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Soil anti-scourability enhanced by herbaceous species roots in a reservoir water level fluctuation zone

Journal of Mountain Science 2021年第2期18卷 392-406页

作者： XU Wen-xiu YANG Ling bao yu-hai LI Jin-lin WEI Jie Key Laboratory of Mountain Surface Processes and Ecological Regulation Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu 610041China School of Geography and Tourism Science Chongqing Normal UniversityChongqing 401331China University of Chinese Academy of Sciences Beijing 100049China

Revegetation is one of the successful approaches to soil consolidation and streambank protection in reservoir water level fluctuation zones(WLFZs).However,little research has been conducted to explore the impact of herbaceous species roots on soil anti-scourability during different growth stages and under different degrees of inundation in this *** study sampled two typical grasslands(Hemarthria compressa grassland and Xanthium sibiricum grassland)at two elevations(172 and 165 m a.s.l.)in the water level fluctuation zone(WLFZ)in the Three Gorges Reservoir(TGR)of China to quantify the changes in soil and root properties and their effects on soil anti-scourability.A simulated scouring experiment was conducted to test the soil anti-scourability in April and August of *** results showed that the discrepancy in inundation duration and predominant herbaceous species was associated with a difference in root biomass between the two *** root weight density(RWD)values in the topsoil(0-10 cm)ranged from 7.31 to 13 mg cm^(-3) for the Hemarthria compressa grassland,while smaller values ranging from 0.48 to 8.61 mg cm^(-3) were observed for the Xanthium sibiricum *** addition,the root biomass of the two herbs was significantly greater at 172 m *** that at 165 m *** the early recovery growth period(April).Both herbs can effectively improve the soil properties;the organic matter contents of the grasslands were 128.06%to 191.99%higher than that in the bare land(CK),while the increase in the water-stable aggregate ranged from 8.21%to 18.56%.Similarly,the topsoil antiscourability indices in both the herbaceous grasslands were larger than those in the *** correlation coefficients between the root length density(RLD),root surface area density(RSAD)and root volume density(RVD)of fine roots and the soil antiscourability index were 0.501,0.776 and 0.936,***,the change in the soil antiscourability index was more sensitive to al

关键词： Herbaceous species root system Soil anti-scourability Water level fluctuation zone Three Gorges Reservoir

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Effect of Axial Magnetic Field on the Microstructure, Hardness and Wear Resistance of TiN Films Deposited by Arc Ion Plating

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Acta Metallurgica Sinica(English Letters) 2015年第8期28卷 984-993页

作者： Yan-Hui Zhao Wen-Jin Yang Chao-Qian Guo yu-Qiu Chen bao-hai yu Jin-Quan Xiao Institute of Metal Research Chinese Academy of Sciences School of Chemistry and Material Science University of Science and Technology of China

TiN films were deposited on stainless steel substrates by arc ion plating. The influence of an axial magnetic field was examined with regard to the microstructure, chemical elemental composition, mechanical properties and wear resistance of the films. The results showed that the magnetic field puts much effect on the preferred orientation, chemical composition, hardness and wear resistance of TiN films. The preferred orientation of the TiN films changed from（111） to（220） and finally to the coexistence of（111） and（220） texture with the increase in the applied magnetic field intensity. The concentration of N atoms in the TiN films increases with the magnetic field intensity, and the concentration of Ti atoms shows an opposite trend. At first, the hardness and elastic modulus of the TiN films increase and reach a maximum value at 5 m T and then decrease with the further increase in the magnetic field intensity. The high hardness was related to the N/Ti atomic ratio and to a well-pronounced preferred orientation of the（111） planes in the crystallites of the film parallel to the substrate surface. The wear resistance of the Ti N films was significantly improved with the application of the magnetic field, and the lowest wear rate was obtained at magnetic field intensity of 5 m T. Moreover, the wear resistance of the films was related to the hardness H and the H3/E＊2 ratio in the manner that a higher H3/E＊2 ratio was conducive to the enhancement of the wear resistance.

