Author(s):

Otitoju O, Otitoju GTO and Boyi R

Abstract: Evaluating the risk of exposure of farmers as well as consumers of agricultural products is an important step in maintaining sound environmental and human health. Rice, one of the staple foods in most Nigerian homes has been implicated to contain some quantities of heavy metals; hence the aim of this research was to assess the heavy metal concentrations in soil and Oryza sativa samples from a farmland in Wukari, Taraba State. Soil and Oryza sativa samples were collected from the Road side (RD) and the farm site (FS) and analysed for heavy metals, minerals and inorganic salt contents. The result showed that samples from RD locations show higher concentrations of Ca and Zn (1.55 and 2.56 ppm respectively) than the FS location which had 1.44 and 1.88 ppm for Ca and Zn respectively. Mg, K, P, Mn and Fe had lower concentrations in soil samples from RD than the FS locations. Heavy metal contents in soil shows that Cu, Pb and Cd concentrations were not significantly higher in the samples from RD. Some mineral elements present in the rice samples shows that Ca, K, Na and P concentrations were higher in rice harvested from road side farms than the farm site locations while Mg, Mn, Fe and Zn concentration was generally lower in roadside farm. The differences observed were not statistically significant (p>0.05). However, heavy metal results show that Cu, Pb, Co and Cd were present in rice harvested from RD at lower concentrations between 0.012-0.42 ppm than samples from the FS location with heavy metal concentrations ranging between 0.02-0.60 ppm. Husk samples harvested from Rd and FS shows that all the mineral elements were generally higher in the FS locations except for Fe concentration which was significantly higher (p<0.05) in the RD locations than FS locations. Generally, Pb and Cr concentrations were higher in rice samples from RD than the FS soil. The increase of about 50% in Pb and Cr concentrations may be due to bioaccumulation potential of Oriza sativa while cadmium concentration however decreased by about 50%. A similar trend was observed in the FS locations where Pb and Cr concentrations increased in the rice samples than the soil samples from the corresponding locations.

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