Spearmint planting in combination with its leaf amendment spurred dissipation of polycyclic aromatic hydrocarbons in...

Oil-bearing aromatic plants are superior to traditional crops and grasses in phytoremediation due to their high stress tolerance and ornamental value. Here, spearmint (Mentha crispa), a model aromatic plant species, with or without spearmint leaf amendment, was used in a pot experiment to evaluate the phytoremediation effects on a PAHs-contaminated soil. After 180 days, the planted pots amended with essential oil-containing spearmint leaves exhibited a $\sum 16\text{PAHs}$ removal rate of 26.80%, significantly higher (p < 0.05) than that by the planted pots added with essential oil-deprived leaves (9.75%) and planting alone (5.13%). The 4-ring PAHs tended to be preferentially removed, leading to compositional alterations of PAHs. Also, the substrate-assisted PAHs degradation was not at the cost of appreciable loss of stable soil organic carbon. Further, combination of planting and oil-containing leaf amendment exhibited relatively more root exudates in abundance which could serve as biostimulants for PAHs rhizodegradation. Spearmint roots and leaves harvested accumulated 2868.42 and 3698.97 ng/g PAHs which were mostly translocated to essential oils during hydistillation, implying that essential oils may be PAHs dissipation enhancers. These results manifest the oil-bearing leaf amendment a spur to phytoremediation of PAHs by spearmint. Spearmint holds promising in remediation and rejuvenation of PAHs-contaminated urban soils.