Availability and transfer of non‑essential elements in a rehabilitated bauxite residue grassland system

Aims This study investigated a 7 yr old rehabilitated grassland established on a bauxite residue storage areas(RSA) in order to assess the availability and eco-system transfer of both nutrient and trace elements, and to determine if defined rehabilitation criteria were sustained. Methods Rehabilitated residue/soil was sampled over depth (0–10 and 10-20 cm) and season (Spring/ Summer and Autumn/Winter) and plant growth stage (green vs. senescent) to determine both essential and non-essential element (Ca, Mg, Na, Al and V) content. Invertebrates samples from both decomposer and predator specimens were assessed to determine if food chain transfer occurred. Results Residue-soil results showed sustained rehabilitation with pH, EC and ESP all within recommended criteria levels. Further, bioavailable fractions of Al and V remained low. Vegetation analysis revealed seasonal variation for both essential and non-essential elements and highlights the need for wider monitoring parameters. Elemental content in invertebrate samples did not indicate food chain transfer and results were comparable to a reference site. Conclusion Results show sustained rehabilitation with low bioavailability of non-essential elements and food chain transfer.