukhu, within Lake Victoria catchment area in Kenya are presented. Sediments and water samples were collected from 11 sampling sites along River Isiukhu. Available phosphorus was determined by a Spectrophotometric method in which the ammonium phosphomolybdate complex, was reduced by ascorbic acid in the presence of antimony to give a distinct blue color complex. Available nitrate was measured spectrophotometrically at 420nm using UVI609PC UV/VIS Spectrophotometer. Physicochemical parameters such as temperature, pH, dissolved oxygen, turbidity, salinity, conductivity, were measured on-site using mobile Hydrolab Quanta. Phosphates concentrations ranged from 1.18 ± 0.09 to 3.28 ± 0.5 in water (mg/l) and 2.30 ± 0.03 to 4.51 ± 0.31 in sediment (mg/kg) and nitrates concentrations ranged from 0.15 ± 0.04 to 0.75 ± 0.03 in water (mg/l) and 0.75 ± 0.02 to 1.93 ± 0.05 in sediment (mg/kg). The coefficient of variation (CV) depicted that all the physical-chemical parameters measured varied widely except pH and temperature. Pearson's correlation matrix was used to show the relationship between nutrients concentrations in sediments and water and also for the physical-chemical parameters at significant differences accepted at P ≤ 0.05. There was variation in Pearson correlation coefficient analysis for all the parameters tested.

phosphates, nitrates, sediments, correlations, River Isiukhu