Geochemical Mapping of Metal Contamination and Distribution in Topsoil, Western Oban Massif Southeastern Nigeria (Published)
This study is to examine heavy metal contamination of topsoil around the western flank of the Oban Massif and environs, southeastern Nigeria. Soil samples were collected in seven locations in farming and quarrying land use locations across the study area. Heavy metals (Al, Fe, Zn, Cu, Mn, V, Pb, As, Cr, Co, Ni, and Mo) were analyzed in soil samples using ICP-Ms. Computation of enrichment factor (EF) and Pollution index (PI) was performed on concentration values of potentially toxic heavy metals (Zn, Cu, Pb, As, Cr, Ni and Co), to determine the extent of pollution caused by human activities in topsoil of farming and quarrying areas. The concentration values of heavy metals in soils were also compared with world average background values of heavy metals. Results showed that the potentially toxic heavy metals enrichment factors and pollution index values were below values considered to be harmful to human health. The soil samples with respect to PI can be classified as deficient to minimal enrichment factor. With exception of Pb, Cr and Co which had PI values slightly above 1 and mean values exceeded 1, other potentially toxic heavy metals do not pose any health threat. The heavy metals: Pb Cr and Co are a health threat. Excess Pb and Co are carcinogenic to human system, while excess chromium causes diabetes and bronchitis. Sources of Pb, Cr and Co should be further investigated to institute appropriate remediation measures and also the bioavailability of these heavy metals be conducted in the human population inhabiting the study area.
Environmental Geochemical studies on the effects of coal mining in Akwuke- Awkanawnaw, Enugu, and Southeastern Nigeria (Published)
Geochemical media such as water, soil, blackshales and plants were collected around Akwuke community in Awkanawnaw in Enugu area of southwestern Nigeria, and analysed for physicochemical parameters, inorganic ions /salts and heavy metal abundance. The ultimate goal was to investigate the geochemical environment and ascertain if the abandoned Okpara coal mine has any contamination effect on geoenvironment. The measured pH range of 3.98-4.42 renders the water as acidic to moderately acidic and consequently unsuitable drinking purposes, vegetation and aquatic life and wild life. Other physical and inorganic /organic parameters in water such as TDS, EC, Turbidity, TOC, total harness, Cl-, NO3, PO4, F, CN, Ca, Mg, Na and K all fall below recommended standard for potable water guidelines by WHO and EU and they do not portend any health threat to the end-users. Heavy metals results indicated that Fe comprise the most abundant metal in all the media except in plants where Zinc top the list. This is evidence that Fe is of main interest in all the media. It is only in soil sample s that the elements: Fe, Zn, Cr, Cd, Pb, Mn, Cu and Ni exceed standards by US EPA for agricultural soils. This high concentration of potentially toxic metals in soils and acidic water condition constitute a threat to the ecosystem. Specifically, acidic and Fe polluted waters are not benign for fish growth and survival of aquatic biota. Also, acidic and ferruginous waters corrode borehole installation materials and produce iron stained water with characteristic reddish colour and offensive odour. Assessment of the comparative heavy metal abundance in water plants, soil and black shale revealed that there is more heavy metal enrichment loading in soil than other media. The hazard potential is that soils serve as a source that can release heavy metals into other media by various processes of remobilization.Therefore, phytoremediation can be adopted in the for heavy metal attenuation in soils.