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81.
Karl F Ehrlich 《Marine pollution bulletin》1977,8(10):228-229
The hatching success of California grunion (Leuresthes tenuis) was significantly reduced by a non-thermal component of the effluent from an electricity generating station. The embryos appeared to develop normally morphologically but showed reduced viability with respect to hatching. 相似文献
82.
Disposal of radioactive waste in the sea floor of fracture zones associated with the flanks of the Mid-Atlantic Ridge may
be a satisfactory alternative to land disposal. Effective physiographic, sedimentary, chemical, and oceanographic barriers
exist in these aseismic deep canyons, especially in the eastern Atlantic. In addition, the major producers of radioactive
wastes are likely to be near the Atlantic Ocean. If such a disposal strategy is adopted, intensive study of the sedimentologic
and oceanographic properties of oceanic fracture zones will be necessary. 相似文献
83.
84.
Robert M. Moore Stephen Punshon Claire Mahaffey David Karl 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(9):1449-1458
Fixed nitrogen is a key nutrient involved in regulating global marine productivity and hence the global oceanic carbon cycle. Oceanic nitrogen (N2) fixation is estimated to supply 8×1012 moles N y?1 to the ocean, approximately equal to current riverine and the atmospheric inputs of fixed N, and between 50 and 100% of current estimates of oceanic denitrification. However, the spatial and temporal variability of N2 fixation remains uncertain, mostly because of the normal low resolution sampling for diazotroph distribution and fixation rates. It is well established that N2 fixation, mediated by the enzyme nitrogenase, is a source of hydrogen (H2), but the extent to which it leads to supersaturation of H2 in oceanic waters is unresolved. Here, we present simultaneous measurements of upper ocean dissolved H2 concentration (nmol L?1), and rates of N2 fixation (μmol N m?3 d?1), determined using 15N2 tracer techniques (at 7 or 15 m), on a transect from Fiji to Hawaii. We find a significant correlation (r=0.98) between dissolved H2 and rates of N2 fixation, with the greatest supersaturation of H2 and highest rates of N2 fixation being observed in the subtropical gyres at the southern (~18°S) and northern (18°N) reaches of the transect. The lowest H2 saturation and N2 fixation were observed in the equatorial region between 8°S and 14°N. We propose that an empirical relationship between H2 supersaturations and N2 fixation measurements could be used to guide sampling for 15N fixation measurements or to aid the spatial interpolation of such measurements. 相似文献
85.
Karl Krejci 《International Journal of Earth Sciences》1925,16(2):99-127
Ohne Zusammenfassung 相似文献
86.
Based on GIS and statistical methods, with the help of searching historical literatures and calculating the landscape indices, the land use changes of Qian'an County in both spatial and temporal aspects from 1945 to 1996 has been analyzed in this paper. And the driving forces of land use changes and their ecological effects are discussed too. The main findings of this study are as follows: (1) Land use changed greatly in Qian'an during 1945-1996, characterized by a decrease in grassland, wetland and water bodies, and an increase in cultivated land, saline-alkali land, and the land for housing and other construction purposes. Grassland decreased by 175,828.66 ha, and cultivated land increased by 102,137.23 ha over the half century. Accordingly, the main landscape type changed from a steppe landscape to a managed agricultural ecosystem. (2) Results of correlation analysis show that the land use change in the study area was mainly driven by the socioeconomic factors. (3) The ecological effects of land use change in the area are characterized by serious salinization, degression of soil fertility and the weakening of landscape suitability. 相似文献
87.
Hubert Engelbrecht Karl B. Föllmi Ursula Baumer Johann Koller 《Swiss Journal of Geoscience》2010,103(1):3-13
A resin nodule was found in glauconite-rich detrital sediments of the Cretaceous Garschella Formation (Aptian to Albian) outcropping at Langer Köchel (Bavaria, S Germany). Gas chromatographic and mass spectrometric analyses of the fossil resin revealed dealkylation and the total defunctionalisation of its polycyclic constituents. Besides many unspecific components a specific one, agathalene, has survived. Agathalene also presents a strongly degraded product, but may have been derived from its natural precursor agathic acid, which is a very specific constituent (biomarker) of recent and fossil kauri resin. Although agathalene is a far less specific secondary biomarker, it indicates the botanic origin of the fossil resin nodule. Besides other potential producers of agathic acid, precursors of the present-day conifer species Agathis dammara and A. australis were distributed in a wider palaeophytogeographic range than today and might have been the botanical source of kauri resin. In view of the east–west directed Early Cretaceous surface current system of the Tethys ocean, the palaeogeographic provenance of the Werdenfels resin nodule probably was a mainland positioned further to the east or southeast of the Helvetic shelf, to where it was transported probably by driftwood of the resin-producing Agathis sp. 相似文献
88.
Over the last years, geospatial web platforms, social media, and volunteered geographic information (VGI) have opened a window of opportunity for traditional Public Participatory GIS (PPGIS) to usher in a new era. Taking advantage of these technological achievements, this paper presents a new approach for a citizen-orientated framework of spatial planning that aims at integrating participatory community work into existing decision-making structures. One major cornerstone of the presented approach is the application of a social geoweb platform (the GeoCitizen platform) that combines geo-web technologies and social media in one single tool allowing citizens to collaboratively report observations, discuss ideas, solve, and monitor problems in their living environment at a local level. This paper gives an account of an ongoing participatory land-zoning process in the Capital District of Quito, Ecuador, where the GeoCitizen platform is applied in a long-term study. 相似文献
89.
Manuela Magliocchetti Steve J. Maddox Ed Hawkins John A. Peacock Joss Bland-Hawthorn Terry Bridges Russell Cannon Shaun Cole Matthew Colless Chris Collins Warrick Couch Gavin Dalton Roberto de Propris Simon P. Driver George Efstathiou Richard S. Ellis Carlos S. Frenk Karl Glazebrook Carole A. Jackson Bryn Jones Ofer Lahav Ian Lewis Stuart Lumsden Peder Norberg Bruce A. Peterson Will Sutherland Keith Taylor 《Monthly notices of the Royal Astronomical Society》2004,350(4):1485-1494
90.