关键词： Magnetic field Arc ion plating TiN films Hardness Wear resistance

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Spatiotemporal variation of the loose deposits in Baisha River Basin after the 2008 Wenchuan earthquake

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Journal of Mountain Science 2022年第9期19卷 2544-2555页

作者： Lyu Jiao-rong bao yu-hai XIE Hang-yu LI Hong HU yun-hua HE Xiu-bin Key Laboratory of Mountain Surface Processes and Ecological Regulation Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu 610299China University of the Chinese Academy of Sciences Beijing 100049China The Third Surveying and Mapping Engineering Institute of Sichuan Province Chengdu 610500China

Extensive landslides were triggered by the Wenchuan earthquake(in China)on 12 May 2008,causing a tremendous amount of loose material suspended on the hillslopes,likely to be eroded and transported by *** is of great significance to study the long-term variation of the quantity and spatiotemporal distribution of loose deposits after a great earthquake in order to understand the restoration process,to assess the risk of future soil erosion,including geological hazards,and to further develop ecological governance *** this study,information about the multi-temporal loose deposits on the ranges of the Baisha River Basin,an alpine valley near the epicenter,was extracted by objectoriented remote sensing interpretation,and analysis on their spatiotemporal variation showed that the earthquake in 2008 resulted in loose deposits covering an additional area of 81.09 km2,with a volume estimated at 0.357 billion *** five years after the earthquake,the vegetation had recovered rapidly,and the extent of the deposits was significantly *** 5 to 13 years after the earthquake,the vegetation continued to recover but at a slower rate and a decreasing trend in newly formed deposits was *** total area,volume and quantity of the loose deposits gradually *** geometric mean center of the loose deposits gradually moved back towards the upstream area after the earthquake and,by 2021,the mean center was about 4 km away from its pre-earthquake *** the mean center of the loose deposits in 2008 as the center,the deposits in the downstream area shrank significantly after the earthquake,but collapses and landslides of deposits persisted in the upstream area to the west-southwest,west-northwest and northnorthwest from the mean center,indicating future source areas of new loose deposits in the basin.

关键词： Wenchuan earthquake Loose deposits earthquake-triggered disaster Soil erosion Remote sensing

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Effects of Substrate Pulse Bias Duty Cycle on the Microstructure and Mechanical Properties of Ti–Cu–N Films Deposited by Magnetic Field-Enhanced Arc Ion Plating

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Acta Metallurgica Sinica(English Letters) 2017年第2期30卷 176-184页

作者： Sheng-Sheng Zhao Yan-Hui Zhao Lv-Sha Cheng Vladimir Viktorovich Denisov Nikolay Nikolaevich Koval bao-hai yu hai-Juan Mei School of Mechanical and Electrical Engineering Shenzhen Polytechnic Institute of Metal Research Chinese Academy of Sciences Institute of High Current Electronics Siberian BranchRussian Academy of Sciences

Ti–Cu–N films were deposited on 316 L stainless steel substrates by magnetic field-enhanced arc ion *** effect of substrate pulse bias duty cycle on the chemical composition,microstructure,surface morphology,mechanical and tribological properties of the films was systemically *** results showed that,with increasing the duty cycle,Cu content decreases from 3.3 to 0.58 at.%.XRD results showed that only Ti N phase is observed for all the deposited films and the preferred orientation transformed from Ti N（200） to Ti N（111） plane with the increase in duty *** surface roughness and deposition rate showed monotonous decrease with increasing the duty *** residual stress and hardness firstly increase and then decrease afterwards with the increase in duty cycle,while the variation of critical load shows reverse *** for the film with duty cycle of 10%,others perform the better wear resistance.

