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《寒旱区科学》2019年第二期中英双语摘要

已有 659 次阅读 2019-10-21 09:25 |系统分类:论文交流

0093−0115  Review on simulation of land-surface processes on the Tibetan Plateau … Rui Chen, MeiXue Yang, XueJia Wang, GuoNing Wan

Abstract: The Tibetan Plateau (TP) has powerful dynamics and thermal effects, which makes the interaction between its land and atmosphere significantly affect climate and environment in the regional or global area. By retrospecting the latest research progress in the simulation of land-surface processes (LSPs) over the past 20 years, this study discusses both the simulation ability of land-surface models (LSMs) and the modification of parameterization schemes from two perspectives, the models' applicability and improved parameterization schemes. Our review suggests that different LSMs can well capture the spatiotemporal variations of the physical quantities of LSPs; but none of them can be fully applied to the plateau, meaning that all need to be revised according to the characteristics specific to the TP. Avoiding the unstable iterative computation and determining the freezethaw critical temperature according to the thermodynamic equilibrium equation, the unreasonable freezethaw parameterization scheme can be improved. Due to the complex underlying surface of the TP, no parameterization scheme of roughness length can well simulate the various characteristics of the turbulent flux over the TP at different temporal scales. The uniform soil thermodynamic and hydraulic parameterization scheme is unreasonable when it is applied to the plateau, as a result of the strong soil heterogeneity. There is little research on the snow-cover process so far, and the improved scheme has no advantage over the original one due to the lack of some related physical processes. The constant interaction among subprocesses of LSPs makes the improvement of a multiparameterization scheme yield better simulation results. According to the review of existing research, adding high-quality observation stations, developing a parameterization scheme suitable for the special LSPs of the TP, and adjusting the model structures can be helpful to the simulation of LSPs on the TP.

青藏高原陆面过程模拟研究进展  陈瑞, 杨梅学, 王学佳, 万国宁

因强大的动力和热力作用,青藏高原陆-气间的相互作用会显著影响着区域甚至全球的气候和环境。本文回顾了过去20年来青藏高原陆面过程模拟的最新研究进展,从模式适用性和参数化方案改进的角度来探讨针对高原独特的陆面过程,陆面模式的模拟能力以及改进的参数化方案。结果表明,不同陆面模式都可以很好地抓住陆面过程物理量的时空变化。但没有一种模式可以完全的适用于高原,都需要针对高原的特点进行参数化改进。规避不稳定的迭代计算并根据热力学平衡方程所确定的冻融临界温度可以改进不合理的冻融参数化方案。复杂的高原下垫面导致没有粗糙度长度参数化方案可以很好地模拟出高原湍流通量在不同时间尺度的变化特征。由于土壤异质性强,模式中不合理的土壤热力学和水力学方案应用于高原时模拟结果较差。目前对于积雪过程研究较少并且由于缺乏某些相关物理过程导致改进后的方案较原方案并没有体现出优势。不断发生相互作用的各个陆面过程的子过程使得多参数化方案的改进会产生更好的模拟效果。基于已有研究回顾,增加高质量的观测站,立足于高原陆面过程的特点发展相适应的参数化方案以及模拟结构的调整能够有助于高原陆面过程的模拟。

                                                

0116–0125  The establishment and development of Haloxylon ammodendron promotes salt accumulation in surface soil of arid sandy land … YongZhong Su, TingNa Liu, JunQia Kong 

Abstract: Haloxylon ammodendron, a representative C4 succulent xerophyte and salt-secreting plant, is widely used in vegetation reestablishment programs to stabilize shifting sand, and is one of the dominant shrubs in the shelter belt used to control desertification in the desert-oasis ecotone in northwestern China. In this study, we collected soil samples in an age sequence of 0-, 2-, 5-, 13-, 16-, 31-, and 39-year-old H. ammodendron plantations to assess the effects of the shrub on soil fertility and salinity. Results show that SOC and total N concentrations increased significantly with increasing plantation age and increased 5.95- (in the interspaces) to 9.05-fold (under the canopy) and 6.15- to 8.46-fold at the 05 cm depth at the 39-year-old plantation compared with non-vegetated sandy land. Simultaneously, H. ammodendron establishment and development resulted in significant salt accumulation in the surface layer. On average, total soil salt content at the 05 cm and 520 cm depth increased 16.8-fold and 4.4-fold, respectively, compared with non-vegetated sandy land. The increase of total salt derived mostly from the accumulation of SO42, Ca2+ and Na+ with H. ammodendron development. The accumulation in salinity was more significant than the increase in fertility, suggesting that improved soil fertility did not limit the impact of salinization. The adverse effect of salt accumulation may result in H. ammodendron plantation degradation and impact community stability in the long run.

