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Physical mechanisms of plant roots affecting weathering and leaching of loess soil

Science china Earth sciences 2006年第9期49卷 1002-1008页

作者： li yong1,2. zhang qingwen1,2. WAN Guojiang3, HUANG Ronggui3, PIAO Hechun3, BAI {2.ngyu2.& {2. Lu2.1. State Key Laboratory of {2. Erosion and Dryland Farming on the Loess Plateau, institute of soil and water conservation, chinese academy of sciences, yangling 712.00, china 2. institute of Agro-Environment and Sustainable Development, chinese academy of Agricultural {12., Beijing 100081, china 3. institute of Geochemistry, chinese academy of sciences, Guiyang 550002. china State Key Laboratory of soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water Conservation Chinese Academy of Sciences Yangling China institute of Agro-Environment and Sustainable Development Chinese Academy of Agricultural Sciences Beijing China institute of Geochemistry Chinese Academy of Sciences Guiyang China

Plant roots have potential impacts on soil mineral weathering and *** objective is to understand the physical mechanisms of plant roots affecting weathering andleaching of loess soil. Root densities were measured through the method of a large-size dug profile,and transport fluxes of soil elements were determined using an undisturbed monolith soilinfiltration device on the hilly and gully regions of the chinese Loess Plateau. The results showthat the improvement effects of soil environment by plant roots are mainly controlled by the densityand weight of the fibrous roots with the diameters less than 1 mm. Plant roots have the strongereffects on soil physical properties than chemical properties. The principal components analysis(PCA) indicates that soil physical properties by plant roots account for 56.7% of variations in soilenvironment whereas soil chemical properties and pH contribute about 2..2. of the soil *** roles of plant roots in controlling soil weathering and leaching increased in the followingorder: infiltration enhancement > increase of bio-active substance > stabilization of soilstructure. The effects of plant roots on soil mineral weathering and leaching can be quantifiedusing the multiple regression models with the high prediction accuracies developed in this study.

关键词： plant roots, soil weathering and leaching rates, soil environment field, principal components analysis (PCA), chinese Loess Plateau.

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Spatial-Temporal Changes of soil Organic Carbon During Vegetation Recovery at Ziwuling,{2.

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Pedosphere 2005年第5期15卷 601-610页

作者： li Yu-Yuan SHAO Ming-An ZHENG Ji-yong {2. Xing-Chang Key Laboratory of water Cycle and Related Land Surface Processes Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 （China） State Key Laboratory of soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water Conservation Chinese Academy of Sciences and Ministry of Water Resources Yangling 712100 （China）

To probe the processes and mechanisms of soil organic carbon (SOC) changes during forest recovery, a 150-yearchronosequence study on SOC was conducted for various vegetation succession stages at the Ziwuling area, in the centralpart of the Loess Plateau,{2.. Results showed that during the 150 years of local vegetation rehabilitation SOC increasedsignificantly (P lightly decreased afterwards. Average SOCdensities for the 0-100 cm layer of farmland, grassland, shrubland and forest were 4.46, 5.05, 9.95, and 7.49 kg C m-3,respectively. The decrease in SOC from 60 to 150 years of abandonment implied that the soil carbon pool was a sink forCO2.before the shrubland stage and became a source in the later period. This change resulted from the spatially variedcomposition and structure of the vegetation. Vegetation recovery had a maximum effect on the surface (0-2. cm) SOCpool. It. was concluded that vegetation recovery on the Loess Plateau could result in significantly increased sequestrationof atmospheric CO2.in soil and vegetation, which was ecologically important for mitigating the increase of atmosphericconcentration of CO2.and for ameliorating the local eco-environment.

关键词： soil organic carbon density spatial-temporal change vegetation recovery vegetation succession

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Assessing and regulating the impacts of climate change on water resources in the Heihe watershed on the Loess Plateau of{2.

