The Mechanisms Controlling the CO2 Outgassing of a Karst Spring–River–Lake Continuum: Evidence from Baotuquan Spring Drainage Area, Jinan City, Northern China

The significance of CO2 emissions at the water–air interface from inland water bodies in global carbon cycle has been recognized and is being studied more more. Although it important to accurately assess emission flux a catchment, little research carried out investigate spatio-temporal variations view continuum. Here, we systematically compared differences control factors degassing across spring–river–lake continuum discharge area Baotuquan Spring July 2017, which typical temperate karst spring Jinan city, northern China, using hydrogeochemical parameters, stable isotope values, flux. Affected by pCO2 concentration gradient between ambient air, showed high (166.19 ± 91.91 mmol/(m2 d)). After outlet, spring-fed river slight increase (181.05 155.61 d)) due flow rate disturbance. was significantly reduced “blockage” lake, promoted survival reproduction phytoplankton provided favorable conditions for aquatic plant photosynthesis, increasing plankton biomass lake 3383.79 × 104/L. In addition, significant decrease dissolved inorganic (DIC) δ13CDIC values also indicated that photosynthesis lake’s plants resulted concentration, thus limiting amount off-gassing (90.56 55.03