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?

Abstract

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.