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991.
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
992.
993.
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
994.
995.
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
996.
Geocentre motion from the DORIS space system and laser data to the Lageos satellites: comparison with surface loading data 总被引:3,自引:0,他引:3
F. Bouillé A. Cazenave J. M. Lemoine J. F. Crétaux 《Geophysical Journal International》2000,143(1):71-82
Surface mass redistribution within the Earth system, especially in the atmosphere, oceans, continents and ice sheets, causes the position of the centre of mass to vary in a reference frame attached to the solid Earth. Space techniques are now precise enough to measure the centre of mass motion. Here we present a determination of the centre of mass coordinates at regular monthly intervals using DORIS data on SPOT‐2, SPOT‐3 and Topex–Poseidon (1993–1997) and laser data on Lageos‐1 and Lageos‐2 (1993–1996). The amplitude and phase of the space‐geodesy‐derived annual cycle for each coordinate are further compared to estimates based on surface mass redistribution at the Earth surface derived from various climatic data sources: surface pressure, soil moisture, snow depth and ocean mass variations. 相似文献
997.
The specific features of the generation and intensification of internal gravity wave structures in different atmospheric-ionospheric regions, caused by zonal local nonuniform winds (shear flows), are studied. The model of the medium has been explained and an initial closed system of equations has been obtained in order to study the linear and nonlinear dynamics of internal gravity waves (IGWs) when they interact with the geomagnetic field in a dissipative ionosphere (for the D, E, and F regions). 相似文献
998.
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
999.
1000.
Astronomy Letters - The formation of the rubidium resonance lines is considered by taking into account the effects of departures from local thermodynamic equilibrium (LTE). A rubidium model atom... 相似文献