Effects Of Hexadecane On Vegetative Growth, Content Of Photosynthetic Pigments And Antioxidant Enzyme Systems In Salvinia Natans (L.) All

With the rapid development of global economy, oil and grease have become one of the most important environmental pollutants. So it is urgent for us to investigate their effects on the ecosystems. In this study, hexadecane, one of the main compounds of oil and grease, was used as a pollutant to treat Salvinia natans (L.) All. for testing its effects on the floating-leaves plant from morphological and physiological perspectives. The major findings are summarized as follow:1. Hexadecane pollution had serious effects on the growth of floating leaves, buds, stems and submerged leaves of S. natans. Hexadecane could significantly reduce the number of floating leaves, total leaf area, stem length, number of axillary buds and length of submerged leaves, and then inhibit the accumulation of biomass of S. natans. The inhibitory effect was more significant with the treatment time and concentration of hexadecane. When its concentration was more than1Omg/L, hexadecane could even lead to death of S. natans.2. Hexadecane could accelerate the floating leaves of S. natans to turn yellow or decomposed. At the end of the experiment, the floating leaves of S. natans in all groups became turning yellow except control, and this effect was correlated closely with the concentration of hexadecane and the exposure time.3. The presence of hexadecane could inhibit the synthesis of chlorophyll in S. natans. In the earlier stage of experiment, hexadecane had a significant impact on the content of chlorophyll in S. natans. When the concentration was higher than20mg/L, hexadecane would significantly reduce the content of chlorophyll; in the later stage, when the concentration was≥160mg/L, the hexadecane would show inhibitory effect on the content of chlorophyll in S. natans.4. Hexadecane pollution also had a profound impact on the antioxidant enzyme systems of S. natans. In the earlier stage of the experiment, low concentrations of hexadecane could increase the activity of peroxidase (POD) of S. natans, while had no effect on the superoxide dismutase (SOD) and catalase (CAT) of S. natans; But in the later stage, high concentrations of hexadecane could make the activities of all the three antioxidant enzymes decreased. The antioxidant enzyme system of S. natans could be seriously hurt when exposure to high concentrations of hexadecane environment prolong. 5. Hexadecane could affect the content of malondialdehyde (MDA) in S. natans. In the earlier stage, hexadecane could induce the MDA to synthesis rapidly, and the higher the concentration was, the more content of MDA would be; in the later stage, the content of MDA showed a trend of downward.6. Hexadecane pollution could also affect the content of soluble protein of S. natans. In the earlier stage, hexadecane, which was among certain range of concentration, could increase the content of soluble protein in S. natans; in the later stage, high concentrations of hexadecane could significantly inhibit the content of soluble protein in S. natans.7. Hexadecane had no effect on the pH value and conductivity of water.From the results we know that hexadecane could influence the growth of S. natans through affecting the main photosynthetic organs-floating leaves, hexadecane could also change the antioxidative enzyme activities, the content of MDA and soluble protein of S. natans. S. natans showed high sensitivity to hexadecane both in morphology and physiology, and we can indicate that S. natans will show more potential of application in monitoring and controlling hexadecane pollution even some oil and grease pollution.