Increased ammonium (NH4-N) concentrations in water bodies have been reported to adversely affect the dominant species of submersed vegetation in meso-eutrophic waters worldwide. However calcareous plants were lowly sensitive to NH4-N toxicity. In order to make clear the function of calcification in the tolerance of calcareous plants to NH4-N stress, we studied the effects of increased HCO3- and additional NH4-N on calcification and utilization of dissolve inorganic carbon (DIC) in Chara vulgaris Linn in a 7-d sub-acute experiment (light:dark 12:12 h) carried out in an open experimental system in lab. Results revealed that calcification was dependent of utilization of dissolve inorganic carbon. Additional HCO3- significantly decreased the increase of pH while additional NH4-N did not. And additional HCO3- significantly improved calcification while NH4-N did in versus in relation to the variation of DIC concentration. However, addition of both HCO3- and NH4-N increased utilization of DIC. This resulted in calcification to utilization of DIC ratio decreased under additional NH4-N condition while increased under additional HCO3- conditions in response to the variation of solution pH. In the present study, external HCO3- decreased the increase of solution pH by increasing calcification, which correspondingly mitigated the toxic effect of high NH4-N. And we argue that the mitigating effect of increased HCO3- on NH4-N toxicity is dependent of plant calcification, and it is a positive feedback mechanism, potentially leading to the dominance of calcareous plants in mesa-eutrophic water bodies. (C) 2013 Elsevier Ltd. All rights reserved.
英文摘要:
Increased ammonium (NH4-N) concentrations in water bodies have been reported to adversely affect the dominant species of submersed vegetation in meso-eutrophic waters worldwide. However calcareous plants were lowly sensitive to NH4-N toxicity.
1.Chinese Acad Sci, Donghu Expt Stn Lake Ecosyst, State Key Lab Freshwater Ecol & Biotechnol China, Inst Hydrobiol, Wuhan 430072, Peoples R China
Recommended Citation:
Wang, Heyun; Ni, Leyi; Xie, Ping.The mitigating effect of calcification-dependent of utilization of inorganic carbon of Chara vulgaris Linn on NH4-N toxicity,CHEMOSPHERE,2013,93(2):373-379
