Surface soil-dust contamination of Phalaris arundinacea grown on former lead mine sites: Implications for biomass use, phytoremediation and phytomanagement.

This study evaluated the contribution of soil dust deposited on the surface of reed canary grass (Phalaris arundinacea) grown on historic lead (Pb) mine sites to the overall contamination of the biomass, with implications for phytoremediation, valorization and utilization. By applying a novel combination of imaging of plant material using X-ray computed tomography (XCT) and scanning electron microscopy (SEM), with washing experiments and bulk analysis, the research aimed to distinguish between (a) Pb uptake through biological processes (phyto-extraction), and (b) surficial dust and physical entrapment of Pb-rich dust on plants cultivated in contaminated soils (surface-contamination). The study established the presence and distribution of Pb-rich particles, which were difficult to remove even by means of sequential washing in 1 M hydrochloric acid and surfactant.

A circular economy approach to drinking water treatment residue management in a catchment impacted by historic metal mines.

Drinking water treatment residues (DWTR) from mining areas which remove and contain potentially toxic elements (PTE) could still potentially be used as a soil amendment to restore contaminated sites in the same catchment, thus eliminating waste and reducing the chemical and physical mobility of the pollutants. To assess this restorative and regenerative approach to DWTR management, field and pot trials were established with soils from a historic Pb-Zn mine site in the North East of England, amended with either local DWTR or the nearest available municipal green waste compost (GWC). Soils from the mine site were found to have very low levels of nutrients and very high levels of PTE (Pb and Zn > 13, 000 mg/kg).