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141.
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   
142.
冬小麦遥感冠层温度监测土壤含水量的试验研究   总被引:7,自引:0,他引:7       下载免费PDF全文
在冬小麦主要生育期(2002年4月初到5月底),对不灌溉的冬小麦测定了冠层温度、地温、气温以及土壤含水量,计算了冠气温差且分析了冠层温度和冠气温差与不同土层厚度的土壤含水量相关关系。结果表明:14:00的冠层温度能较好地反映20cm土层的土壤含水量变化,但与其它各土层相关性有较大的波动性;14:00的冠气温差能较好地反映40cm以上土层的土壤含水量变化,二者的相关性很高,在20cm、40cm土层,两者相关系数R2分别为0.98866、0.99389,这为用区域遥感数据反演主要生育期冬小麦的冠气温差进而监测区域40cm土壤含水量提供了实验性的依据;拔节期和灌浆期,用14:00冠气温差来拟合各土壤层的土壤含水量有较高的精度,从而为用区域遥感数据监测区域土壤含水量提供了经验性的模型。  相似文献   
143.
Sequential aerial photography, sonar bathymetry, ground-penetrating radar (GPR), and sediment sampling and analysis provide the basis for calculating the volumetric and mass rate of progradation of the delta of Fitzsimmons Creek, a steep, high-energy, debris-flow-dominated channel draining about 100 km2 of the southern Coast Mountains of British Columbia. Fitzsimmons Creek is typical of small mountain rivers in the region. GPR imaging is used to define the pre-depositional morphology of the receiving basin, a technique that improves the accuracy of the volumetric survey. The 52-year record (1947–1999) of progradation yielded an average annual volumetric transport rate of 1.00±0.16×104 m3 year−1 for bed load, corresponding to a mass transport rate of 1.60±0.28×104 Mg year−1. Bed load yields are consistent with those obtained in hydrogeomorphically similar basins in the region and elsewhere. Decade-based annual rates, which vary from 0.64±0.11×104 to 2.85±0.38×104 Mg year−1, provide poor estimates of the 52-year average. Indeed, the 52-year record may also not be long enough to fully integrate the significant fluctuations in the sediment efflux from Fitzsimmons Creek. The methodology proposed in this paper can be transferred to other comparable mountain environments worldwide.  相似文献   
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Volcanic aerosol emissions have been studied for the first time by in situ photoelectric charging. Explorative studies on Mt Etna reveal large concentrations of particles below 1000 nm with the spectrum peaking in the size range of 100–1000 nm diameter. Although a large fraction of the particles is already charged upon emission, the net electrical charge carried by the aerosol turned out to be close to zero.Particles with high photoelectric yield vary greatly in their relative abundance and seem to occur mainly at active points of the volcano.  相似文献   
150.
Authigenic iron and titanium oxides occur in three main textural varieties in the St. Bees Sandstone, a Triassic red bed succession in Cumbria. These are: (a) overgrowths of haematite, titaniferous haematite, anatase, and rutile which generally occur on detrital host grains of similar compositions. The overgrowths may occur as syntaxial rim cements or rhombohedral and prismatic projections and are always in optical continuity, (b) discrete crystals of anatase (including octahedrite) and haematite 10-40 μm in size occur in pore spaces, and (c) fine grained ( < 1 μm) pigmentary haematite occurs as grain coatings around detrital grains and in the interstitial matrix. The euhedral nature and pore-filling habit clearly indicate the authigenic origin of these iron- and titanium oxides. All three textural varieties are believed to have been precipitated from ground waters containing dissolved ferrous and titanium ions. These ions were derived from the intrastratal solution of detrital iron and titanium bearing grains including ferromagnesian silicates and iron-titanium oxides. The precipitation of iron oxides from migrating ground waters in the manner described here goes some way to explaining how thick, uniformly red successions can be formed.  相似文献   
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