CAS IR GRID研究单元&专题: 寒区旱区环境与工程研究所中国科学院寒区旱区环境与工程研究所(简称中科院寒旱所;英文Cold and Arid Regions Environmental and Engineering Research Institute,Chinese Academy of Sciences,简称CAREERI,CAS),是按照中国科学院“知识创新工程试点工作”的战略布局要求,由原中国科学院兰州冰川冻土研究所、原中国科学院兰州沙漠研究所和原中国科学院兰州高原大气物理研究所根据学科定位,机构调整,研究领域交叉融合等原则整合而成。http://www.irgrid.ac.cn:8080/handle/1471x/5095212024-03-28T17:17:17Z2024-03-28T17:17:17ZDiverse responses of vegetation growth to meteorological drought across climate zones and land biomes in northern China from 1981 to 2014Xu, Hao-jieWang, Xin-pingZhao, Chuan-yanYang, Xue-meihttp://www.irgrid.ac.cn:8080/handle/1471x/25583152019-10-09T03:19:54Z2019-10-09T03:19:54Z题名: Diverse responses of vegetation growth to meteorological drought across climate zones and land biomes in northern China from 1981 to 2014
作者: Xu, Hao-jie; Wang, Xin-ping; Zhao, Chuan-yan; Yang, Xue-mei
摘要: Improving our understanding of present and future impacts of drought on the vegetation in northern China is heightened by expectations that drought would increase its vulnerability and subsequently accelerate land degradation. The response of vegetation activity to drought and the underlying mechanisms are not well known. By using the third-generation Normalized Difference Vegetation Index (NDVI) and the Standardized Precipitation Evapotranspiration Index (SPEI), we investigated the relationship between NDVI and SPEI, across different climate regimes and land cover types, and determined the dominant time-scales at which different biome types respond to drought during the period of 1981-2014. Our results showed that biome response is coupled with drought trends in most regions of northern China. The highest correlation between monthly NDVI and SPEI at different time scales (1-48 months) assessed the impact of drought on vegetation, and the time scales resulting in the highest correlation were an effective indicator of drought resistance, which was related to the interactive roles of mean water balance and divergent drought survival traits and strategies. Diverse responses of vegetation to drought were critically dependent on characteristic drought time-scales and different growing environments. This study highlighted the most susceptible ecosystem types to drought occurrence under current climate, including temperate steppes, temperate desert steppes, warm shrubs and dry forests. Given that drought will be more frequent and severe under future climate scenarios, it may threaten the survival of mesic ecosystems, such as temperate meadows, alpine grasslands, dwarf shrubs, and moist forests not normally considered at drought risk. We propose that future research should be focused on arid and semi-arid ecosystems, where the strongest impact of drought on vegetation is occurring and the need for an early warning drought system is increasingly urgent.2019-10-09T03:19:54ZEffects of ecological water transport on photosynthesis and chlorophyll fluorescence of Populus euphraticaZhao, Chun YanSi, Jian HuaFeng, QiYu, Teng FeiDeo, Ravinesh C.Luo, Huanhttp://www.irgrid.ac.cn:8080/handle/1471x/25583142019-10-09T03:19:52Z2019-10-09T03:19:52Z题名: Effects of ecological water transport on photosynthesis and chlorophyll fluorescence of Populus euphratica
作者: Zhao, Chun Yan; Si, Jian Hua; Feng, Qi; Yu, Teng Fei; Deo, Ravinesh C.; Luo, Huan
摘要: This study investigated the physiological response of Populus euphratica (P. euphratica) to ecological water transport. Results showed significant increases in net photosynthetic (32.71%), stomatal conductance (27.58%), and transpiration (25.18%) rates of P. euphratica prior to the ecological water transport treatment. Internal CO2 concentrations (Ci) decreased significantly compared with the day preceding the treatment (23.69%; P < 0.05). During the treatment, the O, J, I, and P steps quickly increased, with the P step exhibiting the most significant change (P < 0.05). Moreover, Fv /Fm and Fv/Fo values were highest 7 d after the ecological water transport treatment. During the treatment, the initial fluorescence (F-0), the