Assessment of Surface Water Qualities in Ihetutu Mining Areas of Ishiagu, Nigeria, using Water Quality Index Model

Abstract

The quality of surface water from rivers, streams and ponds around Ihetutu mining areas in Ishiagu, was evaluated using Water Quality Index (WQI) model, to assess their suitability for drinking purposes at different seasons. Surface water samples were collected in rainy, late rainy, dry and late dry seasons, from 10 cm below water surface of the streams, ponds, and mine pits into 1.0 L polyethylene bottles, rinsed thoroughly with deionized water. The samples were preserved at 4°C in an ice box and then transported to the laboratory for analysis. Samples were digested and analyzed, using standard methods for nine physico-chemical parameters including pH, Cl-, SO42-, NO3 -, DO, BOD5, Ca2+, Mg2+, K+. NESREA regulatory values for surface water were used as standard values while mean values of the physico-chemical parameters were used as observed values to determine the WQI for each sampling station. Ranges of the physico-chemical parameters were: pH = 6.52–7.49; Cl- = 13.70–795.25 mg/L; SO42- = 19.28-229.25 mg/L; NO3 - = 0.33–3.72 mg/L; DO = 5.72–8.76 mg/L; BOD5 = 12.19–18.20 mg/L; Ca2+ = 6.56–130.44 mg/L; Mg2+ = 2.06–20.89 mg/L; and K+ = 4.51-32.93 mg/L. Average and seasonal WQI values were found to be >100 which indicated that the surface water resources in the area were unsuitable for drinking, though Iyiogwe stream had a WQI value of 98 in the late dry season, indicating rather a very poor quality of its surface water. The results revealed that untreated mine wastewater, dumps, and other contaminants discharged from point and non-point sources into the rivers, streams, and ponds/pits were responsible for the extremely poor quality of the surface water, and must therefore be treated properly before use to avoid water related ailments. The study created a database for current status of surface water on Ihetutu hills, which can be used for the management of ponds/pits, stream and river water in the area, and the study of the impact of mining activities on the surface water qualities.