Heavy Metal Contamination of Soils and Vegetation around Solid Waste Dumps in Port Harcourt, Nigeria

Abstract

Assessment of the levels of copper, zinc and lead in soils and vegetation around solid waste dumpsites in Port Harcourt and environs were carried out in 2005 using Atomic Absorption spectrophotometric technique. Physical parameters such as pH and particle size were also determined. The results show that the mean concentrations of copper in transect and profile soils and vegetation were 1.20 ± 0.83ppm, 2.57 ± 1.87ppm, 1.48 ± 1.61ppm respectively at the East-West road dumpsite and 2.42 ± 1.87ppm, 1.40 ± 0.61ppm, 1.39 ± 0.67ppm respectively at the Kaduna/Afam street dumpsite. The mean concentrations of zinc in soil and vegetations along the transect were 12.83 ± 4.65ppm, 2.68 ± 1.82ppm, 1.33 ± 0.64ppm, 0.80 ± 0.60ppm respectively at the Kaduna/Afam street dumpsite. The mean concentrations of lead in soils and vegetation were 0.26 ± 0.21ppm, 0.28 ± 0.24ppm, 1.48 ± 0.12ppm respectively at the East-West road dumpsite and 0.45 ± 0.37ppm, 0.20 ± 0.08ppm, 0.39 ± 0.17ppm respectively at the Kaduna/Afam street dumpsite. The order of occurrence of the heavy metals in the topsoils of the study areas was Zn > Cu > Pb. The levels of copper and zinc in soils from the waste dumpsite were significantly different (P <0.05) from soil sample elsewhere. The differences in the levels of copper, zinc and lead in soils and vegetations as well as dumpsite and outside dumpsite were not significant (P <0.05). The results indicate that solid wastes contributed to the levels of heavy metals in soils and vegetation. Also the concentrations of the metals in soils do not depend on the age of the waste dump rather, on the source, composition and the topography of the dumpsite. @ JASEM Heavy metals are found naturally in undisturbed soils and, in fact, small amounts of many metals are required by plants to remain healthy. Metals found in waste dumps exist in various forms either as the pure metal or alloyed with various other metals. Heavy metals impairing the quality of our environment come from various sources that can be categorized into urban-industrial aerosols, liquid and solid wastes from animal and man, mining and industry and agricultural chemicals (Gerard, 1996).