Greenhouse Gas Emission Characteristics And Influencing Factors Of Water Bodies In The Zhongtianshe River Basin In The Tianmu Lake Area

At present,global warming has become a increasingly serious environmental change problem.Increasingly human activities affect the balance of carbon and nitrogen elements in the water environment,resulting in the general supersaturation of CO₂,CH₄ and N₂O in the surface water,making the water ecosystem an important source of greenhouse gases.Therefore,this study takes Zhongtianshe River Basin in Tianmu Lake area as an example,selects representative sample points of different water body types,uses a variety of greenhouse gas emission monitoring methods,and analyzes the greenhouse gas emission characteristics of Zhongtianshe River Basin in2019 through a one-year field greenhouse gas emission monitoring activity in monthly units,explored the impact of various environmental factors on greenhouse gas emissions and obtained the following conclusions:?1?Through the comparative study of static chamber method and diffusion-model method,it is concluded that there is a certain gap between the flux results obtained by different water body greenhouse gas monitoring methods,but the two methods are significantly correlated.In the Zhongtianshe River Basin,for the three gases N₂O,CH₄ and CO₂,the model CC98,model CW03a,and model RC01,respectively,are the closest to the flux results of static chamber method.?2?Based on the 24-hour continuous monitoring of gas emissions in spring,summer and autumn,it is found that there is no obvious diurnal variation of N₂O and CH₄ fluxes in Zhongtianshe River Basin,and the river is the source of N₂O and CH₄in all three seasons.The CO₂ flux showed a clear diurnal variation pattern as a single-peak trend,rising at night and falling during the day,and the overall performance was in the spring and autumn as sinks and in summer as the source.The representative sampling periods closest to the mean values of N₂O,CH₄ and CO₂exchange fluxes in the whole day are concentrated in the daytime from 10:00 to 12:00in each season,and due to the influence of solar radiation,different collection periods in a day will cause a large gap in CO₂ exchange fluxes.?3?According to the annual monthly gas emissions monitoring,on the time scale,the N₂O and CH₄ exchange fluxes in the Zhongtianshe River Basin are generally higher in summer and lower in winter.The basin is the source of N₂O and CH₄in all months of the year,which is mainly regulated by the positive effect of water temperature.The flux of CO₂ exchange is lower in the first half of the year and higher in the second half of the year.The source sink conversion is realized with the seasonal change,which is mainly controlled by the side effects of p H and dissolved oxygen.?4?According to the gas emission monitoring of different water bodies samples,the results of N₂O,CH₄ and CO₂fluxes in ponds are greater than those in rivers at the spatial scale.For river samples,the gas exchange fluxes increase gradually from upstream to downstream,and the increase of organic matter and nutrients caused by human activities promotes the emission of greenhouse gases.?5?The GWP?Global Warming Potential?of rivers in the Zhongtianshe River Basin is 238.63 CO₂ m^-2 a^-1,of which the GWP of N₂O is 41.62 CO₂ m^-2 a^-1 and the GWP of CH₄ is CO₂ m^-2 a^-1,CO₂ is 185.99 CO₂ m^-2 a^-1;the GWP of the pond water is1834.27 CO₂ m^-2 a^-1,of which the GWP of N₂O is 184.94 CO₂ m^-2 a^-1,the GWP of CH₄ is 24.07 CO₂ m^-2 a^-1,the GWP of CO₂ is 1625.26 CO₂ m^-2 a^-1.Compared with the research results of other water bodies that also belong to the subtropical region of China,in Zhongtianshe River Basin,the GWP of rivers is lower than other studies,while the GWP of ponds is higher than other studies.