Vegetative Barrier Acts as a ‘Trapper’ Rather than a ‘Filter’ for Potentially Toxic Element Contaminated Wind-Erodible Particles at the Vicinity of an Industrial Brownfield: Evaluation of a Nature-Based Solution

Abstract

Brownfields can represent sources of multiple contaminants and may present health risks through airborne particle dispersion and incidental soil ingestion for surrounding populations. Remediation with nature-based solutions to mitigate legacy industrial pollution is therefore a relevant step to consider and requires further evaluation. Vegetative barriers offer potential mitigation strategies, yet their effectiveness in diffuse, multi-source pollution contexts remains underexplored. This study evaluated a spontaneous perennial vegetative barrier contiguous to a former lead smelter in Marseille, France, situated within a historically industrial multisource contamination context. As public access to the site is formally prohibited, this study constitutes a methodological proof-of-concept: characterizing barrier functioning under regulated conditions without active exposure risk designed to provide a transferable framework applicable to sites where human exposure is real and risk management decisions are required. PTE concentrations were assessed in soil (pseudo-total, exchangeable, EDTA-extractable and wind-erodible soil fraction considered as surface soil) and leaf (total) samples collected from both barrier sides along with human oral bioaccessibility assessments of the wind-erodible fraction. Results revealed substantial contamination in soil fractions and leaves, with the wind-erodible fraction (< 250 μm) exhibiting significantly higher concentrations of As, Cu, Pb, Sb, and Zn (p ≤ 0.005). Exchangeable fractions remained low (< 1%), while those mobilizable were substantial, particularly for Pb (58%). Oral bioaccessibility assessments showed gastric phase extraction reaching ca. 1126 mg.kg −1 for Pb highlighting that bioaccessible Pb concentrations would represent a concern at any comparable accessible site. PTE accumulations were found in leaf tissues and leaf surface deposits on both barrier sides, suggesting trapping occurs despite the absence of unidirectional filtering gradients assumed in barrier studies. These findings demonstrated that spontaneous vegetative barriers contribute to PTE stabilization and capture even in a complex, diffuse pollution context, acting as trappers rather than filters. Their preservation and/or implementation should be prioritized in brownfield management strategies to reduce erosion-mediated PTE dispersion, particularly at sites where surrounding populations may be exposed.