Moss ecological niches regulate the interception of potentially toxic elements in the petrifying spring of Tongren, Guizhou

Urbanization and industrialization have heightened the risk of groundwater contamination in karst regions, threatening the safety of petrifying spring water. Petrifying spring-moss systems serve as critical interfaces for groundwater-surface water interaction, retaining potentially toxic elements (PTEs) and improving water quality in karst ecosystems. However, it remains uncertain whether the niche differentiation among moss species influences their capacity for the retention of PTEs. This study examines the petrifying spring-moss system in Tongren Grand Canyon, Guizhou Province, a typical karst region in southwestern China. Four dominant moss species with distinct ecological niches were selected for this study. Inductively coupled plasma mass spectrometry (ICP-MS) was used to quantify PTEs in the petrifying spring-moss systems and their associated water flows. Ecological niche analysis was integrated to evaluate the PTEs enrichment efficiencies of different petrifying spring-moss systems. The results identified Fissidens grandifrons Brid., Hydrogonium majusculum (C. Muell.) Chen, Brachythecium curtum (Lindb.) Limpr., and Cratoneuron filicinum (Hedw.) Spruc. var. filicinum as representative species of distinct ecological niches. After filtration through the petrifying spring-moss systems, the concentrations of PTEs in the water were significantly reduced (P < 0.05). The retention capacities of moss species varied significantly across ecological niches and were ranked as follows: C. filicinum var. filicinum > B. curtum > F. grandifrons > H. majusculum. This study demonstrates that karst petrifying spring-moss systems efficiently intercept PTEs in groundwater and reveals, from a niche theory angle, the link between moss niche differentiation and their retention efficiency, which offers innovative strategies for ecological remediation of PTEs pollution in global karst groundwater systems.