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Elevational distribution of forests and its spatiotemporal dynamics in subtropical China from 2000 to 2019

Science China Earth Sciences 2024年第8期67卷 2563-2582页

作者： Zhencan ZHENG Liuwen ZHUANG Guofang MIAO Han LIU Zhiqiang CHENG Wenyu LI Rong SHANG Peng GONG Jing Ming CHEN Institute of Geography Fujian Normal University Key Laboratory of Humid Subtropical Eco-Geographical Process (ministry of Education) Fujian Normal University School of Geographical Sciences Fujian Normal University National land Consolidation center Ministry of Natural Resources Key Laboratory of land Consolidation and Rehabilitation Ministry of Natural Resources Key Laboratory of Digital Mapping and land information Application Ministry of Natural Resources Department of Geography & Planning University of Toronto Department of Geography The University of Hong Kong

The subtropical region of China possesses abundant forest resources and features a mountainous *** the implementation of policies such as natural forest protection,the Grain for Green Project,and other initiatives since the beginning of the 21st century,coupled with climate change,the forest resources in this region have undergone significant changes compared to historical *** addition,forest resources distributing mainly in mountainous areas also implies that these changes may vary significantly with *** explore the spatiotemporal dynamics of forest distribution in subtropical China since 2000,especially the trend of changes with elevation,we analyzed the data from two land cover products focusing on forest cover and forest *** used a hierarchical approach,in which coarse-classification forest cover data with relatively small uncertainties impose constraints on forest type data with larger uncertainties,to achieve a reasonable balance between obtaining more details and reducing data *** first divided the forest cover data into‘unchanged'and‘changed'*** the constraints by the forest cover results,we further analyzed the‘unchanged'and‘changed'forest *** results indicated that,since the implementation of ecological engineering and management policies,54%of the area in the subtropical region had maintained unchanged forest cover attributes over the past 20 years,which implied the good state of ecological *** results also showed that dynamic conversions existed in the long term between forests and lands for essential production needs like *** elevational variations of forest cover suggested that the dominant changes came from the conversion between forests and croplands in low-elevation regions below 700 m,the conversion between forests and shrublands in mid-elevation regions of 700–1500 m,and the conversion between forests and grasslands in high-elevation regions above 2000 *** the regio

关键词： Subtropical China land cover Forest cover Forest type Elevational distribution

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Extract lithium from clay-type lithium ore by mixed acid and its mechanism Author links open overlay panel

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Particuology 2024年第8期91卷 323-332页

作者： Wuchang Zhou Ruiqi Xie Xiong Tong Xian Xie Yang Liu Zhihui Zhao Faculty of land Resource Engineering Kunming University of Science and TechnologyKunming650093China Technology Innovation center for Comprehensive Utilization of Strategic Mineral resources Ministry of Natural ResourcesChengdu610041China National&Regional Engineering Research center for Green comprehensive Utilization of Tailing resources from Metal Minerals Kunming650093China

A roasting-leaching test was carried out for the efficient utilization of clay-type lithium ore in the central region of Yunnan *** test used the mixed acid of sulfuric acid and phosphoric acid as the leaching *** the conditions of roasting temperature of 600℃,roasting time of 1 h,liquid-solid ratio of 5:1,volume ratio of H_(2)SO_(4)solution to H_(3)PO_(4)solution of 45:5,leaching time of 2 h and leaching temperature of 80℃,the leaching rate of lithium was as high as 97.83%.The leaching mechanism was studied by SEM,pore property analysis,XRD and *** was found that the morphology of the ore changed obviously after roasting and leaching,and a certain degree of collapse and fragmentation occurred,which provided favorable spatial conditions for the leaching of *** porosity,total intrusion volume and total pore area also increased after roasting and leaching,thus promoting the leaching of Li^(+).The results showed that chemical reaction taken placed during the roasting and *** phase of the sample changed from chlorite,kaolinite and diaspore(boehmite)mainly to corundum,hematite,periclase and quartz after ***,after leaching,no new phase was produced in the ore sample,and no S and P elements were found on the surface of the ore sample,indicating that the leaching mechanism of lithium might be the ion exchange between H^(+)and Li^(+).

