ABSTRACT
Variation of groundwater quality in any area is a function of its physical and chemical parameters, which are greatly influenced by geological formations and anthropogenic conditions. This research work is, therefore, aimed at assessing the groundwater quality in Akinyele, Afijio, Ido and Lagelu Provinces of Southwestern Nigeria.
A total of one hundred and two (102) water samples were collected from the study area, which lies between Longitude 7030Ꞌ00ꞋꞋ- 8000Ꞌ00ꞋꞋ and Latitude 3040’00”-4010’00” within the basement complex of Nigeria and they were sent for laboratory analysis at the Redeemer laboratory, Ede, Osun state using inductively coupled plasma-mass spectrometry (ICP-MS) geochemical method.
The statistical analysis of groundwater parameter ranges from (26.70-32.40C)0C for Temperature, (24.00-715.00mg/l conductivity), (30.00-750.00mg/l TDS); (5.50-8.50 pH); (8.00-92.80mg/l Ca); (1.20-57.60mg/l Mg); (1.07-33.69mg/l K); (0.57-17.22mg/l Na), (0.00-75.00)mg/l SO4; (0.80-286.40mg/l HCO3); (3.00-122.00 mg/l Cl); (0.04-297.40 mg/l NO3); (0.01-2.97 mg/l Fe); (0.02-2.18 mg/l F) and (0.04-1.07 mg/l PO4) signifying a good portable water. Strong and positive correlation exist between the chemical parameters that range from ‘r’ = 0.67-0.80 signifying a strong geochemical environment. Stiff diagram shows dominant Ca, Mg and -HCO3 and can be classified as Normal – Earth Alkaline water. Also, Piper diagram indicate high Ca, Mg and SO4 indicating a Normal – Earth Alkaline water. Calculation of ion balancing shows that only 20 (58.8%) of the locations passed the test, signifying that the other 14 locations have excess positive ions, Ca and Mg, contributed from geogenic and anthropogenic inputs. Sodium Absorption Ratio (SAR) range from (0.22- 2.91) in all the locations which fall within SAR guideline (<3) indicating suitability for irrigation. Residual Sodium Bicarbonate, RSC were above the guideline limit (2.5 meq/l) in 27 locations at (3.6- 210.4 meq/l) indicating high HCO3 value which reacts with Ca and Mg to raise hardness of the water.
The geochemical map revealed low pH values at the NW and SE regions suggesting an acidic environment while high concentration for TDS, Ca and Mg was observed at the NE and SE area indicating high total hardness of the water. This might have been derived from weathered metamorphic minerals and feldspars in the metamorphic rocks of the study area.
Ca, Mg, HCO3, and SO4 were the most significant chemical contaminants in the groundwater that was investigated. It is therefore recommended that further research be carried out on trace metals in the groundwater of the study area.