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Science china Earth sciences 2010年第5期53卷 710-720页

作者： li Zhi1,2. liU WenZhao2. {2. XunChang3 & ZHENG Fenli2.1 College of Resources and Environment, Northwest Agriculture & Forestry University, yangling 712.00,{2. 2.6}, chinese academy of sciences & Ministry of water Resources, yangling 712.00,{2. 3 USDA-ARS Grazinglands Research Laboratory, 73036, El Reno, Oklahoma, USA College of Resources and Environment Northwest Agriculture & Forestry University Yangling China institute of soil and {2. conservation Chinese Academy of Sciences & Ministry of Water Resources Yangling China USDA-ARS Grazinglands Research Laboratory El Reno USA

Climate change can cause considerable changes in water resources and assessing the potential impacts can provide important information for regional sustainable development. The objectives were to evaluate the possible impacts of climate change during 2.10-2.39 on water resources (runoff, {2. water content, and evapotranspiration) in the Heihe watershed on the Loess Plateau of china and to further explore adaptive measures to cope with the changes. Projections of four climate models (CCSR/NIES, CGCM2. CSIRO-Mk2. and HadCM3) under three emission scenarios (A2. B2. and GGa) were used to estimate future changes in precipitation, maximum and minimum temperature based on Change Factor method. The {2. and water Assessment Tool (SWAT) was employed to simulate the hydrologic responses to climate changes. The CA-Markov model was used to develop land use scenarios. Compared with the present climate, the climate models predicted a -2.3% to 7.8% change in annual precipitation, 0.7 to 2.2.C rises in maximum temperature, and 1.2.to 2.8°C rises in minimum temperature. Without consideration of land use change, SWAT predicted a -19.8% to 37.0% change for runoff, -5.5% to 17.2. change for {2. water content, and 0.1% to 5.9% increase for evapotranspiration during 2.10–2.39 under all climate scenarios. Though the change of hydrometeorolocial variables are complex, they would possibly increase with great probability, and the hydrological regime would be influenced such as a decrease in runoff in winter months. With land use changes, the projected land use of 2.15 would increase {2. water content by 4.0% and surface runoff by 5.7% while slightly decrease evapotranspiration by 0.6% compared with the 2.00 land use. This result showed that adjustment of land use patterns was capable of regulating water resources and could be used to mitigate the adverse effects of climate change.

关键词： climate change water resources SWAT the Loess Plateau

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Changes in global land surface frozen ground and freeze-thaw processes during 1950-2.2. based on ERA5-Land data

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Advances in Climate Change Research 2024年第2期15卷 265-274页

作者： yong YANG Ren-Sheng CHEN yong-Jian DING Hong-Yuan {2. {2.-Wen {2.U Qilian Alpine Ecology and Hydrology Research Station Key Laboratory of Ecological Safety and Sustainable Development in Arid LandsNorthwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 73000China State Key Laboratory of Cryospheric sciences Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 73000China Shandong Provincial Key Laboratory of water and soil {2. and Environmental Protection College of Resources and EnvironmentLinyi UniversityLinyi 276000China

Frozen ground(FG)plays an important role in global and regional climates and environments through changes in land freeze-thaw processes,which have been conducted mainly in different ***,the changes in land surface freeze-thaw processes under climate change on a global scale are still *** on ERA5-Land hourly land skin temperature data,this study evaluated changes in the global FG area,global land surface first freeze date(FFD),last freeze date(LFD)and frost-free period(FFP)from 1950 to *** results show that the current FG areas(1991-2.2. mean)in the Northern Hemisphere(NH),Southern Hemisphere(SH),and globe are 68.50×10^(6),9.03×10^(6),and 77.53×10^(6)km^(2.,which account for 72.4%,2..8%,and 60.4%of the exposed land(excluding glaciers,ice sheets,and {2. bodies)in the NH,SH and the globe,respectively;further,relative to 1951-1980,the FG area decreased by 1.9%,8.8%,and 2.8%,*** FG at lower latitudes degrades to intermittently FG,and intermittently FG degrades to non-frozen ground,which caused the global FG boundary to retreat to higher latitudes from 1950 to *** annual FG areas in the NH,SH,and globe all show significant decreasing trends(p1950 to 2.2. at-0.32.10^(6),-0.2.×10^(6),and-0.54×10^(6)km^(2.per decade,*** FFP prolongation in the NH is mainly influenced by LFD advance,while in the SH it is mainly controlled by FFD *** prolongation trend of FFP in the NH(1.34 d per decade)is larger than that in the SH(1.15 d per decade).

