Sulphur and heavy metals contents in soils and Grewia bicolor leaves around the Selibe Pikwe Cu-Ni mine (BCL), Botswana

Abstract

This study investigated environmental pollution due to mining activities at the BCL mine in Selibe- Phikwe town, Botswana and assessed the level of heavy metals and sulphur in soil and Grewia bicolor leaves adjacent to the mine. Soil and G. bicolor were contaminated with heavy metals on the downwind side, where also concentrations of sulphur in the soil and G. bicolor were found to be elevated when compared to the upwind side. The leaves samples, were significantly difference at P = 0.00 and soil were significantly different at P = 0.03 for both west and east side. A mean soil pH of 4.12 in the prevailing wind direction suggested that atmospheric deposition from the mine has caused acidification. With further distance from the mine concentration in soil and leaves appeared to reflect a decreasing deposition of heavy metals and sulphur. Elevated concentration of heavy metals in leaves represent a high risk of bioaccumulation and biomagnifications in the food chain because G. bicolor leaves are grazed on by farmed animals and are common ingredients of traditional medicines.