关键词: 碳排放通量;温室气体;城市化;城市河流;碳达峰;碳中和;

Abstract: The intensification of human activities caused by urbanization not only breaks the carbon cycle balance of the river systems, but also increases the carbon emission flux of river systems, which has a negative impact on global carbon emission reduction.Mastering the carbon emission characteristics and the influencing factors of urban rivers in the background of 'double carbon'(carbon peak and carbon neutrality)is helpful to formulating a reasonable strategy for watershed ecological management(restoration),and to ensuring the sustainable development of urban ecosystems.This paper discussed the impact of urbanization on carbon emissions in rivers, summarized the key influencing factors of urban river carbon emissions, and proposed the future direction of research in this field.The results showed that the carbon emission fluxes of urban rivers were significantly higher than those of natural rivers with less human disturbance, and according to the urbanization disturbance on river systems, the carbon emission influencing factors were categorized into four major types: water environment factor, hydrological characteristic factor, meteorological factor, and seasonal factor.Among water environment factors, the water temperature was positively correlated with carbon emission, DO and pH were negatively correlated, and the algal dominated metabolic modes in river systems were different due to the different nutrient load of nutrient salts, so the carbon emission from algal was diverse.Among the hydrological factors, high flow velocity(within a certain range)would promote carbon emission, while changes in flow and water level were mostly indirectly influenced by water environmental factors and showed uncertainty in carbon emission.Among meteorological factors, high wind speed would promote carbon emissions, while air pressure was negatively correlated with it.In the study of seasonal factors, it was generally believed that carbon emission was higher in autumn, moderate in summer and winter, and lower in spring, but it was also possible that the temperature difference of days and nights was higher in summer, which resulted in higher carbon emission in summer.The results of this study can provide a scientific basis for the ecological governance(restoration)of urban rivers in the context of double carbon.

Key words: carbon emission flux; greenhouse gases; urbanization; urban rivers; carbon peak; carbon neutrality;