排序方式： 共有9条查询结果，搜索用时 15 毫秒
1
1.
The change of hydrological regimes may cause impacts on human and natural system. Therefore, investigation of hydrologic alteration induced by climate change is essential for preparing timely proper adaptation to the changes. This study employed 24 climate projections from the Coupled Model Intercomparison Project Phase 5 (CMIP5) under Representative Concentration Pathway (RCP) 4.5 scenario. The climate projections were downscaled at a station‐spacing for seven Korean catchments by a statistical downscaling method that preserves a long‐term trend in climate projections. Using an ensemble of future hydrologic projections simulated by three conceptual rainfall‐runoff models (GR4J, IHACRES, and Sacramento models), we calculated Hydrologic Alteration Factors (HAFs) to investigate degrees of variations in Indicators of Hydrologic Alteration (IHAs) derived from the hydrologic projections. The results showed that the seven catchments had similar trend in terms of the HAFs for the 24 IHAs. Given that more frequent severe floods and droughts were projected over Korean catchments, sound water supply strategies are definitely required to adapt to the alteration of streamflow. A wide range of HAFs between rainfall‐runoff models for each catchment was detected by large variations in the magnitude of HAFs with the hydrologic models and the difference could be the hydrologic prediction uncertainty. There were no‐consistent tendency in the order of HAFs between the hydrologic models. In addition, we found that the alterations of hydrologic regimes by climate change are smaller as the size of catchment is larger. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
2.
Nur Mun’im Mohd Han Mohd Talib Latif Murnira Othman Doreena Dominick Noorlin Mohamad Hafizan Juahir Norhayati Mohd Tahir 《Environmental Earth Sciences》2014,72(3):849-859
This study was carried out in order to determine the concentration of heavy metals, e.g., lead (Pb), cadmium (Cd), copper (Cu), zinc (Zn), iron (Fe), manganese (Mn), nickel (Ni) and chromium (Cr) in road dust in Kuala Lumpur’s city centre. Samples were collected from four sampling locations, each of which had four sampling points and three replications. Heavy metals from different fractions of particles separated by different diameter sizes: d < 63 μm (Fraction A), 63 < d < 125 μm (Fraction B) and 125 < d < 250 μm (Fraction C) were analyzed using inductively coupled plasma mass spectrometry. The results from this study showed that concentration of heavy metals was dominated by the smallest particle size: <63 μm and that Fe was the most abundant heavy metal overall, followed by Cu > Mn > Zn > Pb > Ni > Cr > Cd. The fact that Cd had the highest enrichment factor value (EF) for all particle sizes indicates that anthropogenic activities contributed to the presence of this metal. There was also a higher EF value for heavy metals in small particle (Fraction A), compared to Fraction B and C, which suggests that fine particles were being produced through anthropogenic activities. Cluster analysis and principal component analysis demonstrated the likelihood of the heavy metals detected in the road dust, originating from road traffic and industrial activities. 相似文献
3.
Gold deposits of Uzbekistan are localized in the Kyzylkum, Nurata, and Kurama ore districts of the Kyzylkum-Kurama metallogenic
belt. They comprise a consecutive series of deposit types corresponding to the series of geochemical associations: (Au-W)—(Au-As)—(Au-Te)—(Au-Ag)—(Au-Sb)—(Au-Hg),
which are arranged as a system of zones in orebodies, deposits, ore fields, and ore districts. The distribution of chemical
elements characterized by average global concentrations in the crust within the ppm-ppb (10−6-10−9 t) range was studied in ores of gold deposits using an ICP MS Elan DRC II device. Mineral nanoassemblages with a grain size
of 10−6 to 10−9 m were examined with a Jeol YXA 8800R Superprobe. The Au-W, Au-As, and Au-Te associations with Bi tellurides and maldonite
in ore dominate at hypo- and meso-abyssal gold deposits of the Kyzylkum district (Muruntau, Myutenbay). The contribution of
the Au-Sb association with Pb, Ag, and Fe sulfoantimonites and aurostibite increases at the Daughyztau, Kokpatas, and Amantaitau
gold deposits. The Au-As, Au-Te, and Au-Sb associations with Bi tellurides, maldonite, sulfoantimonites, and aurostibite dominate
at the mesoabyssal gold deposits of the Nurata district (Charmitan, Guzhumsay). The Au-Te and Au-Ag associations with Au,
Ag, Pb, Sb, Bi, and Hg tellurides and Bi selenides dominate at the hypabyssal gold deposits of the Kurama district (Kochbulak,
Kayragach). The gold-silver deposits of the Kyzylkum district (Kosmanachi, Vysokovol’tnoe) and the Kurama district (Kyzylalmasay,
Arabulak) are close in composition. They are characterized by development of intermetallides, sulfides, sulfosalts, and selenides
of Au-Ag and occasionally Au-Sb associations. Fineness of gold decreases from early to late geochemical associations, whereas
the size of gold grains increases in the same direction from nanogold to visible gold. The studies at the micro- and nanolevel
make it possible to establish the attributes of specific gold mineralization, to substantiate prospecting guides, and to estimate
the erosion level and resource potential of hidden ore objects. The greater and more diverse a set of micro- and nanominerals,
the larger a gold deposit is. 相似文献
4.
