以乌江梯级水库及相关河段为研究对象, 对溶解CO2和NO3− 含量的时空变化特征进行了研究. 溶解CO2平均值为(113.6±105.7) μmol·L−1, 变化为1.6934.6 μmol·L−1; NO3− 平均值为(163.0±104.9) μmol·L−1, 变化为0.4632.0 μmol·L−1. 水库采样点溶解CO2和 NO3− 的含量以及振幅均小于相应河流采样点. 由于来源及影响因素不同, 河流采样点CO2和 NO3−不存在显著性相关. 筑坝建库后, 水库浮游植物生物作用增强, 成为影响物质循环的重要因素. 光合作用和呼吸作用将C和N的生物地球化学循环耦合在一起, 致使水库CO2和 NO3− 表现出显著性相关. 研究结果表明, 梯级水电开发显著改变了原始河流C和N的生物地球化学循环特征.
Concentrations of dissolved CO2 and NO3− were investigated in cascade reservoirs and related river reaches along the Wujiang River to understand temporal and spatial variations. The average of dissolved CO2 were (113.6±105.7) μmol·L−1, ranging from 1.6 to 934.6 μmol·L−1. The average of NO3− were (163.0±104.9) μmol·L−1, ranging from 0.4 to 632.0 μmol·L−1. Averages and amplitudes of dissolved CO2 and NO3− in the reservoirs are less than those in the rivers. Due to different resources and influencing factors, no significant correlation was found between dissolved CO2 and NO3− in rivers. After damming, the activity of phytoplankton was enhanced, and became an important factor controlling material cycle in reservoirs. Photosynthesis and respiration couple C and N biogeochemical cycle, and dissolved CO2 and NO3− in reservoirs were significantly correlated. The results indicate that C and N biogeochemical cycles in the original rivers are changed by cascade hydropower exploitation.
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