Heavy Metals Levels in Lichens, Soils, Sediments and Water Bodies of Teberebie and its Environs in the Western Region of Ghana
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Date
2009-08-11
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Abstract
Mining and industrial processing are among the main sources of heavy metals contamination in the environment. Heavy metals may accumulate to toxic level which can cause a potential risk to human health. Several years of large scale and small scale mining in Teberebie and surrounding areas are a potential source of environmental pollution. Consequently, in situ lichens (Parmelia sulcata), soils, water and sediments samples have been used in assessing atmospheric, soil and stream heavy metal contamination in Teberebie, Mile 6, Mile 7 and Mile 8. The research involved the determination of total heavy metals (As, Al, Cd, Co, Cu, Hg, Mn, Sb, Th, and V) levels in the environmental samples using instrumental neutron activation analysis (INAA). The atmospheric pollution levels were evaluated using pollution index factor (PIF) and pollution load index (PLI). The results from the lichen revealed high levels of Sb, Mn, Cu, V, Al, Co, Hg, Cd and As in excess of the background values. The enrichment factor (EF) and estimated background concentration (EC) analyses of the lichen data using Al as a reference element showed that Sb, Mn, V, Co, Hg, Cd and Th were enriched in the lichens by active biological processes from atmospheric deposition, clearly indicating point and non-point origins of these elements. Pollution source identification of heavy metals in lichens using principal component analysis (PCA) and cluster analysis (CA) resulted in 3 groups of elements. Group 1 (Sb, V, Al and Cu) may have resulted from both anthropogenic activities (gold mining and agricultural activities) and natural sources, Group 2 (Mn, Hg, Co and As) from anthropogenic (gold mining) activities, whereas the source of Group 3 (Cd and Th) could be natural. Also, the sampling sites were clustered into 2 groups as relatively moderate pollution (MP) sites and a relatively high polluted (HP) sites. The PCA, CA and PLI results suggest that atmospheric deposition of point source pollutants decrease with distance from the pollution sources. The levels of As, Cd, Co, Cu, Th and Hg in soil samples from all sampling points were lower than reference values reported in literature and within the normal soil range values. This indicates that the mining activities have not affected the soils in the study area greatly. The results generally showed elevated levels of all the ten examined elements in water and sediment samples. Angonabeng and Bediabewu rivers recorded high levels (exceeding WHO guidelines for drinking water) for Sb, Mn, Cu, Al, Co, Hg and As in their water samples. The Contamination Factor (CF) assessment of the contamination of sediments has revealed that Teberebie springs are mainly polluted with Sb, Mn V, Al and Cd, and unpolluted to slightly polluted with Cu, Co, As, Hg and Th. Mile 7 spring sediment is mainly polluted with Sb, and slightly to unpolluted with Mn, V, Cu, Co, Al, Hg, As, Cd and Th. The water-sediment correlation matrix, Pollution Load Index (PLI) and the Contamination degree (Cd) results from this study have revealed that the amount of the examined elements in the water depends on the amount in the sediments, and they are directly proportional. The water quality with respect to the monitored elements in borehole water in general can be said to be good. However, there were high levels of Mn and Al in the borehole water samples which exceeded the WHO guidelines for drinking water quality.
Description
A Thesis submitted to the Department of Environmental Science,
Kwame Nkrumah University of Science and Technology, in partial fulfillment of the requirements for the degree of Master of Science (Enviromental Science).