Effects of environmental factors on the methane and carbon dioxide fluxes at the middle of Three Gorges Reservoir

Abstract

In recent years, scientists have paid special attention to the greenhouse gas emissions of the Three Gorges Reservoir. This study took Fuling to Wanzhou, located at the middle section of the Three Gorges Reservoir, as the research locations. From August 2017 to August 2018, the partial pressure of carbon dioxide (CO2) and methane (CH4) and the flux of CO2 and CH4 at the water–gas interface were studied. Spearman's correlation between the partial pressure and discharge flux of CO2 and CH4 in water and environmental variables was analyzed. The research results showed that the variation of partial pressure and flux was consistent. At different sample locations, there was no statistical difference in CO2 and CH4 fluxes, but under different operating periods, the CO2 and CH4 fluxes were significantly different. The highest values happened during the drainage period as well as the low-water period, respectively. Total organic carbon and total nitrogen were significantly positively correlated, and dissolved oxygen was extremely negatively correlated. The high value of CH4 flux in the middle of the reservoir area was related to the spatial distribution of the sediment and the amount of sediment deposition.