关键词： Clay-type lithium ore Lithium extraction Roasting Leaching

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Coal-based activated carbon prepared by H2O activation process for supercapacitors using response surface optimization method

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Frontiers of Chemical Science and Engineering 2024年第6期18卷 31-40页

作者： Shanxin Xiong Fengyan Lv Chenxu Wang Nana Yang Yukun Zhang Qingyong Duan Shuaishuai Bai Xiaoqin Wang Zhen Li Jianwei Xu College of Chemistry and Chemical Engineering Xi’an University of Science and TechnologyXi’an 710054China Key Laboratory of Coal resources Exploration and Comprehensive Utilization Ministry of Land and ResourcesXi’an 710021China Institute of Sustainability for Chemicals Energy and EnvironmentJurong Island 627833Singapore

The scalable production of high grade activated carbon from abundant coal for supercapacitors application is an efficient way to achieve high value-added utilization of coal ***,this technology is challenging due to lack of comprehensive understanding on the mechanism of activation process and effect of external *** this paper,the effect of activating temperature and time on the specific capacitance of coal-based activated carbon prepared by H2O steam activation was studied using the response surface *** optimal conditions,coal-based activated carbon exhibits the largest specific capacitance of 194.35 F·g^(−1),thanks to the appropriate pore/surface structure and defect *** functional theory calculations explain in detail the mechanism of contraction of aromatic rings and overflow of H2 and CO during the ***,oxygen-containing functional groups are introduced,contributing to the pseudocapacitance property of coal-based activated *** mechanism of reactions between aromatic carbon and H2O vapor provides understanding on the role of water during coal processing at the molecular level,offering great potential to regulate product distribution and predict rate of pore *** insight would contribute to the advancement of other coal processing technology such as gasification.

关键词： response surface optimization coal-based activated carbon supercapacitor activating mechanism

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Examining the pathway and mechanism of comprehensive land consolidation through the lens of rural neo-endogenous development

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Journal of Geographical Sciences 2024年第9期34卷 1739-1760页

作者： LUO Xiuli JIN Xiaobin LIU Xiaojie HONG Buting ZHOU Yinkang School of Geography and Ocean Science Nanjing UniversityNanjing 210023China Key Laboratory of Coastal Zone Exploitation and Protection Ministry of Natural ResourcesNanjing 210023China Key Laboratory of Carbon Neutrality and Territory Optimization Ministry of Natural ResourcesNanjing 210023China Jiangsu Province land Consolidation and Ecological Restoration Research center Nanjing 210023China

land consolidation(LC) stands as a globally recognized strategy for rural development. In China, it has evolved towards comprehensive land consolidation(CLC) to support the rural revitalization initiative. However, there are ongoing challenges in understanding CLC's specific pathway and mechanism, particularly its role in stimulating rural endogenous development. This study aims to investigate the localization process of international experiences, examine the pathway of CLC, and scrutinize its mechanism in rural development from a novel perspective of neo-endogenous development. Field research and semi-structured interviews were conducted in Nanzhanglou village, renowned for its early adoption of CLC practices inspired by German experiences since 1988. Overall, key findings underscore the advantages of CLC in spatial restructuring, industrial development, and human capital enhancement in rural areas. Additionally, international experiences emerge as crucial exogenous forces, primarily by knowledge embedding, which catalyzes rural neo-endogenous development via the “resource-engagement-identity-endogenous” mechanism. Collectively, by introducing a neo-endogenous theoretical framework, this study offers valuable insights into the CLC implementation in China and beyond, and emphasizes the positive impact of knowledge embedding as an exogenous force in promoting rural neo-endogenous development to address existing research gaps. Recommendations for sustainable rural development involve enhancing rural planning practicality, governance capacity, and local leadership, while prioritizing agricultural modernization and increasing investments in education and vocational training to ensure that villagers benefit from industrial development.

