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In-situ measurement on air-water flux of CH_(4),CO_(2) and their carbon stable isotope in lakes of northeast Tibetan Plateau

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Advances in Climate Change Research 2022年第2期13卷 279-289页

作者： Lei WANG Cun-De XIAO Zhi-Heng DU Damien T.MAHER Jing-Feng LIU Zhi-Qiang WEI state key laboratory of earth surface processes and resource ecology Beijing Normal UniversityBeijing 100875China state key laboratory of Cryospheric Science Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Southern Cross Geoscience Southern Cross UniversityLismoreNSW 2480Australia College of Geography and Environmental Science Northwest Normal UniversityLanzhou 730070China zhuhai branch of state key laboratory of earth surface process and resource ecology Beijing Normal UniversityZhuhai 519087China

Inland waters are important sources of greenhouse gases(GHGs)to the atmosphere that may partially offset the terrestrial carbon ***,GHG emissions from high altitude saline lakes on the Tibetan Plateau are currently poorly *** this study,we measured methane(CH_(4))and carbon dioxide(CO_(2))concentrations and their carbon stable isotope(δ13C),and calculated diffusive water-to-air fluxes from two saline high-altitude lakes,Qinghai Lake and Hala Lake,located in northeast Tibetan Plateau in October *** two lakes were mostly supersaturated in CH_(4)(89.8%-4623.9%sat)and acted as sources of CH_(4) to the ***,more than 96%investigated area of Qinghai Lake and all investigated area of Hala Lake was a sink of CO_(2).The average diffusive fluxes of CH_(4) and CO_(2) in the surface waters of Qinghai Lake were 34.51μmol m−2 d−1 and−1.29 mmol m−2 d−1,while diffusive fluxes of CH_(4) and CO_(2) in Hala Lake averaged 5.48μmol m−2 d−1 and−5.24 mmol m−2 d−1,***(Sal),fluorescent dissolved organic matter(fDOM),temperature(Temp)and dissolved oxygen(DO)are key factors for diffusive CH_(4) and CO_(2) flux in Qinghai Lake and Hala ***_(4) diffusive fluxes across water-air interface from Qinghai Lake and Hala Lake were found to be significantly lower than other freshwater lakes,likely due to their saline nature.A simple isotope mixing model(Miller-Tans plots)revealed a distinctly different isotopic source values of CO_(2) and CH_(4) in Qinghai Lake and Hala *** CH_(4) production pathway of Qinghai Lake was mainly by the acetate fermentation,while that of Hala Lake was mainly by the CO_(2) *** results show that the continuous measurement can help capture the spatial variability of GHGs fluxes in saline lakes.

关键词： Greenhouse gas Air-water flux Carbon stable isotope Tibetan Plateau Saline lakes

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Method for land cover classification accuracy assessment considering edges

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Science China earth Sciences 2016年第12期59卷 2318-2327页

作者： LIU Meng CAO Xin LI Yang CHEN Jin CHEN XueHong state key laboratory of earth surface processes and resource ecology Beijing Normal University College of Global Change and earth System Science Beijing Normal University

Land cover, as the direct description of the earth surface, has close relationships to the circle of global substances and energy, climate change, and economic activities of human society. The acquisition of land cover products is usually based on image classification. The accuracy of image classification is highly important to the monitoring and investigation of global environment as well as in decision-making support. Thus, classification accuracy assessment of land cover products is an important procedure. Given that many mixed pixels are located in between different classes, the accuracy of edge pixels tend to be lower than that of interior pixels. This scenario leads to the increment of heterogeneity to the classification accuracy of each class and to the increase of uncertainty of accuracy assessment. This study presents a method named stratified sampling considering edges(SSCE) based on traditional stratified sampling(SS) to optimize the process of classification accuracy assessment. Theoretical derivations and experimental results indicate that SSCE has high stability and accuracy on the estimation of overall accuracy and kappa. SSCE has high accuracy on estimating classification accuracy when only a few sampling points exist. SSCE needs less sampling points than SS under the same tolerance of error. The higher the difference on accuracy is and the more equal the areas between edge regions and interior regions are, the more accurate SSCE is on accuracy assessment. In a word, SSCE costs minimal sampling points. It also has high accuracy and stability on the assessment of land cover classification accuracy.

