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51.
Marina Bisson Claudia Spinetti Marco Neri Alessandro Bonforte 《International Journal of Digital Earth》2016,9(7):710-732
High-resolution digital topography is essential for land management and planning in any type of territory as well as the reproduction of the Earth surface in a geocoded digital format that allows several Digital Earth applications. In a volcanic environment, Digital Elevation Models are a valid reference for multi-temporal analyses aimed to observe frequent changes of a volcano edifice and for the relative detailed morphological and structural analyses. For the first time, a DTM (Digital Terrain Model) and a DSM (Digital Surface Model) covering the entire Mt. Etna volcano (Italy) derived from the same airborne Light Detection and Ranging (LiDAR) are here presented. More than 250 million 3D LiDAR points have been processed to distinguish ground elements from natural and anthropic features. The end product is the highly accurate representation of Mt. Etna landscape (DSM) and ground topography (DTM) dated 2005. Both models have a high spatial resolution of 2?m and cover an area of 620?km2. The DTM has been validated by GPS ground control points. The vertical accuracy has been evaluated, resulting in a root-mean-square-error of ±?0.24?m. The DTM is available as electronic supplement and represents a valid support for various scientific studies. 相似文献
52.
53.
On Conditions of Phytoplankton Blooms in the Coastal Waters of the North-Western East/Japan Sea 总被引:1,自引:0,他引:1
Seasonal changes of abundance of the main phytoplankton groups of species (diatoms, dinoflagellates, chrysophytes, small flagellates
and cryptophytes) and a set of environmental parameters were investigated in coastal and preestuarine waters of Peter the
Great Bay (East/Japan Sea) in May-October of 1998 and 1999. Three periods of mass development were revealed: spring, summer
and autumn blooms, with successive change of species. The conditions favourable for each group of species were determined.
Driving mechanisms of the succession include nutrients transport through seasonal pycnocline by turbulent mixing, terrestrial
nutrients supply by monsoon floods, nutrients supply by upwellings, and light control by the thickness of upper mixed layer.
Summer succession could be explained by a simple SST-MLD diagram similar to Pingree S-kh diagram with sea surface temperature
as indicator of stratification (S) and mixed layer depth as indicator of light availability (kh). 相似文献
54.
Characterization of the proteinaceous matter in marine aerosols 总被引:1,自引:0,他引:1
Marine aerosols play a dominant role in the transfer of oceanic material to the atmosphere. Most marine aerosol originates when air bubbles burst at the sea surface ejecting material from the sea surface microlayer and bubble surface layers into the air. Concentrations of chemical compounds in these surface layers often differ from their concentrations in bulk water. We examined the enrichment of aerosols with proteinaceous matter and attempted to characterize the physical nature and sources of this matter. We measured concentrations of dissolved free (DFAA), dissolved combined (DCAA), and particulate (PAA) amino acids, transparent stainable particles (TSP), and bacteria and virus-like particles as carriers of protein, in natural and simulated aerosols. We also evaluated D/L ratios certain amino acids in all amino acid fractions.DFAA and DCAA enriched the aerosols we sampled by 1.2–20 times compared to bulk seawater; PAA enrichment was usually higher (up to 50-fold). Aerosols contained particles typical of seawater, e.g., microorganisms, organic debris, inorganic particles with adsorbed organic matter, but also a large number of semitransparent gel-like particles, which all contained amino acids. Some of these particles were probably scavenged from bulk water, but new particles produced as bubbles burst at the surface comprised at least 10% of total proteinaceous matter in the aerosol. D/L ratios of certain amino acid suggested that the particles were most likely made from dissolved polymers secreted by phytoplankton that were concentrated on bubble surfaces and in the microlayer. Examination with Alcian Blue (a dye that targets carbohydrates) and Coomassie Blue (a dye that targets proteins) showed that most TSP in the aerosols contained both proteins and polysaccharides. Microorganisms enriched the aerosols by up to two orders of magnitude, but contributed less than 4% to the total protein pool. 相似文献
55.