关键词： Frozen ground Freeze-thaw processes Frost-free period First freeze date Global warming

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Paddy soil Stability and Mechanical Properties as Affected by Long-Term Application of Chemical Fertilizer and Animal Manure in Subtropical china

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Pedosphere 2007年第5期17卷 568-579页

作者： li Jiang-Tao zhang Bin School of Geographic and Oceanographic sciences Nanjing University Nanjing 210093 （China） institute of soil Science Chinese Academy of Sciences Nanjing 210008 （China）

Wet stability, penetration resistance （PR）, and tensile strength （TS） of paddy soils under a fertilization experiment for 2. years were determined to elucidate the function of soil organic matter in paddy soil stabilization. The treatments included no fertilization （CK）, normal chemical fertilization （NPK）, double the NPK application rates （2.PK）, and NPK mixed with organic manure （NPK＋OM）. Compared with CK, Fertilization increased soil organic carbon （SOC） and soil porosity. The results of soil aggregate fragmentation degree （SAFD） showed that fast wetting by water was the key fragmentation mechanism. Among the treatments, the NPK＋OM treatment had the largest size of water-stable aggregates and greatest normal mean weight diameter （NMWD）（P ≤ 0.05）, but the lowest PR and TS in both cultivated horizon （Ap） and plow pan. The CK and 2.PK treatments were measured with PR 〉 2.0 MPa and friability index 〈 0.2., respectively, in the Ap horizon, suggesting that the soils was mechanically unfavourable to root growth and tillage. In the plow pan, the fertilization treatments had greater TS and PR than in CK. TS and PR of the tested soil aggregates were negatively correlated to SOC content and soil porosity. This study suggested that chemical fertilization could cause deterioration of mechanical properties while application of organic manure could improve soil stability and mechanical properties.

关键词： soil aggregate stability chemical fertilization organic matter penetration resistance tensile strength

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Dredged marine soil stabilization using magnesia cement augmented with biochar/slag

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第3期16卷 1000-1017页

作者： Chikezie Chimere Onyekwena Qi li yong Wang Ishrat Hameed Alvi Wentao li Yunlu Hou Xianwei zhang Min zhang State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China University of chinese academy of sciences Beijing100049China School of Civil Engineering Architecture and EnvironmentHubei University of TechnologyWuhan430068China School of Urban Construction Wuhan University of Science and TechnologyWuhan430065China School of Civil Engineering and Archtitecture Henan UniversityKaifeng475001China

Dredged marine soils(DMS)have poor engineering properties,which limit their usage in construction *** research examines the application of reactive magnesia(rMgO)containing supplementary cementitious materials(SCMs)to stabilize DMS under ambient and carbon dioxide(CO_(2.)curing *** proprietary experimental tests were conducted to investigate the stabilized ***,the carbonation-induced mineralogical,thermal,and microstructural properties change of the samples were *** findings show that the compressive strength of the stabilized DMS fulfilled the 7-d requirement(0.7-2.1 MPa)for pavement and building *** rMgO with SCMs such as biochar or ground granulated blast-furnace slag(GGBS)altered the engineering properties and particle packing of the stabilized soils,thus influencing their *** increased the porosity of the samples,facilitating higher CO_(2. uptake and improved ductility,while GGBS decreased porosity and increased the dry density of the samples,resulting in higher *** addition of SCMs also enhanced the {2. retention capacity and modified the pH of the *** analysis revealed that the hydrated magnesium carbonates precipitated in the carbonated samples provided better cementation effects than brucite formed during rMgO ***,incorporating SCMs reduced the overall global warming potential and energy demand of the rMgO-based *** biochar mixes demonstrated lower toxicity and energy ***,the rMgO and biochar blend can serve as an environmentally friendly additive for soft soil stabilization and permanent fixation of significant amounts of CO_(2. in soils through mineral carbonation,potentially reducing environmental pollution while meeting urbanization needs.

