Toward a New Paradigm for Tailings Phytostabilization – Nature of the Substrates, Amendment Options and Anthropogenic Pedogenesis

Base metal tailings (BMT) are normally sulfidic and contain high abundance of residue metals. Their adverse impacts on the environment can last for decades to centuries if without appropriate stabilization. While in situ phytostabilization has been thought to be a promising approach to stabilize surface tailings, few studies have reported a success in constructing a sustainable plant community in BMT so far, implying that a new paradigm involving a sophisticated understanding of the nature of BMT is needed for BMT phytostabilization. Using a property database of BMT worldwide built in this study as a backdrop, this review explores how BMT are different from normal soils and how these differences influence the strategies of BMT phytostabilization. It is found that BMT are mineralogically and chemically different from natural soils, which endows BMT with unstable geochemistry and inherent extreme toxicity. Studies have documented that amendment options and soil development in BMT phytostabilization are largely constrained by these abiotic factors. From a viewpoint of pedogenesis, BMT can be seen as novel parent materials rather than soil. Accordingly, we propose that in BMT phytostabilization, extensive engineering efforts are required to increase the biocapacity of tailings (i.e., anthropogenic pedogenesis) rather than focus on the selection and establishment of plants.

贱金属尾矿（Base metal tailings, BMT）通常为硫化物型，并富含残留金属。若未采取恰当的稳定化处置措施，其对环境的不利影响可存续数十年乃至数百年。尽管原位植物稳定化（in situ phytostabilization）被认为是稳定地表尾矿的极具前景的技术手段，但迄今为止鲜有研究实现在贱金属尾矿中构建可持续植物群落，这表明要实现贱金属尾矿的植物稳定化，亟需建立一套基于对贱金属尾矿本质深入认知的全新研究范式。本研究构建了全球贱金属尾矿属性数据库，以此为研究背景，本综述系统探讨了贱金属尾矿与普通自然土壤的差异，以及这些差异如何影响贱金属尾矿植物稳定化的实施策略。研究表明，贱金属尾矿在矿物学与化学组成层面均与自然土壤存在显著差异，这赋予其不稳定的地球化学特性与固有的极端毒性。已有研究证实，贱金属尾矿植物稳定化过程中的改良措施与土壤发育进程，在很大程度上受限于上述非生物因子。从土壤发生学（pedogenesis）视角来看，贱金属尾矿可被视为新型成土母质，而非普通土壤。据此，我们提出：在贱金属尾矿植物稳定化实践中，需投入大量工程手段以提升尾矿的生物承载能力（即人为土壤发生（anthropogenic pedogenesis）），而非仅聚焦于植物的筛选与定植。