Temporal stability of soil moisture in an oasis of northwestern China          下载免费PDF全文

Shuaipu Zhang  Mingan Shao 《水文研究》2017,31(15):2725-2736

Temporal stability of soil moisture has been widely used in hydrological monitoring since it emerged. However, the spatial analysis of temporal stability at the landscape scale is often limited because of insufficient sampling numbers. This work made an effort to investigate the spatial variations of temporal stability of soil moisture in an oasis landscape. The specific objectives of the study were to explore the spatial patterns of temporal stability and to determine the controlling factors of temporal stability in the desert oasis. A time series of soil moisture measurements were gathered on 23 occasions at 118 locations over 3 years in a rectangular transect of approximately 100 km². The nonparametric Spearman's rank correlation coefficient, standard deviation of relative difference (SDRD), and mean absolute bias error (MABE) were used to quantify the temporal stability of soil moisture. Results showed that the temporal stability of soil moisture was depth dependent and season dependent. The spatial pattern of soil moisture in a deep soil layer and between two same seasons generally had a high temporal stability. SDRD and MABE were spatially autocorrelated and exhibited strong spatial structures in the geographic space. The concept of temporal stability can be extended to describe the time‐stable areas of soil moisture with geostatistics. There were great differences between SDRD and MABE in describing the temporal stability of soil moisture and in identifying the controlling factors of temporal stability. In this case, MABE was a better alternative to estimate the areal mean soil moisture using representative locations than SDRD. Land use type, soil moisture condition, and soil particle composition were the dominant controls of temporal stability in the oasis. These insights could help to better understand the essence of temporal stability of soil moisture in arid regions.  相似文献   

In‐situ analysis of trace elements and Sr–Pb isotopes of K‐feldspars from Tongshankou Cu–Mo deposit,SE Hubei Province,China: Insights into early potassic alteration of the porphyry mineralization system          下载免费PDF全文

Yao‐Ming Xu  Shao‐Yong Jiang 《地学学报》2017,29(6):343-355

In the Tongshankou porphyry deposit (SE Hubei Province, South China), three types of K‐feldspars are recognized: (I) the phenocryst type in the porphyry that crystalized during the magmatic stage, (II) the megacryst type and (III) the vein type in the altered porphyry and orebody that was produced by hydrothermal fluids. A detailed in‐situ analysis of trace elements and Sr–Pb isotopes was carried out on K‐feldspars in an attempt to unravel their formation processes and to trace the element sources during potassic alteration. The Type III K‐feldspars show lower Sr contents and Sr‐isotope ratios but higher Pb contents and Pb‐isotope ratios than the Type I and II K‐feldspars, possibly reflecting a contribution from the country carbonate rocks with less radiogenic Sr but more radiogenic Pb sources, and indicate that the ore‐forming fluids and materials may have been partially derived from external sources such as the host sedimentary rocks during the early potassic alteration stage.  相似文献   

一次寒潮背景下降水相态变化特征分析   总被引：3，自引：0，他引：3  

邵宇翔  李周 《气象与环境科学》2016,39(1):89-95

利用常规气象观测资料和NCEP再分析资料,对2013年4月18日到20日河南出现的一次区域性寒潮天气过程的环流背景、影响系统及寒潮期间降水多相态转换的成因进行了分析。结果表明:本次寒潮过程属于横槽转竖型,冷锋迅速南下,导致寒潮暴发;此次寒潮天气的大气温度层结存在逆温层结构特征,温度廓线的变化会导致降水相态发生变化;受低层冷空气持续影响,暖层强度即融化层遭到一定程度的破坏或消失,冷层即冻结层强度增强,0℃层高度下降,以致降水相态发生相应的改变;降水相态的变化与暖层温度及0℃层高度密切相关。根据本次寒潮过程中NCEP再分析数据得到:当降水相态为雨时,暖层温度≥2℃,0℃层高度≤975 h Pa;当降水相态为雪时,暖层温度≤-1℃,0℃层高度≌1000 h Pa;当降水相态为冰粒时,2℃≥暖层温度≥-1℃,1000 h Pa≥0℃层高度≥975 h Pa。  相似文献   

Study on the Relationship between Large Volcanic Eruptions and Temperature Variation Based on Tree-Ring Data in the Eastern Tibetan Plateau during the Past Millennium   总被引：1，自引：0，他引：1  

