Chemical weathering and CO2 consumption in the glaciated Karuxung River catchment,Tibetan Plateau     

Fan Zhang  Xiong Xiao  Lijie Wang  Chen Zeng  Zhengliang Yu  Guanxing Wang  Xiaonan Shi 《水文研究》2021,35(8):e14330

Climate factors play critical roles in controlling chemical weathering, while chemically weathered surface material can regulate climate change. To estimate global chemical weathering fluxes and CO₂ balance, it is important to identify the characteristics and driving factors of chemical weathering and CO₂ consumption on the Tibetan Plateau, especially in glaciated catchments. The analysis of the hydro-geochemical data indicated that silicate weathering in this area was inhibited by low temperatures, while carbonate weathering was promoted by the abundant clastic rocks with fresh surfaces produced by glacial action. Carbonate weathering dominated the riverine solute generation (with a contribution of 58%, 51%, and 43% at the QiangYong Glacier (QYG), the WengGuo Hydrological Station (WGHS), and the lake estuary (LE), respectively). The oxidation of pyrite contributed to 35%, 42%, and 30% of the riverine solutes, while silicate weathering contributed to 5%, 6%, and 26% of the riverine solutes at the QYG, WGHS, and LE, respectively. The alluvial deposit of easily weathering fine silicate minerals, the higher air temperature, plant density, and soil thickness at the downstream LE in comparison to upstream and midstream may lead to longer contact time between pore water and mineral materials, thus enhancing the silicate weathering. Because of the involvement of sulfuric acid produced by the oxidation of pyrite, carbonate weathering in the upstream and midstream did not consume atmospheric CO₂, resulting in the high rate of carbonate weathering (73.9 and 75.6 t km⁻² yr⁻¹, respectively, in maximum) and potential net release of CO₂ (with an upper constraint of 35.6 and 35.2 t km⁻² yr⁻¹, respectively) at the QYG and WGHS. The above results indicate the potential of the glaciated area of the Tibetan Plateau with pyrite deposits being a substantial natural carbon source, which deserves further investigation.  相似文献   

Three dimensional numerical simulation of residential building on shrink–swell soils in response to climatic conditions          下载免费PDF全文

Xiong Zhang  Jean‐Louis Briaud 《国际地质力学数值与分析法杂志》2015,39(13):1369-1409

Shrink–swell soils can cause distresses in buildings, and every year, the economic loss associated with this problem is huge. This paper presents a comprehensive system for simulating the soil–foundation–building system and its response to daily weather conditions. Weather data include rainfall, solar radiation, air temperature, relative humidity, and wind speed, all of which are readily available from a local weather station or the Internet. These data are used to determine simulation flux boundary conditions. Different methods are proposed to simulate different boundary conditions: bare soil, trees, and vegetation. A coupled hydro‐mechanical stress analysis is used to simulate the volume change of shrink–swell soils due to both mechanical stress and water content variations. Coupled hydro‐mechanical stress‐jointed elements are used to simulate the interaction between the soil and the slab, and general shell elements are used to simulate structural behavior. All the models are combined into one finite element program to predict the entire system's behavior. This paper first described the theory for the simulations. A site in Arlington, Texas, is then selected to demonstrate the application of the proposed system. Simulation results are shown, and a comparison between measured and predicted movements for four footings in Arlington, Texas, over a 2‐year period is presented. Finally, a three‐dimensional simulation is made for a virtual residential building on shrink–swell soils to identify the influence of various factors. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

基于RT-Thread的波浪滑翔器控制系统设计与实现     

熊斯年  王海军  吴小涛 《数字海洋与水下攻防》2020,3(4):339-344

波浪滑翔器是一种新型海洋无人自主航行器，拥有无污染、能耗低、续航时间长、航程远、生存能力强等诸多特点，已逐步成为国内外研究的热点。控制系统作为波浪滑翔器的重要组成部分之一，它的稳定与准确性直接影响着波浪滑翔器的航行性能尤其是走航和定点的控位精度。介绍了一种基于 RT-Thread 实时操作系统的波浪滑翔器控制系统设计，通过多次海上长时间连续试验表明，基于 RT-Thread 的波浪滑翔器控制系统具有良好的准确性和可靠性。  相似文献   

