Dynamic distribution and accumulation of polycyclic aromatic hydrocarbons in Pueraria lobata during growth based on field experiment

The regulation investigation of the uptake, distribution, and accumulation of polycyclic aromatic hydrocarbons (PAHs) in the crop growing is essential for human health risk assessments. As an important crop with Chinese medicine homologous food function, Pueraria lobata (P. lobata) was selected as the model crop with rhizome as the products to explore the absorption, and distribution of PAHs under the natural field environment for the first time. After treated with PAHs in soil at different growth stages, the detailed PAHs in soil and tissue were analyzed. The results showed the agronomics traits of P. lobata had no obvious change after treated with PAHs, especially at the maturity stage. The accumulation of Σ₁₆PAHs in the soil had obvious seasonal dependence, and increased by 31 %, 76 % and 90 % treated with low-, medium-, and high-dose treatment at maturity stage, respectively. The tissues absorption of PAHs were selective with the leaves preferring low-rings and roots for high-rings, due to high-rings PAH being difficult to migrate to the above-ground part through transpiration flow. Notably, low-dose PAHs treatment could promote the production of total polysaccharides and main isoflavone, while medium-dose and high-dose PAHs treatment inhibited their production. The above result confirmed that PAHs could be adsorbed by P. lobata with different routes, roots mainly absorbed PAHs by root uptake from soil, leaves mainly accumulated PAHs by the foliar uptake, and the absorbed PAHs could affect the quality of P. lobata. Based on these results, the concentration of PAHs in the field should be strictly monitored.