Evaluation of Selected Heavy Metals Distribution on Bitter Leaf (Vernonia amygdalina) Grown around e-Waste Dumpsite in Abraka Delta State, Nigeria

Abstract

The level of heavy metals in soil and V–amygdalina plant planted around e-waste dump site were investigated in this work, due to their associated pollution that is not biodegradable but accumulate in plants and animals. The soil around the e-waste dump site and two sample of V-amygdalina, i.e. both polluted and control soil were collected and analyzed via digestion and Atomic Absorption Spectrophotometer (AAS). The heavy metals mean concentrations ranged from 2.60 mg/kg (20 – 30 cm) – 1759.54 mg/kg (0 – 10 cm) across depths the trends where Fe > Co > Mn > Pb > Zn > Cr > Cu > Ba > Ni > Cd across depths. The polluted V-amygdalina (bitter leaf) plant mean concentrations follows the trend of unwashed leaf > washed leaf > stem > root across each metals. The statistical analysis displayed minimal significant difference that spanned from t = 0.06 – 0.22 and p = 7.27 – 88.34 for all the metals. The comparison of the heavy metals concentrations on the polluted plant with control and WHO/FAO permissible limit, it shows that pollution of some of the metals were observed on the plant while the reveres is the case for other metals since their values were above and below the control and WHO/FAO value. Contamination factors were low for all the metals in the categories of CF< 1, except Cd which displayed negative and high CF of CF > 6 on both polluted and control plant. The leaf (washed and unwashed)and stem displayed very high concentrations that fell in the categories of Cdeg ≥ 32, while only the unwashed and stem displayed very high Cdeg. The root displayed considerable Cdeg of 16 ≤ Cdeg < 32 respectively. The transfer factor follows the trend of Cu > Fe > Ba > Co > Ni > Zn > Cd > Cr > Pb > Mn respectively. Pollution were observed when heavy concentration were compared with control and WHO/FAO concentration limit, hence effort should be made to control the rate of dumping e-waste indiscriminately.