Assessment of Heavy Metal Pollution in Kubwa and its Environs, North Central Nigeria

Abstract

The aim of this study was to assess the extent of heavy metals (Cu, Co, Cd, Fe, Ni,
Zn, Pb and Cr) pollution in water and soil around dumpsites in Kubwa and its
environs. A total of 28 samples (20 water and 8 soils) were collected within the
dumpsite vicinity and away from the dumpsite and analyzed in the laboratory for
some heavy metals using Atomic Absorption Spectrometry technique. Physical
parameters of groundwater such as pH, Temperature and TDS were measured. The
temperature of groundwater ranged from 26.1⁰C to 28.8⁰C with a mean value of
27.2⁰C; pH ranges from 5.42 to 7.53 with a mean value of 6.49 and TDS ranged from
3mg/l to 62mg with an mean value of 21.85mg/l. Concentration of heavy metals
(Fe, Cr, Cu, Ni, Pb, Zn and Co) in groundwater ranged from Fe (0.059 to 1.852 mg/l),
(Cr0.071 to 0.973 mg/l), Cu (0.139 to 0.228mg/l), Ni (0 to 0.196 mg/l), Pb (0.009 to
0.283mg/l), Zn ( 0mg/l to 0.206mg/l) and Co(0 to 0.003mg/l) respectively, while Cd
was not detected in groundwater samples. Heavy metal concentration in water is in
the decreasing order of; Fe>Cr>Cu>Pb> Ni> Zn>Co>Cd in the study area. Results of
geochemical analysis in groundwater were compared with the WHO (35) drinking
water guidelines. Samples analyzed indicated some level of groundwater
degradation by Pb, Cr, Ni and Fe. On the other hand, the mean concentration of
heavy metals in soil of the study area ranged from; Fe (3188.75ppm to 14053ppm),
Cr (104.25ppm to 183.75ppm), Cu (67.5ppm to 110.25ppm), Ni (94.75ppm to
164.25ppm), Zn (15.5 ppm to 122.75ppm), Co (25ppm to 73ppm) while Cd was also
not detected in soil of study area. The level of heavy metal pollution in soil is in the
decreasing order as follows; Fe>Cr>Ni>Cu>Zn>Co>Pb>Cd. Environmental pollution
indices such as contamination factor and geo-accumulation index were also used to
further assess soil and water pollution. Consequently, results indicate no
contamination in groundwater of study area while soil of study area records low to
moderate contamination with metals except Cd, Pb and Fe. Correlation coefficient
revealed a strong positive correlation of most metals as follows; Co vs Fe (0.867),
Cu vs Co (0.938), Zn vs Fe(0.871), Zn vs Co (0.802), Cr vs Fe (0.923), Ni vs Fe, Ni vs
Co (0.970), Pbvs Fe (0.817), Pbvs Zn (0.822) except Cd indicating similar source of
contamination. This infers a relationship between open dumps and pollution in the
area.