Physicochemical characteristics and investigation of some selected heavy metals in water samples of ejersa river woliso, Ethiopia

Abstract

Water is the most abundant substance on the earth's surface that is essential for the survival of all known forms of life. The present study is undertaken to investigate the water quality of Ejersa river interms of physicochemical characteristics and some selected heavy metals by considering effluent discharged from municipal wastes, Abattoir, prison and flooding.In the study, four sampling sites along the river course were selected. Composite sampling technique were used to collect the water samples and analyzed for some physicochemical parameters on site and heavy metals were analyzed in the lab by using GFAAS. The instrument was calibrated by using de-ionized water and standard solution by following standard procedures. The obtained results range (pH 5.7±0.15 to 6.51± 0.25, TDS 1686 ±6.22 to 3523±8.26 mg/L, EC 3340 ±6.05 to 6996 ±4.18 µS/cm, T° 18.7 ±0.15 to 19.56 ±0.41 o C, NO3 -36.6±0.5 to59.33±0.05 mg/L, Color 21.66±0.57to 30.66±1.15 HU, Salinity 2046 ±3.55 to 4406±4.63 mg/L, Turbidity 141.66 ±1.52 to 233.66±1.5 NTU, Nitrite 0.47±0.02 to 0.96±0.01, Phosphate 0.46±0.01 to 0.84±0.02) were recorded minimum and maximum at site A and Site C respectively. The level of heavy metals was found to be in the range (Zn 0.134±0.03 to 0.833±0.06 mg/L, Cu 0.062±0.01 to 0.529±0.02 mg/L, Co 0.173±0.07 to 0.239±0.04 mg/L, Cr 0.156±0.04 to 0.188±0.01 mg/L, Cd 0.077±0.02 to 0.0819±0.04 and Pb 0.321±0.04 to 0.404± mg/L) were recorded minimum and maximum at sites A and C respectively. These results however implicated site C to be the most polluted site, probably being the point of discharge. A comparison of the measured parameters with the national and international standards set by EDWQ (2010) and WHO (2008) shows that all the parameters measured (except PO4 3-, NO2 -, Cu and Zn) were above the standards. This indicates that the river water was significantly contaminated and therefore not suitable for domestic, agricultural and industrial uses. The concentrations of each parameter (except Cd) among the selected sites were significantly different (ANOVA, p≤ 0.05). The findings indicate that, there is a need to protect the quality of the river system. Therefore, it recommended that the government and other responsible authorities have to take appropriate corrective action and should support further study has to be conducted on other physical, chemical and untested biological parameters of significant health concern and identification of potential source of the contaminants of the river