HEAVY METALS POLLUTION LEVELS OF HAND-DUG WELLS IN TARKA LOCAL GOVERNMENT AREA, BENUE STATE-NIGERIA

Abstract

This presents study assessed some physicochemical parameters (temperature, pH, conductivity, turbidity and dissolved oxygen) in hand dug well water from ten (10) locations within Wannune in Tarka LGA of Benue State, Nigeria. Ten (10) heavy metals concentration zinc (Zn), mercury (Hg), Arsenic (As), chromium (Cr), copper (Cu), nickel (Ni), iron (Fe), cadmium (Cd) and lead (Pb) were also determined using atomic absorption spectrophotometry (AAS). The results revealed the mean values for temperature, pH, conductivity, turbidity and dissolved oxygen to be 2.79±0.876 oC, 6.35±0.313, 153.4±99.633 µs/cm, 3.85±1.556 NTU, and 5.70±0.666 mg/L respectively. The results also revealed very low concentrations of heavy metals (within WHO and NSDWQ standard for portable water) except for Fe (0.51 mg/L) from W4 which is slightly above the prescribed limit (0.3 mg/L) prescribed by WHO and NSDWQ and is attributed to mechanical repairs of vehicles, use of engine oils on daily basis and rusting from iron buckets used for abstracting water from the well. Hg, As, Cu and Mn were not detected in any of the well water samples. The authors therefore recommend that the water is safe for drinking and domestic use but members of the community should construct wells away from dumpsites or sites where mechanical activities occur also adopt a better practice of abstracting well water than the use of iron buckets.