Exploring a green-approach for 6PPD and 6PPD-Q removal: Riverine plants in natural wetlands

The tire-derived antioxidant 6PPD and its highly toxic transformation product (TP) 6PPD-Q represent an emerging threat to aquatic ecosystems. For example, 6PPD-Q is identified as the cause of acute mortality in coho salmon. This study investigates the phytoremediation potential of riverine plants in natural wetlands (e.g. Typha minima (T. minima)) to remove 6PPD and 6PPD-Q. T. minima accelerated the removal of 6PPD and 6PPD-Q from the medium compared to the unplanted controls, with a half-life of 21.31 min and 23.97 h respectively. Total 80 TPs were identified in roots and leaves. Multiple novel pathways were proposed to elucidate the biotransformation processes. The formation of hydrophilic TPs demonstrated the potential of T. minima in detoxifying 6PPD and 6PPD-Q. The occurrence of TPs was related to the activities of detoxification enzymes, such as cytochrome P450 monooxygenase. Although 6PPD and 6PPD-Q resulted in oxidative stress symptoms in T. minima, these stresses could be mitigated by their antioxidant defense system. The findings of the present study provide insights into the metabolic fate of 6PPD and 6PPD-Q in T. minima. This offers a foundation for natural wetlands in mitigating the ecological risks of tire-derived micropollutants in river basin management.