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971.
Altan Yilmaz Mustafa Erdogan Hadi Hakan Maras Bahadir Aktug Suleyman Sirri Maras 《Arabian Journal of Geosciences》2016,9(4):324
In this study, the geometric accuracy comparison of aerial photos and WorldView-2 satellite stereo image data is evaluated with the different number and the distribution of the ground control points (GCPs) on the basis of large scale map production. Also, the current situation of rivalry between airborne and satelliteborne imagery was mentioned. The geometric accuracy of Microsoft UltraCam X 45 cm ground sampling distance (GSD) aerial imagery and WorldView-2 data both with and without GCPs are also separately analyzed. The aerial photos without any GCP by only using global navigation satellite system (GNSS) and inertial measurement unit (IMU) data with tie points give an accuracy of ±1.17 m in planimetry and ±0.71 m in vertical that means nearly two times better accuracy than the rational polynomial coefficient (RPC) of stereo WorldView-2. Using one GCP affects the accuracies of aerial photos and WorldView-2 in different ways. While this situation distorts the aerial photo block, it corrects the shift effect of RPC in WorldView-2 and increases the accuracy. By using four or more GCPs, ½?pixel (~0.23 m) accuracy in aerial photos and 1 pixel (~0.50 m) accuracy in WorldView-2 can be achieved in horizontal. In vertical, aerial photos have 1 pixel (~0.55 m) and WorldView-2 has 1.5 pixels (~0.85 m) accuracy. These results show that Worldview-2 imagery can be used in the production of class I 1:5000 scale maps according to the ASPRS Accuracy Standards for Digital Geospatial Data in terms of geometric accuracy. It is concluded that the rivalry between aerial and satellite imagery will continue for some time in the future. 相似文献
972.
Haddouche Omar Boutaleb Abdelhak Chamam Madjid Ysbaa Saadia Hammouche Hanafi Boubaya Djamel 《Arabian Journal of Geosciences》2016,9(5):422
Analysis and integration of geological/metallogenic data and digitally processed gravimetric/aeromagnetic data to the oriental Saharan Atlas domain were carried out to understand the spatial distribution and structural control on Pb-Zn (Ba) deposits of the oriental Saharan Atlas. The use of this combined technique suggests that most of mineral deposits appear to be regionally controlled by structural trends (subparallel NE-SW-trending) along margins of subsiding sedimentary basins. Mineralization occurs along or near major NE-SW-trending faults, locally intersected by NW-SE-trending faults. In addition, mineral deposits are usually either inside anticlinal hinge zones (example, Merouana, Ichmoul and Ain Mimoum ore deposits) or on the flanks of anticlinal structures (example, Ain Bougda ore deposit). In “diapiric zone”, mineral deposits are generally located on diapiric structures borders (peridiapiric concentrations), related to NE-SW/NE-SW and E-W-trending faults. Other mineral concentrations occurs along the margins of tectonic troughs zones (example, Morsott trough) resulting probably by NW-SE-trending deep faults movement. In summary, our research suggested that regional parameters, such as NE-SW/NW-SE-trending lineaments, intersections of these lineament zones and margins of subsiding sedimentary basins/diapiric structures, serve as significant indicators and provides a valuable framework for guiding the early stages of Pb-Zn (Ba) mineral exploration; other considerations must then be applied in this region, like integration of surficial geochemical anomalies that allows better delineation of targets for further mineral exploration. 相似文献
973.
Jong-Hyeob Kim Seung Hyeon Kim Young Kyun Kim Kun-Seop Lee 《Ocean Science Journal》2016,51(4):635-645
Seagrasses require a large amount of nutrient assimilation to support high levels of production, and thus nutrient limitation for growth often occurs in seagrass habitats. Seagrasses can take up nutrients from both the water column and sediments. However, since seagrasses inhabiting in the intertidal zones are exposed to the air during low tide, the intertidal species may exhibit significantly different carbon (C) and nitrogen (N) dynamics compared to the subtidal species. To examine C and N dynamics of the intertidal seagrass, Zostera japonica, C and N content and stable isotope ratios of above- and below-ground tissues were measured monthly at the three intertidal zones in Koje Bay on the southern coast of Korea. The C and N content and stable isotope (δ13C and δ15N) ratios of seagrass tissues exhibited significant seasonal variations. Both leaf and rhizome C content were not significantly correlated with productivity. Leaf δ13C values usually exhibited negative correlations with leaf productivity. These results of tissue C content and δ13C values suggest that photosynthesis of Z. japonica in the study site was not limited by inorganic C supply, and sufficient inorganic C was provided from the atmosphere. The tissue N content usually exhibited negative correlations with leaf productivity except at the upper intertidal zone, suggesting that Z. japonica growth was probably limited by N availability during high growing season. In the upper intertidal zone, no correlations between leaf productivity and tissue elemental content and stable isotope ratios were observed due to the severely suppressed growth caused by strong desiccation stress. 相似文献
974.
975.
