Assessment of the impact of effluents discharge from Murang’a town and its environs on the water quality of river Mathioya, Murang’a County, Kenya

Abstract

Chemical fertilizers, leaching through the soil from agricultural activities, sewerage effluents and runoff from residential areas reaching water resources cause serious pollution. The purpose of this study was to determine the impact of effluent discharges on water quality of River Mathioya in Murang’a County, Kenya. Samples were collected upstream and downstream of Murang’a town along the river. The pH, Dissolved Oxygen, Electrical Conductivity, Total Dissolved Solid, Total Suspended Solids and Temperature were determined using the respective meters. Heavy metals were determined using Flame Atomic Absorption Spectrometry while Sodium and Potassium were determined using Flame Emission Photometry. Nitrates and Phosphates were determined using UV/Visible Spectrophotometry. Ion Selective Electrode was used to determine Fluoride levels. The mean values of water temperature, TSS, TDS, DO, pH, EC, phosphates, nitrates and fluorides were found to be 22.44± 0.23o C, 48.33± 0.59 mg/l, 5.74± 0.18 mg/l, 5.74± 0.05 mg/l, 7.34± 0.05 70.26± 0.89 μs/cm, 0.68± 0.04 mg/l, 10.84± 0.38 mg/l and 0.79± 0.01 mg/l respectively. The mean values of Fe, Mn, Zn, Cu, Pb, Cr, K and Na were found to be 1.01± 0.05, 1.50± 0.11, 0.07± 0.01, 0.03± 0.01, LOD, 0.03± 0.01, 9.51± 0.62 and 94.58± 0.44 mg/l respectively. The data was analyzed using Student-Newman-Keuls test. The study showed that there was small amounts of heavy metals in the water samples, though the levels were below WHO maximum permissible levels for Zn, Cr, Pb, and Cu. The levels of iron and manganese were higher than the recommended level of 0.5 mg/l and 0.04 mg/l respectively. The concentrations of the physicochemical parameters, nitrates and phosphates were found to be within the WHO limits for domestic water. It was recommended that close monitoring, proper use and disposal of agrochemicals, proper planning of vehicle repair and maintenance garages and proper location of car washing areas should be done.