关键词： Magnetic field Arc ion plating Ti-Cu-N film Residual stress Hardness

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Soil nutrients in relation to vertical roots distribution in the riparian zone of Three Gorges Reservoir,China

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Journal of Mountain Science 2018年第7期15卷 1498-1509页

作者： ZHONG Rong-hua HU Jin-ming bao yu-hai Wang Fei HE Xiu-bin yunnan Key Laboratory of International Rivers and Transboundary Eeo-security Kunming 650091 China Institute oflnternational Rivers and Eco-security Yunnan University Kunming 650091 China Key Laboratory of Mountain Surface Processes and Ecological Regulation Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610041 China

Since the impoundment of the Three Gorges Reservoir(TGR), the riparian zone has been subjected to numerous environmental changes. This study was conducted to recognize the distribution of grass roots and its impacts on soil nutrients in the water level fluctuation zone of TGR. Roots of four predominant herbaceous plants in the study area, specifically, Cynodon dactylon, Hemarthria altissima, Hemarthria compressa, and Paspalum paspaloides, and their corresponding relation with soil nutrient contents were investigated. Root surface area density was determined with Win RHIZO, and the relationships of root distribution with soil depths and soil nutrient contents were studied. The results indicates that most roots are distributed in the top soil layer of 0-10 cm. Estimated root surface area density for the selected grass species ranges from 0.16 to 13.44 cm^2/cm^3, and decreases exponentially with an increase in soil depth. Soil organic matter and total nitrogen contents are significantly lower on bare control area than the corresponding values on the grasslands. Total nutrient contents on grasslands of C. dactylon and H. compressa are higher than those of other grass areas. Root length density and root surface area density are significantly correlated with soil organic matter and total nitrogen content for the four grasslands. The present results suggests that plant roots have significant effects on the distribution of soil nutrients in soil profiles in the riparian zone along the TGR. Nevertheless, additional investigations are needed to reveal the specific interactions between plant roots distribution, soil nutrients and water level fluctuations.

关键词： Roots distribution Soil nutrients Water level fluctuations Riparian zone Root surface area density Root length density

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Effect of Axial Magnetic Field on the Microstructure and Mechanical Properties of CrN Films Deposited by Arc Ion Plating

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Acta Metallurgica Sinica(English Letters) 2016年第6期29卷 546-553页

作者： Yan-Hui Zhao Li Xu Chao-Qian Guo Wen-Jin Yang Guo-Qiang Lin bao-hai yu Institute of Metal Research Chinese Academy of Sciences Key Laboratory of Materials Modification by Laser Ion and Electron Beams (Dalian University of Technology) Ministry of Education Dalian University of Technology

CrN films were deposited on the high-speed-steel substrates by arc ion plating. The effect of an axial magnetic field on the microstructure and mechanical properties was investigated. The chemical composition, microstructure, surface morphology, surface roughness, hardness and film/substrate adhesion of the film were characterized by X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscope（SEM）, surface morphology analyzer, Vickers microhardness test and scratch test. The results showed that the magnetic field puts much effect on the microstructure,chemical composition, hardness and film/substrate adhesion of the Cr N films. The N content increases and Cr content decreases when the magnetic flux density increases from 0 to 30 m T. All of the Cr N films were found to be substoichiometric. With an increase in the magnetic flux density, the film structures change in such way： Cr_2N →Cr_（2-N）＋CrN→CrN＋Cr_2N→*** SEM results showed that the number of macroparticles（MPs） on the film surface is significantly reduced when the magnetic flux density increases to 10 mT or higher. The surface roughness decreases with the magnetic field, which is attributed to the fewer MPs and sputtered craters on the film surface. The hardness value increases from 2074 HV_（0.025） at 0 mT（without magnetic field） and reaches a maximum value of 2509 HV_（0.025） at 10 m *** further increase in the magnetic flux density leads to a decrease in the film hardness. The critical load of film/substrate adhesion shows a monotonous increase with the increase in magnetic flux density.

