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171.
Robert Emmett Roberto Llansó Jan Newton Ron Thom Michelle Hornberger Cheryl Morgan Colin Levings Andrea Copping Paul Fishman 《Estuaries and Coasts》2000,23(6):765-792
West Coast estuaries are geologically young and composed of a variety of geomorphological types. These estuaries range from large fjords to shallow lagoons; from large to low freshwater flows. Natural hazards include E1 Niños, strong Pacific storms, and active tectonic activity. West Coast estuaries support a wide range of living resources: five salmon species, harvestable shellfish, waterfowl and marine birds, marine mammals, and a variety of algae and plants. Although populations of many of these living resources have declined (salmonids), others have increased (marine mammals). West Coast estuaries are also centers of commerce and increasingly large shipping traffic. The West Coast human population is rising faster than most other areas of the U.S. and Canada, and is distributed heavily in southern California, the San Francisco Bay area, around Puget Sound, and the Fraser River estuary. While water pollution is a problem in many of the urbanized estuaries, most estuaries do not suffer from poor water quality. Primary estuarine problems include habitat alterations, degradation, and loss; diverted freshwater flows; marine sediment contamination; and exotic species introductions. The growing West Coast economy and population are in part related to the quality of life, which is dependent on the use and enjoyment of abundant coastal natural resources. 相似文献
172.
173.
E. H. Wickens H. C. Woodrow D. W. Proctor J. E. Farrow I. Newton C. D. Burnside J. A. Allan J. Taylor 《The Photogrammetric Record》1985,11(65):473-492
The XVth International Congress of Photogrammetry and Remote Sensing, organised by the International Society for Photogrammetry and Remote Sensing, was held at Rio Centro. Rio de Janeiro from 17th to 29th June, 1984. Reports on the activities of the seven technical Commissions as well as on the Exhibition and the General Assembly were given to a meeting of the Photogrammetric Society on 16th October, 1984. Papers were published in the International Archives of Photogrammetry and Remote Sensing 25. 相似文献
174.
Enthalpies of solution of synthetic enstatite (Mg2Si2O6), forsterite (Mg2SiO4), akermanite (Ca2MgSi2O7), monticellite (CaMgSiO4), and merwinite (Ca3MgSi2O8) and their component oxides were determined in eutectic (Li, Na)BO2 at 1073 K. Resulting enthalpies of formation at 1073 are enstatite: ; forsterite: ; akermanite: ; monticellite: ; and merwinite: . The value for the synthetic monticellite of composition Mo.965Fo.035 was corrected slightly for non-stoichiometry based on experimental monticellite-forsterite phase equilibrium relations.The enthalpies of formation of enstatite and forsterite are somewhat less negative than yielded by several other solution calorimetric studies but are in good agreement with the recent Pb2B2O5 solution calorimetry of Kiselevaet al. (1979), and are in good agreement with values to be derived from reliable phase equilibrium data in the system MgO-Al2O3-SiO2. The enthalpies of formation of akermanite, monticellite and merwinite are all much less negative than values tabulated by robieet al. (1978) and helgesonet al. (1978) but are shown to be compatible with reliable phase equilibrium data for the system CaO-MgO-SiO2, whereas the tabulated values are not. Several methods of analysis yield an entropy of monticellite at 1000 K of . 相似文献
175.
An example of cluster analysis applied to a large geologic data set: Aerial radiometric data from Copper Mountain, Wyoming 总被引:1,自引:0,他引:1
Fredric L. Pirkle Jo Ann Howell George W. Wecksung Benjamin S. Duran Newton K. Stablein 《Mathematical Geology》1984,16(5):479-498
One objective of the aerial radiometric surveys flown as part of the U.S. Department of Energy's National Uranium Resource Evaluation (NURE) program was to ascertain the spatial distribution of near-surface radioelement abundances on a regional scale. Some method for identifying groups of observations with similar -ray spectral signatures and radioelement concentration values was therefore required. It is shown in this paper that cluster analysis can identify such groups with or without a priori knowledge of the geology of an area. An approach that combines principal components analysis with convergentk-means cluster analysis is used to classify 6991 observations (each observation comprising three radiometric variables) from the Precambrian rocks of the Copper Mountain, Wyoming area. This method is compared with a convergentk-means analysis that utilizes available geologic knowledge. Both methods identify four clusters. Three of the clusters represent background values for the Precambrian rocks of the area, and the fourth represents outliers (anomalously high214Bi). A segmentation of the data corresponding to geologic reality as interpreted by other methods has been achieved by perceptive quantitative analysis of aerial radiometric data. The techniques employed are composites of classical clustering methods designed to handle the special problems presented by large data sets. 相似文献
176.
177.
Robert R. Newton 《Surveys in Geophysics》1973,1(2):123-145
In this paper, we review the current state of knowledge about the acceleration of the Earth's spin, and about the closely related acceleration of the Moon. It is now established at a high confidence level that the acceleration of the Moon, when taken respect to Universal time, has changed by a large amount, and that it has even changed sign, within historic times. This almost certainly means that the acceleration of the Earth's spin has also changed by a large amount. At present we do not have enough information to say whether the changes have been in the contributions from tidal friction, in the contributions that do not arise from tidal friction, or both. Further, we do not know yet whether or not the variations in the Earth's rotation can account for the observed fluctuations in the longitudes of the Sun, the Moon, and the planets. 相似文献
178.
Victor C Anderlini Layla Al-Harmi Brock W De Lappe Robert W Risebrough Wayman Walker Bernd R.T Simoneit Amos S Newton 《Marine pollution bulletin》1981,12(2):57-62
Concentrations of total hydrocarbons within the boiling point range of the alkanes n-C14 and n-C32 were determined in oysters, Pinctada margaratifera, from coastal waters of Kuwait. Levels of petroleum-derived hydrocarbons were highest in an area adjacent to the major oil loading facilities. Whether the use of dispersants to treat minor spills increases levels of incorporation of petroleum compounds into the food webs could not be concluded from the data of this study. Levels of total petroleum-type hydrocarbons in the oysters at this site were equivalent to those in mussels, Mytilus sp., from harbours, bays and urban coastal areas of California. The Kuwaiti oysters lacked a C28 pentacyclic triterpane that was present in extracts of mussels from southern California that had been recently exposed to a minor spill or to a natural seepage. Levels of DDE and PCB were comparable to those in relatively unpolluted areas of North America. 相似文献