maximal fluorescence intensity (Fm), PI, and RC/CSo quickly increased, with an increasing percentage of 9.67%, 46.15%, 59.17%, and 48.54%. In contrast, V-j, ABS/RC, TRo/RC, and ETo/RC rapidly decreased, with a decreasing percentage of 30.43%, 43.54%, 37.50%, and 39.04%, respectively. After the treatment, the average chlorophyll content of a, b, and a+b increased by 26.36%, 8.89%, and 21.93%, respectively, compared with the day preceding the treatment. This study also found that the relationship between soil water content and the net photosynthetic rate, stomatal conductance, the transpiration rate, the internal CO2 concentration, Fv/Fm, and Fv/Fo of P. euphratica were strongest during ecological water transport.2019-10-09T03:19:52ZEvaluation of soil resistance formulations for estimates of sensible heat flux in a desert vineyardLi, YanKustas, William P.Huang, ChunlinKool, DiliaHaghighi, Erfanhttp://www.irgrid.ac.cn:8080/handle/1471x/25583132019-10-09T03:19:51Z2019-10-09T03:19:51Z题名: Evaluation of soil resistance formulations for estimates of sensible heat flux in a desert vineyard
作者: Li, Yan; Kustas, William P.; Huang, Chunlin; Kool, Dilia; Haghighi, Erfan
摘要: For irrigated vineyards, accurate estimates of the sensible heat flux from the soil surface (H-s) is essential for determining the contribution of soil evaporation (E) to evapotranspiration (ET) using thermal-based energy balance approaches. A key to an accurate estimate of H-s is a robust physically-based soil resistance formulation. Here we compare the performance of two soil resistance formulations: a conventional resistance model (r(KN)) derived from field and laboratory studies which has been extensively implemented in the thermal-based Two-Source Energy Balance (TSEB) model, and a recently developed physically-based soil resistance formulation (r(HO)) that explicitly accounts for near-surface interactions affecting scalar fluxes at the soil surface in the presence of bluff-body roughness elements. Estimates of H-s using the two resistance formulations were evaluated using in-situ observations from a drip-irrigated vineyard in the arid central Negev Highlands of Israel. The results indicate that the soil resistance model r(HO) outperforms the r(KN) formulation using standard model coefficients and provides robust estimates of H-s independent of model calibration or parameter tuning. This offers an opportunity to advance the utility of TSEB model when applied to sparsely vegetated areas where ground-based calibration data are not available for adjusting coefficients in the r(KN) formulation, and potentially improves its practical applications to heterogeneous landscapes by obviating its reliance on semi-empirical coefficients.2019-10-09T03:19:51ZModification on the contact model of LiPb and noncondensable gas in RELAP/SCDAPSIM/MOD4.0 and application to LOCA of China DFLL-TBMSun, QianPeng, TianjiZhou, ZhiweiChen, ZhibinWang, Shishenghttp://www.irgrid.ac.cn:8080/handle/1471x/25583122019-10-09T03:19:50Z2019-10-09T03:19:50Z题名: Modification on the contact model of LiPb and noncondensable gas in RELAP/SCDAPSIM/MOD4.0 and application to LOCA of China DFLL-TBM
作者: Sun, Qian; Peng, Tianji; Zhou, Zhiwei; Chen, Zhibin; Wang, Shisheng
摘要: In-TBM breeder box coolant leak is one of four reference accidents identified for China Dual-functional Lithium Lead Test Blanket Module (DFLL-TBM), which will result in the pressurization of the TBM LiPb breeding zones and cooling system. In order to analyze In-TBM breeder box coolant leak accident, there is a need to simulate the mixing of liquid metal and non-condensable gas. While the current system safety code RELAP/SCDAPSIM/MOD4.0 which was initially designed to predict the behavior of light water reactor systems is incapable of modeling the mixture of liquid metal fluids and non-condensable gas. This paper first briefly introduce the reason for RELAP/SCDAPS/MOD4.0's incapability of modeling liquid metal in contact with a non-condensable gas. Then, a solution to solve the problem and the