Bioaccumulation and oxidative stress in submerged macrophyte Ceratophyllum demersum L. upon exposure to pyrene.

Laboratory experiments were carried out to investigate pyrene bioaccumulation and its consequent biological responses in submerged macrophyte Ceratophyllum demersum. Plants were exposed to different levels (0.01, 0.02, 0.05, 0.07, 0.1 mg/L) of pyrene for 10 days, and the pyrene content, and total free radicals in plant were analyzed. The pyrene concentration in plant was highly correlated to exposure concentration (R(2)=0.990). Electron paramagnetic resonance (EPR) analysis revealed that pyrene exposure significantly increased total free radicals in the plants. A strong positive correlation (R(2)=0.956) between O(2)(*-) generation and pyrene contents implied that pyrene exposure induced reactive oxygen species (ROS) and led to oxidative stress in C. demersum. The activities of antioxidant enzymes and the contents of glutathione were determined. Change in the contents of malondialdehyde (MDA) was also studied. Results indicated that the bioaccumulation of pyrene resulted in the changes of the antioxidant defense system and the production of ROS with the oxidative stress, ultimately induced damnification in C. demersum.