Konstantin A. Rogachev Eddy C. Carmack Alexander S. Salomatin Marina G. Alexanina 《Progress in Oceanography》2001,49(1-4)
Here we examine the consequences of strong tidal mixing on spatial and temporal distributions of biota and sea ice above Kashevarov Bank, Sea of Okhotsk, using data from field surveys (hydrography, pressure gauge and current meter moorings, and bio-acoustic soundings) and remote sensing (NOAA AVHRR). Fortnightly variations in the amplitude of diurnal tidal currents, primarily resulting from the K1–O1 interaction, are shown to dominate water motion over the bank. These currents (with maximum velocities 2 m s−1) create a sharp tidally-mixed front that separates well-mixed water above the bank from stratified water along its flanks. Such mixing draws water upward from the cold dichothermal layer (100–150 m) into the surface layer, and thus serves to ventilate the intermediate layers of the Sea of Okhotsk. In summer, fortnightly modulation of the tidal mixing creates temporal variations in water column stratification, a critical factor in the joint supply of nutrients and light required to sustain phytoplankton growth. As such, chlorophyll-a and oxygen values vary in response to the fortnightly cycle, and zooplankton likewise form dense aggregations within the tidally-mixed front in response to the phytoplankton production. It is further noted that the brood cycle of dominant zooplankton species on the bank matches the fortnightly modulation of the tidal currents. In winter, tidal mixing draws relatively warm water upward from mid-depth to maintain a polynya that cyclically opens and closes in response to fortnightly variation in vertical heat flux. 相似文献
56.
A study of inorganic iodine speciation in the water column of a naturally eutrophicated anchialine pond (Rogoznica Lake, East Adriatic Coast) was conducted in a period between April and July 2004 to obtain information how close the inorganic iodine system is to that of inorganic nutrients during spring, when phytoplankton activity is at maximum, and how the system changes up to summer, when highly reducible redox-conditions prevail in deep water. 相似文献
57.
58.
Gennady G. Boeskorov Peter A. Lazarev Andrei V. Sher Sergei P. Davydov Nadezhda T. Bakulina Marina V. Shchelchkova Jonas Binladen Eske Willerslev Bernard Buigues Alexey N. Tikhonov 《Quaternary Science Reviews》2011,30(17-18):2262-2272
A nearly complete frozen mummy of a woolly rhinoceros (Coelodonta antiquitatis Blum., 1799) was discovered in a gold mine on the lower reaches of the Kolyma River, north–eastern Siberia. This is the first find of the whole body of woolly rhino in permafrost. A large part of the mummified body was preserved, including the left part of the body, covered by skin, including skin of the head and ear, fore and hind legs. The skull with 2 horns and the lower jaw were also preserved. Most of the internal organs were lost, except the intestines, stomach, and their contents. A rib fragment from this individual was dated by AMS-radiocarbon method to 39,140 ± 390 years BP (OxA-18755). Spore and pollen analyses of the stomach contents indicate that grasses and sagebrushes formed the main part of the diet of C. antiquitatis in this region of Arctic Siberia. 相似文献
59.
The historical-genetic method developed at the Institute of Oceanology of the Russian Academy of Sciences for the assessment of the petroleum resource potential is discussed with consideration of its main tasks and the successive procedures in its application. Such studies are crowned by a compilation of separate maps demonstrating scales of oil and gas generation and maps of hydrocarbon genesis zoning of basins with outlining centers of oil and gas generation and defining different-phase hydrocarbon-generation zones. The method was tested in over twenty continental-marginal and intracontinental basins studied to a different extent. The sedimentary basins of the Atlantic continental margin off Africa and the Caspian and Black seas were used as objects for applying the historical-genetic method for assessing their petroleum resource potential. 相似文献
60.
Giovanni Bearzi Arianna Azzellino Elena Politi Marina Costa Mauro Bastianini 《Ocean Science Journal》2008,43(4):175-182
Bottlenose dolphins are the only cetaceans regularly observed in the northern Adriatic Sea, but they survive at low densities
and are exposed to significant threats. This study investigates some of the factors that influence habitat use by the animals
in a largely homogeneous environment by combining dolphin data with hydrological and physiographical variables sampled from
oceanographic ships. Surveys were conducted year-round between 2003 and 2006, totalling 3,397 km of effort. Habitat modelling
based on a binary stepwise logistic regression analysis predicted between 81% and 93% of the cells where animals were present.
Seven environmental covariates were important predictors: oxygen saturation, water temperature, density anomaly, gradient
of density anomaly, turbidity, distance from the nearest coast and bottom depth. The model selected consistent predictors
in spring and summer. However, the relationship (inverse or direct) between each predictor and dolphin presence varied among
seasons, and different predictors were selected in fall. This suggests that dolphin distribution changed depending on seasonal
forcing. As the study area is relatively uniform in terms of bottom topography, habitat use by the animals seems to depend
on complex interactions among hydrological variables, caused primarily by seasonal change and likely to determine shifts in
prey distribution. 相似文献