梭梭建植和生长发育促进了干旱区沙地表层土壤盐分的积累  苏永中,刘婷娜,孔君恰

梭梭,一种C4荒漠稀盐盐生灌木,广泛用于西北干旱区植物固沙,是荒漠-绿洲过渡带沙漠化防治植被防护体系建设的主要灌木种。本项研究在临泽荒漠-绿洲过渡带选择0-, 2-, 5-, 13-, 16-, 31-, 39年栽植年限的梭梭林,取样分析和评价梭梭对土壤肥力和盐分的影响。结果表明:土壤有机碳和全氮含量随梭梭栽植年限的增加而显著增加,与流动沙地比较,栽植39年梭梭林,0~5 cm表层土壤有机碳增加了5.95倍(梭梭行间)和9.05倍(冠层下),全氮含量相应增加6.15倍和8.46倍。同时,梭梭的生长发育导致了表层土壤盐分的显著积累。39年梭梭林土壤0~5 cm5~20 cm土层平均全盐量较流动沙地分别增加16.8倍和4.4倍。在盐分组成中,主要是SO42 , Ca2+Na+含量随梭梭生长必育而显著增加。盐分的积累较养分的增加更为显著,表明土壤肥力的提高并不能限制盐分增加的负面影响,盐分积累的负效应可能导致梭梭林的退化和植被群落的长期稳定。

 

01260138  Holocene climatic change reconstructed from trace elements of an Aeolian deposit in the southeastern Mu Us Desert, northern China … Bing Liu, HeLing Jin, LiangYing Sun, WenPing Xue, ZhenYu Liu 

Abstract: In semi-arid and arid desert regions of northern China, aeolian deposits document the framework variation of an Asian monsoon during the late Quaternary. However, there is still a lack of detailed data pertaining to Holocene Asian monsoonal variation especial in the modern Asian summer monsoonal boundary belt. In this study, we reconstructed Holocene millennial-scale climatic changes in the Mu Us Desert, northern China, through systematic analysis of the variation of trace elements (324 samples) in different lithological units of the palaeosol-aeolian sand deposit, in combination with 14C and OSL chronology. Statistical results, correlation and clustering analysis indicate that the high content of 11 trace elements (V, Y, Cr, Nb, P, Mn, Cu, Zr, As, Ni and Rb, represented by P) and lower Sr content corresponding to periods of palaeosol development, marked increase of vegetation, weathering degree, and enhanced Asian summer monsoonal strength. In contrast, their opposed variation are coincident with accumulated aeolian sand layers, implying weaker summer monsoons and less geochemical weathering and degraded vegetation. These associations can be considered as signaling regional humid and dry changes of the Holocene environment. Accordingly, relatively arid conditions dominated the region before 7.2 ka, and there was an optimal humid climate in 7.24.6 ka. Afterwards, the climate became obviously dry, accompanied with several cycles of relatively wet and dry, such as relatively wet intervals around 4.13.7 ka, 3.53.3 ka and 2.5 ka. In addition, six millennial-scale dry events were recorded, and these events were consistent with weaker Asian summer monsoonal intervals in low latitudes, declined palaeosol development and precipitation in middle latitudes, as well as increased winter monsoon and periodic ice-rafting events in high latitudes of the Northern Hemisphere, within limits of accuracy of existing dating ages. This possibly suggests a noteworthy synchronism between millennial-scale climatic changes in this region and on a global scale.

