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Assessment of Impacts of Artisanal and Small-Scale Mining Activities on Groundwater Quality of Ijero-Ekiti, South- Western Nigeria

Talabi AO, Afolagboye LO, Aladejana JA, Akinola OO, Aturamu AO

This study focused on assessment of possible impacts of artisanal and small scale mining activities on groundwater in Ijero-Ekiti. Thirty groundwater samples (2 from the mining pits, 5 in the vicinity of the mining pits and the remaining 23 randomly selected from other parts of the study area) were collected and analysed for the anions and cations using Ion Chromatography and Atomic Absorption Mass Spectrometer methods respectively. Physical parameters (Temp.°C, pH, ECμS/cm) were measured in-situ using a Multi-parameter TestrTm 35 series Meter. The average values of pH (8.36), EC (371.40μS/cm) and average ionic concentrations in mg/L {Ca2+ (18.21), Mg2+(7.45), Na+(43.10), K+(28.56), HCO3 -(20.15), SO4 2-(8.41), Cl-(256.34) and NO3 -(0.38)} for the samples (7) from the mining pits and their vicinity showed no significant difference from the average concentrations of groundwater samples from the remaining 23 samples randomly selected from other parts of the study area except that more solutes were introduced into the groundwater system as residence time and length of transportation increase. The 23 samples have average values of pH (8.41), EC (558.91μS/cm) and average ionic concentrations in mg/L {Ca2+ (53.94), Mg2+ (20.49), Na+(45.79), K+(64.98) HCO3 -(29.62), SO4 2-(13.82), Cl-(304.63) and NO3 -(0.38)}. Increase in solute input into the groundwater system as shown by the 23 samples from other parts of the study area might equally arise from lithological variations. The order of cations concentration in the study area is Ca2+ >Na > K+ > Mg2+ while that of anions is Cl-> HCO3 -> SO4 2-> NO3 -. All ions concentrations are within WHO standard for drinking water quality except chloride that exceeded it in few locations due to local anthropogenic contamination. The Piper trilinear diagram indicated Ca–(Mg)- Cl-(SO4) and Na-(K)-Cl-(SO4 as the dominant water. All water samples have low sodium hazard as well as low– medium salinity hazard while all irrigation indices (sodium absorption ratio, residual sodium bicarbonate and Kelly ratio) showed that the groundwater is suitable for irrigation. This study revealed that the groundwater of Ijero is low mineralized, chemically potable and suitable for irrigation while artisanal and small-scale mining activities have no significant impact on the groundwater.