Use of Enrichment, Ecological Risk and Contamination Factors with Geoaccumulation Indexes to Evaluate Heavy Metal Contents in the Soils around Ameka Mining Area, South of Abakaliki, Nigeria

Abstract

Use of enrichment, ecological risk and contamination factors with geo-accumulation indexes were employed to evaluate the Content of Cd, Cu, and Ni in the soils around Ameka mining area, South of Abakaliki, Nigeria. Ecological risk indices and contamination indexes namely, enrichment factor, geo-accumulation index, degree of contamination, contamination factor and pollution load index were used in the assessment of level of metal contamination in the soils around Ameka mining area, Southern Benue Trough Nigeria. Fifteen (15) soil samples were collected at the depth of 5 cm from various locations for laboratory analysis. From the results, the variation of Cu, Zn and Cd concentrations is controlled by anthropogenic intense agriculture activities. For all sites, concentrations of heavy metal in the soils do not exceed the permissible US EPA standard. From the results the pollution load index values ranged from 0.19 to 0.86 indicating that the soils were moderately contaminated. As for the single-factor pollution, the average values ranging from 0.25 to 6.52 indicate that the potential ecological risk of the metals in the three sampling sites all has low ecological risk level. The ecological risk assessment revealed the possibility of soils being not polluted. The significant spatial variation recorded in the concentrations of some parameters used in characterizing the sediment quality is a reflection of impacts of anthropogenic activity on quality of the mining area. The geo-accumulation index also revealed that the sediments at all stations were practically uncontaminated by heavy metals. The results of all the contamination indexes used agreed well in explaining the contaminated levels and possible sources of the metals present in the mining area samples. This study recommends an immediate plan for analysis of the quality of drinking water and some staple crops grown in the area to determine the levels of these noxious metals and uptake by plants, to be followed by a comprehensive mitigation plan.