关键词： Dredged marine soil CO_(2.uptake Reactive magnesia Biochar Ground granulated blast-furnace slag

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Experimental and discrete element numerical analysis of side slope instability induced by fissure water underlying impervious bed

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Science china(Technological sciences) 2005年第Z1期48卷 65-80页

作者： liU Bingshan1, li Shihai1, {2. Lei1,2.& WANG Jianguo31. institute of Mechanics,{2., Beijing 100080, china 2. Graduate School,{2., Beijing 100060, china 3. Tropical Marine Science institute, National University of Singapore, 10 Kent Ridge Crescent, Singapore 1192.0 institute of Mechanics Chinese Academy of Sciences Beijing 100080 China Graduate School Chinese Academy of Sciences Beijing 100060 China Tropical Marine Science institute National University of Singapore 10 Kent Ridge Crescent Singapore 119260 Singapore

When the sliding mass contains impervious bed, rainfall can infiltrate into mountain via crevices and form higher artesian aquifer at impervious bed inferior. This will decrease slip resistance and increase sliding forces of the sliding mass, thus lowering the safety factor, and inducing landslide disasters. In this paper, a landslide experimental apparatus is designed for experimental studies on the mechanism of this type of landslides. Meanwhile, the non-dimensional parameters in the model experiment are taken into account using dimensional analysis. The experimental results show that (1) the ratio of the cleft water pressure to the overlying pressure is a crucial parameter affecting the stability of the slope; (2. when the shut-in pressure reaches 80% of the normal component of the pressure on the slip surface made up of rock and soil, landslide will occur; (3) the whole slope will start to slide when the shut-in pressure is equal to the normal component of the pressure formed by the overlying rock and soil on the upper 30% area. In this article, a discrete element method simulation is used to investigate the influence of cleft water pressure and shearing strength on the landslide stability. It can be concluded that the critical value of Ccr, ?cr, which determines the slide mass stability, increases with the increase of the water pressure; if the water pressure reaches a high level, the stability of the slide mass depends mainly on C, while the influence of ? becomes smaller than C.

关键词： impervious bed, rainfall infiltration, pore water pressure, landslide experiment, displacement monitor, discrete element method.

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Particle size characterization and sources of sediments in the Uzhumqin sand dunes

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Journal of Mountain Science 2024年第8期21卷 2631-2645页

作者： zhang Hao liU Yang DANG Xiaohong MENG Zhongju li Shuangli GAO yong Inner Mongolia Agricultural University Inner Mongolia 010018China Inner Mongolia Autonomous Region water Resources Research {2. Hohhot 010020China

Sediment constitutes the fundamental basis for forming and evolving aeolian *** characteristics of sediment particle size offer insights into the development and evolution of sandy terrain,making their study critical to understanding aeolian geomorphology and sand *** this study,we combined high-density collection of surface sediments in the Uzhumqin sand dunes and GIS spatial analysis to analyze the particle size parameters and changes in the spatial distribution of surface sediments in this *** addition,we used an end-member analysis to identify the potential sources of the *** results showed that surface sediments in the Uzhumqin sand dunes had distinct spatial *** and coarse grain sands dominated the sediments in the dunes,and the mean grain size and the sorting coefficient generally increased along the prevailing wind direction,with high values in individual areas related to factors such as material sources and vegetation *** was strongly influenced by factors such as landform change and human activity,and spatial variability became more *** and the soil fractal dimension showed generally decreasing trends along the prevailing wind *** dune fixation,the contents of clay and powder particles in the soil increased;the mean particle size,the sorting coefficient,and the fractal dimension of the soil gradually increased,and the skewness and kurtosis gradually *** end-member analysis results indicated the existence of five end-members(EM)in the dune *** 1 was a mixed component of wind-deposited fine sands and nearby fluvial *** 2.was the main component of sediments in the study area and was the result of sorting lake sediments by wind action and by the local *** 3 may be a product of river flood *** 4 and EM 5 had coarser grain *** 4 was a lake-phase sediment product influenced by topographic and vegetation cover factors,and EM

关键词： Sediment Particle size Spatial differences End-member analysis Uzhumqin sand dunes

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Iron–doped bismuth oxybromides as visible-light-responsive Fenton catalysts for the degradation of atrazine in aqueous phases

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Journal of Environmental sciences 2024年第3期137卷 321-332页

作者： yong-li Cai Yu-Hang Xu Ji-Zun Xiang Zhi-Qiang {2. Qiu-Xiang He Ya-Feng li Jian Lü Fujian Provincial Key Laboratory of soil Environmental Health and Regulation College of Resources and EnvironmentFujian Agriculture and Forestry UniversityFuzhou 350002China State Key Laboratory of Photocatalysis on Energy and Environment Fuzhou UniversityFuzhou 350116China