关键词： Land cover Classification accuracy assessment Stratified sampling Edges regions Interior regions

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Influence of the carbon cycle on the attribution of responsibility for climate change

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Chinese Science Bulletin 2014年第15期59卷 2356-2362页

作者： Ting Wei Wenjie Dong Wenping Yuan Xiaodong Yan Yan Guo state key laboratory for earth surface process and resource ecology Beijing Normal University

The carbon cycle is one of the fundamental climate change *** long-term evolution largely affects the amplitude and trend of human-induced climate change,as well as the formulation and implementation of emission reduction policy and technology for stabilizing the atmospheric *** earth system models incorporating the global carbon cycle,the Community earth System Model and the Beijing Normal University-earth System Model,were used to investigate the effect of the carbon cycle on the attribution of the historical responsibility for climate *** simulations show that when compared with the criterion based on cumulative emissions,the developed(developing)countries’responsibility is reduced(increased)by 6%–10%using atmospheric CO2concentration as the *** discrepancy is attributed to the fact that the developed world contributed approximately61%–68%(61%–64%)to the change in global oceanic(terrestrial)carbon sequestration for the period from 1850 to2005,whereas the developing world contributed approximately 32%–49%(36%–39%).Under a developed world emissions scenario,the relatively larger uptake of global carbon sinks reduced the developed countries’responsibility for carbon emissions but increased their responsibility for global ocean acidification(68%).In addition,the large emissions from the developed world reduced the efficiency of the global carbon sinks,which may affect the long-term carbon sequestration and exacerbate global warming in the ***,it is necessary to further consider the interaction between carbon emissions and the carbon cycle when formulating emission reduction policy.

关键词：全球碳循环责任归属气候变化碳排放量 CO2浓度发达国家地球系统北京师范大学

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Carbon Reduction Policies: A Regional Comparison of Their Contributions to CO_2 Abatement in Six Carbon Trading Pilot Schemes in China

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Atmospheric and Oceanic Science Letters 2015年第4期8卷 233-237页

作者： XIU Jin-Feng CHOU Jie-Ming DONG Wen-Jie YANG Zhi-Yong DAI Ru-Feng state key laboratory of earth surface processes and resource ecology Beijing Normal University Future earth Research Institute Beijing Normal University Zhuhai

The contributions of carbon reduction policies were evaluated and compared for six carbon trading pilot schemes in China, in four municipalities(Beijing, Shanghai, Tianjin, and Chongqing) and two provinces(Guangdong and Hubei). The carbon emissions accounting method of the Intergovernmental Panel on Climate Change was used to calculate the actual CO2 and the support vector machine model was used to predict CO2. Chinese carbon reduction policies abated CO2 in the six carbon trading pilot schemes after the comprehensive policies came into force. However, the contribution of policies to CO2 abatement varied among regions, and the effect of carbon reduction policy on municipality pilot schemes was greater than on provincial pilot schemes. The largest contribution of carbon reduction policy to CO2 abatement was 28.3%, for the pilot carbon trading scheme in Beijing, and the smallest contribution was 3.7%, for that in Hubei. It is crucial to consider "carbon leakage" and a carbon trading linking program in order to evaluate the effects of carbon reduction policies.

