Peroxidation damage and antioxidative capability of Ceratophyllum demersum under

The current article investigated the effects of ammonia nitrogen concentration and pH on peroxidation damage and antioxidative capability of Ceratophyllum demersum. The pH ranges (7 and 9) were carefully controlled to distinguish between the effects of unionized ammonia (NH3) and ionized ammonia ( ). The addition of ammonia significantly decreased chlorophyll a content. Peroxidase and superoxide dismutase activities as well as glutathione content under high ammonia conditions (10 mg N/L) significantly increased at pH 7 but were no different or reduced at pH 9. Catalase activity as well as ascorbic acid and malondialdehyde contents significantly increased under all ammonia treatments at pH 7 and 9. C. demersum suffered from stress at pH 9 under high ammonia conditions. Higher pH in water may induce C. demersum to exhibit more severe physiological responses.