The significance of quality groundwater for daily societal usage cannot be overemphasized. Papalanto district in Ewekoro Local Government area is one of the carbonaceous sub-basins of Dahomey embayment and supplies water to the neighbouring autonomous communities in this part of Ogun State, South-West Nigeria. Currently, it is susceptible to pollution from point and near point sources due to an increase of unplanned urban developments, industrial, agricultural and domestic activities thereby compromising its quality. Having subjected the collected water samples to varying standard laboratory tests, the results were consequently analyzed. Major hydrochemical facies were identified; the dominant water types patterned in the following order based on the abundance of major ions in relation to its corresponding cation abundance is K+ > Na+ > Ca2+ > Mg2+. Emerging cationic concentrations indicate about 70% of the samples to be lower than or well within the present allowable limit of 200, 150, 200 and 12 mg/L respectively of the approved National and International standards including WHO and NESREA. The dominant water types are in the order of Chloride (Cl-) type > HCO3 −+CO3 2- > SO4 2-+Cl- ; (Na++K+) > (Ca2++Mg2+) with further analyses revealing that 2% are of NaHCO3 type, 68% are of NaCl type while the remaining 30% are of mixed CaNaHCO3 type with no geochemical contribution from the CaHCO3, mixed CaMgCl2 and CaCl2 types. The vast majority of samples in both groundwater sources (boreholes and wells) are mixed CO3 2- + HCO3 −− Cl- dominant fluids. The mechanism controlling groundwater chemistry originally regulated by the geochemical contribution of weathered limestone formation and evaporation process as dominated by mixing of low salinity water and carbonate rock constituents caused from surface and possible underground contamination sources, such as the liquid and solid waste discharged into the nearby land and channels, domestic wastewater, septic tank effluents, and irrigation return flow with existing underground minerals followed by ion exchange process while HCO3 −+CO3 2- − Cl- and Na+ + K+− water types suggesting dissolution of mineralogical constituents; an interaction between rock and water within the matrix of subsurface hydrogeological compartment and recharge of freshwater.

Water of good quality for domestic, industrial and agricultural purposes is very essential to public health and overall wellbeing of the people. Domestic and agricultural activities are carried out within the study area without considering the geochemical and biological processes that occur in the groundwater zone. The water quality of Jalingo Area NE Nigeria was investigated with the aim of determining its suitability for domestic, industrial and agricultural purposes. A total of 50 water samples were collected from surface water and groundwater sources which were analysed using standard methods: Atomic Absorption spectrophotometry for cations and conventional titration for anions. The water was characterized employing chemical indicators such as pH, sulphate, chloride and nitrate and the results indicate that most groundwater samples and some surface water samples are largely suitable for human consumption. Most of the surface water samples revealed total coliform bacteria values above the international permissible limits whereas most of the groundwater samples indicate values that are less than the international permissible limits. The chemistry of the different water sources suggests that alkaline earths (Ca+Mg) significantly exceed the alkalis (Na+K), and weak acids (HCO3+CO3) exceed the strong acids (CI+SO4) suggesting the dominance of CO3 weathering followed by silicate weathering. Hydrogeochemical studies disclosed the Ca2+-SO4 2- , Ca2+-CI-, Na+-HCO3 - and Na+-Cl- as the dominant ion types for surface water samples and Na+-HCO3 2- and Ca2+-HCO3 as the major ions for groundwater samples. The homogenous composition of groundwater indicates a common origin and source whereas the nonhomogenous composition of surface water samples reveals active groundwater mixing and significant water-rock interaction, the irrigation indices determined revealed 642 values of TDS (<421 mg/l), SAR (<10), EC (<750 μS/cm) and TH (<250 mg/l) obtained for most of the water sources are found to be within the safe permissible limits for irrigation. However, some samples which displayed values of MAR (> 50%), PI (<25%), KR (>1.00) and SSP (>75%) suggest salinity hazards and should be treated before use. The groundwater samples are generally slightly acidic, largely soft, with fairly low to moderate concentrations of dissolved solids that fall within the international limits for drinking domestic and irrigation. The concentration of nitrate in about 71% of the water samples is higher than the recommended limits of 0.3 mg/l and 10 mg/l respectively should be treated before use.

