TITLE:
Geospatial Assessment of Selected Heavy Metal Concentrations in and around Chetambe Hills, Kenya
AUTHORS:
Mukanda Kere Wanyama, Michael Nakitare Waswa, Felix Wanjala Omonya
KEYWORDS:
Geoaccumulation Assessment, EDXRF, Potential Ecological Risk
JOURNAL NAME:
Open Access Library Journal,
Vol.13 No.5,
May
6,
2026
ABSTRACT: A geospatial assessment of selected heavy metal concentration and associated human exposure risks in and around Chetambe Hills has been done in this study in soils at different depths using the Energy Dispersive X-ray Fluorescence (EDXF). 16 soil samples were collected at different depths and analyzed for elemental concentrations using the AXIL software. The heavy metals analyzed were Ni, Cu, Zn, Pb and As. Ni concentrations ranged from 289 ± 12.3 ppm to 478.4 ± 2.3 ppm with an average of 409.1 ± 26.3 ppm which was higher than the permissible limit of 100ppm given by WHO. Cu heavy metal concentrations varied from a minimum of 33.6 ± 8.19 ppm to 383.1 ± 23.0 ppm with an average of 319.4 ± 17 ppm. Zn concentrations varied from 39.93 ± 0.8 ppm to 619.5 ± 34.8 ppm with an average of 125.8 ± 11.4 ppm. The heavy metal concentrations of Pb ranged from a minimum of 24.7 ± 1.5 ppm to a maximum of 159.2 ± 23 ppm with a mean of 60.4 ± 9.32 ppm, As concentrations ranged from 0.4 ppm to 7.1 ppm with an average of 0.7 ppm. The metal pollution indices were also computed to assess the level of contamination for the five selected heavy metals. Geo-accumulation assessment (Gaa) values ranged from 0.12 (As) to 2.89 (Cu), corresponding to contamination levels from unpolluted to moderately polluted up to moderately to seriously polluted. From the study Cu and Ni showed the highest accumulation. Potential Ecological Risk (PER) values varied from 0.59 for As to 71.94 for Cu. Cu showed a moderate ecological risk, while Ni, Zn, Pb, and As posed low risks. Synthesized Potential Ecological Risk (SPER), was determined as 117.81, suggesting a moderate risk. This SPER value is an indication that while the ecosystem is not severely at risk, there is moderate risk, mainly from Cu and Ni concentrations since overall, the indices show that the study area is moderately polluted with Cu and Ni as the primary pollution risk contributors, while Zn, Pb, and As remain within safe limits.