Heavy Metal Interactions Impact Tropical Native Grass in Iron-Rich Environments

Anthropogenic actions are driving environmental degradation, emphasizing the need for remediation strategies. The species Paspalum densum (Poaceae) has demonstrated resistance to excess iron (Fe) in mining-degraded environments, though these areas may also contain high concentrations of chromium (Cr) and cadmium (Cd). The capacity of P. densum to accumulate Cr and Cd (Fe-rich media) was examined. P. densum exhibited high Cd absorption, whereas Cr negatively affected the photosynthetic rate, stomatal conductance, and transpiration and biomass, with decreases of 83.3%, 74.4%, and 25.3%, respectively. Combined exposure to excess Cr, Cd, and Fe resulted in severe effects. Although the use of P. densum is effective for Cd-contaminated iron-rich sites, interactions with Cr disrupt its metabolic stability.

Heavy metal interactions could impact the tolerance capability of a phytoremediator species. This study reveals that excessive Cr uptake interacting with Cd and Fe hinders the physiological responses of a tropical native grass used for mining-site rehabilitation.