# 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.

## Key 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.