关键词： CO2 abatement carbon trading pilot scheme support vector machine reduction contribution

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The impact of geomorphology of marsh creeks on fish assemblage in Changjiang River estuary

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Chinese Journal of Oceanology and Limnology 2014年第2期32卷 469-479页

作者：金斌松许旺郭立陈家宽傅萃长 Center for Watershed ecology Institute of Life Science and Key Laboratory of Poyang Lake Environment and Resource UtilizationMinistry of EducationNanchang University Ministry of Education key laboratory for Biodiversity Science and Ecological Engineering Institute of Biodiversity ScienceFudan University state key laboratory of earth surface process and resource ecology Beijing Normal University

Tidal marshes are an important habitat and nursery area for fi *** the past few decades,rapid economic development in the coastal areas of China has led to the interruption and destruction of an increasing number of tidal *** growing interest in tidal marsh restoration has increased the need to understand the relationship between geomorphological features and fi sh assemblages in the design of marsh restoration *** studied temporal variations in,and the effects of creek geomorphological features on,the estuarine tidal creek fi sh *** modifi ed channel nets,we sampled fi sh monthly from March 2007 to February 2008 from seven tidal creeks along an intertidal channel system in Chongming Dongtan National Nature *** creek geomorphological variables were measured or derived to characterize intertidal creek geomorphological *** Gobiidae,with 10 species,was the most speciesrich *** most abundant fi sh species were Liza affi nis,Chelon haematocheilus,and Lateolabrax *** fi sh community was dominated by juvenile marine transients,which comprised about 80% of the total *** highest abundance of fi sh occurred in June and July,and the highest biomass occurred in *** redundancy analyses demonstrated that depth,steepness,cross-sectional area,and volume signifi cantly affected the fi sh species *** nis favored small creeks with high *** ommaturus,Acanthogobius luridus,and Carassius auratus preferred deep,steep creeks with a large cross-sectional area and *** fi ndings indicate that the geomorphological features of tidal creeks should be considered in the conservation and sustainable management of fi sh species and in the restoration of salt marshes.

关键词： intertidal environment habitat selection geomorphology restoration salt marshes Changjiang (Yangtze) River estuary

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Analyses of Extreme Climate Events over China Based on CMIP5 Historical and Future Simulations

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Advances in Atmospheric Sciences 2014年第5期31卷 1209-1220页

作者： YANG Shili FENG Jinming DONG Wenjie CHOU Jieming state key laboratory of earth surface process and resource ecology Beijing Normal University key laboratory of Regional Climate–Environment for East Asia Institute of Atmospheric PhysicsChinese Academy of Sciences College of Global Change and earth System Science Beijing Normal University

Based on observations and 12 simulations from Coupled Model Intercomparison Project Phase 5 （CMIP5） models, cli- matic extremes and their changes over China in the past and under the future scenarios of three Representative Concentration Pathways （RCPs） are analyzed. In observations, frost days （FD） and low-temperature threshold days （TN10P） show a de- creasing trend, and summer days （SU）, high-temperature threshold days （TX90P）, heavy precipitation days （R20）, and the contribution of heavy precipitation days （P95T） show an increasing trend. Most models are able to simulate the main char- acteristics of most extreme indices. In particular, the mean FD and TX90P are reproduced the best, and the basic trends of FD, TN10P, SU and TX90P are represented. For the FD and SU indexes, most models show good ability in capturing the spatial differences between the mean state of the periods 1986--2005 and 1961-80; however, for other indices, the simulation abilities for spatial disparity are less satisfactory and need to be improved. Under the high emissions scenario of RCP8.5, the century-scale linear changes of the multi-model ensemble （MME） for FD, SU, TN10P, TX90P, R20 and P95T are -46.9, 46.0, -27.1, 175.4, and 2.9 days, and 9.9%, respectively; and the spatial change scope for each index is consistent with the emissions intensity. Due to the complexities of physical process pararneterizations and the limitation of forcing data, great uncertainty still exists with respect to the simulation of climatic extremes.

