Hydrochemical facies, groundwater evolution, and physicochemical reactions between soil or rock and water are of considerable importance when evaluating or predicting the nature of anthropogenic impacts on groundwater...Hydrochemical facies, groundwater evolution, and physicochemical reactions between soil or rock and water are of considerable importance when evaluating or predicting the nature of anthropogenic impacts on groundwater quality. In this respect a total of 67 ground water samples were collected randomly in Akure, southwestern, Nigeria from hand pump/dug wells and analyzed for major cations and anions. The domination of cations and anions was in the order of Ca2+ > K+ > Na+ > Mg2+ and ?> Cl- > ?> ?respectively. The pH and Eh of the water samples show an acidic condition, with low salinity hazard (generally less than 250 μS/cm). The Piper classification for hydrogeochemical facies indicates carbonate hardness (secondary alkalinity) exceeds 50% that is by alkaline earths and weak acids, with Ca2+ + Mg2+ + ?water-type. This also suggests a meteoric origin of water quality caused by rock-water interaction. The ratio of ?and Cl- is greater than 1 and implies recharge area or upper water flow course of carbonate rocks (interaction of water with aquifer material). The Na+:Cl- is less than 0.7 signifying loss of Na+ through precipitation of evaporating water;the water is Ca2+ rich and Na+ depleted with Mg2+:Ca2+ less than 0.5 and Na+:K+ less than 15. The Na+:Ca2+ (<1) indicates reverse ionic exchange. The Ca2+:?+ ?for the samples is less than 1.0 suggestive of flow of water through the normal hydrological cycle. The calculated range of values of sodium absorption ratio (1.89 - 26.42), permeability index (42.67 - 170.24), residue sodium carbonate (-1 to 5), magnesium ratio (4 - 53), Kelly ratio (0.04 - 0.84), percent sodium (0.41 - 3.45) suggest good water suitable for irrigation purposes. In addition, the Wilcox plot shows that 98% of the water samples belong to “good to permissible category” for irrigation use.展开更多
文摘Hydrochemical facies, groundwater evolution, and physicochemical reactions between soil or rock and water are of considerable importance when evaluating or predicting the nature of anthropogenic impacts on groundwater quality. In this respect a total of 67 ground water samples were collected randomly in Akure, southwestern, Nigeria from hand pump/dug wells and analyzed for major cations and anions. The domination of cations and anions was in the order of Ca2+ > K+ > Na+ > Mg2+ and ?> Cl- > ?> ?respectively. The pH and Eh of the water samples show an acidic condition, with low salinity hazard (generally less than 250 μS/cm). The Piper classification for hydrogeochemical facies indicates carbonate hardness (secondary alkalinity) exceeds 50% that is by alkaline earths and weak acids, with Ca2+ + Mg2+ + ?water-type. This also suggests a meteoric origin of water quality caused by rock-water interaction. The ratio of ?and Cl- is greater than 1 and implies recharge area or upper water flow course of carbonate rocks (interaction of water with aquifer material). The Na+:Cl- is less than 0.7 signifying loss of Na+ through precipitation of evaporating water;the water is Ca2+ rich and Na+ depleted with Mg2+:Ca2+ less than 0.5 and Na+:K+ less than 15. The Na+:Ca2+ (<1) indicates reverse ionic exchange. The Ca2+:?+ ?for the samples is less than 1.0 suggestive of flow of water through the normal hydrological cycle. The calculated range of values of sodium absorption ratio (1.89 - 26.42), permeability index (42.67 - 170.24), residue sodium carbonate (-1 to 5), magnesium ratio (4 - 53), Kelly ratio (0.04 - 0.84), percent sodium (0.41 - 3.45) suggest good water suitable for irrigation purposes. In addition, the Wilcox plot shows that 98% of the water samples belong to “good to permissible category” for irrigation use.