Li Mingqi  Shao Xuemei 《地球科学进展》2016,31(6):634-642

Volcanic eruptions can significantly cool the global troposphere on the time scales from several months up to a decade due to reflection of solar radiation by sulfate aerosols and feedback mechanisms in the climate system. The impact of volcanic eruptions on global climate are discussed in many studies. However, few studies have been done on the impact of volcanic eruption on climate change in China in the past millennium. The 1300-year and 600-year temperature series were reconstructed based on the six tree-ring temperature proxy data in northeastern and southeastern Tibetan Plateau, respectively. Three warm periods occurred in 670-920,1000-1310 and 1590-1930, and three cold periods happened at 920-1000,1310-1590 and 1930-2000 in the northeastern Tibetan Plateau. There were two obviously warm periods (1385-1450 and 1570-1820) and two cold periods (1450-1570 and 1820-2000) in southeastern Tibetan Plateau. Contrasting with volcanic eruption chronology, we analyzed the relationship between volcanic activity and temperature variation in the eastern Tibetan plateau during the past millennium using Superposed Epoch Analysis (SEA) method. The results indicated that the temperature decreased one year after large volcanic eruptions located beteen 10°S and 10°N in latitude in northeastern Tibetan Plateau and two years in southeastern Tibetan Plateau. The volcanic eruptions occurred at different latitudes have different impacts on the temperature variations, which may be caused by regional difference, the nature of the eruption, the magnitude of the resulting change in incoming solar radiation, prevailing background climate and internal variability, season, latitude, and other considerations.  相似文献   

白缘(鱼央)5S rDNA的扩增分析及其在染色体上的FISH定位     

张伟伟  付元帅  邵燕  王宝琴  石东里  张兰 《海洋学报》2016,38(6):82-88

本文分别对雌雄白缘(鱼央)的5S rDNA进行了PCR扩增和序列分析,并采用双色荧光原位杂交(FISH)技术,以白缘(鱼央)的5S rDNA序列和小麦的45S rDNA为探针,对其在白缘(鱼央)雌雄中期染色体上进行了FISH定位研究。结果表明,白缘(鱼央)5S rDNA序列无雌雄差异;5S rDNA的保守区序列为117 bp;5S rDNA和45S rDNA分别被定位于白缘(鱼央)的性染色体和第5号染色体上。同时从GenBank中获得了22种鱼的5S rDNA,运用DNAman软件构建了23种鱼的系统发育树,对白缘(鱼央)的进化地位进行了初步研究。本研究为阐明白缘(鱼央)在鱼类系统进化中的位置、重复序列在脊椎动物性染色体上的分布状况以及与性别决定与分化的关系,提供了资料积累和分析依据。  相似文献   

深海嗜热异化铁还原菌Caloranaerobacter ferrireducens DY22619T对不同铁氧化物的铁还原特性   总被引：1，自引：0，他引：1  

李曦  曾湘  张昭  邵宗泽 《海洋学报》2016,38(8):83-92

异化铁还原微生物在铁元素的地球化学循环中具有重要意义。深海热液活动是大洋铁元素的重要来源,目前深海热液环境中铁代谢相关微生物研究很少。本文对一株分离自深海热液区的嗜热异化铁还原菌新种Caloranaerobacter ferrireducens DY22619T的铁还原特性进行分析,比较了该菌对无定形羟基氧化铁、无定形铁氧化物和针铁矿3种不同铁氧化物的铁还原速率;并利用透射电镜对矿化产物进行矿物形貌、组成元素和晶型的分析。研究发现该菌生长在指数期至稳定期时,铁还原速率最快,其中对无定形羟基氧化铁和无定形铁氧化物的还原速率较高,达2.82 μmol/h和2.15 μmol/h;透射电镜结果表明,该菌可将3种不同胞外铁氧化物均还原矿化形成颗粒状磁铁矿,由针铁矿矿化形成的磁铁矿少但粒径最大,而由无定形铁氧化物形成的磁铁矿晶面不同于另外两种铁氧化物。结果表明,该菌有很强的铁还原和矿化能力,能厌氧呼吸还原三价铁氧化物,但是铁氧化物的性质对该菌胞外铁还原能力和矿化形成的磁铁矿的性质有重要影响。本研究为认识深海热液环境中异化铁还原菌在铁元素的地球化学循环和生物成矿过程提供了参考。  相似文献   

