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951.
The population and distribution of carbon-oxidizing and sulfate-reducing bacteria in the soils of the Mozhaisk Reservoir are studied. 相似文献
952.
The evolution of views and practical decisions regarding the problem of collecting payment for the use of surface waters with regard to their quality in the former USSR and present-day Ukraine is discussed. A simple and feasible method is proposed for differentitation of regional (basin) rates of payment for the use of surface water in Ukraine with allowance made for its quality assessed based on a system of environmental classifications. 相似文献
953.
954.
Susanne I. Schmidt Hans J. Hahn Gerald D. Watson Robert J. Woodbury Thomas J. Hatton 《洁净——土壤、空气、水》2004,32(2):131-137
Groundwater bores act as traps. Net samplers are regularly used for sampling this type of trap for fauna. To enable direct comparisons of faunal communities in groundwater bores and stream sediments, stream sediment tubes were built similar to groundwater bores and were sampled with net samplers for fauna. These stream sediment tubes consisted of a tube anchored in the stream sediment, also called interstitial space. To test the efficacy of this trap method in stream sediments, it was compared to another type of trap, Hahn's trap. Faunal communities sampled by a net in the stream sediment tubes did not differ hugely from fauna in Hahn's trap samples. Physical and chemical factors of sampled water in both the stream sediment tubes, the surrounding interstitial sediments and the second type of traps, Hahn's traps, showed that water in both the tubes and Hahn's traps was closely related to interstitial water. The net sampler is inexpensive and easy to handle. It is suggested that sampling stream tubes with nets may be an appropriate method for long‐term monitoring studies. 相似文献
955.
The present paper focuses on land cover dynamics pattern in Balkhila sub-watershed situated in Garhwal Himalayas. This study
contributes example from human shaped ecosystem in mountainous regions where fragmentation of natural resources is active.
The remote sensing and GIS has been used to understand the land cover dynamics along the topography. The results report that
the land cover dynamics is dependent on the aspect due to sun illumination. The altitude and slope are no more a barrier for
resource extraction and the human activity zone is shifting towards higher altitudes and slopes. The changes are also defined
along the road and settlements. 相似文献
956.
The most important advantage of the low resolution National Oceanic and Atmospheric Administration’s Advanced Very High Resolution
Radiometer (NOAA AVHRR) data is its high temporal frequency and high radiometric sensitivity which helps in vegetation detection
in the visible and near-infrared spectral regions. In areas where most of the crop cultivation is in large contiguous areas,
and if the AVHRR data are selected for time period such that the crop of interest is well discriminated from other crops,
these data can be used for monitoring vegetative growth and condition very effectively. The present study deals with the application
of AVHRR data for the monitoring of the wheat crop in its seventeen main growing districts of the Rajasthan state. The fourteen
date AVHRR data covering the entire growth period have been used to generate the normalized difference vegetation index (NDV1)
growth profile for the crop by masking the non-crop pixels following the two-date NDVI change method. The growth profile parameters
and other derived parameters, such as post-anthesis senescence rate and areas under the entire growth profile or under selected
growth periods have been related to the district average wheat yield through statistical regression models. Various methods
adopted for wheat pixels masking have been critically evaluated. It is found that the wheat yield can be predicted well by
the area under the profile in different growth periods. 相似文献
957.
R. Ramakrishnan S. Manthira Moorthi N. Padmanabhan P. Gupta 《Journal of the Indian Society of Remote Sensing》2004,32(1):103-111
Panchromatic data of pixel resolution 5.8 m obtained from IRS-1C and IRS-1D satellites proved to be very useful for mapping
purposes. One of the popular data product is the 70 km swath mosaic which is covered by a combination of 3 CCD line sensors,
each with 4096 pixels. Each CCD-line sensor with different imaging times causes geometric problems of mosaicing three strips
data together. In this paper, we propose the details of the design elements of system that caters to the need for accurate
and automatic multi strip image registration without any second resampling of the data. The systematic geometric correction
grid mapping is improved to facilitate accurate mosaicing by automatic image registration task that makes use of the overlap
data within image strips and image registration is achieved up to sub-pixel level. 相似文献
958.
