Comparative Analysis of Cadmium Accumulation in Xerophytic Plants: Implications for Species Selection in Phytoremediation

TL;DR

This study compares how different woody plants absorb and store cadmium, helping choose the best species for cleaning up metal pollution.

Contribution

The study identifies three functional groups of plants based on cadmium accumulation and translocation patterns, offering a new framework for phytoremediation strategies.

Findings

Roots are the primary accumulation sites for cadmium, with bark as a secondary storage organ.

Leaves show strict cadmium restriction, minimizing phytotoxicity in photosynthetic tissues.

Three functional groups of plants were identified based on their cadmium accumulation and translocation patterns.

Abstract

This study systematically investigates cadmium (Cd) accumulation and translocation mechanisms in woody plants through integrated analysis of 16 species. Roots consistently exhibited the highest Cd concentrations (0.26 ± 0.13 mg/kg), serving as primary accumulation sites, while bark functioned as a critical secondary storage organ (0.22 ± 0.09 mg/kg) with strong physiological coordination to roots (r = 0.72, p < 0.001). Leaves demonstrated strict Cd restriction (0.09 ± 0.05 mg/kg) and low variability (CV = 48.7%), indicating evolutionary adaptations to minimize phytotoxicity in photosynthetic tissues. Three functional groups were identified: hyperaccumulators (e.g., Ulmus pumila, root/leaf ratio = 6.37), excluders (e.g., Malus spectabilis, root/leaf ratio = 1.12), and intermediate species (e.g., Syringa oblata) with balanced translocation patterns. Strong root-bark correlations (r = 0.68) and negative stem-leaf associations (r = −0.42) revealed complex interorgan translocation dynamics. Cd speciation analysis showed dominant residual fractions in soils (60–80%) and elevated water-soluble or weakly bound Cd in roots (35–52%). These findings provide a mechanistic basis for designing species-specific phytoremediation strategies, including phytoextraction and ecological stabilization. It will identify suitable tree species for effectively stabilizing or containing the metal pollution within a defined area, thereby preventing its lateral spread or leaching.

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