Siliceous drift pumice was collected from a total of 40 beaches around the main island of New Caledonia, Southwest Pacific, in order to determine its provenance. New Caledonia is enclosed by a barrier reef lagoon whose 2008 designation as a UNESCO World Heritage Site brought attention to the environmental degradation caused by a century of open cast nickel mining. The frequent, voluminous pumice eruptions in the Southwest Pacific provide ample source material that is somewhat durable, highly transportable in water, and easy to collect and analyze. Geochemical and mineralogical analyses were used to identify the source of the pumice in order to map the transport vector across the open ocean and into the lagoon. Drift pumice was sampled during 2008 and 2010. The mineral assemblage of the pumice was consistently calcic plagioclase, clinopyroxene, orthopyroxene, and opaque minerals. All of the pumice was of fairly uniform geochemistry: low in mafic elements, low in alkalis, with LILE enriched compared to HFSE, and negative Eu, Ti, and Zr anomalies. The pumice is predominately dacitic and tholeiitic. This geochemical signature was consistent with published data from the Tonga arc, which is further supported by the mineralogy. With the exception of two samples (which probably came from either the Kermadec arc or Vanuatu) all of the pumice comes from the Tonga arc. The samples from 2008 are consistent with pumice erupted from Metis Shoal in 2006, and the majority of 2010 samples are consistent with pumice erupted from an unnamed volcano (0403-091) that erupted in 2001. 相似文献
976.
Modern and fossil benthic foraminifera were examined from nine surface sediments and two piston cores along the ~131°W transect in the equatorial Pacific Ocean. This study was conducted to clarify the biotic response of abyssal benthic foraminifera during the last 220 ka to changes in the seasonal extent of the Intertropical Convergence Zone (ITCZ). The abundance of modern benthic foraminifera was high at stations between the equator and 6°N, whereas it was low at stations north of 6°N, which is generally consistent with the latitudinal CaCO3 distribution of surface sediments. The northward increase of Epistominella exigua from the equator to ~6°N is similar to the seasonal variations in chlorophyll-a concentrations in the surface water and ITCZ position along ~131°W. This species was more common at core PC5103 (~6°N) than at core PC5101 (~2°N) after ~130 ka, when the Shannon-Wiener diversity (H’) between the two cores started to diverge. Hence, the presentday latitudinal difference in benthic foraminifera (E. exigua and species diversity) between ~2°N and ~6°N along ~131°W has been generally established since ~130 ka. According to the modern relationship between the seasonality of primary production and seasonal ITCZ variations in the northern margin of the ITCZ, the latitudinal divergence of benthic foraminiferal fauna between ~2°N and ~6°N since ~130 ka appear to have been induced by more distinct variations in the seasonal movement of ITCZ. 相似文献
977.
978.
We investigated seasonal variations in cyanobacterial biomass and the forms of its dominant population(M. aeruginosa) and their correlation with environmental factors in the water source area of Chaohu City,China from December 2011 to October 2012. The results show that species belonging to the phylum Cyanophyta occupied the maximum proportion of phytoplankton biomass,and that the dominant population in the water source area of Chaohu City was M. aeruginosa. The variation in cyanobacterial biomass from March to August 2012 was well fitted to the logistic growth model. The growth rate of cyanobacteria was the highest in June,and the biomass of cyanobacteria reached a maximum in August. From February to March 2012,the main form of M.aeruginosa was the single-cell form; M.aeruginosa colonies began to appear from April,and blooms appeared on the water surface in May. The maximum diameter of the colonies was recorded in July,and then gradually decreased from August. The diameter range of M. aeruginosa colonies was 18.37–237.77 μm,and most of the colonies were distributed in the range 20–200 μm,comprising 95.5% of the total number of samples. Temperature and photosynthetically active radiation may be the most important factors that influenced the annual variation in M. aeruginosa biomass and forms. The suitable temperature for cyanobacterial growth was in the range of 15–30°C. In natural water bodies,photosynthetically active radiation had a significant positive influence on the colonial diameter of M.aeruginosa(P0.01). 相似文献
979.
Pyropia haitanensis (T. J. Chang et B. F. Zheng) N. Kikuchi et M. Miyata (Porphyra haitanensis) is an economically important genus that is cultured widely in China. P. haitanensis is cultured on a larger scale than Pyropia yezoensis, making up an important part of the total production of cultivated Pyropia in China. However, the majority of molecular mechanisms underlying the physiological processes of P. haitanensis remain unknown. P. haitanensis could utilize inorganic carbon and the sporophytes of P. haitanensis might possess a PCK-type C4-like carbon-fixation pathway. To identify microRNAs and their probable roles in sporophyte and gametophyte development, we constructed and sequenced small RNA libraries from sporophytes and gametophytes of P. haitanensis. Five microRNAs were identified that shared no sequence homology with known microRNAs. Our results indicated that P. haitanensis might posses a complex sRNA processing system in which the novel microRNAs act as important regulators of the development of different generations of P. haitanensis. 相似文献
980.
Photo-protective functions were investigated in phytoplankton assemblages at Kongsfjorden, Svalbard in spring, using their UV-absorbing compounds (mycosporine-like amino acids (MAAs)), xanthophyll pigments (diadinoxanthin (DD) and diatoxanthin (DT)) and < beta >- dimethylsulphoniopropionate (< beta >-DMSP). The dominant phytoplankton species in the inner bay were dominated by Phaeocystis spp. and nanoflagellates, while the offshore waters were dominated by Thalassiosira spp. In the inner bay, UVabsorbing compounds and xanthophyll pigments exhibited higher ratios of MAA to chlorophyll a (MAA:chl a ratio), and both DD and DT to chlorophyll a (DD:chl a ratio and DT:chl a ratio), respectively. Thus, the photoprotective-pigments such as DD and DT appear to complement MAAs in the natural phytoplankton assemblage. However, the ratio of < beta >-DMSP to chlorophyll a (< beta >-DMSP:chl a ratio) did not show a distinct spatial distribution according to environmental factors or interspecies differences. In this study, we found that photoprotective compounds occurred in a manner dependent on the phytoplankton species composition in Kongsfjorden Bay, where Phaeocystis is the dominant species. 相似文献