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  • 1
    Publication Date: 2018-07-19
    Description: Late Quaternary forest succession in Wyoming’s Rocky Mountains, occurred in random patterns, because it reflects differences between the Glacial vegetation at lower elevations on the east vs. the west of the Rockies, as well as along the mountain crest to the south. Differential melting of mountain glaciers resulted in differences in the timing of recolonization. Significant variations in the composition of plant assemblages occurred due to delays in species’ arrival, and even in the exclusion of species. Holocene climate variability, especially ongoing global warming, added to the complex dynamics of plant assemblages with warm climate species replacing early Holocene, cooler climate species. The pollen record from Green Lake (located in a glacial cirque on the west side of the Teton Mountains in Teton County, Wyoming) addresses the local vegetation response from just before the fall of Mazama ash to the end of the middle Holocene warm period. Although the earlier portion of the pollen sequence records some of the last adjustments as some plant species were still arriving after de-glaciation, by the time Mazama ash fell it was climate variation that determined most of the dynamics observed in the Green Lake record. The results reveal a sequence of wetter and drier periods based upon the presence of diagnostic tree species.  A moist late early Holocene was followed by a dry middle Holocene, which ended about 6,400 cal. B.P., and was followed between 5,000 to 2,800 cal. B.P. by a sequence of drier and moister climate episodes.
    Print ISSN: 1927-0542
    Electronic ISSN: 1927-0550
    Topics: Geosciences
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  • 2
    Publication Date: 2018-07-18
    Description: Runoff from roads is well recognized as containing a host of heavy metals that may degrade water quality. This awareness has driven a focus towards management strategies intended to attenuate the transport of heavy metals to nearby water bodies. Composted biomass has been shown to have the ability to retain common roadway runoff pollutants, leading to interest in its use as a filter material for the protection of environmentally sensitive areas. Compost biofilters can be constructed in a tubular geometry to intercept surface flow and can be amended with polymers for the targeted removal of specific pollutants. Addressing the need for validation of this concept under field conditions, commercially available tubular biofilters with three different polymeric amendments were studied to assess their efficiency in removing heavy metals and total suspended solids. The filters each contained a mixture of municipal compost and were installed in series as a treatment train adjacent to a busy section of highway 401 in southern Ontario, Canada. Untreated inflow concentrations of chromium, cadmium, copper and lead exceeded Ontario Provincial Water Quality Objectives (PWQO). The biofilter treatment train reduced chromium to below its PWQO, while copper remained above. Results demonstrate removal efficiencies for the treatment train ranging from 15.5% (nickel) to 93.6% (chromium). The low removal efficiency of nickel is attributed in part to its low inflow concentration. Each consecutive filter also reduced TSS concentrations, with an event mean removal efficiency of 50% for the treatment train as a whole. 
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  • 3
    Publication Date: 2018-07-10
    Description: To a certain extent, the development of sand body in lishui depression determines the success of oil and gas exploration, so the development models of sand body become the focus of current research. Based on seismic interpretation and exploration practice, five types of sand body development model were developed in lishui depression, including gentle slope-valley typed sand control model, steep slope-valley typed sand control model, trough fault controlling axial typed sand control model, gentle slope -contemporaneous fault typed sand control model and bulge steep slope-cross section typed sand control model. Different sand body development model determines the development characteristics of sand body and indicates the direction of exploration.
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  • 4
    Publication Date: 2018-07-10
    Description: Bohai L oilfield develops a complex fluvial sedimentary system, which includes many types of fluvial sedimentary facies. Based on the coring well of oil field, the distribution characteristics of mudstone are analyzed, it is shown that the mudstone has similar internal structure and can be classified into four types according to its color: gray to grayish, variegated, brown to gray-brown and khaki, the assemblage has a large gray to grayish mudstone section, large gray to grayish mudstone intercalated thin layer sandstone, gray to grayish mudstone associated with variegated (brown) mudstone, grayish mudstone associated with lacustrine sand grain bedding sandstone, concomitant generation of large staggered bedding sandstone and grayish mudstone, mixed (gray-brown) mudstone associated with large staggered bedding sandstone, interaction between different colors of mudstone and sandstone and large interlaced sandstone intercalated with thin layer mudstone. The mudstone color is mainly gray and grayish, and very few oxidized mudstone is developed alone, which indicates that fluvial mudstone may be formed in the reductive environment in humid climate, and the fluvial mudstone in this area may be formed in the oxidizing environment, which is different from the general understanding of fluvial facies, the oxidation color is the result of the later transformation.
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  • 5
    Publication Date: 2018-05-22
    Description: Accurate modelling of flood flow hydrographs in ungauged catchments is a challenging task due to large errors in the estimation of its response time using existing empirical equations. The time of concentration ( T c ) is a key catchment response time parameter needed for forecasting of the peak discharge rate and the timing of the flood event. At least eight different definitions have been presented in the literature for the time of concentration. In this study, a new definition of “Reference Tc” is presented along with a practical procedure for its estimation using readily available basin catchment characteristic parameters with the aim of standardizing this key parameter for practitioners. Nine different empirical models were calibrated and tested on nine catchments of the Credit River watershed, Ontario, Canada to determine which method would provide the most accurate prediction of the Reference Tc. The NRCS velocity method (1986) proved once again to be the most reliable and an accurate method. This study shows that the main reason for the higher accuracy of the NRCS velocity method predictions compared to the empirical equations is attributed to the inclusion of the Manning's roughness coefficient.
