Effects of water quality of the basin caused by nitrogen loss from soil in drought     

B. B. Huang  D. H. Yan  H. Wang  B. F. Cheng  X. H. Cui 《Natural Hazards》2015,75(3):2357-2368

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Erratum to: Sudden surface collapse disasters caused by shallow partial mining in Datong coalfield,China     

Ximin Cui  Yongge Gao  Debao Yuan 《Natural Hazards》2015,75(1):1005-1005

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Experimental and Numerical Study on the Bubble Dynamics near Two-Connected Walls with An Obtuse Angle     

Li  Shi-min  Cui  Pu  Zhang  Shuai  Liu  Wen-tao  Peng  Yu-xiang 《中国海洋工程》2020,34(6):828-839

China Ocean Engineering - This study is concerned with the dynamic characteristics of bubbles near two connected walls (one horizontal and the other inclined with an obtuse angle from the...  相似文献   

Exploring the interaction of surface roughness and slope gradient in controlling rates of soil loss from sloping farmland on the Loess Plateau of China     

Taotao Li  Longshan Zhao  Hongteng Duan  Yifan Yang  Yu Wang  Faqi Wu 《水文研究》2020,34(2):339-354

Surface roughness and slope gradient are two important factors influencing soil erosion. The objective of this study was to investigate the interaction of surface roughness and slope gradient in controlling soil loss from sloping farmland due to water erosion on the Loess Plateau, China. Following the surface features of sloping farmland in the plateau region, we manually prepared rough surfaces using four tillage practices (contour drilling, artificial digging, manual hoeing, and contour plowing), with a smooth surface as the control measure. Five slope gradients (3°, 5°, 10°, 15°, and 20°) and two rainfall intensities (60 and 90 mm/hr) were considered in the artificial rainfall simulation experiment. The results showed that the runoff volume and sediment yield increased with increasing slope gradient under the same tillage treatment. At gentle slope gradients (e.g., 3° and 5°), the increase in surface roughness prevented the runoff and sediment production, that is, the surface roughness reduced the positive effect of slope gradient on the runoff volume and sediment yield to a certain extent. At steep slope gradients, however, the enhancing effect of slope gradient on soil erosion gradually increased and surpassed the reduction effect of surface roughness. This study reveals the existence of a critical slope gradient that influences the interaction of surface roughness and slope gradient in controlling soil erosion on sloping farmland. If the slope gradient is equal to or less than the critical value, an increase in surface roughness would decrease soil erosion. Otherwise, the increase in surface roughness would be ineffective for preventing soil erosion. The critical slope gradient would be smaller under higher rainfall intensity. These findings are helpful for us to understand the process of soil erosion and relevant for supporting soil and water conservation in the Loess Plateau region of China.  相似文献   

Spatial and temporal variations of albedo on nine glaciers in western China from 2000 to 2011          下载免费PDF全文

Jie Wang  Baisheng Ye  Yuhuan Cui  Xiaobo He  Guojing Yang 《水文研究》2014,28(9):3454-3465

This research demonstrates the spatiotemporal variations of albedo on nine glaciers in western China during 2000–2011, by the albedo derived from two types of datasets: Landsat TM/ETM + images and MOD10A1 product. Then, the influence factors of glacier albedo and its relationship with glacier mass balance are also analyzed by the correlation approach, which is frequently used in geostatistics. The paper finds that there are different spatiotemporal variations over the glaciers in western China: (1) For a single glacier, the albedo varies gently with altitude on its tongue and increases fast in the middle part, while in the accumulation zones, the albedo value appears in the form of fluctuation. This could provide a quantitative method to retrieve the snowline by determining the threshold albedo value of snowpack and bare ice. (2) For the glaciers in western China, the albedo decreases with distance to the center of Tibetan Plateau (TP). This may relate to the elevation of glacier, for the speed of glacier retreat highly depends on air temperature. (3) In the summer period, albedo on most glaciers declines over the last 12 years, and it decreases much faster in southeastern TP than other regions, for which air temperature overwhelms the black carbon concentration. In addition, the trend of glacier albedo in summer is greatly correlated with that of measured glacier mass balance, which implies that the long‐term albedo datasets by remote sensing technology could be used to monitor and predict the change of glacier mass balance in the future. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Pattern and chronology of glacial Lake Peace shorelines and implications for isostacy and ice‐sheet configuration in northeastern British Columbia,Canada          下载免费PDF全文

Adrian S. Hickin  Olav B. Lian  Victor M. Levson  Yao Cui 《Boreas: An International Journal of Quaternary Research》2015,44(2):288-304

Recognition of positions of glacial lakes along the margin of continental ice sheets is critical in reconstructing ice configuration during deglaciation. Advances in remote sensing technology (e.g. LiDAR) have enabled the generation of accurate digital‐elevation models (DEMs) that reveal unprecedented geomorphic detail. Combined with geographical information systems, these tools have considerably advanced the mapping and correlation of geomorphic features such as relict shorelines. Shorelines of glacial Lake Peace (GLP) developed between the Laurentide and Cordilleran ice sheets in northeastern British Columbia and northwestern Alberta. Shoreline mapping from high resolution DEMs produced more than 55 500 elevation data points from 3231 shorelines, enabling the identification of four major phases of GLP: Phase I (altitude 960–990 m a.s.l.); Phase II (890–915 m a.s.l.); Phase III (810–865 m a.s.l.); and Phase IV (724–733 m a.s.l.). The timing of Phase II of GLP is estimated by two optical ages of <16.0±2.5 and 14.2±0.5 ka BP. Extensive mapping of the shorelines allows for measuring of glacial isostatic adjustment as ice retreated. Shorelines currently dip to the northeast at around 0.4–0.5 m km^?1. This slope reflects the asynchronous retreat of the Cordilleran (CIS) and Laurentide (LIS) ice sheets. The relative uplift in the southwest of the study area within the Rocky Mountains and foothills suggests that the Late Wisconsinan (MIS 2) CIS persisted in the foothill after the LIS lost mass and retreated, or that the Late Wisconsinan CIS was very thick and caused deep crustal loading, which resulted in more uplift in the southwest before reaching equilibrium during, or shortly after deglaciation.  相似文献   