Arthur Raj Binupriya Muthuswamy Sathishkumar Dhamodaran Kavitha Krishnaswamy Swaminathan Sei‐Eok Yun Sung‐Phil Mun 《洁净——土壤、空气、水》2007,35(2):143-150
Batch biosorption experiments were carried out for the removal of Congo red from aqueous solution using native and pretreated mycelial pellets/biomass of Trametes versicolor. The effect of process parameters such as contact time, dye concentration, and pH on the extent of Congo red biosorption has been investigated. Higher dye concentrations resulted in lower biosorption. Increases in biomass dosage led to increases in the levels of biosorption. Biosorption kinetics and equilibrium data are essential basic requirements to develop an effective and accurate design model for the removal of the dye. A kinetic study showed that the biosorption of the dye on fungal biomass was a gradual process. Pseudo‐first‐order, pseudo‐second‐order, and Bangham's model were used to fit the experimental data. The results of the kinetic studies showed that the second‐order kinetic model fitted well for the present experimental data. Equilibrium isotherms were analyzed by Langmuir, Freundlich, Dubnin‐Radushkevich, and Temkin isotherms. The biosorption equilibrium data obeyed the Langmuir and Temkin isotherms well. Acidic pH was favorable for the biosorption of the dye. Studies on the pH effect and desorption show that chemisorption seems to play a major role in the biosorption process. Among the native and pretreated biomass studied, autoclaved biomass showed a better biosorption capacity. 相似文献
5.
Floods in Malaysia have been increasing in frequency and magnitude as reflected in the Kelantan Flood event in 2014 that resulted in a huge loss of lives and properties. Whereas remote sensing (RS) and geographical information system (GIS) tools have been extensively applied in flood disaster management, there are few reports and studies on the impact of floods on the land use/land cover environment in a post-disaster assessment. In this study, an integrated modelling approach was developed that used Landsat 8 OLI TIRS (Operational Land Imager (OLI) and Thermal Infrared Sensor) data, flood indexing and classification processes to estimate the impact of flood on the environment. The Normalized Difference Flood Index-3 (NDFI3) is an improvement on NDFI2 that takes into account the effects of cloud shadow in the images when extracting flood index areas. The flood model developed showed good agreement when compared with flooded areas shown in SAR (synthetic-aperture radar) image. The results of the flood extent as a proxy for damage estimation showed that the total flooded area was 502.34 km2 for the Kelantan Flood event in 2014, with plantation and built-up area accounting for 43 and 34.6% respectively. The least affected land uses/land covers were deforested area and forest, which accounted for 12.2 and 10.2% respectively. The RS and GIS technique developed in this post-disaster damage assessment is effective, relatively inexpensive and simple to implement by local authorities in support of post-flood disaster planning and decision-making. 相似文献
6.
This paper involves an evaluation of a relationship describing the evolution in yield stress of unsaturated soils during hydraulic hysteresis, and an application of this relationship in an elasto-plastic framework to predict the compression curves of unsaturated soils under drained (free outflow of air and water with constant suction) or undrained (constant water content with no outflow of water and varying suction) conditions. The yield stress was quantified as the apparent mean effective preconsolidation stress obtained from compression tests reported in the literature on specimens that had experienced different hydraulic paths. It was observed that the preconsolidation stress does not follow a hysteretic path when plotted as a function of matric suction, but does when plotted as a function of the degree of saturation. Accordingly, an existing logarithmic relationship between the preconsolidation stress and matric suction normalized by the air entry suction was found to match the experimental preconsolidation stress results. This same relationship was also able to satisfactorily predict the trends in preconsolidation stress with degree of saturation by substituting the hysteretic soil–water retention curve (SWRC) into the place of the matric suction. The relationship between preconsolidation stress and suction was combined with an elasto-plastic framework to predict the compression curves of soils during drained compression, while the wetting-path relationship between preconsolidation stress and degree of saturation was combined with the framework to predict the compression curves of soils during undrained (constant water content) compression. A good match was obtained with experimental data from the literature, indicating the relevance of considering the hysteretic SWRC and preconsolidation relationships when simulating the behavior of unsaturated soils following different hydro-mechanical paths. 相似文献
7.
A structural integrity assessment technique of pavements that considers the backcalculation of material properties is herein proposed. In order to carry out the backcalculation, a Nelder–Mead simplex (NMS) search is applied to estimate the elastic moduli of layered structures using the deflection data simulated by falling weight deflectometer (FWD) tests. In order to utilize a forward calculation engine of the numerical simulation in the FWD testing, a wave analysis program of layered pavement systems is used based on a spectral element method. The performance of the NMS inversion technique is evaluated based on a comparison with the Levenberg–Marquardt method. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
8.
Effect of Phototrophic Bacteria on Water Blooming 总被引：1，自引：0，他引：1
The eutrophication-induced blooming of sea or fresh water is found to be due to an anomalous burst of plankton development, which, in addition to diatom and euglena algae involves the predominance of blue-green and dinophytes (especially dinoflagellates). Characteristic representatives of plankton and toxin-generating algae are recognized. Data on the irrigation systems and drainage basins, subject to eutrophication as a result of a wide use of chemicals at paddy rice plantation in Oogata-Mura, Akita prefecture, Japan, are used to demonstrate the effect of phototrophic bacteria on organic matter decomposition in bottom sediment, which reduces water blooming and improves water quality. 相似文献
9.
G. L. Koff A. M. Ivanova M. A. Kondrat’eva I. V. Chesnokova Kim Chun Un Ten Su Mun A. A. Malakhovskii 《Seismic Instruments》2010,46(4):325-340
The results of a survey of a number of objects in the field and towns of Nevelsk and Gornozavodsk, which were in the epicenter
of an earthquake, are presented. 相似文献
1