Transfer of heavy metals from soil to cabbage (Brassica oleracea) grown in irrigated farmlands of Kaduna Metropolis

Abstract

In this research work the accumulation of heavy metal and its transfer from the growing medium which is soil to the vegetable mainly cabbage was investigated. Twenty sampling sites were selected from irrigated farmlands of Kaduna metropolis were there is intense agricultural practice, and one control site were there is less human activities. The Concentrations of heavy metals (Cd, Fe, Cu, Zn and Pd) for the soil and cabbage were determined with the help of atomic absorption spectrophotometer (AAS) after acid digestion. The results revealed that all transfer factors are below 1 with the exception of samples from Rigasa (18.25 μgg^-1 for Cd), Kakuri (1.27 μgg^-1 for Cd), Kawo (2.35 μgg^-1 for Cd), Unguwan Sanusi (15.66 μgg^-1 for Cd), Tudunwada (2.95 μgg^-1 for Cd), Costain (1.00 μgg^-1 for Cu) and Kurmi mashi (1.07 μgg^-1 for Cu and 1.15 μgg^-1 for Pb). The transfer factor values obtained in most of the sampling sites were lower than that obtained from Rigachikun (control site) 0.45 μgg^-1 for Cd, 0.24 μgg^-1 for Fe, 0.43 μgg^-1 for Zn, 0.94 μgg^-1 for Cu and 0.55 μgg^-1 for Pb . It was also established that the highest metal transfer from soil to cabbage is cadmium. After this, increasing order of transfer factor in this analysis are lead, copper, iron and zinc. That is, Cadmium > lead > copper > iron > zinc. This is as a result of increasing usage of fertilizers,biosolids and other related amendments to boost agricultural production.

Keywords: Soil, cabbage, transfer factor, heavy metals, atomic absorption spectrophotometer, Kaduna Metropolis, Nigeria.