Study On Carbon Emissions Regularity Of Freshwater Peatlands Under Climate Change

Peatlands are important carbon pools of wetland ecosystems,and they are also important sources of carbon dioxide?CO₂?and methane?CH₄?in the atmosphere.In this study,an in situ observation of the forest peatland in Thuringia,Germany was employed with Fourier transform infrared spectroscopy?FTIR?and carbon and nitrogen isotope technology.Then we discussed the relationship between the greenhouse gases emissions of peat soils and the degree of organic carbon decomposition under natural conditions.At the same time,peat soils from Mer Bleue peatland which was well researched before were employed as simulation experiments in the changes of hydrological and meteorological conditions,and discussed the main factors of greenhouse gases emissions under changing environment.Then we explored the law of greenhouse gas emissions of peat soil at different depths,intend to clarify the impact of changing groundwater level and historical environment on peat soil,so as to assess the important factors affecting greenhouse gases emissions.The results showed that under natural conditions,the CO₂ concentration of peatland generally decreased with depth,while the CH₄ concentration increased with depth.The emissions of CO₂ and CH₄ increased with increasing temperature.CH₄ emission is more affected by temperature than CO₂.Therefore,the emissions of CO₂ and CH₄ will increase with the occurrence of climate warming.The increase in CH₄ emissions was much larger than that of CO₂.At the same time,because the global warming potential of CH₄ is greater than that of CO₂,the greenhouse effect caused by the increasing of CH₄ emissions will also be very strong.The results of incubation experiments showed that the CO₂ emissions increased with the increasing p H values.When the p H value at 5?6,CH₄ emissions reached the maximum.Therefore,it can be inferred that the increasing precipitation will make the peatland flooding time longer.The peat soil with the original p H value of 4 is raised to 5?6,which significantly increases carbon emissions,especially CH₄ emissions,which aggravates climate warming.The experimental results of peat soil cultivation at different depths showed that CO₂ and CH₄emissions were relatively high in 50 cm depth.The main reason could be that this area is an area where the groundwater level fluctuates frequently and is an active zone of the earth's surface biogeochemical process,so soil organic carbon can be easily decomposed to produce greenhouse gases,so when using model methods to account for carbon emissions,we must fully consider the geochemical processes in this critical zone.Although,the low concentration of dissolved organic carbon and the low p H value limited soil organic carbon decomposition,when the environmental conditions change,the area can be transformed into a huge carbon source.In summary,the changes in temperature and precipitation can promote the release of soil organic carbon in forms of CO₂ and CH₄.It is estimated that when the global average surface temperature increases by 1.5?and 2?due to climate warming,the annual peatland CO₂ emissions in peatland increase by several thousands to nearly one hundred thousand tons,while CH₄ emissions increase by several tens to hundreds of thousands.Global wetland CO₂and CH₄ emissions would increase by exceed tens of billions of tons.The change in the p H values of the peat below ground caused by precipitation factors can increase the annual CO₂emissions of the in situ peatland by several thousands to more than twenty thousands tons,and the CH₄ emissions by several thousands to nearly one hundred thousand tons.Global wetland CO₂ emissions would increase by tens of billions to hundreds of billions of tons,and CH₄emissions are tens of billions of tons.