Occasioned by the paucity of pumping test data, population explosion, and unplanned drilling of boreholes within the Western Niger Delta Nigeria, this study was, therefore undertaken to provide a lucid representation of the hydrogeological framework and estimate aquifer parameters of the study area from geological (lithological logs, borehole depth (static water level (SWL), hydraulic head, etc.) and pumping test data respectively. The methods used include diagrammatic representations of the geological data while the Cooper-Jacob straight-line graph was utilized to analyse the time-drawdown. The range of borehole depth (38.5 m–189 m), SWL (0.40 m – 116 m), and hydraulic head (0.60 m – 120 m) denotes the existence of shallow and deep aquifers. The hydrostratigraphic layers revealed that the water-bearing layers comprised the recent deltaic sands, alluvium, coastal plains etc., which are unassigned equivalents of the Benin Formation, and Ogwashi-Asaba Formation. The geohydraulic parameters computed using data obtained from the pumping test indicated a range of 0.1 m2 /day – 5145.47 m2 /day, 0.01 m/day – 677.04 m/day, and 0.000053 m/hr/m to 222.1 m/hr/m for Transmissivity, Hydraulic conductivity and Specific capacity respectively. The results showed that except few boreholes within the study area, the majority of the boreholes possess geohydraulic parameters.

In most developing countries like Nigeria, groundwater constitutes major source of water because it is less vulnerable to contamination. This assured safety could be easily compromised in a populated environment where dispensing of petroleum-products is common activity. This study is aimed at evaluating quality of groundwater in Apata-NNPC area of Ibadan, southwestern Nigeria. In-situ measurement of physico-chemical parameters such as pH, Temperature and TDS were carried-out on twenty randomly collected Groundwater samples from hand-dug wells and boreholes across the study area. Electrical Conductivity was derived for samples. Atomic Absorption Spectrometer, Flame Photometer, Colorimetric and Titrimetric methods were used to analyse the concentration of ions in the samples. In-situ measurements revealed temperature ranged from 26.70 to 33.00⁰C, pH ranged from 7.00 to 8.30, TDS ranged from 40 to 310ppm and EC ranged from 59.70 to 462.69μS/cm. The major ionic concentrations (in mg/L) ranged from 1.18 - 47.74 for Ca2+, 1.42 - 59.32 for K+, 1.5 - 34.85 for Mg2+, 9.84 - 55.23 for Na+, 54.9 – 305 for HCO3 -, 25.2 – 136.8 for Cl-, 0.07 - 2.81 for SO4 2-, 0.01 - 0.76 for PO4 3- and 0.02 - 4.45 for NO3 -. The relative abundance of cations was in order of K+ > Na+ >Ca2+ > Mg2+ and anions were in order HCO3 - > Cl- > NO3 - > SO4 2- >PO4 3-. Contamination indices of trace/heavy elements such as Revelle index (RI) and Heavy Metal Evaluation Index (HEI) revealed unaffected to slightly affected contaminations and low heavy metals in the study area. Irrigation parameters such as Sodium Adsorption Ratio (SAR) showed good water quality. Gibbs plot revealed that 60% of the groundwater plotted in the rock –water interaction and 40% in the evaporation precipitation dominance. This observation suggests that dissolution of silicate minerals and anthropogenic sources controls the ground water chemistry in the study area. This observation suggests dissolution of silicate minerals and anthropogenic sources controls the ground water chemistry, water is fairly good in terms of portability and fairly suitable for irrigation. Also, industrial activities showed limited impact on water quality except in few areas which are close to the depot.