Abstract: With the seedlings of model plant Arabidopsis thaliana and the polycyclic aromatic hydrocarbon fluoranthene as test materials, this paper studied the physiological responses of plants to polycyclic aromatic hydrocarbons from the aspects of antioxidases and membrane protection system that are tightly related to abiotic stresses. The results showed that under fluoranthene stress, the seedlings experienced oxidative stress and membranelipid peroxidization. At 0.75 mmol·L^-1 of fluoranthene, the photosynthetic process was inhibited; at 1.00 mmol·L^-1of fluoranthene, the malonaldehydic acid (MDA) content increased and the ascorbate peroxidase (APX) activity decreased significantly, indicating an accelerated membrane-lipid peroxidization; and at 1.25 mmol·L^-1 of fluoranthene, the peroxidase (POD) activity decreased significantly and H₂O₂ had a high accumulation, making the seedlings injured severely.

Key words: CO₂ concentration, traffic volume, stable carbon isotope, urban green space system, leaf area index