关键词： extreme climate China CMIP5 RCPs

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CH_(4) and C0_(2) observations from a melting high mountain glacier,Laohugou Glacier No.12

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Advances in Climate Change Research 2022年第1期13卷 146-155页

作者： Zhi-Heng DU Lei WANG Zhi-Qiang WEI Jing-Feng LIU Peng-Lin LIN Jia-Hui LIN Yan-Zhao LI Zi-Zhen JIN Ji-Zu CHEN Xiao-Xiang WANG Xiang QIN Cun-De XIAO state key laboratory of Cryospheric Science Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China state key laboratory of earth surface processes and resource ecology Beijing Normal UniversityBeijing 100875China zhuhai branch of state key laboratory of earth surface processes and resource ecology Beijing Normal UniversityZhuhai 519087China College of Geography and Environment Science Northwest Normal UniversityLanzhou 730000China Qilian Shan Station of Glaciology and Ecological Environment State Key Laboratory of Cry ospheric ScienceNorthwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China

With global warming,glaciers in the high mountains of China are retreating ***,few data have been reported on whether greenhouse gases from these glaciers are released into the atmosphere or absorbed by glacial *** this study,we collected meltwater and ice samples from Laohugou Glacier No.12 in western China and measured CH_(4)and CO_(2)*** from the glacier terminus was continually sampled between 3 and 5 August 2020 to measure CH_(4)and CO_(2)*** results demonstrated that meltwater is a source of CH_(4)because the average saturations are over 100%.It could be con eluded that CH_(4)in the atmosphere can be released by glacial ***,the CO_(2)saturations are various,and CO_(2)fluxes exhibit positive(released CO_(2))or negative(absorbed CO_(2))values because the water and atmospheric conditions are *** importantly,the CH_(4)and CO_(2)concentrations were higher in meltwater samples from the glacier terminus than in samples from the surface ice(including an ice core)and a surface *** the meltwater effect from the upper part of the glacier cannot be excluded,we speculated that subglacial drainage systems with an anaerobic environment may represent the CH_(4)source,but it needs to be further investigated in the ***,high mountain glaciers are currently ignored in global carbon budgets,and the increased melting of glaciers with global warming may accelerate the absorption of much more CO_(2)and lead to the release of CH_(4).

关键词： CO_(2) CH_(4) Source and sink:Subglacial drainage systems Laohugou glacier No.12

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New Developments and Perspectives in Physical Geography in China

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Chinese Geographical Science 2019年第3期29卷 363-371页

作者： FU Bojie TIAN Tao LIU Yanxu ZHAO Wenwu state key laboratory of Urban and Regional ecology Research Center for Eco-Environmental Sciences Chinese Academy of Sciences state key laboratory of earth surface processes and resource ecology Faculty of Geographical Science Beijing Normal University

Physical geography is the cornerstone of geography. In this article, the starting points of disciplines in physical geography in recent years in China are discussed. With the coupling of systems set as the research object, and sustainable development as the ultimate goal, the upgrade of physical geography can be deconstructed into three steps: deepen physical geography from the perspective of pattern-process coupling, improve the focus of physical geography from ecosystem processes to ecosystem services, and increase the understanding of the physical geography ‘pattern, process, service, sustainability' research cascade. The incorporation of human activities into physical geographic processes is essential to conduct integrated analysis on physical and human factors at different scales. The development of ecosystem service models that couple supply-demand and sustainable development are of great importance to bridge the role of ecosystem services between the natural environment and human well-being. Moreover, human-land systems and sustainable development have become the core areas and frontiers of integrated physical geography and even geography in general. China faces the great strategic demand of constructing an ecological civilization in a new era, and the development of the disciplines of physical geography should give full access to the advantages of intersecting and comprehensive disciplines, focus on the human-land system patterns,processes, and services in key research areas, and provide disciplinary support for regional, national, and global sustainable development.