风成沉积微量元素记录的毛乌素沙地东南缘全新世气候变化  刘冰,靳鹤龄,孙良英,薛文萍,刘振宇

中国北方干旱-半干旱沙漠地区的风成沉积记录了晚第四纪亚洲季风演变的框架性过程,但是,对于季风边缘区全新世亚洲夏季风的详细变化仍然缺乏。本研究通过系统分析风成沙-古土壤序列不同岩性单元微量元素的变化,并结合14COSL年代,重建了毛乌素沙地东南缘全新世千年尺度的气候变化过程。统计结果,相关和聚类分析发现11种元素含量(VYCrNbPMnCuZrAsNiRb,以P为代表)较高而Sr含量较低对应于古土壤发育阶段,反映亚洲夏季风增强,植被和风化程度增加;相反,上述元素含量在风成沙层出现反向变化,标志着亚洲夏季风减弱,化学风化程度降低,植被退化。这一变化可以作为区域全新世气候干湿变化的信号。据此,发现7.2 ka之前该区气候最为干旱,7.2~4.6 ka气候最为湿润,此后,该区气候明显变干,尽管存在多个相对湿润和干旱的旋回,如相对湿润时期发生在4.1~3.7 ka3.5~3.3 ka 2.5 ka。此外,微量元素还记录了6次千年尺度的干旱事件,在现有年代精确性的范围之内,这些事件一致于北半球低纬度亚洲夏季风减弱阶段、中纬度古土壤发育程度和降雨量降低阶段和高纬度冬季风增强、周期性冰筏事件。这可能表明区域和全球尺度全新世千年尺度气候变化存在显著的同步性。


0139–0149  Shifts in community structure and function of ammonia-oxidizing archaea in biological soil crusts along a revegetation chronosequence in the Tengger Desert … LiNa Zhao, XinRong Li, ShiWei Yuan, YuBing Liu 

Abstract: Metagenomic studies have demonstrated the existence of ammonia-oxidizing archaea (AOA) and revealed they are responsible for ammoxidation in some extreme environments. However, the changes in compositional structure and ammonia-oxidation capacity of AOA communities in biological soil crusts (BSCs) of desert ecosystems remain poorly understood. Here, we utilized Illumina MiSeq sequencing and microbial functional gene array (GeoChip 5.0) to assess the above changes along a 51-year revegetation chronosequence in the Tengger Desert, China. The results showed a significant difference in AOA-community richness between 5-year-old BSCs and older ones. The most dominant phylum during BSC development was Crenarchaeota, and the corresponding species were ammonia-oxidizing_Crenarchaeote and environmental_samples_Crenarchaeota. Network analysis revealed that the positive correlations among dominant taxa increased, and their cooperation was reinforced in AOA communities during BSC succession. Redundancy analysis showed that the dominant factor influencing the change in AOA-community structure was soil texture. GeoChip 5.0 indicated that the amoA gene abundances of AOA and ammonia-oxidizing bacteria (AOB) were basically the same, demonstrating that AOA and AOB played an equally important role during BSCs development. Our study of the long-term succession of BSC demonstrated a persistent response of AOA communities to revegetation development in desert ecosystems.

腾格里沙漠人工固沙植被恢复过程中生物土壤结皮氨氧化古菌群落结构和功能变化研究  赵丽娜,李新荣,原世伟,刘玉冰

本文以腾格里沙漠东南缘沙坡头人工固沙植被区不同演替阶段(515283451年)生物土壤结皮(简称结皮)为研究对象,利用高通量测序和基因芯片技术分别测定了不同演替阶段结皮样品中氨氧化古菌(AOA)群落结构及功能变化情况,结合环境变化因子分析了影响AOA群落结构变化的原因。结果显示,在结皮演替过程中,AOA群落丰富度在5年结皮和其他年龄的结皮之间存在显著差异(P 0.05);AOA群落的优势门均为泉古菌门,且其优势门的相对百分比在5年结皮时显著小于在其他年龄结皮时(P 0.05)。群落相关性网络分析显示,AOA类群之间的正相互作用随着结皮演替而增多,表明AOA群落组成之间合作关系和群落稳定性加强。基因芯片分析显示,在结皮演替过程中,AOA群落发挥着较为稳定的氨氧化功能,且其与氨氧化细菌共同承担着氨氧化作用。另外,研究发现驱动结皮演替中AOA群落结构变化的主要环境因子为土壤质地。本研究阐明了结皮演替过程中AOA群落的组成和功能变化特征,证实了AOA群落对荒漠生态系统结皮演替过程的持续性响应,并为荒漠生态系统生态修复的可持续性提供了氮素营养来源。

 

0150–0158  Analysis of vegetation changes and dominant factors on the Qinghai-Tibet Plateau, China … HongWei Wang, Yuan Qi, ChunLin Huang, XiaoYing Li, XiaoHong Deng, JinLong Zhang 

