为探究三峡库区低水位运行期间库尾支流河坝对其上下游水体CO2分压、水气界面扩散通量的影响，于2019年8月对三峡库区库尾典型筑坝支流御临河进行采样研究。原位测定关键理化环境因子，采用顶空平衡法，结合亨利定律和薄边界层理论计算水体CO2分压（pCO2）及水气界面扩散通量（Flux（CO2））。结果表明，库区低水位运行期御临河水体表层pCO2为54.55~336.73 Pa，均值为206.68 Pa，Flux（CO2）为1.65~67.84 mmol/（m2·d），均值为39.01 mmol/（m2·d），表现为大气CO2排放源排放水平显著高于三峡库区中下游支流。御临河受其下游筑坝影响，河坝上游较近河段表现为湖泊型水体（流速v<0.05 m/s），上游较远河段和下游表现为过渡型水体（v=0.05~0.2 m/s）。湖泊型水体pCO2和Flux（CO2）显著低于过渡型水体，且pCO2随水深增加迅速增大。相关性分析及多元逐步回归分析表明，库区低水位运行期御临河pCO2及Flux（CO2）受水温、pH、DO、Chl-a等理化环境指标影响显著，Chl-a是影响pCO2的最主要因素，pCO2是影响Flux（CO2）的最主要因素。
To investigate the impact of damming on CO2 partial pressure and CO2 release from water-air interface in tail tributary of the Three Gorges Reservoir during low water level period, the Yulin River, one of the dam-building tail tributaries of Three Gorges Reservoir was sampled in August 2019. The key physical and chemical environmental factors were measured in situ, the CO2 partial pressure (pCO2) and water-air interface diffusion flux (Flux(CO2)) were calculated by headspace equilibrium method combined with Henry's law and thin boundary layer theory. The results show that the surface water pCO2 of the Yulin River during low water level period is 54.55~336.73 Pa, with an average of 206.68 Pa, the Flux(CO2) is 1.65~67.84 mmol/(m2·d), with an average of 39.01 mmol/(m2·d), which is the source of atmospheric CO2 emission. The emission level of CO2 from the Yulin River is significantly higher than that of the tributaries in the middle and lower reaches of the Three Gorges Reservoir area. The near reach of the upstream of the dam is lake-type's water (velocity <0.05 m/s), while the far reach of the upstream and downstream are transition-type's water (velocity:0.05~0.2 m/s). The pCO2 and Flux(CO2) of lake-type's water are significantly lower than that of transition-type's water, and pCO2 increases rapidly with the increase of water depth. Correlation analysis and multiple stepwise regression analysis show that pCO2 and Flux(CO2) in the Yulin River during low water level period were significantly affected by physical and chemical environmental indexes such as water temperature, pH, DO and Chl-a, and Chl-a is the most important factor affecting pCO2, while pCO2 is the most important factor affecting Flux(CO2).