Annual Variation of CO₂ Absorption and Release in Caotang River of Three Gorges Reservoir

¹ China Institute of Water Resources and Hydropower Research, 100038, Beijing, China
² State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, 100038, Beijing, China

Abstract

To analyze the annual variation of CO₂ absorption and release in Caotang River of Three Gorges Reservoir, this paper selected six sections from the Yangtze River and Caotang River between July 2017 and June 2018, and monitored CO₂ emission at the water-gas interface using static closed chamber. The results are as follows: during the investigation, the variation rate of CO₂ averaged 0.66-2.05 ppm/Min in Caotang River, and the number was 1.02 ppm/Min and 2.67 ppm/Min in Yangtze River. In November, CO₂ in Caotang River experienced dramatic variation as it was released from the water body to the atmosphere. The highest release rate occurred at the CT02 section, which was up to 42.58ppm/min. From July to October of 2017, most sections of the river absorbed CO₂ without a fixed pattern in space. From January to March of 2018, the absorption and release rate of CO₂ slowed down, with its absolute value between 0.20-2.28 ppm/min. The release or absorption rate of CO₂ from April to June was slightly higher than that from January to March.