Risk assessment of chromium and nickel in soils Of Sharada Industrial Estate, Kumbotso Local Government Area, Kano State

Abstract

Treatment of industrial chemical wastes being discharged into the environment is rarely done in Nigeria. These wastes are known to contain heavy  metals which when released untreated, accumulate in the soil and pose serious environmental problems thereafter. In this study, operationally  determined speciation analysis and potential mobility factor of Chromium and Nickel were carried out in the Tannery, Dye pit, Ceramic and Plastic  industry soils of Sharada Industrial Estate. Levels of metals in the various fractions were determined using Atomic Absorption Spectrophotometer (Buck  211VGP AAS). The results indicated that the total concentrations of the heavy metals in these industries were 126.46, 116.28, 116.89 and 117.91 mg.kg  for Ni; 1498.54, 1446.33, 164.52, 117.93 mg.kg^-1 for Cr, respectively. The residual fraction for Cr at the sites ranged from  61.60 mg.kg^-1 at Plastic  Industrial site to 706.85 mg.kg^-1 at Tannery site, while that of Ni ranged from 59.80 mg.kg^-1 at Plastic Industrial site to 84.98 mg.kg^-1 at Tannery site.  Results showed that most of the Cr and Ni fractions were bound to the residual fraction indicating that they were as a result of the lithogenic property of  the soil. The mobility of Ni and Cr were calculated using Potential Mobility Factor (PMF), which for Ni across all industries gave 10.52%, 13.37%, 13.85%,  14.90%, while for Cr, the values were 0.72%, 11.08%, 8.36%, 11.55%. The PMF for Ni appeared to have a higher value compared to that of Cr, but the two  values were statistically the same as they fell within the same medium stability and risk class (10 < PMF ≤ 30). Risk assessments of these metals in the  soils were found to pose no immediate health challenges.