Evaluation of Heavy Metals Pollution Status of the Groundwater around Riruwai Mining Area, Kano State, Nigeria

The aim of this study was to investigate the heavy metals pollution status of the groundwater of Riruwai mining area, Kano State, Nigeria. A total of 31 groundwater samples were collected from five sampling locations which include: underground mining site (RGWI), tap water, (RGW2), surface mining ponds (RGW3), borehole (RGW4) and the well water samples (RGW5) during the dry and rainy seasons. The concentrations of seven heavy metals (As, Cd, Cr, Hg, Mn, Pb and Zn) and some physical parameters (pH, EC, and TDS) were determined using Atomic Absorption Spectrometer and Deluxe Water and Soil Analysis Kit respectively. The results of the analysis revealed that pH, EC and TDS were within the desirable limits recommended by WHO and NSDWQ in all sampling locations except in RGW1 and RGW3 for both seasons. The concentrations of heavy metals ranged as follow: As (ND to 0.15), Cd (ND to 0.1), Cr (ND to 0.25), Hg (ND to 0.09), Mn (0.12 to 0.66), Pb (0.003 to 0.06) and Zn (2.29 to 11.75), and As (0.005 to 020), Cd (0.001 to 0.15), Cr (0.001 to 0.17), Hg (ND to 0.14), Mn (0.16 to 0.92), Pb (0.007 to 0.09) and Zn (2.85 to 14.05) during the dry and rainy seasons respectively. The heavy metals concentrations changed along with the sampling sites in decreasing order of RGW1 > RGW2 > RGW3 > RGW4 > RGW5 in both seasons. The concentrations of all heavy metals were above the desirable limits recommended by WHO and NSDWQ during both seasons except well water samples (RGW5) and some few locations where the heavy metals were not detected. Therefore, it is recommended that water resources of the Riruwai mining area should be monitored closely, and more efforts should be made to reduce heavy metals concentrations level, particularly As, Cd, Cr and Zn.