modification of the RELAP/SCDAPSIM/MOD4.0 code is proposed. Several typical problems involving liquid metal in contact with helium were simulated and the results demonstrate the feasibility and validity of the modified RELAP/SCDAPS/MOD4.0 in modeling the mixing of liquid metal and non-condensable gas. Last but not least, the modified RELAP/SCDAPS/MOD4.0 is used for transient analysis of In-TBM breeder box coolant leaks. Since both lead-lithium eutectic alloy and helium serve as TBM coolants, the Lithium Lead Cooling System (LLCS) and the Helium Cooling System (HCS) were modeled to investigate the thermal-hydraulic characteristic of the TBM system and its influence on ITER safety under the accident conditions. Results show that LLCS pressurization during In-TBM breeder box coolant leak is adequately handled by the safety accessories provided in LLCS and the highest temperature of the first wall is far below its melting point during the accident process.2019-10-09T03:19:50ZEffective sorption of selenite by Fe-Mn binary oxide: influence of preparation methodWen, XiaohuZhang, Gaoshenghttp://www.irgrid.ac.cn:8080/handle/1471x/25583112019-10-09T03:19:49Z2019-10-09T03:19:49Z题名: Effective sorption of selenite by Fe-Mn binary oxide: influence of preparation method
作者: Wen, Xiaohu; Zhang, Gaosheng
摘要: In this study, two Fe-Mn binary oxide sorbents with a same Mn:Fe molar ratio of 1:3 were prepared using two methods (coprecipitation and mechanical mixing), and they are denoted as Fe-c-Mn and Fe-m-Mn, respectively. Both Fe-m-Mn and Fe-c-Mn are amorphous and have similar structure with 2-line ferrihydrite. The Fe-c-Mn has a much higher specific surface area than the Fe-m-Mn. Selenite sorption on both Fe-m-Mn and Fe-c-Mn is pH dependent, decreasing with an increase in pH value. The estimated maximal sorption capacity of Se(IV) on the Fe-m-Mn and Fe-c-Mn is 48.6 and 70.5 mg/g at pH 7.0, respectively. In addition, the Fe-Mn binary oxide is able to adsorb selenite in the presence of competing anions and across a wide range of pH values. Among the co-existing anions, phosphate is the greatest competitor for adsorptive sites on the surface of oxide. Selenite may be sorbed onto the surface of the Fe-Mn binary oxide by formation of inner-sphere surface complexes. The high sorption capacity, low cost and environmental friendliness of the Fe-Mn binary oxide make it a potentially attractive sorbent for the removal of Se(IV) from water.2019-10-09T03:19:49ZBeam dynamics and commissioning of CW RFQ for a compact deuteron-beryllium neutron sourceDou, Wei-PingChen, Wei-LongWang, Feng-FengWang, Zhi-JunLi, Chen-XingWu, QiWang, ChaoWang, Wang-shengJia, HuanZhang, PengWu, Jian-QiangYang, Xiao-DongHe, Yuanhttp://www.irgrid.ac.cn:8080/handle/1471x/25583102019-10-09T03:19:48Z2019-10-09T03:19:48Z题名: Beam dynamics and commissioning of CW RFQ for a compact deuteron-beryllium neutron source
作者: Dou, Wei-Ping; Chen, Wei-Long; Wang, Feng-Feng; Wang, Zhi-Jun; Li, Chen-Xing; Wu, Qi; Wang, Chao; Wang, Wang-sheng; Jia, Huan; Zhang, Peng; Wu, Jian-Qiang; Yang, Xiao-Dong; He, Yuan
摘要: The Institute of Modern Physics (IMP) of the Chinese Academy of Sciences (CAS) is building a compact neutron source using a superconducting linac. The injector RFQ will operate in continuous wave (CW) mode, accelerating a 10-mA deuteron beam from 20 keV/u to 1.5 MeV/u. To minimize the possibility of beam loss in the downstream superconducting linac and maintain high acceleration efficiency, we take the 99.9% longitudinal beam emittance as the key optimization parameter for the beam dynamics design of the RFQ, and include an internal buncher to reduce the longitudinal beam emittance. This paper describes the design procedures, beam dynamics simulations and preliminary beam commissioning results for this RFQ. Simulation results show that 99.9% longitudinal beam emittance at the RFQ exit is optimized to 3.5 pi mm mrad, which is 0.13 times the longitudinal acceptance of the downstream superconducting linac. Beam commissioning results demonstrate that the RFQ can accelerate 7.8 mA H-2(+) to 3.11 MeV. The transmission efficiency from a Faraday cup before the RFQ to the beam dump after the RFQ is 97.6%. The measured transmission efficiency agrees well with simulation results at different values for the inter-vane voltage.2019-10-09T03:19:48ZField simulation of urban surfaces runoff and estimation of runoff with experimental curve numbersLiu, WenChen, WeipingFeng, Qihttp://www.irgrid.ac.cn:8080/handle/1471x/25583092019-10-09T03:19:46Z2019-10-09T03:19:46Z题名: Field simulation of urban surfaces runoff and estimation of runoff with experimental curve numbers
