The analysis of potentially toxic heavy metal contamination in the Lake Bogoria geothermal springs

Abstract

Lake Bogoria geothermal system is a natural geological site in Kenya that boasts a habitat for Flamingos which attract tourists, and its water find applications in agriculture and recreation. Accordingly, its geological processes, closed water systems and anthropogenic activities may lead to accumulation of potential toxic metal contamination. The present study focused on the analysis of potentially toxic metals — manganese (Mn), cadmium (Cd), lead (Pb), copper (Cu) and nickel (Ni) using atomic absorption spectrometry (AAS) in geothermal spring water samples after acid digestion method, and evaluated their health risks through dermal and ingestion exposures. Principal component analysis (PCA), enrichment factors (EF) and Pearson correlation coefficient (PCC) were performed to determine the sources and correlation between the metals investigated. Manganese, Cu and Ni recorded mean concentrations (ppm) of 0.19 ± 0.08, 0.02 ± 0.02 and 0.03 ± 0.02, respectively, which were below the permissible World Health Organisation (WHO) limits, whereas Pb (0.06 ± 0.04) and Cd (0.05 ± 0.02) levels were above the threshold standards. PCA revealed that these metals may have originated from geological regimes and surface run-offs. Copper and Cd metals were highly enriched indicating an anthropogenic origin. The Hazard quotients (HQ) of Pb and Cd were $$>1,$$ > 1 , hence they are potential precursors for non-carcinogenic and carcinogenic risks in both children and adults. The findings of this study showed possible Pb and Cd metal contamination from geothermal waters. Therefore, there is need for remediation, continuous monitoring and assessment of geothermal waters before utilization for recreation, crop production and geothermal energy exploitation to ensure environmental conservation and human safety.