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

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.