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Inner Mongolia University (2021)

Diurnal Variation Pattern of Greenhouse Gases at Water-air Interface in an Eutrophic Shallow Lake of Semi-arid Area

张状状

Titre : Diurnal Variation Pattern of Greenhouse Gases at Water-air Interface in an Eutrophic Shallow Lake of Semi-arid Area

Auteur : 张状状

Grade : Master These 2021

Université : Inner Mongolia University

Résumé partiel
Lakes are an important part of the global carbon cycle,among which eutrophic shallow lakes are important objects for studying the carbon cycle of lakes because of their frequent material exchange,high primary productivity,and abundant organic matter.In this paper,the eutrophic meadow shallow lake Ulansuhai in Urad Qianqi,Inner Mongolia Autonomous Region,was selected as the study area.S1 site with Huangtai outbreak and the S2 site without Huangtai outbreak in the submerged vegetation area in the lake were selected,and in situ diurnal monitoring was conducted once a month from April to October 2019(the ice-free period of the lake).The partial pressures of greenhouse gases(pCO2,pCH4)at the surface and bottom layers of the water column were measured by the headspace equilibrium method,and the greenhouse gas fluxes(FCO2,FCH4)at the water-gas interface were measured by the floating chamber method.Then,the diurnal variation patterns of greenhouse gas partial pressures,greenhouse gas fluxes,and the relationships with environmental factors,were analyzed.The main results are as follows.1.Diurnal variation of pCO2 and FCO2 at S1 and S2 sites in the Lake Ulansuhai:The overall variation of surface and bottom pCO2 at S1 site showed decrease gradually after sunrise and reached the minimum value in the afternoon,and then the pCO2gradually increases at night and reached the maximum value before sunrise.By comparing the bottom and surface pCO2,we found that the bottom pCO2 was usually larger than the surface pCO2,and the variation of surface pCO2 within a day was usually larger than that of bottom pCO2.The FCO2 at S1 site was positive during nighttime and was the source of CO2,and the emission rate gradually increased after sunrise and reached the maximum before sunrise,and the emission at S1 site during nighttime accounted for most of the emission throughout the day.During the daytime,the change of FCO2 is that the emission rate gradually decreases after sunrise and the absorption rate gradually increases,and generally reaching the minimum emission rate or the maximum absorption rate in the afternoon.The pCO2 in the surface and bottom layer at S2 site showed that a decreasing trend during the day and night,but the change during the day is greater than during the night,and there is a small difference between pCO2 in the surface layer and pCO2 in the bottom layer during the day.The pCO2 in the surface layer and bottom layer at S2 site have the same change pattern during the daytime and nighttime

Mots clés : partial of greenhouse gases ;flux of greenhouse gases ;water-air interface ;eutrophication;Huangtai algae ;submerged aquatic vegetation ;lake Ulansuhai ;

Présentation (CNKI)

Page publiée le 1er novembre 2021