Stream channel erosion in a rapidly urbanizing region of the US–Mexico border: documenting the importance of channel hardpoints with Structure‐from‐Motion photogrammetry          下载免费PDF全文

Kristine T. Taniguchi  Trent W. Biggs  Eddy J. Langendoen  Carlos Castillo  Napoleon Gudino‐Elizondo  Yongping Yuan  Douglas Liden 《地球表面变化过程与地形》2018,43(7):1465-1477

Urbanization can lead to accelerated stream channel erosion, especially in areas experiencing rapid population growth, unregulated urban development on erodible soils, and variable enforcement of environmental regulations. A combination of field surveys and Structure‐from‐Motion (SfM) photogrammetry techniques was used to document spatial patterns in stream channel geometry in a rapidly urbanizing watershed, Los Laureles Canyon (LLCW), in Tijuana, Mexico. Ground‐based SfM photogrammetry was used to map channel dimensions with 1 to 2 cm vertical mean error for four stream reaches (100–300 m long) that were highly variable and difficult to survey with a differential GPS. Regional channel geometry curves for LLCW had statistically larger slopes and intercepts compared with regional curves developed for comparable, undisturbed reference channels. Cross‐sectional areas of channels downstream of hardpoints, such as concrete reaches or culverts, were up to 64 times greater than reference channels, with enlargement persisting, in some cases, up to 230 m downstream. Percentage impervious cover was not a good predictor of channel enlargement. Proximity to upstream hardpoint, and lack of riparian and bank vegetation paired with highly erodible bed and bank materials may account for the instability of the highly enlarged and unstable cross‐sections. Channel erosion due to urbanization accounts for approximately 25–40% of the total sediment budget for the watershed, and channel erosion downstream of hardpoints accounts for one‐third of all channel erosion. Channels downstream of hardpoints should be stabilized to prevent increased inputs of sediment to the Tijuana Estuary and local hazards near the structures, especially in areas with urban settlements near the stream channel. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

Implication of Apatite and Anhydrite for Formation of an Iron‐Oxide‐Apatite (IOA) Rare Earth Element Prospect,Benjamin River,Canada          下载免费PDF全文

Mihoko Hoshino  Yasushi Watanabe  Yoshiaki Kon 《Resource Geology》2017,67(4):361-383

The Benjamin River apatite prospect in northern New Brunswick, Canada, is hosted by the Late Silurian Dickie Brook plutonic complex, which is made up of intrusive units represented by monzogranite, diorite and gabbro. The IOA ores, composed mainly of apatite, augite, and magnetite at Benjamin River form pegmatitic pods and lenses in the host igneous rocks, the largest of which is 100 m long and 10–20 m wide in the diorite and gabbro units. In this study, 28 IOA ore and rock samples were collected from the diorite and gabbro units. Mineralogical observations show that the apatite–augite–magnetite ores are variable in the amounts of apatite, augite, and magnetite and are associated with minor amounts of epidote‐group minerals (allanite, REE‐rich epidote and epidte) and trace amounts of albite, titanite, ilmenite, titanomagnetite, pyrite, chlorite, calcite, and quartz. Apatite and augite grains contain small anhydrite inclusions. This suggests that the magma that crystallized apatite and augite had high oxygen fugacity. In back scattered electron (BSE) images, apatite grains in the ores have two zones of different appearance: (i) primary REE‐rich zone; and (ii) porous REE‐poor zone. The porous REE‐poor zones mainly appear in rims and/or inside of the apatite grains, in addition to the presence of apatite grains which totally consist of a porous REE‐poor apatite. This porous REE‐poor apatite is characterized by low REE (<0.84 wt%), Si (<0.28 wt%), and Cl (<0.17 wt%) contents. Epidote‐group minerals mainly occur in grain boundary between the porous REE‐poor apatite and augite. These indicate that REE leached from primary REE‐rich apatite crystallized as allanite and REE‐rich epidote. Magnetite in the ores often occurs as veinlets that cut apatite grains or as anhedral grains that replace a part of augite. These textures suggest that magnetite crystallized in the late stage. Pyrite veins occur in the ores, including a large amount of quartz and calcite veins. Pyrite veins mainly occur with quartz veins in augite. These textures indicate pyrite veins are the latest phase. Apatite–augite–magnetite ore, gabbro–quartz diorite and feldspar dike collected from the Benjamin River prospect contain dirty pure albite (Ab₉₈Or₂–Ab₁₀₀) under the microscope. The feldspar dikes mainly consist of dirty pure albite. Occurrences of the dirty pure albite suggest remarkable albitization (sodic alteration) of original plagioclase (An_25.3–An₆₀ in Pilote et al., 2012) associating with intrusion of monzogranite into gabbro and diorite. SO₄^2? bearing magma crystallized primary REE‐rich apatite, augite and anhydrite reacted with Fe in the sodic fluids, which result in oxidation of Fe²⁺ and release of S^2? into the sodic fluids. REE, Ca and Fe from primary REE‐rich apatite, augite and plagioclase altered by the sodic fluids were released into the fluids. Then Fe³⁺ in the sodic fluids precipitated as Fe oxides and epidote‐group minerals in apatite–augite–magnetite ores. Finally, residual S^2? in sodic fluids crystallized as latest pyrite veins. In conclusion, mineralization in Benjamin River IOA prospect are divided into four stages: (1) oxidized magmatic stage that crystallized apatite, augite and anhydrite; (2) sodic metasomatic stage accompanying alteration of magmatic minerals; (3) oxidized fluid stage (magnetite–epidote group minerals mineralization); and (4) reduced fluid stage (pyrite mineralization).  相似文献   

