A PHYTO ANALYSIS OF HEAVY METAL POLLUTION IN ABANDONED QUARRY IN MPAPE, FCT, ABUJA, NIGERIA

Abstract

Mining activities are known to cause heavy metal pollution as a result of exposure of the heavy elements to the environment. Thus, this study assessed the heavy metals contaminations in vegetation and soils around the abandoned quarry sites in Mpape, FCT, Abuja. This was achieved by determining the presence of heavy metals in soil and vegetation, compare the concentration of heavy metals with WHO standards and determine the implication of the concentration on the quality of the environment. The sample frame was Julius Berger quarry and data acquired from the site were heavy metals concentration in soil and plants samples of the study area. Seven plant species growing on contaminated mine tailings were harvested from three sampling plots, having geographical coordinates of 9.13539N, 7.48659E, 9.13537N, 7.48659E and 9.13538N, 7.48658E respectively each 10m2 within the study area, Also Six soil samples comprising of three surface soil A B and C (0-15cm) and three subsurface soils A, B and C(15-30cm) around the roots (rhizosphere) of the harvested plants were collected. The plants parts collected included the root and leaves. Plants collected include; Mesosphaerum suaveolens (Pignut), Ricinus communis (Caster bean), Ageratum conyzoides (Tropical whiteweed), Ipomea aquatica (Water spinach), Arivela viscosa (Asian spider flower), Iberis sempervirens (Evergreen candytuft), and Persicaria Lapathifolia (Pale smartweed) respectively. Mean concentration of heavy metals in plants organs (leaves and roots) were computed using Microsoft Excel 2010 while the mean differences between concentrations of heavy metals in the plants and sediments were compared using Tukey-B One-Way Analysis of Variance (ANOVA) at a significance level of 5% in SPSS version 20 environment. The study revealed that spinach had the highest concentration (0.93mg) of zinc in its leaf while caster bean had the highest concentration of zinc (0.87mg) in it root. Similarly, spinach had the highest concentration (112.3mg and 116.0mg) of copper in its leaf and root respectively. Also, spinach had the highest concentration (0.74mg) of lead in its leaf while caster bean had the highest concentration (0.4mg) of lead in it root. Evergreen candy tuf had the highest concentration (2.32mg and 2.02mg) of iron in its leaf and root accordingly. The study also revealed that surface-soil C and sub-surface A had the highest (0.93mg and 0.9mg) concentration of zinc, surface-soil B and sub-surface B had the highest (81.0mg and 81.0mg) concentration of copper, surface-soil C and sub-surface C had the highest (4.1mg and 3.34mg) concentration of iron and surface-soil B and C and sub-surface A and C had the highest (0.5mg and 0.4mg) concentration of lead in the study area. The study similarly reveals that the concentration of zinc and iron in the study area were within the WHO standard for concentration of zinc in plants and soils. Unlike zinc, the concentration of copper in the study area were not within the WHO standard for concentration of copper in plants and soils. Furthermore, the study reveals that plants like evergreen candy tuf, Arivela viscosa were below WHO standard for lead while plants like pignut and spinach were above the standard for lead in the study area. Base on the aforementioned findings, the study recommends that government should pay attention to environmentally friendly mining policies which will expose the soil and plants of the study area to minimum concentration of heavy metals.