Rare earth elements (REEs) in soils and plants of Bangka Island (Indonesia) focussing on (hyper)accumulation

Background and Aims: Indonesia is one of the most biodiverse regions in the world, but only a few metal hyperaccumulator plants have been reported from this vast country. This study aimed to discover rare earth element (REE) hyperaccumulator plants on Bangka Island, an area known to have REE enriched soils associated with tin placer deposits. Methods: Prior to this study, herbarium specimens at the Universitas Bangka Belitung Herbarium were screened using non-destructive X-ray Fluorescence (XRF) scanning to detect specimens with anomalous REE concentrations. Fieldwork was subsequently conducted to collect samples from plant species suspected to be (hyper)accumulators based on the earlier XRF survey. Scanning electron microscopy and micro-XRF were used to verify the possibility of surface contamination by soil particles in plant specimens, and inductively coupled plasma atomic emission spectroscopy (ICP-AES) was used to determine total elemental concentrations in the plant material. Results: Blechnopsis orientalis was found to hyperaccumulate REEs up to 3000 µg g⁻¹ as well as arsenic up to 2100 µg g⁻¹. The non-destructive analysis found no dust or soil contamination on B. orientalis specimens, confirming it as a genuine REE and arsenic hyperaccumulator. Additionally, the known REE hyperaccumulator Dicranopteris linearis was confirmed to be a REE hyperaccumulator on Bangka Island. Conclusion: Blechnopsis orientalis is a REE hyperaccumulator with high potential for phytoextraction as it is a faster growing and larger species than D. linearis. As B. orientalis and D. linearis are native to Bangka Island, both should be studied further for their application in rehabilitating and extracting REEs from the (abandoned) tin mine areas.