Fractured Rock Permeability as a Function of Temperature and Confining Pressure     

A. K. M. Badrul Alam  Yoshiaki Fujii  Daisuke Fukuda  Jun-ichi Kodama  Katsuhiko Kaneko 《Pure and Applied Geophysics》2015,172(10):2871-2889

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Toward seamless indoor-outdoor applications: Developing stakeholder-oriented location-based services     

Kohei Ogawa  Edward Verbree  Sisi Zlatanova  Naohiko Kohtake  Yoshiaki Ohkami 《地球空间信息科学学报》2013,16(2):109-118

Location-Based Services (LBS), an emerging new business based on smartphone and mobile networks, are becoming more and more popular. Most of these LBSs, however, only offer non-seamless indoor/outdoor applications and simple applications without giving stakeholders the chance to play an active role. Our specific aim is to solve these issues. This paper presents concepts to solve these issues by expanding the Open Location Services Interface Standard (OpenLS) to allow seamless indoor/outdoor positioning and to extend the content of the services to include information recommended by stakeholders.  相似文献   

Toward seamless indoor-outdoor applications: Developing stakeholder-oriented location-based services     

Kohei OGAWA  Edward VERBREE  Sisi ZLATANOVA  Naohiko KOHTAKE  Yoshiaki OHKAMI 《地球空间信息科学学报》2011,14(2):109-118

Location-Based Services (LBS),an emerging new business based on smartphone and mobile networks,are becoming more and more popular.Most of these LBSs,however,only offer non-seamless indoor/outdoor applications and simple applications without giving stakeholders the chance to play an active role.Our specific aim is to solve these issues.This paper presents concepts to solve these issues by expanding the Open Location Services Interface Standard (OpenLS) to allow seamless indoor/outdoor positioning and to extend the content of the services to include information recommended by stakeholders.  相似文献   

Groundwater flow system under a rapidly urbanizing coastal city as determined by hydrogeochemistry     

Makoto Kagabu  Jun Shimada  Robert Delinom  Maki Tsujimura  Makoto Taniguchi 《Journal of Asian Earth Sciences》2011,40(1):226-239