Rift structures and its related unconformities on and adjacent the Dongsha Rise: insights into the nature of the high-velocity layer in the northern South China Sea     

Lei  Chao  Ren  Jianye  Pang  Xiong 《Marine Geophysical Researches》2019,40(2):99-110

Marine Geophysical Research - It is curious that the typical feature of high-velocity layer (HVL) underneath the crust for the magma-rich margin was found in the magma-poor margin of the South...  相似文献   

Diatom‐based reconstruction of summer sea‐surface salinity in the South China Sea over the last 15 000 years     

Hui Jiang  Mads F. Knudsen  Marit‐Solveig Seidenkrantz  Meixun Zhao  Longbin Sha  Lihua Ran 《Boreas: An International Journal of Quaternary Research》2014,43(1):208-219

We present a new reconstruction of summer sea‐surface salinity (SSS) over the past 15 000 years based on a diatom record from piston core 17940, located on the northern slope of the South China Sea (SCS). The reconstructed diatom‐based summer SSS values for the modern period are in accord with instrumental observations of summer SSS in the area. Here, the modern summer SSS is primarily controlled by river runoff, in particular from the Pearl River. The reconstruction presented in this study shows that the summer SSS varied between 33.3 and 34.2 psu over the past 15 000 years. The long‐term summer SSS trend closely followed the trend of the orbitally controlled solar insolation at 20°N, suggesting that orbital forcing was the dominant driver of changes in summer SSS in this area. Comparisons to speleothem δ¹⁸O data and studies of surface hydrography in the region suggest that changes in solar insolation affected the summer SSS through changes in the East Asian Monsoon and sea‐level changes associated with the last deglaciation. Univariate spectral analyses indicate that centennial‐scale oscillatory variations in summer SSS were superimposed on the long‐term trend. During the deglacial period (c. 12 000–9000 cal. a BP), the dominant periodicity was centred around 230–250 years, whereas a ～350‐year oscillation dominated in the period 2200–4500 cal. a BP. The balance of evidence suggests that these centennial‐scale changes in summer SSS may have been driven by solar‐induced changes in the East Asian Monsoon, but further evidence is needed to firmly establish this relationship.  相似文献   

Investigations into the thermal non-equilibrium of W UMa-type contact binaries     

Xiao Xiong  Liang Liu  Sheng-Bang Qian 《天文和天体物理学研究(英文版)》2018,(5)

Traditionally, some physical details(e.g., magnetic braking, energy transfer, angular momentum loss, etc.) have to be taken into consideration during investigations into the evolution of contact binaries. However, the real evolutionary processes which usually contain several of these physical mechanisms are very complicated as a result of strong interaction between components. To avoid dealing with these factors, a linear relationship is applied to the temperatures of components. It is found that the higher the mass ratio(M_2/M_1) of a contact system, the weaker the deviation from thermal equilibrium.On this basis, a variation trend of fill-out factor(f) changing with mass ratio can be inferred, which is consistent with observations. Moreover, if we stick to this point of view, it should be natural that the number of semi-detached binaries in the predicted broken-contact phase of relaxation oscillations is less than the number in the contact phase.  相似文献   

Flotation characteristics of two different types of ilmenite with sodium oleate     

Zhang Jie  Liu Weijun  Wang Weiqing  Xiong shuqing  Wang dezhi  Yan Wu  Deng Jie 《Mineralogy and Petrology》2015,109(3):299-306

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Landform‐oriented flow‐routing algorithm for the dual‐structure loess terrain based on digital elevation models          下载免费PDF全文

Liyang Xiong  Guoan Tang  Shijiang Yan  Shijie Zhu  Yiying Sun 《水文研究》2014,28(4):1756-1766

