Assessment of trace element concentrations in sediment and vegetation of mesic and arid African savannahs as indicators of ecosystem health

Abstract

The savannah biome supports unique biodiversity and provides a multitude of ecosystem services. Defining background concentrations for trace elements in the environment is beneficial for the determination of nutrient deficiencies/hotspots and for the management of pollution. Sediment and corresponding vegetation samples were collected around 48 surface water points in two savannah wildlife areas for assessment and comparison of 20 trace elements using ICP-MS. Site-specific and matrix-specific differences were evident for essential B, Co, Cu, Fe, Mn, Mo, Ni, Se and Zn, potentially toxic As, Cd, Cr, Hg, Pb and V and additional elements Al, Ba, Sb, Sn and Sr analysed. Sediment and vegetation from all sampled locations at both sites contained single or multiple potentially toxic elements at various concentrations. Although the presence of all elements can be linked to underlying geology and geochemistry specific to each site, evidence of anthropogenic cause was also evident at both sites. This paper covers the widest range of trace elements assessed in protected terrestrial wildlife reserves in the South African savannah biome to date and highlights the potential for deleterious consequences of trace element contamination of the environment.