In the Jakarta area (Indonesia), excessive groundwater pumping due to the rapidly increasing population has caused groundwater-related problems such as brackish water contamination in coastal areas and land subsidence. In this study, we adopted multiple hydrogeochemical techniques to demonstrate the groundwater flow system in the Jakarta area. Although almost all groundwater existing in the Jakarta basin is recharged at similar elevations, the water quality and residence time demonstrates a clear difference between the shallow and deep aquifers. Due to the rapid decrease in the groundwater potential in urban areas, we found that the seawater intrusion and the shallow and deep groundwaters are mixing, a conclusion confirmed by major ions, Br^?:Cl^? ratios, and chlorofluorocarbon (CFC)-12 analysis. Spring water and groundwater samples collected from the southern mountainside area show younger age characteristics with high concentrations of ¹⁴C and Ca–HCO₃ type water chemistry. We estimated the residence times of these groundwaters within 45 years under piston flow conditions by tritium analysis. Also, these groundwater ages can be limited to 20–30 years with piston flow evaluated by CFCs. Moreover, due to the magnitude of the CFC-12 concentration, we can use a pseudo age indicator in this field study, because we found a positive correlation between the major type of water chemistry and the CFC-12 concentration.  相似文献   

Formation Process of Zircon Associated with REE‐Fluorocarbonate and Niobium Minerals in the Nechalacho REE Deposit,Thor Lake,Canada     

Mihoko Hoshino  Yasushi Watanabe  Hiroyasu Murakami  Yoshiaki Kon  Maiko Tsunematsu 《Resource Geology》2013,63(1):1-26

The two drill holes, which penetrated sub‐horizontal rare earth element (REE) ore units at the Nechalacho REE in the Proterozoic Thor Lake syenite, Canada, were studied in order to clarify the enrichment mechanism of the high‐field‐strength elements (HFSE: Zr, Nb and REE). The REE ore units occur in the albitized and potassic altered miaskitic syenite. Zircon is the most common REE mineral in the REE ore units, and is divided into five types as follows: Type‐1 zircon occurs as discrete grains in phlogopite, and has a chemical character similar to igneous zircon. Type‐2 zircon consists of a porous HREE‐rich core and LREE–Nb–F‐rich rim. Enrichment of F in the rim of type‐2 zircon suggests that F was related to the enrichment of HFSE. The core of type‐2 zircon is regarded to be magmatic and the rim to be hydrothermal in origin. Type‐3 zircon is characterized by euhedral to anhedral crystals, which occur in a complex intergrowth with REE fluorocarbonates. Type‐3 zircon has high REE, Nb and F contents. Type‐4 zircon consists of porous‐core and ‐rim, but their chemical compositions are similar to each other. This zircon is a subhedral crystal rimmed by fergusonite. Type‐5 zircon is characterized by smaller, porous and subhedral to anhedral crystals. The interstices between small zircon grains are filled by fergusonite. Type‐4 and type‐5 zircon grains have low REE, Nb and F contents. Type‐1 zircon is only included in one unit, which is less hydrothermally altered and mineralized. Type‐2 and type‐3 zircon grains mainly occur in the shallow units, while those of type‐4 and type‐5 are found in the deep units. The deep units have high HFSE contents and strongly altered mineral textures (type‐4 and type‐5) compared to the shallow units. Occurrences of these five types of zircon are different according to the depth and degree of the hydrothermal alteration by solutions rich in F and CO₃, which permit a model for the evolution of the zircon crystallization in the Nechalacho REE deposit as follows: (i) type‐1 (discrete magmatic zircon) is formed in miaskitic syenite. (ii) LREE–Nb–F‐rich hydrothermal zircon formed around HREE‐rich magmatic zircon (type‐2). (iii) type‐3 zircon crystallized through the F and CO₃‐rich hydrothermal alteration of type‐2 zircon which formed the complex intergrowth with REE fluorocarbonates; (iv) the CO₃‐rich hydrothermal fluid corroded type‐3, forming REE–Nb‐poor zircon (type‐4). Niobium and REE were no longer stable in the zircon structure and crystallized as fergusonite around the REE–Nb‐leached zircon (type‐4); (v) type‐5 zircon is formed by the more CO₃‐rich hydrothermal alteration of type‐4 zircon, suggested by the fact that type‐4 and type‐5 zircon grains are often included in ankerite. Type‐3 to type‐5 zircon grains at the Nechalacho REE deposit were continuously formed by leaching and/or dissolution of type‐2 zircon in the presence of F‐ and/or CO₃‐rich hydrothermal fluid. These mineral associations indicate that three representative hydrothermal stages were present and related to HFSE enrichment in the Nechalacho REE deposit: (i) F‐rich hydrothermal stage caused the crystallization of REE–Nb‐rich zircon (type‐2 rim and type‐3), with abundant formation of phlogopite and fluorite; (ii) F‐ and CO₃‐rich hydrothermal stage led to the replacement of a part of REE–Nb–F‐rich zircon by REE fluorocarbonate; and (iii) CO₃‐rich hydrothermal stage resulted in crystallization of the REE–Nb–F‐poor zircon and fergusonite, with ankerite. REE and Nb in hydrothermal fluid at the Nechalacho REE deposit were finally concentrated into fergusonite by way of REE–Nb–F‐rich zircon in the hydrothermally altered units.  相似文献   