The loess landform in the Loess Plateau of China is with typical dual structure, namely, the upper smooth positive terrain and the lower cliffy negative terrain (P–N terrain for short). Obvious differences in their morphological feature, geomorphological mechanism, and hydrological process could be found in the both areas. Based on the differences, a flow‐routing algorithm that separately addresses the dual‐structure terrain would be necessary to encompass this spatial variation in their hydrological behaviour. This paper proposes a mixed flow‐routing algorithm to address aforementioned problems. First, the loess landform surface is divided into P–N terrains based on digital elevation models. Then, specific catchment area is calculated with the new algorithm to simulate the water flows in both positive and negative terrain areas. The mixed algorithm consists of the multiple flow‐routing algorithm (multiple‐flow direction) for positive areas and the D8 algorithm for negative areas, respectively. The approach is validated in two typical geomorphologic areas with low hills and dense gullies in the northern Shaanxi Loess Plateau. Four indices are used to examine the results, which show that the new algorithm is more suitable for loess terrain in simulating the spatial distribution of water accumulation, as well as in modeling the flow characteristics of the true surface by considering the morphological structures of the terrain. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

中尺度暖涡对热带气旋强度变化的影响及作用机制   总被引：1，自引：0，他引：1  

孙佳  王桂华  熊学军  回贞立  胡筱敏  凌征  于龙  杨光兵  郭延良  鞠霞  陈亮 《海洋学报(英文版)》2020,39(8):1-2

基于两组理想化数值试验，对比研究了分布于热带气旋不同位置处的海洋中尺度暖涡所引发的热带气旋强度变化的时空特征。研究发现，热带气旋中心附近的暖涡对热带气旋强度有增强作用，而位于热带气旋外围的暖涡则会抑制热带气旋的发展。本研究将暖涡增强（减弱）热带气旋强度的区域称为内（外）区。随着时间的推移，内（外）区暖涡对热带气旋强度的增强（减弱）幅度逐渐减小（增大），区域范围同步减小（增大）。内区暖涡增强了热带气旋的次级环流和结构对称性、增加了海气界面热通量，同时减弱了外围螺旋雨带，进而导致热带气旋强度增强；若暖涡在外区，其对热带气旋的作用相反，导致热带气旋强度减弱。由于理想化试验中热带气旋静止不动，因此研究结果可能只适用于传播速度较慢的热带气旋。本研究结果有助于更好地理解热带气旋和海洋中尺度暖涡之间的相互作用，并通过引入热带气旋外区暖涡的影响助力提高热带气旋强度预报工作。  相似文献   

印度暴力袭击事件的时空演变及其驱动机制     

曾卓  熊理然  蒋梅英 《热带地理》2019,39(6):869-879

基于全球恐怖主义数据库（GTD）和南亚恐怖主义门户网站（SATP）所收录的印度暴力袭击事件数据,借助统计分析和核密度分析法,对1980—2017年印度暴力袭击事件时空演变及其驱动机制进行分析。结果表明：印度国内的暴力袭击事件频发,1980年以来呈现出波动上升态势。从空间上看,印度国内的暴力袭击事件具有自西到东、从北到南以及由边境地区向内地发展的扩散特点,展现出局部集中、面上扩散的发展趋势;呈现出以西北部的查馍-克什米尔地区和旁遮普邦、东北部的阿萨姆邦和曼尼普尔邦、中部的恰蒂斯格尔邦和东部的贾坎德邦、比哈尔邦和西孟加拉邦为主的四大集聚中心;形成以印度河上游—恒河—布拉马普特拉河一线为横轴,东高止山脉及其北部山区为纵轴的“T”字形空间格局。印度暴力袭击事件的时空演变受到身份认同、经济问题、历史问题和利益诉求等多方面因素的影响,通过宗教极端主义组织、民族分离主义组织、武装革命主义组织推动以及行动主体之间的互相作用,推动了暴力袭击事件的时空演变。要从根本上解决印度国内暴力袭击事件频发的态势,需要从政治、经济、宗教、社会等多方面进行综合施策。  相似文献