骆马湖水质对菹草不同生长期的响应研究

采用原位观测手段研究了骆马湖菹草生长区水质与菹草不同生长期的响应关系。结果表明:指数生长期和石芽生成期,水体中的pH值、ORP值和DO质量浓度升高,COD质量浓度降低;植株衰亡期则相反,菹草腐烂导致有草区的水体TP质量浓度升高,但是由于反硝化作用,水体中TN与硝氮质量浓度反而下降。菹草在生长过程中直接吸收水体中的硝氮,对氨氮的去除则为间接作用,此时水体中的氮以硝氮为主;当菹草衰亡时,氨氮成为水体中氮的主要存在形态。菹草密度是影响水体各形态氮浓度的重要因素,在菹草生长时,菹草密度与TN和硝氮质量浓度显著负相关(P 0.01);当菹草衰亡时,与菹草稀疏区相比,菹草密集区TN和硝氮质量浓度更低,而氨氮质量浓度更高。指数生长期,骆马湖最优菹草密度为83.75 g/m~3。

Response of water quality to different growth periods of Potamogeton crispus in Luoma Lake

The response of water quality to different growth periods of Potamogeton crispus was studied by in situ observation. The results show that the pH and ORP values and mass concentration of DO increase and the mass concentration of COD decreases during exponential growth period and stone bud formation period. On the contrary, in the period of plant decay, the mass concentration of TP increases due to the decay of Potamogeton crispus, but the mass concentration of TN and nitrate nitrogen decreases due to denitrification. In the process of growth, Potamogeton crispus absorbs nitrate nitrogen directly, but removes ammonia nitrogen indirectly. At this time, nitrate nitrogen is the main nitrogen in water. Ammonia nitrogen becomes the main form of nitrogen in water when Potamogeton crispus decay. The density of Potamogeton crispus is an important factor affecting the concentration of different nitrogen forms in water. The density of Potamogeton crispus is negatively correlated with the concentration of TN and nitrate nitrogen(P < 0. 01)during the growth of Potamogeton crispus. When the Potamogeton crispus decays, the mass concentration of TN and nitrate nitrogen in the Potamogeton crispus intensive area is lower than that in the sparse area, while the mass concentration of ammonia nitrogen was higher. During the exponential growth period, the optimum density of Potamogeton crispus in Luoma Lake is 83.75g/m³.