Revealing carbon balance characteristics in a water conveyance-type lake and differences in carbon sources through its connective hydrological channels

Water Conveyance-Type Lake Systems Shift toward Carbon Sources under Regulatory Balanced Water Level Metabolic Processes

“…Since endogenously derived photosynthesis preferentially utilizes “lighter” C, higher δ 13 C-DIC content is indicative of more dominant endogenously derived photosynthesis . When NEP < 6 g O 2 m –2 d –1 , δ 13 C-DIC was positively correlated to NEP and was lower during the high-water-level period (Figure D), which confirms results from our previous study . Endogenously derived photosynthesis was more dominant as NEP increased, while p CO 2 underwent explosive growth at sampling points with higher DIC, which became the active C emission areas (Figure G).…”

“…Among these, the Ganjiang River is the largest of Poyang Lake’s tributaries, accounting for 58.4% of river flow into the lake . Poyang Lake is a typical water conveyance-type lake system, which is connected to large river systems that subsequently flow into the Yangtze River after being regulated and stored . The Poyang Lake basin belongs to a typical subtropical monsoon climate, with a total annual rainfall of approximately 1622 mm, of which rainfall from April to June accounts for 42–53%, , resulting in Poyang Lake’s extensive variation in the interannual inflow.…”

“…42 When NEP < 6 g O 2 m −2 d −1 , δ 13 C-DIC was positively correlated to NEP and was lower during the high-water-level period (Figure 7D), which confirms results from our previous study. 28 Endogenously derived photosynthesis was more dominant as NEP increased, while pCO 2 underwent explosive growth at sampling points with higher DIC, which became the active C emission areas (Figure 7G). Extremely high NEP (>6 O 2 m −2 d −1 ) corresponded to low δ 13 C-DIC and DIC (Figure 7).…”

“…27 Poyang Lake is a typical water conveyance-type lake system, which is connected to large river systems that subsequently flow into the Yangtze River after being regulated and stored. 28 The Poyang Lake basin belongs to a typical subtropical monsoon climate, with a total annual rainfall of approximately 1622 mm, of which rainfall from April to June accounts for 42−53%, 29,30 resulting in Poyang Lake's extensive variation in the interannual inflow. Therefore, as previously defined, 31 the contour line of Poyang Lake is characteristic of a lake during its high-water-level period and a river during its low-water-level period.…”

Future Climate Change Hotspots Under Different 21st Century Warming Scenarios

“…The recent unprecedented rate of global warming will have potentially profound effects on both natural ecosystems and human societies, for example, by promoting natural hazards growth (Kumar & Mishra, 2020; Wahl et al., 2015), accelerating the hydrologic cycle (Giorgi et al., 2019) and carbon cycle (Gao et al., 2021; Lu et al., 2021), reducing food security (Fujimori et al., 2019; Tai et al., 2014), and facilitating the geographic expansion of many infectious diseases (Liang & Gong, 2017; Waits et al., 2018), resulting in serious economic losses and a range of adverse health effects (Dottori et al., 2018; Sun et al., 2019; Surendran Nair et al., 2020; Watts et al., 2020). In late 2015, the 21st Conference of the Parties to the United Nations Framework Convention on Climate Change (UNFCCC) resolved to restrict the increase in global mean surface temperature to well below 2°C above pre‐industrial levels and to pursue efforts to limit this even further, to 1.5°C (UNFCCC, 2015).…”