Phytomining potential of naturally colonising vegetation on coal colliery spoil heaps in South Yorkshire, United Kingdom and Upper Silesia, Poland

The environmental legacy of coal mining is characterised by the widespread accumulation of spoil heaps enriched with elements, representing both a persistent ecological liability and an underutilised secondary resource. Phytomining has emerged as a promising sustainable strategy for the recovery of valuable metals from such substrates while simultaneously facilitating environmental remediation. This study evaluates the phytomining potential of two legacy coal colliery spoil heaps located at Barnsley Main (South Yorkshire, United Kingdom) and Kopalnia Węgla Kamiennego (KWK) Dębieńsko (Upper Silesia, Poland). Specific and naturally colonising species were sampled and analysed using X-ray fluorescence (XRF) spectrometry to quantify elemental accumulation within stem and leaf tissues. The results reveal pronounced inter site variability in both species composition and metal uptake capacity. Barnsley Main exhibited elevated concentrations of economically significant metals, particularly Zinc ( Zn) and Copper (Cu) , with Jacobaea vulgaris and Leucanthemum vulgare demonstrating notable accumulation potential. In contrast, KWK Dębieńsko displayed greater colonial floristic diversity with more spatially distributed, moderate accumulation across multiple taxa. Climatic variability between sites further influences metal mobility and bioavailability, thereby affecting uptake dynamics. Collectively, these findings underscore the viability of coal colliery spoil heaps as substrates for phytomining, while highlighting the importance of site specific environmental and biological factors in determining operational feasibility. The study contributes to the advancements of phytomining as an integrated approach to resource recovery and ecological restoration in post-industrial landscapes.