三峡不同蓄水阶段澎溪河CO2通量的初步研究

为掌握不同蓄水阶段温室气体通量强度,揭示水生生态系统在水库蓄水后的重建过程,选择2004年(蓄水后第1年)、2008年(蓄水后第5年)为典型年,结合同期主要环境参量,比较研究了三峡典型支流澎溪河回水区水柱表层CO₂分压p(CO₂)及其扩散通量F_CO2特征。研究发现,2004年澎溪河双江大桥处水柱表层p(CO₂)、F_CO2年均值分别为(101.9±7.5)Pa、(13.99±1.58)mmol/(m²·d),2008年相应为(129.1±16.4)Pa、(19.92±3.55)mmol/(m²·d)。水位上升淹没土地带来更多有机质降解,可能引起了p(CO₂)和F_CO2的总体升高;蓄水过程水域生态系统逐渐完善,浮游植物生长对p(CO₂)和F_CO2的影响逐渐显现。

Air-water CO2 flux in the Pengxi River under different impounding stages of the Three Gorges Reservoir

To discuss the greenhouse gas flux at water-air interface in different impoundment stages and to elucidate the reconstruction of aquatic ecosystem after impoundment, partial pressure of CO₂ p(CO₂) at water surface and CO₂ diffusive flux F_CO2 were compared between 2004 (the 1st year after impoundment) and 2008 (the 5th year after impoundment) in the backwater area of the Pengxi River (PBA), a typical tributary of the Yangtze River in the Three Gorges Reservoir. It was found that annual p(CO₂) and F_CO2 in 2004 were (101.9±7.5)Pa and (13.99±1.58)mmol/(m²·d) respectively, and the values in 2008 were (129.1±16.4)Pa and (19.92±3.55)mmol/(m²·d). Impoundment of the reservoir created more organic carbon to be degraded in the new flooded land. This increased the level of p(CO₂) and F_CO2 in the PBA from 2004 to 2008. However, with the reconstruction of aquatic ecosystem, increase in primary production and growth of phytoplankton regulate the seasonal variations of p(CO₂) and F_CO2 obviously.