关键词： Magnetic field Arc ion plating CrN films Hardness Adhesion

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Effect of Surface Layer Structural-Phase Modification on Tribological and Strength Properties of a TiC–(Ni–Cr) Metal Ceramic Alloy

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Acta Metallurgica Sinica(English Letters) 2018年第5期31卷 547-551页

作者： bao-hai yu V.E.Ovcharenko K.V.Ivanov A.A.Mokhovikov Yan-Hui Zhao Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Tomsk Polytechnic University Tomsk 634050 Russia Institute of Strength Physics and Materials Science Siberian Branch of the Russian Academy of Sciences Tomsk 634021Russia

This paper reports TiC–（Ni–Cr） metal ceramic alloy（ratio of components 50：50） with nanoscaled components formed in the surface layer and smoothly transformed into the initial inner structure throughout the material under pulsed electron irradiation of the alloy surface. Principal changes in the surface layer are ascribed to the formation of gradient structure leading to the increase in wear resistance of the surface layer, drop of friction coefficient and improvement of specimen bending resistance when stressing on the irradiated surface side. The above changes of tribological and strength properties in the surface layer under pulsed electron irradiation become more apparent with increasing atomic mass of a plasma-forming inert gas.

关键词： Metal ceramic alloy Particle-reinforced composite Interphase boundaries Tribological behavior Bending strength Electron beam treatment

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Dry cropland changes in China's Three Gorges Reservoir Region during the period 1990 to 2015

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Journal of Mountain Science 2020年第3期17卷 516-527页

作者： WANG Ming-feng TIAN Feng-xia HE Xiu-bin Raheel ANJUM bao yu-hai Adrian LCOLLINS Key Laboratory of Mountain Surface Process and Ecological Regulation Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu 610041China University of Chinese Academy of Sciences Beijing 100049China Department of Tourism and Geography Tongren UniversityTongrenGuizhou Province554300China Abdul Wali Khan University MardanPakistan Sustainable Agriculture Sciences Department Rothamsted ResearchNorth WykeOkehamptonDevon EX202SBUK

Monitoring and analyzing changes in the extent of cultivated land may inform strategic decisions on issues of environmental and food *** dry cropland area of 12000 km^2in the Three Gorges Reservoir Region(TGRR)of China is essential for feeding the local population of^20 million,but is highly prone to soil erosion,leading to the delivery of excessive amounts of sediment and associated pollutants to the Three Gorges Reservoir(TGR),and causing serious eco-environmental *** this background,this paper used Landsat images and a digital elevation model to analyze the altitudinal distribution of,and dynamic changes in,the area of dry cropland during the period 1990 to *** results suggest that dry cropland was mainly distributed in the elevation range of 200-600 *** dry cropland area decreased from 12525.37 km^2to 11796.27 km^2during the 25-year study period,including a particularly significant decrease in the rate of decrease from 6.93 km^2/yr to 43.99 km^2/yr after *** largest decline in the dry cropland area occurred in the elevation range of 600-900 *** transformations between dry cropland and forest revealed the impact of the TGR operation on the extent of dry cropland.A total of 528.79 km^2of dry cropland with slopes>25°were converted to forest after 2000,whereas a total of 642 km^2of forest was converted to dry cropland during the study period,and these conversions mainly occurred between the elevation of 200–900 *** spatiotemporal changes in the dry cropland area are likely to raise new issues concerning food security in the TGRR.

关键词： Dry cropland Altitude Reservoir operation Three Gorges Reservoir Region Landuse change Soil erosion

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Fractal characterization of sediment particle-size distribution in the water-level fluctuation zone of the Three Gorges Reservoir, China

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Journal of Mountain Science 2019年第9期16卷 2028-2038页

作者： LI Jin-lin bao yu-hai WEI Jie HE Xiu-bin TANG Qiang Jean de Dieu NAMBAJIMANA Key Laboratory of Mountain Surface Processes and Ecological Regulation Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610041 China Chongqing Key Laboratory of Earth Surface Processes and Environmental Remote Sensing in the Three Gorges Reservoir Area Chongqing 401331 China University of Chinese Academy of Sciences Beijing 100049 China Sustainable Agriculture Sciences Department Rothamsted Research North Wyke Okehampton Devon EX20 2SB UK