胶州湾沉积物中石油降解菌的降解能力及多样性研究     

高伟  高祥兴  米铁柱  韩彬  张毅然  李馨子  尹晓斐  孙承君  李倩  崔志松  栾晓  于志刚  郑立 《海洋学报(英文版)》2019,38(6):54-64

2013年青岛输油管道爆炸，大量石油污染了附近海岸。课题组采集了污染的沉积物样品，以原油为唯一碳源和能源，富集了四个石油降解菌群。生物多样性和群落分析表明，Luteibacter、Parvibaculum 和属于食烷菌科的一个属是降解菌群的主要优势菌，都属于变形菌门。从石油降解菌群中分离筛选，获得了9株具有不同16S rRNA基因序列的降解菌，分别属于8个属。重量法测定降解菌的石油降解率，其中5株的石油降解率大于30%。GC-MS分析结果表明，石油降解菌多倾向于降解烷烃，对多环芳烃的降解能力较差，其中5株细菌的烷烃降解率较大，仅1株菌D2对多环芳烃的降解率较大，其降解率在34.9%到77.5%。通过对高通量数据的分析，表明食烷菌属是菌群A和菌群E的主要降解菌群，其中筛选获得的菌株E4可能是菌群E的一株优势降解菌。本研究所筛选菌株证明了其石油降解潜力，为油污染海滩生物修复提供了菌株资源。  相似文献   

L1范数与IQR统计量组合的GNSS坐标序列粗差探测算法     

明锋  曾安敏  景一帆 《测绘科学技术学报》2016,(2):127-132

GNSS坐标时间序列中不可避免地含有粗差,未剔除的粗差将会导致参数估计有偏。因此,粗差探测与剔除是GNSS坐标序列分析中一项重要的数据预处理工作。针对GNSS坐标时间序列特点,提出了一种将L1范数(L1-norm)估计与四分位距统计量IQR(interquartile range)组合的移动开窗粗差探测算法,称之为L1_Mod IQR。该方法的主要思想是,首先利用L1范数估计得到较"真实"的残差,然后再对残差采用IQR统计量进行粗差探测。将L1_Mod IQR法与"3σ"法、基于最小二乘的τ检验法等粗差探测算法进行了模拟计算与对比,验证了该算法的有效性。进一步采用L1_Mod IQR算法对中国区域10个IGS站的高程时间序列进行了分析,结果表明中国区域IGS站高程序列的粗差剔除率最小为0.1%,最大为2.6%。并且以WUHN站为例与SOPAC提供的结果进行了对比,结果表明SOPAC提供的"Clean"数据仍含有大量的粗差,而L1_Mod IQR算法能够有效地剔除粗差。  相似文献   

GNSS相应坐标系之间的关系及其影响     

曾安敏  杨元喜  明锋  景一帆 《测绘科学技术学报》2016,(6):551-556

不同的GNSS采用的坐标系定义几乎相近,但参考椭球及其坐标实现不同,这将影响多GNSS融合导航定位效果。根据各GNSS坐标系所采用参考椭球的基本常数,计算比较了不同坐标系参考椭球参数的差异;导出了相应的正常重力公式,比较了这些正常重力公式确定的正常重力值差异;最后分别从坐标系统的定义与实现两个方面分析了其对定位结果的影响。结果表明:1)GPS(BDS)与Galileo和GLONASS所使用的参考椭球引起正常重力差约为0.15和0.30 mgal;2)GPS与BDS,Galileo及GLONASS所使用参考椭球引起纬度分量最大差异约为0.1 mm,3 cm和3 cm,高程分量约为0.1 mm,0.5 m和1 m;3)各GNSS所使用坐标框架间转换参数引起的坐标变化达到厘米级。  相似文献   

X射线荧光光谱-电子探针在中酸性火山岩鉴定中的应用   总被引：2，自引：1，他引：1  

徐翠  李林庆  张洁  何丽  张桂凤  王艳龙 《岩矿测试》2016,35(6):626-633

中酸性火山岩多具斑状结构,基质可见微晶状结构、隐晶状结构、玻璃质结构等,由于基质矿物颗粒多细小,常用的偏光显微镜受放大倍数的限制,很难准确鉴定矿物种属及含量,这类岩石仅依靠偏光显微镜分类命名会存在误差。本文采用X射线荧光光谱(XRF)、电子探针(EMPA)和偏光显微镜下观察相结合的方法,对中酸性火山岩进行鉴定。结果表明:对于基质呈隐晶质、显微晶质的中酸性火山岩,基质特征相似,偏光显微镜下无法确定长石、石英的含量,因此无法对岩石准确命名;再通过XRF进行主量元素分析,并对分析结果进行标准矿物QAPF双三角图解分类、TAS图解分类及李氏火山岩定量分类,对比结果显示三种分类命名方法存在差异;通过电子探针对矿物进行校验显示,QAPF及李氏火山岩定量分类图解与显微镜下鉴定相符,TAS图解与其他分析结果存在一定偏差。因此,对于中酸性火山岩准确命名,应采用多种分析方法相结合的方式,避免测试单一引起的误差。  相似文献