Hydrogeochemistry and Groundwater Quality Assessment of Oji- River, Southeastern Nigeria Using Pollution Load Index (PLI) and Irrigation Parameters
Abstract
The hydro geochemistry and groundwater quality assessments of Oji-River Local Government Area was carried out to check the groundwater suitability for domestic and irrigation uses using pollution index(PI), Contamination factor, and irrigation suitability such as sodium absorption ratio (SAR), Kelly’s Ratio, Percentage Sodium, Magnesium Hazard Two water samples (Test and Control) from boreholes proximal and distal from coal fly ash dump site were collected and investigated for this study. The physical parameters such as pH, EC, DO were measured in-situ using digital meters. While the chemical parameters were investigated using Atomic Absorption Spectrometry (AAS). The Test and Control samples physicochemical parameters were largely below the WHO standard guideline for drinking water except total chloride in test sample with a value of 999.69 mg/l against 250 mg/l of WHO 2017 standard. Analysis from the geochemical water faces plots showed that the water is of Na+K-Cl water type and possibly of marine origin or deep ancient water. The pollution index of the test sample with mean value of 1.67 indicates high pollution, while that of the Control sample 0.432 is not polluted comparing with the PI critical value of 1. From Sodium Absorption Ratio (SAR) analysis, the groundwater is excellent for irrigation activities. The Test and control samples have pH values of 3.14 and 3.40 respectively which is lower than the WHO Guideline Value, 2011 of 6.5 - 8.5, which indicates high acidity, the high acidity of the groundwater may favor the extraction of metal ions from fly ash into groundwater in the study area The concentrations of chemical ions for the test sample (calcium 7.57 mg/L, magnesium 2.97 mg/L, sodium 2.58 mg/L, potassium 50.00 mg/L, bicarbonate 32.00 mg/L, chloride 999.69 mg/L, sulphate 5.00 mg/L, fluoride 0.26 mg/L, iron 0.02 mg/L, zinc 0.208 mg/L, copper 0.189 mg/L, manganese 1.62 mg/L, lead 0.013 mg/L, arsenic 0.401 mg/L, mercury 1.584 mg/L, and nil for cadmium)and control sample (calcium 8.41 mg/L, magnesium 0.59 mg/L, sodium 2.33 mg/L, potassium 50.00 mg/L, bicarbonate 12.00 mg/L, chloride 141.96 mg/L, , fluoride 0.18 mg/L, iron 0.03 mg/L, zinc 0.320 mg/L, copper 0.040 mg/L, , arsenic 0.021 mg/L, mercury 0.839 mg/L,) are low comparing it with the WHO Standard (calcium 75 mg/L, magnesium 50 mg/L, sodium 200 mg/L, chloride 250 mg/L, sulphate 250 mg/L, fluoride 1.5 mg/L, iron 0.3 mg/L, zinc 3.0 mg/L, copper 2.0 mg/L, lead 0.01 mg/L, arsenic 0.01 mg/L, mercury 0.001 mg/L, and cadmium 0.003 mg/L) , and this could be as a result of the low/non-permeable stratigraphic layers (Nsukka Formation and Imo Shale) above the aquiferous layer (Ajali Sandstone) which reduces the rate of leaching of chemical ions into the groundwater.