The combined effect of periodic water impoundment and seasonal natural flood events has created a 30 m high water-level fluctuation zone(WLFZ) around the Three Gorges Reservoir(TGR), China, forming a unique eco-landscape. Siltation, eutrophication, enrichment of heavy metals, and methane emissions in the WLFZ have been widely associated with sediment and soil particles generated from the upstream catchment or upland slopes. However, little attention has been paid to the complexity of sediment particle-size distributions in the WLFZ. In the present study, core samples(from a 345 cm thick sediment core from the base of the WLFZ), slope transect surface samples(across/up a WLFZ slope), and along-river/longitudinal surface samples(from the reservoir reaches) were collected. Laser granulometry and a volume-based fractal model were used to reveal the characteristics of sediment particle-size distributions. Results indicate that the alternation of coarse and fine particles in the sedimentary core profile is represented as a fluctuation of low and high values of fractal dimension(D), ranging from 2.59 to 2.77. On the WLFZ slope transect, surface sediment particles coarsen with increasing elevation, sand content increases from 3.3% to 78.5%, and D decreases from 2.76 to 2.53. Longitudinally, surface sediments demonstrate a downstream-fining trend, and D increases gradually downstream. D is significantly positively correlated with the fine particle content. We conclude that D is a useful measure for evaluating sediment particle-size distribution.

关键词： Spatial differentiation Sediment particle Fractal dimension Water-level fluctuation zone Three Gorges Reservoir

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Estimation of soil reinforcement by the roots of four postdam prevailing grass species in the riparian zone of Three Gorges Reservoir, China

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Journal of Mountain Science 2016年第3期13卷 508-521页

作者： ZHONG Rong-hua HE Xiu-bin bao yu-hai TANG Qiang GAO Jin-zhang YAN Dan-dan WANG Ming-feng LI yu Key Laboratory of Mountain Surface Processes and Ecological Regulation Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu 610041China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Urban and Regional Ecology Research Center for Eco-environmental SciencesChinese Academy of SciencesBeijing 100085China

Soil erosion and bank degradation is a major post-dam concern regarding the riparian zone of the Three Gorges Reservoir. The development and succession of vegetation is a main countermeasure,especially to enhance bank stability and mitigate soil erosion by the root system. In this study, the roots of four prevailing grass species, namely, Cynodon dactylon, Hemarthria altissima, Hemarthria compressa, and Paspalum paspaloides, in the riparian zone were investigated in relation to additional soil cohesion. Roots were sampled using a single root auger. Root length density（RLD） and root area ratio（RAR） were measured by using the Win RHIZO image analysis system. Root tensile strength（TR） was performed using a manualdynamometer, and the soil reinforcement caused by the roots was estimated using the simple Wu＇s perpendicular model. Results showed that RLD values of the studied species ranged from 0.24 cm/cm3 to20.89 cm/cm3 at different soil layers, and RLD were significantly greater at 0–10 cm depth in comparison to the deeper soil layers（＆gt;10 cm）. RAR measurements revealed that on average 0.21% of the reference soil area was occupied by grass roots for all the investigated species. The measured root tensile strength was the highest for P. paspaloides（62.26MPa） followed by C. dactylon（51.49 MPa）, ***（50.66 MPa）, and H. altissima（48.81MPa）. Nevertheless, the estimated maximum root reinforcement in this investigation was 22.5 k Pa for *** followed by H. compressa（21.1 k Pa）, ***（19.5 k Pa）, and C. dactylon（15.4 k Pa） at0–5 cm depth soil layer. The root cohesion values estimated for all species were generally distributed at the 0–10 cm depth and decreased with the increment of soil depth. The higher root cohesion associated with H. altissima and H. compressa implies their suitability for revegetation purposes to strengthen the shallow soil in the riparian zone of the Three Gorges Reservoir. Although the soil reinforcement induced by roots is only as

关键词： Bank stabilization Root area ratio Root tensile strength Soil reinforcement Riparian zone Three Gorges Reservoir

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