Hydrogeochemical and bacteriological investigation of groundwater in Agbor area, southern Nigeria
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Date
2007
Authors
Olobaniyi, S.B
OGALA, J.E
NFOR, N.B
Journal Title
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Volume Title
Publisher
Journal of Mining and Geology
Abstract
Agbor, a town in southwestern Nigeria, is underlain by the Miocene to Recent Benin Formation. Groundwater occurrence
within the formation has been investigated for its quality, from which inferences are drawn on its usability and the prevalent hydrogeochemical processes in the water systems. The results indicate a chemical attribute of low pH, low total dissolved solids (TDS) and salinity. Cationic concentrations including Na+, K+, Ca2+, Mg2+ have values ranging from 0.9 to 18.9 mg/l, 0.1 to 4.2 mg/l, 1.2 to 12.8 mg/l and 0.2 to 3.5 mg/l respectively. Concentration values of Fe2+, Zn2+, Mn2+ and Pb2+ range from 0.08 to 1.92mg/l, 0.12 to 4.35 mg/l, 0.0 to 0.42 mg/l and 0.0 to 0.04 mg/l respectively. Anions including HCO3-, CO3, Cl, SO4, NO3, PO4 have respective concentration values ranging from 1.0 to 10.0 mg/l, 0.1 to 0.9 mg/l, 3.2 to 24.0mg/l, 0.0 to 10.3 mg/l, 0.0 to 18.4 mg/l and 0.0 to 2.4 mg/l. The bacteriological constituents of the water samples include Total aerobic bacteria counts (5 - 535cfu/ml) and Total coliform (10 - 70MPN/100ml). A comparison of these results with various quality guidelines, suggests that the groundwater may be suitable in its untreated state for crop irrigation, but will require pH remediation and microbial disinfection to upgrade its quality for potability and use in food processing industries. Factor analysis reveals three main hydrogeochemical activities operative within the groundwater system. Factor 1 is dominant and can be related to water-soil interaction and incorporation of leached formation water along the groundwater flow path. Factor 2 is related to pollution by biochemical related substances resulting from agricultural practices in the area. Factor 3 indicates fresh groundwater recharge. An inter-play of these processes, and base exchange reactions produced dominant chloride water types (Ca-Cl, Ca-Mg-Cl, Mg-Ca-Cl, Na-Ca-Cl and NaCl), and localized occurrences of bicarbonate types (NaHCO3 and Na-Ca-HCO3
.
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Keywords
groundwater , chloride water , quality
Citation
Olobaniyi, S. B., Ogala, J. E., & Nfor, N. B. (2007). Hydrogeochemical and bacteriological investigation of groundwater in Agbor area, southern Nigeria. Journal of Mining and Geology, 43(1), 79-89.