河岸带湿地土壤CH4和N2O温度敏感性的纬度和垂直变化规律OA

Methane(CH4)and nitrous oxide(N2O)are the two most important greenhouse gases(GHGs)after carbon dioxide(CO2),and their global warming potentials are 28 and 265 times higher than for CO2.Thus,accurately determining the temperature sensitivity(Q10)for CH4 and N2O emission rates is key for assessing and predicting the feedback relationships between GHG emissions and climate change.The Q10 of CO2 emission has been extensively examined in previous studies,but the Q10 values for CH4 and N2O emissions and their spatial variation remain unclear.Riparian wetlands,located in a transition zone between aquatic and terrestrial ecosystems,are often hot spots of biogeochemical cycling and serve as important sources and sinks of greenhouse gases.In this study,30 representative rivers in the tropical-subtropical and temperate zones in a latitude range of 21.76°-45.08° N across eastern China were selected for research,and we investigated the latitudinal and vertical variations of Q10 for CH4 and N2O emissions from riparian soils,and the driving mechanisms.Soil samples were collected from both shallow(0-20 cm)and deep(40-60 cm)layers of riparian wetlands,and a 56-day soil microcosm incubation experiment was used to determine the emission rates of CH4 and N2O at 15 ℃ and 25 ℃.The Q10 value of CH4 emission(CH4-Q10)increased with increasing latitude and soil depth,but the N2O-Q10 did not change significantly with either latitude or soil depth.Correlation analysis and structural equation modeling(SEM)revealed that environmental factors such as geographic location,climate and soil properties jointly regulated the spatial variability of CH4-Q10.In temperate zone soils,CH4-Q10 was negatively correlated with soil bulk density and positively correlated with total carbon(TC)and the carbon to nitrogen ratio(C/N).In tropical-subtropical soils,CH4-Q10 was positively correlated with pH and negatively correlated with nitrate nitro-gen(NO3--N).The CH4-Q10 in topsoil was weakly influenced by environmental factors,but CH4-Q10 in deep soil was primarily regulated by climatic factors,such as mean annual precipitation.Further,N2O-Q10 was weakly associated with environmental factors.The study confirms that N2O emissions were more sensitive to warming,and the CH4-Q10 in temperate subsoil was the highest,making them a potential key source of CH4 emissions under future climate warming.The findings of this study will improve estimation of greenhouse gas emission potential in the riparian wetlands of China and better predict the potential im-pacts of global warming on GHG emissions.