By Akpah, Fabian Apeh
This work is a hydrogeochemical study of groundwater and the impact of over twenty
five years of iron ore exploration and mining on groundwater quality in Itakpe and
environs. Measurements were carried out on water samples from eight shallow hand dug
open wells, four deep boreholes and a seasonal river flowing through the mine area.
Groundwater in the area occurs within weathered rocks, fractured and faulted terraces.
Depths to water level in the open wells were generally below 15m. Chemical and
physical analyses were carried out on the groundwater samples collected from the study
area. Parameters measured include pH, temperature, electrical conductivity, concentration
of cations, anions and trace metals. Groundwater in Itakpe is slightly acidic with pH
values between 6.03 and 6.80 and temperatures between 28OC and36"C. Statistical
analysis using pie charts, stiff plots Schoeller semi-logarithmic diagram and piper
trilinear diagrams were used to characterize the groundwater in Itakpe. Three water types
were commonly found to characterize the area. They include Ca-Mg-CI-SO4 type water,
Na-K-CI-SO4 type water and mixtures of Ca - Mg- Na - K- CI - SO4 waters with no
single cation dominating. Results of the analysis were compared with an apriori data of
groundwater analysis from the area as well as world health organization (WHO)
standards for portable water. Water in the study area has increased in acidity, electrical
conductivity, hardness and concentrations of major cations and trace metals over time.
Concentration of iron (0.9mgA - 1.63mgll) and manganese (0.2mgll- 0.44mgA) was
found to be well above WHO 0.1 mgA iron and 0.05mgll manganese recommended for
portable water respectively. Recommendations were made on how to reduce and control
the impact of iron ore mining activities on groundwater at Itakpe.