作者: Liu, Wen; Chen, Weiping; Feng, Qi
摘要: In this study, runoff responses of typical urban surfaces were investigated by scale models under artificial rainfall simulation, and the Soil Conservation Service (SCS) model was used to assess the impacts of land use changes and green infrastructures implementation on surface runoff of Beijing urban areas. The results showed that: Runoff coefficient of the impervious surface was about 2.1 times than that of the grassland. Time to runoff of the grassland was about 22.0 times that of the impervious surface. The concaved grassland, compared with the impervious surface, can significantly delay by 6.2minutes the time to runoff, while the porous pavement significantly reduces 28.1% of the runoff coefficient. The runoff coefficient of Beijing urban areas increased from 0.68 in 2002 to 0.72 in 2012, due to the substantially increased impervious surfaces. The runoff coefficient decreased by 2.7%, 15.3% and 22.2% respectively under three green infrastructure scenarios.2019-10-09T03:19:46ZImpacts of recent climate extremes on spring phenology in arid-mountain ecosystems in ChinaHe, ZhibinDu, JunChen, LongfeiZhu, XiLin, PengfeiZhao, MinminFang, Shuhttp://www.irgrid.ac.cn:8080/handle/1471x/25583082019-10-09T03:19:45Z2019-10-09T03:19:45Z题名: Impacts of recent climate extremes on spring phenology in arid-mountain ecosystems in China
作者: He, Zhibin; Du, Jun; Chen, Longfei; Zhu, Xi; Lin, Pengfei; Zhao, Minmin; Fang, Shu
摘要: Phenological responses of terrestrial ecosystems to climate extremes are of growing concern due to the increasing frequency and intensity of extreme climatic events associated with climate change which will in turn affect vegetation seasonality more than gradual changes. However, studies are rare in arid mountain regions where plant development is commonly regulated by both temperature and precipitation. To better understand how arid mountain (AM) ecosystems may respond to climate anomalies, we identified recent extreme climatic events (including intense warming, severe drought, and excessive wetness), and analyzed spring onset of vegetation growth in the Qilian Mountains of northwestern China. Phenological sensitivity was assessed from satellite-based data as departures from maps displaying mean onsets of growth for years 1983-2013. Our results revealed remarkable shifts in the start date of the growing season (SOS) under climate extremes, with different responses depending on ecosystem and altitude. Recent warming induced a general advancement of SOS. Higher spring temperatures enhanced the accumulation of heat needed for bud-burst and leaf expansion; elevated winter temperatures reduced the chilling days before bud dormancy release, significantly decreasing the risk of freezing injury in AM plants. Changes in SOS observed in this study suggested that AM plants may have relatively low chilling requirement for dormancy release. Contrary to warming, a drought resulted in a widespread delay in spring phenology, with sensitivity peaking over a shrubland ecosystem at medium elevations. This result demonstrated that subalpine shrubs were most susceptible of the studied ecosystems to hydroclimatic extremes, highlighting the great importance in this biome of concerns. Moreover, during the year when multiple extreme events (e.g. intense warming and heavy rainfall) coincided, their combined influence appeared to arise from synergistic mechanisms that are in urgent need of further research.2019-10-09T03:19:45ZExperimental and analytical investigation on frost heave characteristics of an unsaturated moderately expansive clayLuo, JunTang, LiangLing, XianzhangGeng, Linhttp://www.irgrid.ac.cn:8080/handle/1471x/25583072019-10-09T03:19:44Z2019-10-09T03:19:44Z题名: Experimental and analytical investigation on frost heave characteristics of an unsaturated moderately expansive clay