关键词： pattern-process coupling ecosystem services sustainability human-land system China’s national demands

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The sediment delivery ratio in a small catchment in the black soil region of Northeast China

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International Journal of Sediment Research 2013年第1期28卷 111-117页

作者： Yi-fan DONG Yong-qiu WU Tian-yu ZHANG Wei YANG Bao-yuan LIU state key laboratory of earth surface processes and resource ecology Beijing Normal University MOE Engineering Center of Desertification and Blown-Sand Control Beijing Normal University key laboratory of Mountain Hazards & surface process Chinese Academy of Sciences School of Geography Beijing Normal University

The black soil region of northeast China,which covers the Provinces of Heilongjiang,Jilin and the Inner Mongolia autonomous region with black soil,chernozem and meadow soil,has experienced soil erosion since intense agricultural reclamation began approximately 100 years ***,the sediment delivery ratio,defined as the fraction of gross erosion that is transported from a given area in a given time interval,is still *** this study,we calculated the delivery ratio and analysed changes in erosive processes within Hebei catchment from 1977 to 2007 based on an analysis of sediments of the Liudui *** original vegetation layer clearly identified the bottom of the reservoir when it was constructed in 1977;thus,the reservoir sediments could be precisely *** delivery ratio,calculated by comparing the sediment deposition in the reservoir with the total soil erosion in the upstream catchment,was found to be exponentially correlated（r;= 0.95,P < 0.01） with decreasing grain size,except for the fraction <0.002 *** delivery ratio for the clays（<0.002 mm） was low,averaging 0.10 during the study period, which indicated partial removal of clays from the *** changes in the reservoir deposition rate reflected the temporal changes in the erosion *** exceptionally high rainfall in 1998 was confirmed by the distributions of;Cs,;Pb,and the grain-size of the *** from the position of the original grass layer,we defined three periods from 1977 to 2007 based on deposition rates:2.40 cm year;from 1977 to 1997,5.60 cm year;in 1998 due to unusually high rainfall,and 1.55 cm year;from 1999 to *** overall average deposition rate for the entire period was 2.26 cm year;.Precipitation was found to be the main factor affecting the soil erosion of the study area.

关键词： Sediment delivery ratio Reservoir sediments Black soils China

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Research on wind erosion processes and controlling factors based on wind tunnel test and 3D laser scanning technology

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Journal of Arid Land 2022年第9期14卷 1009-1021页

作者： YAN Ping WANG Xiaoxu ZHENG Shucheng WANG Yong LI Xiaomei Faculty of Geographical Science Beijing Normal UniversityBeijing 100875China zhuhai branch of state key laboratory of earth surface processes and resource ecology Beijing Normal UniversityZhuhai 519087China state key laboratory of earth surface processes and resource ecology Beijing Normal UniversityBeijing 100875China MOE Engineering Research Centre of Desertification and Blown-sand Control Beijing 100875China Institute of Geographical Sciences Henan Academy of SciencesZhengzhou 450052China School of Geography and Tourism Shaanxi Normal UniversityXi'an 710119China

The study of wind erosion processes is of great importance to the prevention and control of soil wind *** this study,three structurally intact soil samples were collected from the steppe of Inner Mongolia Autonomous Region,China and placed in a wind tunnel where they were subjected to six different wind speeds(10,15,17,20,25,and 30 m/s)to simulate wind erosion in the wind *** each test,the soil surfaces were scanned by a 3D laser scanner to create a high-resolution Digital Elevation Model(DEM),and the changes in wind erosion mass and microtopography were *** on this,we performed further analysis of wind erosion-controlling *** study results showed that the average measurement error between the 3D laser scanning method and weighing method was 6.23%for the three undisturbed soil *** increasing wind speed,the microtopography on the undisturbed soil surface first became smooth,and then fine stripes and pits gradually *** the initial stage of wind erosion processes,the ability of the soil to resist wind erosion was mainly affected by the soil *** the late stage of wind erosion processes,the degree of soil erosion was mainly affected by soil organic matter and CaCO_(3)*** results of this study are expected to provide a theoretical basis for soil wind erosion control and promote the application of 3D laser scanners in wind erosion monitoring.

关键词： 3D laser scanning technology wind erosion wind tunnel test wind erosion depth microtopography soil hardness

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