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 (<i>Chrysopogon zizanioides</i>) 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 (<i>E_r</i> 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.