Using pollution indices to develop a risk classification tool for gold mining contaminated soils

Area of Science:

• Environmental Science
• Environmental Chemistry
• Toxicology

Background:

• Potentially toxic elements (PTEs) in soil and plants pose risks to human health and ecosystems.
• Gold mining activities are a significant source of PTE contamination.
• Traditional medicinal plants can accumulate PTEs, impacting their safety and efficacy.

Purpose of the Study:

• To assess PTE contamination in soil and the Vachellia karroo plant near gold mine tailings in Matjhabeng Local Municipality, South Africa.
• To evaluate the health risks associated with PTE accumulation in a medicinal plant.
• To develop a risk classification tool for pollution assessment.

Main Methods:

• Soil and Vachellia karroo leaf samples were collected and analyzed for PTE concentrations.
• Enrichment factor (EF) and geoaccumulation index (Igeo) were calculated to assess soil pollution levels.
• A risk classification tool was developed based on quantified pollution indicators.

Main Results:

• High concentrations of copper, cadmium, lead, nickel, and zinc were found in soil, exceeding permissible limits.
• Soil pollution was confirmed as heavy for copper, nickel, zinc, cadmium, and selenium.
• Vachellia karroo accumulated toxic levels of lead and selenium, indicating potential health risks.

Conclusions:

• Gold mine tailings have led to significant PTE soil contamination in the study area.
• The medicinal Vachellia karroo plant accumulates toxic PTEs, posing a health risk to local populations.
• A pollution risk classification tool identified 17% high-risk, 53% moderate-risk, and 20% low-risk areas.