Application of vetiver grass phytoremediation for trace element removal in dioxin-contaminated soils at Bien Hoa Airbase, Vietnam.

The study assessed trace element contamination and the phytoremediation potential of vetiver grass (Chrysopogon zizanioides) for removing toxic elements (As, Cd, Cr, Cu, Ni, Pb, and Zn) from dioxin-contaminated soils at Bien Hoa Airbase, Vietnam. Over a 40-month field experiment, six 100 m² plots (three planted with vetiver, three controls) were monitored for trace element concentrations, distribution, ecological risk, and vetiver uptake, with soil and plant samples analyzed every 5-6 months. Significant contamination was detected, with Cd (max. 26 mg/kg), Zn (max. 373 mg/kg), and Cu (max. 166 mg/kg) surpassing national and international limits. The modified contamination degree (mC_d) ranged from moderate (2.97) to extremely high (30.19), with Cd posing the highest ecological risk (E_r 328-5650). Vetiver effectively remediated Cd and Zn, primarily through phytostabilization-accumulating metals in roots (max BAF: 3.15) while minimizing translocation to shoots (low TF: 0.008-0.334). However, the remediation of As, Cr, Cu, Ni, and Pb was limited due to their low mobility and strong binding to stable soil fractions. These findings highlight vetiver grass as a cost-effective solution for Cd and Zn phytoremediation, stressing the need to consider element speciation for optimal soil rehabilitation and broader application in complex contaminated environments.