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131.
132.
毛乌素沙地西南缘灌丛沙丘沉积物的粒度和元素特征 总被引:2,自引:4,他引:2
对毛乌素沙地白刺(Nitraria tangutorum)灌丛沙丘沉积物粒度和元素特征进行了采样分析.结果表明:灌丛沙丘沉积物来源单一,几乎全部由丘间地物质组成,其粒度和元素特征与丘间地物质极其相似;相对而言,灌丛沙丘沉积物比丘间地物质含有更多粗颗粒物,主要因丘间地可做跃移运动的中沙和细沙更易被灌丛阻挡而堆积;灌丛沙丘沉积物中大部分元素含量比丘间地物质低,主要因这些元素易被淋溶迁移到丘间地富集;灌丛沙丘发育以来,虽然其沉积环境存在波动,但相对稳定,未发生过显著变化. 相似文献
133.
基于敏感性-稳定性-响应3维要素构建指标体系,运用熵值法和ARIMA-BP组合预测模型研究中国人海经济系统环境适应性的演化及预警。结果表明:① 2001~2016年中国人海经济系统环境适应性呈稳定上升态势,总体集中于中警状态,期间经历了“人海环境系统比较优势阶段→耦合协调阶段→人海经济系统比较优势阶段”的双螺旋适应过程,预计2017~2020年再次进入相互契合的轻警状态;② 16 a间中国人海经济系统环境适应性波动存在上升期短-衰退期长现象,预计未来4 a人海经济系统环境适应性在经济下行和生态约束背景下的速率不容乐观;③ 权衡人海经济系统和人海环境系统的关系,追求总体效益最大化,延长适应性周期波动中扩张期活动,差别化和灵活性的适应行为是未来主要排警对策。 相似文献
134.
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
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
135.
Based on the NCEP (National Centers for Environmental Prediction) data, the relationship between the Sea Surface Temperature
Anomalies (SSTAs) in the North Pacific and the atmospheric circulation anomalies in January 2008 is analyzed in this study.
The SSTA mode most correlated with the Geopotential Height anomalies (GHAs) in January 2008 in the North Pacific exhibited
a basin-wide horseshoe pattern with a warm center in November 2007. This persistent SSTA pattern would induce positive GHAs
in the Aleutian Low area and East Asia and the northward extension of the West Pacific Subtropical High in January 2008 by
maximum diabatic heating in the atmosphere over the Kuroshio Oyashio Extension (KOE) area, leading to the occurence of the
circumpolar trough-ridge wave train anomaly in January 2008. 相似文献
136.
Marina Hruška William Corea Donald Seeburger William Schweller William H. Crane 《Mathematical Geosciences》2009,41(6):703-716
We describe a wavelet-transform-based method for automated segmentation of resistivity image logs that takes into account
the apparent dip in the data and addresses the problem of discriminating lithofacies boundaries from noise and intrafacies
variations. Our method can be applied to borehole measurements in general, but might have an advantage when applied to resistivity
image logs as it addresses explicitly the large variability in facies segments recorded with a high-resolution multiple-sensor
tool. We have developed an algorithm based on this method that might outperform other existing segmentation methods in the
cases of low to moderate dip. We made a detailed comparison of the segmentation from our method with the one done by a geologist
to delineate different lithofacies blocks in a well drilled in a deepwater depositional environment. Our results show considerable
success rates in reproducing the geologically defined lithofacies boundaries, and the generality of our procedure suggests
it could also be applied to other depositional environments. 相似文献
137.
ZHENG Xiaodong XIAO Shu WANG Zhaoping WANG Rucai 《中国海洋大学学报(英文版)》2007,6(4):393-397
The secretion function of mantle is closely related to shell formation in some bivalves and gastropods. Up to now, few researches have been reported for cuttlebone formation in the class Cephalopoda. In this study, the structure and secretion function of cuttlebone sac of the golden cuttlefish Sepia esculenta was analyzed using the histological and histochemical methods. The results showed that high and columnar cells located in sac epithelium, and flat cells existed near the base membrane. A lot of fibroblasts were found in the lateral mantle collective tissue. Some mucus, mucopolysaccharide and alkaline phosphatase (ALP) were found in the sac. The ultrastructural characteristics of Quasi-connective-tissue-calcium cells (QCTCC) were observed using a transmission electron microscope (TEM). The relationship between cuttlebone sac secretion function and shell formation was discussed. 相似文献
138.