A portable narrowband spectroradiometer was used to detect sclerotinia stem rot infection, caused by the fungus Sclerotinia sclerotiorum in soybeans. Increasing levels of fungal inoculum were used to cause a gradient of disease infection in the field. Canopy reflectance measured in narrowband R/sub 675/-R/sub 685/ and broadband R/sub 635/-R/sub 685/ could estimate 86% of the variation in soybean plants damage measured by a count of early dead plants. Plant damage was also associated with the chlorophyll absorption in reflectance and the normalized pigment chlorophyll vegetation indexes, showing a loss of chlorophyll pigment compared to healthy plants. A new field approach is suggested for the investigation of plant damage with narrowband spectroradiometry. 相似文献
959.
In this study, a capillary barrier system was designed and tested for an arid land environment. To simulate arid land conditions
of high temperature and sub-irrigation systems, the barrier was subjected to thermal and hydraulic gradients in opposite directions;
to test the barrier system under these severe conditions, an experimental apparatus was designed and fabricated. The multilayer
capillary barrier consisted of three layers made of silica sand, a mixture of sand and bentonite in equal portions, and a
mixture of clay (25%) and aggregate (75%). Several one dimensional coupled heat and moisture tests were performed. Temperature
variations along the thickness of the barrier were recorded as a function of time, and at the end of each test, the barrier
was sliced into small sections, for the determination of volumetric water content as a function of distance from the heat
source. The experimental results were discussed in view of the barrier's intended purpose of its ability to store moisture
for long time durations.
Coupled heat and moisture flow equations were developed and solved numerically via a finite difference method. Diffusivity
parameters were calculated by using experimental results, a numerical model, and Powell's conjugate directions method of nonlinear
optimization. The model was calibrated and the results were discussed. Good agreement between calculated and experimental
results was obtained.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
960.
Isotope provinces, mechanisms of generation and sources of the continental crust in the Central Asian mobile belt: geological and isotopic evidence 总被引:17,自引:0,他引:17
V. I. Kovalenko V. V. Yarmolyuk V. P. Kovach A. B. Kotov I. K. Kozakov E. B. Salnikova A. M. Larin 《Journal of Asian Earth Sciences》2004,23(5):605-627
The available geological, geochronological and isotopic data on the felsic magmatic and related rocks from South Siberia, Transbaikalia and Mongolia are summarized to improve our understanding of the mechanisms and processes of the Phanerozoic crustal growth in the Central Asian mobile belt (CAMB). The following isotope provinces have been recognised: ‘Precambrian’ (TDM=3.3–2.9 and 2.5–0.9 Ga) at the microcontinental blocks, ‘Caledonian’ (TDM=1.1–0.55 Ga), ‘Hercynian’ (TDM=0.8–0.5 Ma) and ‘Indosinian’ (TDM=0.3 Ga) that coincide with coeval tectonic zones and formed at 570–475, 420–320 and 310–220 Ma. Continental crust of the microcontinents is underlain by, or intermixed with, ‘juvenile’ crust as evidenced by its isotopic heterogeneity. The continental crust of the Caledonian, Hercynian and Indosinian provinces is isotopically homogeneous and was produced from respective juvenile sources with addition of old crustal material in the island arcs or active continental margin environments. The crustal growth in the CAMB had episodic character and important crust-forming events took place in the Phanerozoic. Formation of the CAMB was connected with break up of the Rodinia supercontinent in consequence of creation of the South-Pacific hot superplume. Intraplate magmatism preceding and accompanying permanently other magmatic activity in the CAMB was caused by influence of the long-term South-Pacific plume or the Asian plume damping since the Devonian. 相似文献