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  • 6
    Publication Date: 2018-05-05
    Description: The accuracy of prediction and ease of use of the three popular flood routing models; simplified dynamic Wave, diffusion wave, and full dynamic wave were evaluated. The models were evaluated along a reach of the Credit River Watershed, in Southern Ontario, Canada. The simplified dynamic wave model showed better accuracy and easier formulation when compared against the diffusion wave and the full dynamic wave models. Indicating that the simplified dynamic wave model can be applied to reaches where the diffusion wave and the full dynamic wave models may not be applicable. The principle novel contributions of the paper are (a) the extension of the flood routing formulations by Keskin and Agiralioglu, (b) the use of a prismatic channel and floodplain with varying top-widths, (c) the validation of the methodology through the application of an event simulation to an actual river reach, and (d) comparison of the modeling results to those obtained using the full dynamic wave model and the diffusion wave models.
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  • 7
    Publication Date: 2018-05-05
    Description: Phosphoric acid production generates unavoidable calcium sulfate by product (i.e. phosphogypsum (PG)) that is usually disposed either within a nearby located gypsum stacking system. However nowadays this type of industry has been faced with two main problems; these are the formation of huge stockpiles of phosphogypsum that affects the environment due to the presence of harmful radiations that is emitted from the uranium. In addition it contains P 2 O 5 〉1.0 wt% and fluorine 〉0.18 wt%, which makes it not suitable for the cement industry. At the same time consuming large quantity of expensive sulphuric acid that becomes a hazardous waste material too. The production ratio of PG verses marketable P 2 O 5 as acid in the world is high as much as 5 tons of PG are produced for each ton of P 2 O 5 ; in Jordan the ratio is around 5.0 – 5.3 ton of PG / ton of P 2 O 5 produced depending on the phosphate rock composition, which means a huge amount of PG will accumulate at the Fertilizer plant in Aqaba. The major advantages of using orthophosphoric acid as leaching solvent is the decreasing ratio of the residual materials verses marketable P 2 O 5 to be589 kg /ton of P 2 O 5 produced. These results were obtained by utilizing the wet agitation leaching technique, compared with 5.0 – 5.3 ton of disposed PG/ton of P 2 O 5 produced by Jordan Phosphate Mines Company Ltd., (JPMC). However, this alternative technique resulted in lowerP 2 O 5 extraction, but decrease in bulk of the residue. The disadvantage is the higher dissolution of calcium phosphate and thus considerable calcium well remain in solution.
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  • 8
    Publication Date: 2018-05-05
    Description: The present paper treats the relationship between geotechnical parameters and the mineralogical compositions, in order to understand the behavior of the Bafang lateritic fine soils and their efficient use as road embankment materials on the other hand. Thus, the field campaigns have permitted to distinguish two facies of Bafang lateritic fine soils: reddish and yellowish facies. The X-ray diffraction (XRD), the thermo-gravimetry analysis (TGA) and the X-ray fluorescence (XRF) have revealed that the reddish facies contents: kaolinite (53.34% -48.29%); hematite (16.62% - 17.40 %); gibbsite (8.26 % - 16.54%), ilmenite (7.6 % -7.98%), quartz (1.92 % - 4.65 %), illite (2.65% - 1.99 %) and accessories minerals as florencite (1.45%); montmorillonite (0.90 %) and plagioclase (0.69 %); while the yellowish facies is composed of : 65.1 % kaolinite, 11.2 % gibbsite, 9.64 % goethite, 7.02 % quartz, 3.23 % ilmenite and 2.08 % of illite. Their Silica/sexquioxide ratios correspond to those of moderate laterite. The geotechnical and mechanical characteristics have shown that the reddish and yellowish facies are respectively silty clay and sandy silt. They are plastic to very high plastic and moderately clayey to clayey materials. Moreover, they are medium swelling to high swelling. The IBR values more than 40% and the soaked CBR values prove that these materials belong to the S4 bearing capacity class. The minimum values of UCS and Rt are respectively 1.7 MPa and 0.17 MPa. Then, the results of geotechnical and mechanical properties combining to those of XRD, TGA and XRF have demonstrated that the fine lateritic soils with low silica/sexquioxide ratios values (less than 1.6) are suitable for road embankment.
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  • 9
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    Canadian Center of Science and Education
    Publication Date: 2018-03-16
    Description: Climate change is at its core an energy problematic. The main anthropogenic source of greenhouse gases is energy consumption. It is vital, because it makes affluence and wealth feasible. Energy demand is projected to double by 2050 at the same time as governments have obliged themselves to drastic decarbonisation. The risk is obvious that energy demand trumps emission reduction.
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  • 10
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    Unknown
    Canadian Center of Science and Education
    Publication Date: 2018-02-01
    Description: Reviewer Acknowledgements for Earth Science Research, Vol. 7, No. 1
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