关键词： comprehensive land consolidation international experience localization rural neo-endogenous development mechanism

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Multiscale causes of the 2022 Yangtze mega-flash drought under climate change

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Science China Earth Sciences 2024年第8期67卷 2649-2660页

作者： Xing YUAN Yumiao WANG Shiyu ZHOU Hua LI Chenyuan LI School of Hydrology and Water resources Nanjing University of Information Science and TechnologyNanjing 210044China Institute of Atmospheric Physics Chinese Academy of SciencesBeijing 100029China Key Laboratory of Hydrometeorological Disaster Mechanism and Warning of ministry of Water resources Nanjing University of Information Science and TechnologyNanjing 210044China

The 2022 Yangtze mega-flash drought is characterized by strong intensity and rapid development both in time and space,accompanied by a persistent anticyclonic circulation ***,the causes of the extreme event remain elusive given the multiscale nature of *** we presented a brief overview for the oceanic and terrestrial causes of the megaflash drought during the summer of 2022,and estimated the risk in a changing *** the soil moisture percentile as the drought index,it was found that the drought expanded to the entire Yangtze River basin within two months,with 80%of basin under severe drought conditions at the end of *** the intensity and onset speed of the 2022 mega-flash drought were ranked as the first during the past 62 years,with return periods of 86 and 259 years,*** results of composite analysis showed that the spring La Ni?a can facilitate the abrupt change from a wet/normal condition in May–June to drought in July–August over the Yangtze River basin,which was beneficial for the increase of flash drought intensity and onset speed *** analysis through the linear regression also indicated that the unprecedented intensity was associated with the negative phase of the Pacific Decadal *** by a coupling strength index for soil moisture and vapor pressure deficit,it was found that there was a strong land-atmosphere coupling over the Yangtze River basin during July–August *** attribution by using CMIP6 climate models suggested that land-atmosphere coupling increased the risks of flash drought intensity and onset speed like 2022 by 61%±6%and 64%±7%under natural climate forcings,and the synergy of coupling and anthropogenic climate change would increase the risks by 75%±22%and 85%±12%.Our findings emphasized the role of landatmosphere coupling combined with anthropogenic climate change in intensifying flash droughts.

关键词： Flash drought Yangtze River basin land-atmosphere coupling Climate change Attribution

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Morphological and Sulfur-Isotopic Characteristics of Pyrites in the Deep Sediments from Xisha Trough,South China Sea

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Journal of Ocean University of China 2024年第1期23卷 138-148页

作者： CHANG Jingyi LIU Yujia LU Hailong LU Jing’an SU Xin YE Jianliang XIE Wenwei College of Engineering Peking UniversityBeijing 100871China Beijing International center for Gas Hydrate School of Earth and Planetary SciencesPeking UniversityBeijing 100871China School of Marine Science Nanjing University of Information Science and TechnologyNanjing 210044China MLR Key Laboratory of Marine Mineral resources Guangzhou Marine Geological SurveyMinistry of Land and ResourcesGuangzhou 510075China School of Ocean Sciences China University of GeosciencesBeijing 100083China

Pyrite is one of the common authigenic minerals in marine *** studies have shown that the morphological and isotopic characteristics of pyrite are closely related to the geochemical environment where it is *** better understand the for-mation mechanism of authigenic pyrite,we analyzed the isotopic composition,morphology,and distribution of pyrite in the sediment at 500m below the seafloor from Xisha Trough,South China *** morphologies were observed by scanning electron micros-copy and Raman spectrography.X-Ray computed tomography was applied to measure the particle size of *** size of pyrite crystals in the matrix sediment mainly ranged between 25 and 65µm(***.40µm),although crystals were larger(***.50μm)in the *** pyrites had a fine-grained truncated octahedral shape with occasionally well-developed growth steps,which implies the low growth rate and weak anaerobic oxidation of methane-sulfate reduction when pyrite was ***δ^(34)S values of pyrites ranged from+20.8‰Vienna-defined Canyon Diablo Troilite(V-CDT)to+33.2‰V-CDT and from+44.8‰V-CDT to+48.9‰,which suggest two growth *** the first stage,with the continuous low methane flux,the pyrite possibly formed in an environment with good access to *** the second stage,the pyrites mainly developed in sediment fractures and appeared in veins,probably due to the limited availability of *** less exposure of pyrite to the environment in the second stage was probably caused by sediment accumulation or *** this study,an episodic pyritization process was identified,and the paleoenvironment was reconstructed for the sediment investigated.