作者: Luo, Jun; Tang, Liang; Ling, Xianzhang; Geng, Lin
摘要: Expansive clay, a kind of clayey soil, is widely distributed in seasonally frozen regions. Numerous studies have attempted to explain the frost heave characteristics of clayey soils, but few of them have paid attention to the frost heave characteristics of unsaturated expansive clay, especially considering the influence of swelling properties. In this study, a series of freezing temperature tests and step-freezing tests on an unsaturated moderately expansive clay and a silty clay were conducted. The silty clay was taken as a reference. The testing program, experimental results are presented and discussed, especially to the freezing point, evolution of temperature in the specimens at different elevations, water content distributions and cryostructures after freezing, frost heave during freezing, and state paths. In this regard, a physico-empirical approach is developed to obtain the relationship between freezing point and initial water contents. Experimental data show that the freezing point of expansive clay varies greatly with initial water contents. The obvious highly exothermic phase change occurs in expansive clay during the early stage of freezing with penetration decrease lagging behind. The heave amount of expansive clay is made up of the displacement caused by increasing water content in the unfrozen zone due to freezing-induced water flux and the frost heave. The state paths show significant variation of saturation and dry density of expansive clay after freezing and have a practical advantage of indicating the extent of possible expansion while thawing. On this basis, the state and variation of pore water are highlighted as the critical primary factors in determining the frost heave characteristics of unsaturated expansive clay in open system. Overall, this study further enhances the understanding of frost heave characteristics of the unsaturated moderately expansive clay.2019-10-09T03:19:44ZPollinator activity and pollination success of Medicago sativa L. in a natural and a managed populationChen, MinZhao, Xue-YongZuo, Xiao-Anhttp://www.irgrid.ac.cn:8080/handle/1471x/25583062019-10-09T03:19:42Z2019-10-09T03:19:42Z题名: Pollinator activity and pollination success of Medicago sativa L. in a natural and a managed population
作者: Chen, Min; Zhao, Xue-Yong; Zuo, Xiao-An
摘要: Medicago sativa L. is an important cash crop in the arid region of northwest China. Pollinator activity is an essential aspect of pollination success, but the relationships between pollinator visitation rate and seed set still need further study of M.sativa. We investigated the following characteristics of M.sativa in natural and managed populations: floral traits, pollinator activity, and breeding system. Our results indicated the management could affect the number of flowers produced; however, there was no detectable effect on the seed set per flower. We found the percentage of seeds among pollinated flowers in the managed population was significantly higher than that in the natural population. Moreover, the increase in the proportion of pollinated flowers could significantly increase seed set per flower, and pollinator visitation rate was the important limiting factor for seed set in both populations. Andrena lebedevi Popov was found to be the most frequent pollinator in both populations. Outcrossing was dominant in the breeding system and insect pollination played an important role in outcrossing. Our study suggested that proper management (artificial selection) could promote pollination success of M.sativa.2019-10-09T03:19:42Z