Physiological Responses of Potamogeton crispus to Different Levels of Ammonia Nitrogen in Constructed Wetland
2016
Yin, Xiaole | Zhang, Jian | Guo, Yeye | Fan, Jinlin | Hu, Zhen
The stress tolerance of wetland plants is crucial for their appropriate application in constructed wetland (CW). Ammonia, one of the major pollutants in wastewater, is nutrition for plants at low concentrations but could be toxic at excess concentrations. This study aimed to investigate the effect of external ammonia at different concentrations (0, 1, 2, 4, 8, 10 mg L⁻¹) to a specific submerged plant Potamogeton crispus (P. crispus), which has been used widely in CW. Results showed that the threshold value of ammonia for P. crispus was 4 mg L⁻¹, under which no obvious variations from the control group were detected in all associated observations. When ammonia concentration exceeded 4 mg L⁻¹, plants displayed significant increase in lipid peroxidation product contents (MDA, O₂ ⁻ and H₂O₂), antioxidant enzyme activities (T-SOD, POD, and CAT), and a corresponding increase in the percentages of electrolyte leakage. However, external ammonia only had slight effect on the chlorophyll synthesis of P. crispus under the studied concentration range. Excess ammonia exposure (≥4 mg L⁻¹) could affect the physiological responses of P. crispus, by inducing oxidative stress and by limitedly altering permeability of cell membrane and plant photosynthesis. The results of this study supplied useful information for the aquatic vegetation collocation in CW design, and it is suggested to take proper application of P. crispus in CW when treating eutrophication or other relatively heavily polluted water.
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