Led by the team of Xinghui Xia and Shaoda Liu (School of Environment, Beijing Normal University), this study integrates existing monitoring data to discuss the characteristics of greenhouse gas (GHG) emissions from reservoirs in the Yellow River Basin. while CO 2 emission flux from reservoirs is lower than that from river channels, the emission fluxes of CH 4 and N 2 O are 1.9 times and 10 times those from rivers, respectively, indicating that the emission of CH 4 and N 2 O is significantly enhanced in reservoirs. Compared to the reservoirs in humid climate, reservoirs in the Yellow River Basin exhibit relatively lower emissions of CO 2 and CH 4 due to lower organic matter concentrations, but significantly higher N 2 O emissions due to higher nitrogen loads.
As influenced by substrate concentrations, water bodies with higher concentrations of dissolved CO 2 and CH 4 are predominantly found in smaller reservoirs situated in the middle-to-lower reach area, where soil organic matter content is higher and exogenous organic carbon inputs to reservoir are higher compared to upstream areas. Those with higher concentrations of dissolved N 2 O are distributed in the middle-to-lower reaches of the main stem, where they are located in areas with dense population, intensive agriculture, and industrial activities, contributing to heightened nutrient levels in the water.
Compared with the Yellow River channel, reservoirs are weaker sources of CO 2 emissions, and they even act as carbon sinks. However, the emission fluxes of CH 4 and N 2 O are 1.9 times and 10 times those from rivers. In contrast to flowing water bodies, the stagnant water in reservoirs provides a favorable environment for life activities of planktonic plants and microorganisms. Primary producers such as algae utilize DIC to synthesize organic matter, resulting in lower CO 2 and higher CH 4 emissions than rivers. Concurrently, the increase in surface dissolved O 2 level favors the generation and emission of N 2 O through nitrification reactions.
Monte Carlo simulations for 237 reservoirs in the Yellow River Basin showed that the median CO 2 emission for the 237 reservoirs in the Yellow River Basin is 41.57 Gmol C yr -1 , the median CH 4 emission is 0.52 Gmol C yr -1 , the median N 2 O emission is 0.041 Gmol N yr -1 . The emission of three GHGs accounts for 1.6%, 0.05%, and 1.9% of the global reservoir emission. Multiplying the flux by the 100-year global warming potential of each gas, the total GHG emission from reservoirs in the Yellow River Basin amount to 3.05 Tg CO 2 -eq yr -1 , approximately 0.39% of the emission from global reservoirs. The land area of the Yellow River Basin accounts for approximately 0.53% of the global land area, indicating that the GHG emissions from reservoirs in the Yellow River Basin are slightly lower than the global average.
Huang S, Zhang P, Zheng W, Zhang J, Li Y, Wang Y, Jiang E, Liu S, Xia X. 2024. Characteristics and influencing factors of greenhouse gas emissions from reservoirs in the Yellow River Basin: A meta-analysis. Science China Earth Sciences, 67(7): 2210–2225, https://doi.org/10.1007/s11430-023-1307-x
Science China Earth Sciences