关键词： pyrite sulfur isotope AOM methane flux Xisha Trough South China Sea

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Evaluation of the Shallow Gas Hydrate Production Based on the Radial Drilling-Heat Injection-Back Fill Method

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Journal of Ocean University of China 2024年第1期23卷 119-128页

作者： CHEN Qiang WAN Yizhao WU Nengyou SUN Jianye WANG Jian LIU Changling LI Yanlong LI Chengfeng HU Gaowei Key Laboratory of Gas Hydrate Ministry of Natural ResourcesQingdao 266071China Laboratory for Marine Mineral resources Laoshan LaboratoryQingdao 266071China CNPC Offshore Engineering Company Limited Beijing 100028China Technology Innovation center for Marine Methane Monitoring Ministry of Natural ResourcesQingdao 266071China

It has been evidenced that shallow gas hydrate resources are abundant in deep oceans *** geological back-ground,occurrence,and other characteristics differ significantly from deep-seated *** of the high risk of well construction and low production efficiency,they are difficult to be recovered by using conventional oil production *** a result,this paper proposes an alternative design based on a combination of radial drilling,heat injection,and backfilling ***-branch holes are used to penetrate shallow gas hydrate reservoirs to expand the depressurization area,and heat injection is utilized as a supplement to improve gas *** information collected from an investigation site close to the offshore production well in the South China Sea is used to assess the essential components of this plan,including well construction stability and gas production *** demonstrates that the hydraulic fracturing of the 60mbsf overburden layer can be prevented by regulating the drilling fluid ***,the traditional well structure is unstable,and the suction anchor is advised for better mechanical *** gas produc-tion rate can be significantly increased by combining hot water injection and depressurization ***,the suitable produc-tion equipment already in use is discussed.

关键词： shallow gas hydrate trail production radial drilling-heat injection-back fill method experimental and numerical simulation

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Uphill or downhill?Cropland use change and its drivers from the perspective of slope spectrum

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Journal of Mountain Science 2024年第2期21卷 484-499页

作者： PAN Sipei LIANG Jiale CHEN Wanxu PENG Yelin College of land Management Nanjing Agricultural UniversityNanjing 210095China National&Local Joint Engineering Research center for Rural land resources Use and Consolidation Nanjing 210095China Jiangsu Provincial Key Laboratory of Geographic information Technology School of Geography and Ocean ScienceNanjing UniversityNanjing 210023China Key Laboratory of Natural resources Monitoring and Supervision in Southern Hilly Region Ministry of Natural ResourcesChangsha 410118China Yunnan Key Laboratory of Plateau Geographic Processes and Environmental Changes Faculty of GeographyYunnan Normal UniversityKunming 650500China Hubei Key Laboratory of Regional Ecology and Environmental Change School of Geography and Information EngineeringChina University of GeosciencesWuhan 430074China

The continuous decrease of low-slope cropland resources caused by construction land crowding poses huge threat to regional sustainable development and food *** spectrum analysis of topographic and geomorphic features is considered as a digital terrain analysis method which reflects the macro-topographic features by using micro-topographic ***,pieces of studies have extended the concept of slope spectrum in the field of geoscience to construction land to explore its expansion law,while research on the slope trend of cropland from that perspective remains *** address the gap,in virtue of spatial analysis and geographically weighted regression(GWR)model,the cropland use change in the Yangtze River Basin(YRB)from 2000 to 2020 was analyzed and the driving factors were explored from the perspective of slope *** showed that the slope spectrum curves of cropland area-frequency in the YRB showed a first upward then a downward *** change curve of the slope spectrum of cropland in each province(municipality)exhibited various distribution *** analysis of morphological parameters of cropland slope spectrum revealed that the further down the YRB,the stronger the flattening characteristics,the more obvious the *** province experienced the greatest downhill cropland climbing(CLC)was Shannxi,while province experienced the highest uphill CLC was *** most common cropland use change type in the YRB was horizontal expansion *** factors affecting average cropland climbing index(ACCI)were quite stable in different periods,while population density(POP)changed from negative to positive during the study *** research is of practical significance for the rational utilization of cropland at the watershed scale.