Assessment of urban groundwater heat contaminant in Jakarta, Indonesia     

Rachmat Fajar Lubis  Makoto Yamano  Robert Delinom  Sudaryanto Martosuparno  Yasuo Sakura  Shusaku Goto  Akinobu Miyakoshi  Makoto Taniguchi 《Environmental Earth Sciences》2013,70(5):2033-2038

Urbanization has become one of the domain processes for city development in Indonesia. The results of the extremely high densities of fast growing population have led to negative subsurface environmental impact. Jakarta, as one of the rapidly developed and urbanized cities in Southeast Asia, has become one of the interesting urbanization city to analyze its effects. In Jakarta, the use of groundwater has greatly accelerated conforming to the rise in its population and the development of the industrial sector, which consume a relatively large amount of water. The increase of groundwater exploitation in Jakarta city has already caused a negative impact on these resources. Therefore, an assessment of groundwater trends in the urban area, including their hazard and risk management, is a necessary action. This paper describes the assessment of urban groundwater loading caused by human concentration in Jakarta city. Subsurface heat contamination under the condition of surface warming shows significant effects of urban groundwater loading during the past century in Jakarta city.  相似文献   

Spatial distribution of sedimentary linear alkylbenzenes and faecal steroids of Santos Bay and adjoining continental shelf, SW Atlantic, Brazil: origin and fate of sewage contamination in the shallow coastal environment   总被引：1，自引：0，他引：1  

Martins CC  Ferreira JA  Taniguchi S  Mahiques MM  Bícego MC  Montone RC 《Marine pollution bulletin》2008,56(7):1359-1363

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Cross-shore variation of long-term average longshore current velocity in the nearshore zone     

Yoshiaki Kuriyama  Yoshimasa Ito  Shinichi Yanagishima 《Continental Shelf Research》2008

The cross-shore variation of long-term average longshore current velocity was investigated on the basis of a 15-year data set of longshore current, wave and wind. The longshore current velocities were measured once a day along a 427-m-long pier. The results show that the direction of the long-term average longshore current velocity away (>200 m) from the shore was the opposite to that near the shore. The southward current was dominant offshore, whereas the northward current was dominant near the shore. The cross-shore variation of the long-term average longshore current velocity was formed owing to a difference between the wave and wind conditions when the northward and southward currents developed. When the northward current developed, the offshore wave height was relatively small and the frequency of the southward wind velocity was almost equal to that of the northward one. As a result, the northward current developed only near the shore and decayed outside the narrow surf zone. On the other hand, when the southward current developed, the offshore wave height was relatively large and the southward wind velocity was predominant, which resulted in the southward current developing not only in the wide surf zone but also outside the surf zone. The superposition of the two cross-shore variations produced a cross-shore variation of the long-term average longshore current velocity with a northward velocity near the shore and a southward velocity away from the shore.  相似文献