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Speciation and Bioavailability of Cd, Cu And Cr in Agricultural Soils Amended With Biosolids

Ekere Nwachukwu Romanus, Utazi Joseph Ike, Ihedioha Janefrances Ngozi, S. Eze Ifeanyi, L. Alum Ogechi and Ogbefi-Chima Fausta

Agricultural soils amended with biosolids were investigated for Cd, Cu and Cr distributions through modified Tessier sequential extraction protocol. Bioavailability of the metals in zea mays and Amarathus Hybridus cultivated on the studied soils were assessed. The results showed that the bioavailable Cu ranges between 3% -10% (0.024 ± 0.003 mg/kg and 0.105 ± 0.022 mg/kg) in all locations. Cd concentrations were between 0.016 ± 0.005 mg/kg and 0.246 ± 0.023 mg/kg). Se and Cr in the bioavailable forms ranged between 40% to 60% (0.183 ± 0.031 mg/kg and 2.257 ± 0.205 mg/kg) and 10% to 60% (0.184 ± 0.006 mg/kg and 0.687 ± 0.081 mg/kg), respectively. The transfer factor (TF) values for Cd, Cr, Cu and Se for crops varied among locations. The daily intake of metals was not high except for Cd consumption by a child through zea mays (0.402 mg/kg/day) and 0.299 mg/kg/day in Amarathus Hybridus. The hazard quotients (HQ) of all the metals were low except for Se. Results of the Principal Component Analysis (PCA) showed that there were strong relationship between Se, Cr and Cd in location A,B, C and D suggesting that Se, Cr and Cd were bounded to the biosolids. The ecological risks of Cu, Se and Cr were low but Cd posed high risk.