Screening-level ecological risk assessment (SLERA) in an abandoned As–Cu mining area (N Spain): implications of phyto-availability and soil properties on vegetation

This study applies a Screening-Level Ecological Risk Assessment (SLERA) to evaluate the potential impact of trace elements on vegetation in an abandoned As-Cu mining area in northern Spain. A total of 27 soil samples were analyzed for pseudo-total (aqua regia) and phyto-available (EDTA 0.05 M) content of As, Cd, Co, Cr, Cu, Ni, Pb and Zn. Contamination and ecotoxicological risk indices were used to identify pollution hotspots and contaminants of ecological concern (COPEC). Arsenic, Cu, Co and Zn pose a potential risk to vegetation across the site. Available concentrations of these elements are high, although average phyto-availabilities are generally low (< 30%). Remarkably, some highly contaminated areas support vegetation, while others remain barren. This suggests that high phyto-available concentrations alone do not fully explain the presence or absence of vegetation. Edaphic properties, such as low soil pH and minimal organic matter content, seem to play a critical role in inhibiting vegetation growth in certain areas. These results underline the importance of considering not only trace element concentrations but also site-specific edaphic properties when assessing ecological risk and planning remediation strategies in contaminated mining areas.