Study On The Seasonal Regularity And Influencing Factors Of Greenhouse Gas Emission Of Typical Wetland In Poyang Lake

Wetland ecosystem is known as the planet's lungs and it is an important part of the global carbon cycle.Wetland systems are also the largest natural source of global greenhouse gases,under the background of global warming,the high collection rate and high decomposition efficiency of carbon in wetland ecosystems are highly concerned by experts at home and abroad.Poyang Lake as the largest freshwater lake in China has unique hydrological features and it also has the largest wetland system in the country and its scientific research value can not be underestimated.The methods and theories for the study of soil greenhouse gas emissions from the Poyang Lake Wetland ecosystem have gradually matured,however,there are still gaps in the research on the ability and influencing factors of greenhouse gas production in Poyang Lake wetland.In order to explore the seasonal emission of CH4 and CO2 in the typical wetland of Poyang Lake and the effect of carbon,nitrogen and phosphorus on its production capacity and deepen understanding of the mechanism of greenhouse gas production in soil,from September 2016 to June 2017,the static box method to study was used to the emission flux of CH4 and CO2 from the Carex grass belt of Xingzi beach during the retreating period of Poyang Lake.At the same time to collect soil samples for laboratory incubation experiments,the effect of different nutrient combinations with carbon,nitrogen,and phosphorus on the ability of CH4 and CO2 production was explored in soils of three transect bands of artemisia halodendron and medicago sativa to assess the impact of human activities on wetlands.The experimental results are as follows:?1?Emissions of CH4 and CO2 from Xingzi beach of Poyang Lake have obvious seasonal changes,CH4 and CO2 emissions in June are highest 0.203 mg·m^-2·h^-1 and 6013.74mg·m^-2·h^-1;in September and April,the methane emission flux is 0.094 mg·m^-2·h^-1 and0.086 mg·m^-2·h^-1,CO₂ emission flux is 5844.93 mg·m^-2·h^-1 and 4642.85 mg·m^-2·h^-1;Minimum CH4 and CO2 emissions in winter is 0.019 mg·m^-2·h^-1 and 1057.66 mg·m^-2·h^-1.CH4 and CO2 emissions are positively correlated with temperature,Linear growth with temperature growth,the influence of Poyang Lake water level on CH4 and CO2 emission flux should not be ignored,however,the way in which the flux increases with the water level is more complicated.?2?Different combinations of glucose,potassium nitrate and potassium dihydrogen phosphate in different ratios under anaerobic conditions have different effects on the release potential of CH4?CO2 in the Anthraquinone and Artemisia ordosica zones.Only adding glucose and potassium dihydrogen phosphate promotes soil production of CH4 and CO2,the addition of glucose and potassium nitrate inhibits the ability to produce soil methane,and the methane accumulation in this experimental group is the lowest,however,for the CO2 release,the release of CO2 in the experimental group with glucose and potassium nitrate was higher than that in the control group.In addition,the release of methane was also inhibited in the experimental group where all three nutrients were added,mainly due to the inhibitory effect of nitrate on the release of methane.However,the three nutrients were added to promote the production of CO2,and their CO2 production was higher than the other four experimental groups.?3?In the aerobic environment,the release of methane from two transects is irregular,and the accumulation and release of methane are reduced in the Rhizoma and Chrysosporium,mainly due to the addition of organics under aerobic conditions will promote the absorption of methane in soil.The release of CO2 from the two transects is consistent,and the addition of nutrients will promote CO2 production and release.The order of CO2 release in the five experimental groups was Add glucose and potassium dihydrogen phosphate experimental group>Add glucose,potassium nitrate and potassium dihydrogen phosphate experimental group>Add glucose experimental group>Add glucose,potassium nitrate experimental group>Blank control group.The order of CO2 emission in the five experimental groups of artemisia halodendron was add glucose,potassium nitrate and potassium dihydrogen phosphate experimental group>add glucose and potassium dihydrogen phosphate experimental group>add glucose,potassium nitrate experimental group>add glucose experimental group>blank control group.?4?Whether under anaerobic or aerobic conditions,because of the different physical and chemical properties of the soil in the two transects,the release amount of CH4 and CO2 in the anthraquinones is higher than that of the wormwood,the water content and nutrient content of the earthworm belt is high with the garland chrysanthemum belt.