Influence of different anionic charges in lead compounds in the remediation of lead by Eleusine indica (Gaertn)

Abstract

The study was carried out to investigate the remediative capacity of Eleusine indica in lead-polluted soil. Soil samples were collected near student hostel (hall 5) in the University of Benin. The soil samples were sun dried to constant weight and was pulverized with wooden roller and sieved with a hand sieve of 2 mm mesh size. The sieved soil was spiked with 0.625 g lead nitrate (PbNO3), lead sulphate (PbSO4), lead carbonate (PbCO3), lead acetetrahydrate (PbC2H6) and lead chloride (PbCl2) separately in three replicate using aqueous standard solutions. Tillers of Eleusine Indica were placed in the metal - polluted soil immediately and the experiment was allowed to stay for 15 weeks. The result showed that the uptake efficiency for Eleusineindica in both shoots and roots for lead nitrate was 0.016% and 0.8%, lead sulphate 0.016 % and 0.352 %, lead carbonate 0.064% and 0.496 %, lead acetetrahydrate 0.032 % and 0.688 %, and lead chloride 0.08 % and 0.72 % respectively, indicating that the plant might have sequestered the metal in the soil rather than accumulating it in the leaves. This was evident in the presentation of the metal sequestration factor of over 70 % irrespective of the nature of the metal. Microbial count of soil before and after contamination with lead nitrate was 1.9x104 and 0.4x104 cfu/g indicating a reduction. The study therefore revealed that Eleusine indica is a high efficient plant in sequestering lead in polluted soil.