Abstract: This research was undertaken to clarify the characteristics of vegetation change and its main influencing factors on the Qinghai-Tibet Plateau. Using the greenness rate of change (GRC) and correlation factors, we analyzed the trend of vegetation change and its dominant factors from 2000 to 2015. The results indicate that the vegetation tended to improve from 2000 to 2015 on the Qinghai-Tibet Plateau, with the improved area accounting for 39.93% of the total; and the degraded area accounting for 19.32%. The areas of degraded vegetation are mainly concentrated in the low-relief and intermediate-relief mountains of the high-altitude and extremely high-altitude areas on the Qinghai-Tibet Plateau, as the vegetation characteristics are impacted by the terrain. Temperature and precipitation have obvious response mechanisms to vegetation growth, but the effects of precipitation and temperature on vegetation degradation are not significant over a short time frame. Overgrazing and population growth are the dominant factors of vegetation degradation on the Qinghai-Tibet Plateau.

青藏高原2000~2015年植被变化及主要影响因素分析  王宏伟,祁元,黄春林,李晓英,邓晓红,张金龙

基于2000~2015年逐月MODIS NDVI遥感数据、土地利用数据、山地地形、气象资料和统计数据,通过植被绿化度计算青藏高原植被变化,分析植被的退化、基本不变和改善区域特征,以及植被变化与不同植被类型、平/山地类型、气候变化以及人类活动的相互关系,揭示植被退化的主导因素。通过分析得出:(12000~2015年,青藏高原植被整体趋于改善,其中改善面积占39.93%,退化面积占19.32%,且草地植被和森林植被退化较为严重。(2)青藏高原的植被退化区主要集中在高海拔区和极高海拔区的小起伏和中起伏山地,植被活动易受地形影响。(3)气温与降水对植被生长具有明显的响应机制,但降水和气温在短时期内对植被退化的影响不显著。(4)超载放牧和人口剧烈增长,是青藏高原植被退化的主导因素。


0159–0172  Effects of freezethaw cycle and drywet alternation on slope stabilityYaLing Chou, LiYuan Sun, BaoAn Li, XiaoLi Wang 

Abstract: The typical loess on high slopes along the BaoLan High-speed Rail, China, was selected as the research object. The influence of the freezethaw cycle and drywet alternation on the shear-strength parameters of the unsaturated loess was investigated by laboratory experimental methods. Moreover, the temperature field, seepage field, and stability of slopes with different gradients were simulated under the effect of the freezethaw cycle and drywet alternation by using the geotechnical analysis software Geo-Studio. The research results showed (1) when the freezethaw cycle was repeated on the slope, with the frozen depth increasing, the melted depth did the same; besides, the closed loop of isotherms formed on the slope; (2) under the action of drywet circulation, the negative pore-water pressure and volumetric water content showed an upward tendency. However, owing to the different slope gradients, rainfall infiltration was not the same. As time went by, the differences of the negative pore-water pressure and volumetric water content between the slopes of different gradients continued to increase; (3) with the freezethaw cycle and drywet alternation increasing, the slope-safety factor decreased. Especially in the early period, the slope-safety factor changed remarkably. For slopes undergoing freezethaw action, the slope-safety factor was negatively correlated with the gradient. However, with regard to slopes undergoing drywet alternation, the result became more complex because the slope-safety factor was related to both seepage strength and slope grade. Accordingly, further research is needed to study the effect of seepage strength and slope grade on the stability of loess slopes.

冻融循环和干湿交替对非饱和黄土边坡稳定性影响  丑亚玲,孙丽源,李宝安,王晓莉

选取宝兰高铁沿线典型高边坡黄土为研究对象,采用实验室测试方法,探究不同循环次数下冻融循环、干湿交替对非饱和黄土剪切强度参数影响。结合数值模拟软件Geo-Studio,分别模拟冻融循环、干湿交替对不同坡度边坡温度场、渗流场及边坡稳定性的影响。主要成果概括如下:(1)冻融循环在边坡土体反复进行,当土层冻结厚度加深时,土层的融化深度也随之增加,并且坡体内会形成等温的闭合圈。(2)在干湿循环作用下负孔隙水压力和体积含水率都呈现循环上升的趋势。而斜坡则由于坡度的不同,导致降雨入渗不尽相同,随着时间的持续,不同坡度的负孔隙水压力和体积含水率的差距将逐渐增大。(3)边坡在冻融循环、干湿交替的持续作用下,边坡安全系数逐渐降低,尤其在前期下降较快。对于冻融边坡而言,坡度与安全系数成负相关;但对于干湿边坡这种认知并不全面,边坡安全系数与渗流强度和坡度都相关。



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