The geomorphological environment is one of the most fundamental variables af-fecting the development of human society.The mission of geomorphological environment research is to explore the most basic environment and features of our Earth’s surface mor-phology.The results can be applied to resource evaluation,environmental protection and reducing and preventing geological disasters.Thus,it can serve to help achieve sustainable development.This paper examines the Shenzhen east coastal zone as a case strongly in-fluenced by urban expansion.We use modern geomorphological theory and methods,along with GIS and RS techniques,to reveal key characteristics of the geomorphological environ-ment and landform classification.Furthermore,coastal ecosystem evaluation and regional resources sustainable utilization should be considered relative to the corresponding geo-morphological environment.Based on this study,we conclude that modern geomorphological theory and methods,supported by "3S" techniques including GIS,RS and GPS,can play an important role in resolving the environment,resources and population problems as well as sustainable development challenges facing humankind at present. 相似文献
139.
Xingping Wen Xiaofeng Yang Guangdao Hu 《Journal of the Indian Society of Remote Sensing》2011,39(2):193-201
Urban heat island (UHI) effect has a close relation to land covers type. This paper investigates the relationship between
land cover ratio and UHI in Guangzhou, south of China using remote sensing and automatic weather stations data. The temperature
data were obtained by Automatic weather stations (AWS) of Guangzhou in October, 2004, at the same time with the CBERS remote
sensing image acquired. Firstly, the hourly mean temperature was computed from hourly AWS data. Secondly, the CBERS remote
sensing image was classified using support vector machine (SVM) and land covers classification were output. Thirdly, the classification
result was overlapped with a round buffer with 1.5 KM radius centered on the AWS, and then the land cover ratio, Edge Density
(ED) and Mean Fractal Dimension (MFRACT) of buffers were computed out. Finally, the correlation coefficient between hourly
mean temperature and land cover ratio, ED and MFRACT was calculated. It concluded that UHI intensity was heavier during nighttime
than daytime. Stations with higher vegetation ratio and higher ED had lower heat island effect. On the contrary, stations
with higher impervious ratio and lower ED had more serious heat island effect. The positive–negative of correlation coefficient
between hourly mean temperature and vegetation ratio during 11:00–17:00 h (local time) was opposite to that during other time.
ED was negatively correlated with hourly mean temperature except during 11:00–17:00 h. On the contrary, MFRACT was positively
correlated with hourly mean temperature. It implied that fragmentations of patches were favorable to UHI alleviation, and
complexities of patch were unfavorable factors. 相似文献
140.
Temporal and spatial dynamical simulation of groundwater characteristics in Minqin Oasis 总被引:3,自引:0,他引:3
XIAO DuNing LI XiaoYu ? SONG DongMei & YANG GuoJing Cold Arid Regions Environmental Engineering Research Institute Chinese Academy of Sciences Lanzhou China Institute of Applied Ecology Chinese Academy of Sciences Shenyang China Institute of Geographic Sciences Natural Resources Research Chinese Academy of Sciences Beijing China 《中国科学D辑(英文版)》2007,50(2):261-273
Application scope of geostatistics has been gradually extended from original geologic field to soil science and ecological field, etc. and its successful application results have been widely demonstrated. But little information is reported as to the direct use of geostatistical method to work out the distribu- tion map of groundwater characteristics. In this paper the semivariogram of geostatistics, in combina- tion with GIS, was used to quantitatively study the spatial variation characteristics of groundwater table depth and mineralization degree and their relation to the landuse changes. F test of the used spherical model reached a very significant level, and the theoretical model can well reflect the spatial structural characteristics of groundwater table depth and mineralization degree and achieve an ideal result. This shows that the application of the method in the dynamical simulation of groundwater is feasible. And this paper also provides useful reference for the application of geostatistics in the study of the dy- namical variations of groundwater resources in the oasis. 相似文献