我国海洋水下文化遗产保护现状与管理探讨          下载免费PDF全文

蔺爱军  林桂兰  董卫卫  胡毅  王立明  许江 《海洋开发与管理》2016,33(12):93-98

海洋水下文化遗产是不可再生的文化资源,在全球海洋开发的浪潮中,做好海洋水下文化遗产的调查和保护是迫切和急需的。文章概述世界上传统海洋大国对海洋水下文化遗产保护和管理的经验,分析我国海洋水下文化遗产保护和管理存在的问题,并提出相关对策:查清海洋水下文化遗产的分布、数量和特征等信息,了解海洋水下文化遗产分布区的地质地貌环境、水动力环境和保存环境条件,建立海洋水下文化遗产档案馆和数据库系统;完善与海洋水下文化遗产保护相关的法规、政策和标准规范等,提升执法效率,做好海洋水下文化遗产保护和海洋开发利用的协调工作;建立海洋水下文化遗产保护示范区,传承和弘扬蓝色文明,实现海洋水下文化遗产的社会利用和可持续保护。  相似文献   

海岸资源质量管理与海岸综合整治修复对策探讨          下载免费PDF全文

董卫卫  林桂兰  蔺爱军 《海洋开发与管理》2016,33(9):75-80

文章讨论海岸资源质量管理的计量手段,根据海岸的类型、资源功能以及自然演变和开发利用过程中出现的问题,探讨海岸资源质量管理的内涵和海岸综合整治修复的对策。建议制定《海岸线修测技术规范》,明确海岸线修测技术方法和海岸线长度计量方法,为海岸资源质量管理奠定计量基础;针对不同的海岸类型和开发利用方式,制定《海岸资源质量评价技术标准》,适应差别化的海岸管控政策;加强海岸资源综合统筹规划管理,强化海岸综合整治修复,保护自然海岸和人工海岸生态环境,修复恢复严重影响海岸生态环境和废弃的人工海岸,最大限度地保育自然海岸。  相似文献   

Identification of the “source” and “sink” patterns influencing non-point source pollution in the Three Gorges Reservoir Area   总被引：6，自引：0，他引：6  

Jinliang Wang  Jing’an Shao  Dan Wang  Jiupai Ni  Deti Xie 《地理学报(英文版)》2016,26(10):1431-1448

Non-point source pollution is one of the primarily ecological issues affecting the Three Gorges Reservoir Area. In this paper, landscape resistance and motivation coefficient, which integrated various landscape elements, such as land use, soil, hydrology, topography, and vegetation, was established based on the effects of large-scale resistance and motivation on the formation of non-point source pollution. In addition, cost models of the landscape resistance and motivation coefficients were constructed based on the distances from the landscape units to the sub-basin outlets in order to identify the “source” and “sink” patterns affecting the formation of non-point source pollution. The results indicated that the changes in the landscape resistance and motivation coefficients of the 16 sub-basins exhibited inverse relationships to their spatial distributions. The landscape resistance and motivation cost curves were more volatile than the landscape resistance and motivation coefficient curves. The landscape resistance and motivation cost trends of the 16 sub-basins became increasingly apparent along the flow of the Yangtze River. The landscape resistance and motivation cost models proposed in this paper could be used to identify large-scale non-point source pollution “source” and “sink” patterns. Moreover, the proposed model could be used to describe the large-scale spatial characteristics of non-point source pollution formation based on “source” and “sink” landscape pattern indices, spatial localization, and landscape resistance and motivation coefficients.  相似文献   

Cloud Forest Conservation in the Central Highlands of Guatemala Hinges on Soil Conservation and Intensifying Food Production     

Ian Pope  Jon Harbor  Laura Zanotti  Guofan Shao  Dawn Bowen  Gary R. Burniske 《The Professional geographer》2016,68(1):1-13

Soil erosion threatens long-term soil fertility and food production in Q’eqchi’ communities native to the Sierra Yalijux and Sierra Sacranix mountain ranges in the central highlands of Guatemala. Environmental factors such as steep topography, erodible soils, and intense precipitation events, combined with land subdivision and reduced fallow periods as a consequence of population growth, contribute to severe erosion and strain soil resources. The preservation of the region's cloud forests hinges on enhancing production of staple crops through agricultural intensification while maintaining soil fertility through implementation of soil conservation measures.  相似文献