Rivers and reservoirs are important sources of atmospheric CO2 emissions.In order to investigate the dynamics of CO2 in a river-reservoir continuum,we analyzed the spatial and temporal changes in CO2 concentration and flux and its influencing factors of Pingqiao River,the reservoir inlet,and the Shahe Reservoir in the low-mountain hilly area of southeast-em China.Monthly sampling was conducted in the autumn(September-November)and winter(December-February)of 2022,and headspace equilibrium-gas chromatography and floating chamber-portable greenhouse gas analyzer methods were used to observe the dissolved CO2 concentrations in surface water and CO2 emission flux at the water-air interface,re-spectively.The results showed that CO2 concentrations and fluxes in the Pingqiao River-Shahe Reservoir continuum ranged from 0.034 to 0.415 mmol/L and-7.835 to 4.481 mmol/(m2·h),respectively.Spatially,CO2 concentrations and fluxes at the reservoir inlet were significantly higher than those in the Pingqiao River and the Shahe Reservoir(P＜0.05);seasonally,CO2 concentrations and fluxes were significantly higher in autumn than in winter(P＜0.05).The influencing factors of CO2 dynam-ics varied considerably in different regions of the Pingqiao River-Shahe Reservoir continuum:CO2 concentrations and fluxes in the Pingqiao River were mainly affected by DO and pH,in the reservoir inlet were mainly affected by DO,pH and NH4+-N,and in the Shahe Reservoir were mainly affected by water temperature,DO,pH,Chl-a,PO43--P,TP,DOC and DIC.This study demonstrated strong temporal and spatial heterogeneity of CO2 emissions and influencing factors in river,in-let and reservoir.Therefore,comprehensively considering the characteristics of CO2 dynamics in different water regions of the source-type river-reservoir continuum is conducive to improving the accuracy of regional carbon budget.
关键词
饮用水源地/温室气体/CO2/时空变化/影响因子
Key words
drinking water sources/greenhouse gases/CO2/spatial and temporal variations/impact factors
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