关键词： Cropland climbing land use change Slope spectrum Driving factors Geographically weighted regression Yangtze River Basin

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Federated Dynamic Client Selection for Fairness Guarantee in Heterogeneous Edge Computing

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Journal of Computer Science & Technology 2024年第1期39卷 139-158页

作者：毛莺池沈莉娟吴俊平萍吴杰 Key Laboratory of Water Big Data Technology of ministry of Water resources Hohai UniversityNanjing 211100China College of Computer and information Hohai UniversityNanjing 211100China center of Networked Computing Temple UniversityPhiladelphiaPA 19122-6096U.S.A

Federated learning has emerged as a distributed learning paradigm by training at each client and aggregat-ing at a parameter *** heterogeneity hinders stragglers from responding to the server in time with huge com-munication *** client grouping in federated learning can solve the straggler problem,the stochastic selection strategy in client grouping neglects the impact of data distribution within each ***,current client grouping ap-proaches make clients suffer unfair participation,leading to biased performances for different *** order to guaran-tee the fairness of client participation and mitigate biased local performances,we propose a federated dynamic client selec-tion method based on data representativity(FedSDR).FedSDR clusters clients into groups correlated with their own lo-cal computational *** estimate the significance of client datasets,we design a novel data representativity evalua-tion scheme based on local data ***,the two most representative clients in each group are selected to optimize the global ***,the DYNAMIC-SELECT algorithm updates local computational efficiency and data representativity states to regroup clients after periodic average *** on real datasets show that FedS-DR improves client participation by 27.4%,37.9%,and 23.3%compared with FedAvg,TiFL,and FedSS,respectively,tak-ing fairness into account in federated *** addition,FedSDR surpasses FedAvg,FedGS,and FedMS by 21.32%,20.4%,and 6.90%,respectively,in local test accuracy variance,balancing the performance bias of the global model across clients.

关键词： federated learning fairness computational efficiency data distribution client selection client grouping

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Assessing and Comparing Smallholders’Vulnerability to Climate Change among Countries in the Pan-Third Pole Region

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Journal of resources and Ecology 2024年第4期15卷 1015-1026页

作者： XU Xiangbo XU Ce LI Chang FU Chao ZHOU Yunqiao Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China International Ecosystem Management Partnership United Nations Environment ProgrammeBeijing 100101China land Consolidation and Rehabilitation center Ministry of Natural ResourcesBeijing 100035China Technology Innovation center for land Engineering Ministry of Natural ResourcesBeijing 100035China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Tibetan Plateau Earth System Resources and EnvironmentInstitute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China

A comprehensive assessment of climate change vulnerability is imperative for formulating effective adaptation strategies and advancing sustainable development *** one of the most climate-vulnerable regions globally,the Pan-Third Pole area lacks transnational vulnerability assessments,which poses a significant obstacle to efficient climate *** study conducted transnational comparisons based on primary micro-survey data collected uniformly across Nepal,Cambodia,Thailand,and Myanmar,which are all located in the Pan-Third Pole *** and comparing the vulnerabilities employed an extended framework of climate change *** findings reveal substantial variations in vulnerability among the countries,with Cambodia exhibiting the highest vulnerability,followed by Thailand,Myanmar,and Nepal in descending order,primarily due to differences in *** exposure to climate change also varied *** scores decreased in the order of Nepal>Cambodia>Thailand>Myanmar,with demographic factors,tap water accessibility,and land being the major contributors and sources of differentiation among the *** adaptability,Thailand demonstrated the highest adaptability,with human and financial capital as the key *** outcomes underscore the need for tailored policy measures addressing the diverse vulnerabilities,including enhancing household disaster prevention and capital ***,targeted international investments are crucial for improving adaptability among smallholders in this unique region.

关键词： climate change vulnerability smallholder sustainable development Pan-Third Pole region

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