Pesticides and its degradation products,being well–known residues in soil,have recently been detected in many water bodies as pollutants of emerging concerns,and thus there is a contemporary demand to develop viable and cost–effective techniques for the removal of related organic pollutants in aqueous ***,a visible-{2.ght-responsive Fenton system was constructed with iron–doped bismuth oxybromides(Fe–BiOBr)as the *** the advantage of sustainable Fe(Ⅲ)/Fe(Ⅱ)conversion and optimized H_(2.O_(2.uti{2.zation,the optimal Fe–BiOBr–2.catalyst showed an excellent atrazine removal efficiency of 97.61%in 12. min,which is superior than the traditional homogeneous Fenton and the majority of heterogeneous processes documented in the *** this photo–Fenton system,hydroxyl(·OH)and superoxide(·O_(2.^(-))radicals were dominant active species contributed to the oxidative degradation of *** to the production of various active radicals,five degradation pathways were proposed based on the identification of intermediates and degradation ***,this work not only demonstrates a fundamental insight into creating highly efficient and atom economic photo-Fenton systems,but also provides a complementary strategy for the treatment of organic pollutants in water.

关键词： Bismuth oxybromide Photo–Fenton Atrazine Catalytic degradation

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Hydraulic properties and drought response of a tropical bamboo (Cephalostachyum pergracile)

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Plant Diversity 2024年第3期46卷 406-415页

作者： Wanwalee Kongjarat Lu Han Amy Ny Aina Aritsara Shu-Bin zhang Gao-Juan Zhao yong-Jiang zhang Phisamai Maenpuen Ying-Mei li Yi-Ke Zou Ming-Yi li Xue-Nan li lian-Bin Tao Ya-Jun Chen CAS Key Laboratory of Tropical Forest Ecology Xishuangbanna Tropical Botanical GardenChinese Academy of SciencesYunnan 666303China University of the chinese academy of sciences Beijing 100049China T-STAR Core Team Xishuangbanna Tropical Botanical GardenChinese Academy of SciencesYunnan 666303China School of Biology and Ecology University of MaineOronoMEUSA Climate Change institute University of MaineOronoME 04469USA School of Biological and Chemical Science Pu’er UniversityXueyuan RoadYunnan 665000China institute of Ecology and Geobotany School of Ecology and Environmental SciencesYunnan UniversityKunmingYunnan 650091China School of Ecology and Environment Southwest Forestry UniversityKunmingYunnan 650224China Yuanjiang Savanna Ecosystem Research Station Xishuangbanna Tropical Botanical GardenChinese Academy of SciencesYuanjiangYunnan 653300China

Bamboo plants are an essential component of tropical ecosystems,yet their vulnerability to climate extremes,such as drought,is poorly understood due to limited knowledge of their hydraulic *** pergracile,a commonly used tropical bamboo species,exhibited a substantially higher mortality rate than other co-occurring bamboos during a severe drought event in 2.19,but the underlying mechanisms remain *** study investigated the leaf and stem hydraulic traits related to drought responses,including leaf-stem embolism resistance(P50leaf;P50stem) estimated using optical and X-ray microtomography methods,leaf pressure-volume and water-releasing ***,we investigated the seasonal water potentials,native embolism level(PLC) and xylem water source using stable *** found that *** exhibited strong resistance to embolism,showing low P50leaf,P50stem,and turgor loss point,despite its rapid leaf water ***,its leaves displayed greater resistance to embolism than its stem,suggesting a lack of effective hydraulic vulnerability segmentation(HVS) to protect the stem from excessive xylem *** the dry season,approximately 49% of the water was absorbed from the upper 2.-cm-deep soil ***,significant diurnal variation in leaf water potentials and an increase in midday PLC from 5.87±2.33% in the wet season to 12.87±4.09%in the dry season were *** summary,this study demonstrated that the rapid leaf water loss,high reliance on surface water,and a lack of effective HVS in *** accelerated water depletion and increased xylem embolism even in the typical dry season,which may explain its high mortality rate during extreme drought events in 2.19.

关键词： Climate change Drought Hydraulic safety Hydraulic vulnerability segmentation Stable isotope Tree mortality

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