Soil environmental monitoring of repurposed railway line operated for 75 years: Case study in Northeast Poland

This study examines the environmental implications of repurposing former railway infrastructure into bicycle paths in northeastern Poland. While lauding the commendable initiative for offering eco-friendly transportation alternatives, the investigation emphasises the potential environmental and consequences linked to contaminated soils resulting from the former railway line, posing risks for both users and the environment. Topsoil samples (0–25 cm) were collected from eight measurement points along the Szczytno - Biskupiec Reszelski railway line (Poland), at varying distances from the railway tracks (5–30 m). Concentrations of specific Potentially Toxic Elements (PTEs), notably Ni, Zn, Pb, and Cd, were analysed in 48 topsoil samples. Furthermore, the soil contamination was assessed by contamination indices, single (Igeo, PI) and integrated (RI, (IPln, MERMQ). The study revealed variations in PTE concentrations, with the highest levels recorded at the fourth and seventh sampling sites (4:34.2–57.5 mg/kg; 7:18.2–42.3 mg/kg). These findings were consistently supported by the MERMQ and RI indices, emphasising the significant risks for the environment and increased soil toxicity. In light of the EU's proposed Soil Monitoring Law, the research emphasises the need for robust data collection, analysis, and contamination monitoring practices to facilitate informed decision-making and sustainable environmental management in repurposed transportation infrastructure.