乌江梯级水库碳氮耦合的生物地球化学循环

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

以乌江梯级水库及相关河段为研究对象,对溶解CO_2和NO_3^-含量的时空变化特征进行了研究.溶解CO_2平均值为(113.6±105.7)μmol·L^(-1),变化为1.6~934.6μmol·L^(-1);NO_3^-平均值为(163.0±104.9)μmol·L^(-1),变化为0.4~632.0μmol·L^(-1).水库采样点溶解CO_2和NO_3^-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CO_2和NO_3^-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CO_2和NO_3^-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 1.6to 934.6 μmol·L^（-1）.The average of NO3 were（163.0±104.9） μmol·L^（-1）,ranging from 0.4to 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.