<b>Characteristics of greenhouse gas emissions and </b><b>their driving </b><b>environmental </b><b>factors</b><b> in cascade reservoirs in the upper reaches of the Yellow River</b>

In this study, the cascade reservoirs of Longyangxia(LYX), Lijiaxia(LiJX),and Liujiaxia (LiuJX) in the upper reaches of the Yellow River were taken as the research objects. The concentrations and fluxes of CO2 and CH4 at the water‒air interface were measured using the static floating box method and gas chromatography. Moreover, water environmental factors, includingwater temperature, pH, dissolved oxygen,and nutrients,were monitored simultaneously. The spatial and temporal characteristics of greenhouse gas emissions from cascade reservoirs and their correlation with water environmental factors were systematically analyzed. The results show that the concentrations of CO2and CH4in the reservoir area are generally higher than those in the natural river area and decrease gradually along the flow direction. The CO2flux increased along the flow direction, whereasthe CH4flux decreased, indicatingobvious spatial heterogeneity. Water environmental factors such as dissolved organic carbon(DOC), total nitrogen (TN),and total phosphorus(TP) were significantly correlated with greenhouse gas fluxes, and the effectsof DOC on CO2flux wereopposite in different reservoirs, reflecting the difference in the balance between photosynthesis and organic matter degradation.This contrasting trend highlights the distinct pathways of CO₂(dominated by aerobic processes) and CH₄(dominated by anaerobic processes) in the context of cascade development..Cascade development significantly affects greenhouse gas emissions by intercepting nutrients and changing hydrological conditions. This study provides data supportingthe carbon cycle mechanism of high-elevationcascade reservoirs and has important reference value for the low-carbon management of reservoirs.