Abstract Remediating historical mining waste creates a paradox when environmental safety conflicts with the preservation of the visual integrity of UNESCO World Heritage sites. This study characterizes the geochemical constraints on Zn-Pb-Ag tailings at the Tarnowskie Góry site (Poland), where strict conservation laws prohibit traditional capping methods. Using X-ray diffraction, SEM-EDS, and sequential extraction, we identified contrasting mobility patterns in potentially toxic elements. While Pb (up to 2.15 wt%) and Zn (up to 11.2 wt%) remain sequestered in stable phases, cadmium (up to 1020 mg kg − 1 ) exhibits lability, with up to 74% partitioned in exchangeable (up to 13%) and carbonate (up to 61%) fractions. Although aqueous leaching demonstrates negligible current mobilization, this partitioning poses a latent risk of release due to localized rhizosphere acidification or microenvironmental carbonate depletion. Furthermore, heritage status effectively restricts the potential extraction of an estimated 150 tons of Ag, 123,000 tons of Zn, and 19,800 tons of Pb. We propose a conceptual dual-zone sustainable management model: (1) Assisted phytostabilization using native calcicolous species for stable slopes; and (2) ‘invisible’ chemostabilization using Fe–modified biochar amendments for protected zones where vegetation would compromise historical industrial aesthetics. Engineered biochar effectively immobilizes labile Cd while preventing the secondary mobilization of background As, a risk typically associated with conventional biochar. Concurrently, it reduces wind erosion without altering the waste’s visual character. These findings provide a scalable conceptual framework for reconciling pollution control with the preservation of Outstanding Universal Value at carbonate-hosted mining legacies globally.
Cabała et al. (Fri,) studied this question.