Effects of Ethylenediaminetetraacetic acid (EDTA) Concentration on Extraction of Added Lead in Soil and its Uptake by Cowpea

Abstract

The effects of EDTA on extraction of added lead in soil and its uptake by cowpea were investigated in a growth chamber experiment. Cowpea seeds were planted and harvested in soil samples treated with Pb+2 added as lead nitrate at the concentrations of 0, 1000, 2000, 3000 and 4000 mg/kg with EDTA concentrations of 0, 10, 50 and 250 mg/kg. EDTA solubilized soil Pb+2 generated by forming a Pb-EDTA complex in a slow reversible process between pH 5.2 and pH 7.7 was highly significant (Pr< 0.01). This facilitated Pb uptake by cowpea leading to significant accumulation in all parts of the plant and decrease in weights of plants harvested compared to the control. From this investigation, EDTA was found to remove considerable amounts of added Pb in soil and hence could be used as remediator of Pb contaminated soils.

Keywords: Cowpea, EDTA, Growth chamber, Lead, Soil