Bioaccumulation of trace elements in paddy soil, paddy plants and rice grains from irrigation schemes, Morogoro-Tanzania

Abstract

Bioaccumulation of trace elements in paddy soil and rice plants was assessed from Morogoro region of Tanzania. Paddy soil, paddy plants and rice grains were sampled from 9 different sampling points within rice fields and one control sample from a separate farm and analyzed in the School of Engineering and Environmental Studies laboratory, Ardhi University, Dar es Salaam. Trace elements were analyzed using a Perkin Elmer Atomic Absorption Spectrophotometer (100-AAS). Heavy metal uptake and translocation indices including BAF, BCF, TF and EF were established. The results showed that all samples (paddy soil, paddy plant and rice grains) contained some concentration of trace elements in various levels. The uptake of trace elements in roots were in the order of Zn>Cu>Pb>Cr>Cd while in shoots the uptake was in the order of Pb>Zn>Cu>Cr>Cd and the Reiwa bio-availability of trace elements concentration in paddy grains were in the order of Zn>Pb>Cu>Cr>Cd. The trend of the total BAF, BCF, TF and EF for each metal were in the order of Cr>Pb>Cd>Zn>Cu; Cr>Pb>Cu>Zn>Cd; Pb>Cr>Cu>Zn and Cd>Pb>Zn>Cu>Cr, respectively. The concentration of Pb ranged from 1.583±0.29 mg kg^-1 to 7.231±1.125 mg kg^-1 above the recommended 0.2 mg kg^-1 limit. Minimizing application of agrochemicals and promoting organic fertilizers in paddy farms is recommended.