Assessment of Heavy Metal Pollution in Soil and Associated Risks in the Environs Adjacent to a Heavy Mineral Sand Mine on the South Coast of Kenya

Heavy metal pollution is a global concern with significant ecological and health implications. However, limited studies have focused on assessing heavy metal pollution in soil resulting from heavy mineral sand (HMS) mining and processing activities, as well as its effects on ecology and human health. In this study, we assessed heavy metal concentrations in soil samples collected near an HMS mine on the south coast of Kenya using Agilent 7700s ICP-MS. Geo-accumulation index (I-geo), enrichment factor (EF), and pollution index (PI) were used to evaluate the extent of soil pollution. The non-carcinogenic (NCR) and carcinogenic (CR) health risk from metal exposure was also evaluated. The results showed moderate pollution by Ti, Mn, Zn, and Nb and high pollution by Cr and As. Mean Cr concentration exceeded the maximum allowable concentration (MAC) and trigger value (TV) by 135 and 61 times, respectively, in topsoil, while As exceeded MAC and TV by 8 and 2 times. Cr and As enrichment factors (EF) were similar to 200 and similar to 25 times higher than the EF threshold value of 1.5. The NCR assessment showed that the population was more susceptible to the effects of As, while the CR assessment indicated a higher risk from Cr and As. Notably, the CR values for both As and Cr exceeded the threshold value of 10(-4). The findings of this study are essential for developing regulations to monitor, control, and mitigate soil pollution from HMS mining activities and its impact on soil and human health.

Automated summary

This study assessed the heavy metal pollution in soil near an HMS mine on the south coast of Kenya and its impact on ecology and human health. The results showed high pollution levels of chromium and arsenic in the soil, exceeding the allowed concentration by several times. The findings of this study are crucial for developing policies to monitor and control soil pollution.