Understanding the distribution, source-pattern and geochemical controls of soils in an artisanal mine site during a ban on illegal mining activities: Is a ban an absolute solution?

There is a continuous increase in heavy metal(loid) pollution globally, especially via mining activities. This study focused on evaluating the soil quality of an illegal mining site at the peak of a ban on illegal mining activities in Ghana, using Kokotro as a case study. It also compares the soil quality of the mine area against residential and pristine areas. Twenty-three (23) physical, heavy metals, metalloids and nutrient parameters were considered in this study. The RCCI, LDA, K-means and hierarchical clusters, factor and correlation analyses were employed in this study. The RRCI results showed that the mine area was affected by the mining activities as 36%, 49% and 15% of the soil samples were within moderate, high and highest, respectively. The LDA showed that in LD1, EC (r = 0.87), moisture (r = -0.68), Mn (r = 0.51), K (r = -0.54), and Na (r = -0.55) had a strong contribution and silt (r = 0.46), sand (r = -0.30), clay (r = -0.34), Fe (r = -0.32), Ca (r = -0.35), Sr (r = 0.32), V (r = -0.31), and As (r = -0.40) had moderate influences on the soil. The factor analysis presented V, Pb, temperature, As, Sr, EC, Zn, Hg and NH₃ as the mine areas’ major factors. Also, the multiple concentric shapes of contour plots pointed to the multi-modal distributions of the elements. The heavy metal and nutrient distributions varied widely in the area. This could be related to the unearthing and indiscriminate removal of fertile soils.