| A systematic study on the cell structures and the physiological and biochemical characteristics of aquatic plants such as Pistia stratiotes L, Lemna paucicostata L, Azolla imbricata (Rexb.) Nakai, Hydrilla varticillata and Spirogyra suffered from two surfactants linear alkylethoxylate (AE) and linear alkylbenzene sulfonate (LAS) was carried out in this paper. And preliminary studies of selection of bacterial strains that could biodegrade AE and LAS, identification of the strains and efficiency of biodegradation were conducted also in this paper. This study filled up the blank of relevant research in environmental biology, and laid a reliable foundation for the further study of the effects of surfactants on the eco-environment, hence it has an important scientific value.1. The damages of surfactants AE or LAS to the structure of aquatic plantsIt was observed that the damages of the cell structures of experimental plants Spirogyra, Pistia stratiotes L and Hydrilla varticillata due to pollution of surfactant LAS or AE with microscope Olympus or transmission electron microscopy H600. The results were follows:(1) Damaged symptoms of Spirogyra cells: In AE polluted environment, chlorophyll carrier of Spirogyra cells disintegrated and spread among the whole cell. The protein bodies disintegrated gradually, and the outer layer of Spirogyra cell walls was dissolved and disappeared, so it was very easy for Spirogyra to break into fragments. Gaps between the plasma membrane and the cell wall enlarged, because the plasma membrane separated from the cell wall. In LAS polluted environment, the damaged symptoms were distinctly difference. The regular spiral of chlorophyll carrier was disturbed and assembled. The protein bodies disintegrated gradually, and the plasma membrane folded and separated from the cell wall, and a large gap could be seen. And the outer layer of the cells was dissolved and disappeared.(2) Damaged symptoms of Hydrilla varticillata cells: In AE polluted environment, the circular movement of the plasma stopped. Chloroplasts deformed and disintegrated gradually, and gas passages disappeared. In the environment with high concentrations of LAS, chloroplasts assembled, the circular movement of the plasma stopped, and gas passages disappeared.(3) Damaged symptoms of Pistia stratiotes L cells: As for Pistia stratiotes L cells,after treated with AE, a distinct damaged symptom appeared in the cells' ultra-structural. The plasma membrane disintegrated gradually, chromatin condensed, electronic density increased, and the damaged chromatin disintegrated gradually. Vacuole membrane broke and was filled with cytoplasm; the chloroplasts expanded and their membranes spoiled with the increase of damage degree, and all the internal material dispersed in the cytoplasm. Mitochondria changed to vacancy because its internal structure disintegrated. Treated with LAS, the leaf tissue of Pistia stratiotes L was damaged distinctly. There were large gaps between the cytoplasm and the cell wall with the cell membrane sinking and separating from the cell wall and disintegrated partly. Many vacancies appeared in the plasma when cytoplasm disintegrated gradually, and vacuoles enlarged. Chloroplasts were damaged seriously with their shape deforming and disintegrating gradually. Meanwhile, it was observed that the leaves of Pistia stratiotes L lost their color and died gradually with increase of the treatment time.(4) According to the damaged symptoms of Spirogyra, Hydrilla varticillata and Pistia stratiotes L, we can conclude that aquatic plant cells suffer from AE or LAS are different. For AE, "dissolution" is the main cause; but for LAS, the changes in shape of protein due to the charges carried by LAS is another main cause, besides dissolution.2. Effects of surfactants on the physiological and biochemical characteristics of aquatic plantsA systematic study on the changes of the physiological and biochemical indices of aquatic plant tissues, such as surperoxide dismutase (SOD), catalase (CAT), peroxid...
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