乌江梯级水库碳氮耦合的生物地球化学循环

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.

Carbon and nitrogen coupled biogeochemical cycle in cascade reservoirs of the Wujiang River

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.