Groundwater vulnerability assessment in shallow aquifer of Kathmandu Valley using GIS-based DRASTIC model   总被引：1，自引：0，他引：1  

Dhundi Raj Pathak  Akira Hiratsuka  Isao Awata  Luonan Chen 《Environmental Geology》2009,57(7):1569-1578

In this paper, groundwater aquifer vulnerability map has been developed by incorporating the major geological and hydro-geological factors that affect and control the groundwater contamination using GIS based DRASTIC model. This work demonstrates the potential of GIS to derive a map by overlying various spatially referenced digital data layers that portrays cumulative aquifer sensitivity ratings across the Kathmandu Valley, Nepal, providing a relative indication of groundwater vulnerability to contamination. In fact, the groundwater is the major natural resources in Kathmandu for drinking purpose. The decline in groundwater levels due to the over exploitation and thus extracted water from shallow aquifer has been contaminated by the infiltration of pollutants from polluted river and land surface is continuous and serious. As the demand for water for human and industrial use has escalated and at the same time, the engineering and environmental costs are much higher for new water supplies than maintaining the existing sources already in use. Management of groundwater source and protecting its quality is therefore essential to increase efficient use of existing water supplies. Aquifer vulnerability maps developed in this study are valuable tools for environmental planning and predictive groundwater management. Further, a sensitivity analysis has been performed to evaluate the influence of single parameters on aquifer vulnerability assessment such that some subjectivity can be reduced to some extent and then new weights have been computed for each DRASTIC parameters.  相似文献   

Tectonic setting of volcanic rocks in the Akara Au mine, north-central Thailand using petrochemical and stratigraphic investigations     

Taweewath NAKCHAIYA  Toshio MITZUTA  Daizo ISHIYAMA  Isao TAKASHIMA  Krit WON-IN  Veerasak LUNWONGSA  Punya CHARUSIRI 《地球学报》2009,30(Z1):48-48

Akara gold mine in north-central Thailand is situated within the Loei-Phetchabun-Nakhon Nayok volcanic belt. The roughly north-south trending, Permo-Triassic volcanic rocks earlier mapped by Thailand Department of Mineral Resources were re-mapped and samples were collected from the main active open pit. Forty-four samples were petrographi-cally classified and geochemically analyzed to docu-ment their stratigraphy. Two types of volcanic rocks are recognized, namely coherent and non-coherent units, in which the former is older on the basis of stratigraphic succession. Several lines of evidence suggest that the studied rocks occurred nearby the volcanic edifices and were dominated by debris flows of submarine environment.  相似文献   

Determination of Nickel in GSJ Standard Rock Samples Using Secondary Ion Mass Spectrometry     

Hisayoshi YURIMOTO  Isao SAKAGUCHI  Norimasa NISHIDA  Shigeho SUENO 《Geostandards and Geoanalytical Research》1991,15(1):155-159

Trace level determination of nickel in silicate rock samples has been achieved using secondary ion mass spectrometry (SIMS) with kinetic energy filtering. Standard rock references, issued by the Geological Survey of Japan, were fused into glass and used as standards for the SIMS analysis. Due to interferences from the glass matrix, the secondary ion of mass 60 was only useful for Ni, although the secondary ion was interfered mainly by CaO+. The contributions of these molecular ions were deconvolved by a least squares regression. Good linear correlation between results after the deconvolution and the Ni concentration in the glass standards was obtained. The uncertainties of the SIMS analysis depend strongly on the degree of contribution of CaO+ molecular ion. Such a method of SIMS analysis is especially useful to study the detailed behavior of Ni on a micro-scale in Ca-poor materials.  相似文献   

Thermal expansion of fayalite,Fe2SiO4     

Isao Suzuki  Kiyoshi Seya  Humihiko Takei  Yoshio Sumino 《Physics and Chemistry of Minerals》1981,7(2):60-63

Thermal expansion of single-crystal fayalite has been measured by a dilatometric method at temperatures between 25 °C and 850 °C. The results show the presence of anomalous expansion in the b axis, which is correlated to the anomalous variation of elastic moduli with temperature. Grüneisen's parameter is 1.10 and the thermal Debye temperature is 565 K, which is close to the acoustic Debye temperature of 511 K.  相似文献   

Study of the relationship between non-dimensional roughness length and wave age, effected by wave directionality     

Naoya Suzuki  Naoto Ebuchi  Chaofang Zhao  Isao Watabe  Yasuhiro Sugimori 《Journal of Earth System Science》2002,111(3):305-313

Relationship between the non-dimensional roughness length and inverse of wave age has been discussed without consideration of wave directions, though wind wave field consists of various directional component waves. In this study we observe wave heights by an array of four wave gauges at the Hiratsuka Tower of (Independent Administrative Institution) National Research Institute for Earth Science and Disaster Prevention (NIED), Japan, and discuss the effect of wave directionality. As a result, the data sets were classified into two different groups according to the directional wave spectrum distribution. In case 1 only swell and wind waves exist and in case 2 there exist wave components from several directions. It is shown that the case of multiple-directional component waves (case 2) may affect the non-dimensional roughness length and friction velocity.  相似文献   

A 100 m laser strainmeter system installed in a 1 km deep tunnel at Kamioka, Gifu, Japan   总被引：1，自引：0，他引：1  

Shuzo Takemoto  Akito Araya  Junpei Akamatsu  Wataru Morii  Hideo Momose  Masatake Ohashi  Ichiro Kawasaki  Toshihiro Higashi  Yoichi Fukuda  Shinji Miyoki  Takashi Uchiyama  Daisuke Tatsumi  Hideo Hanada  Isao Naito  Souichi Telada  Nobuo Ichikawa  Kensuke Onoue  Yasuo Wada 《Journal of Geodynamics》2004,38(3-5):477

We have installed a laser strainmeter system in a deep tunnel about 1,000 m below the ground surface at Kamioka, Gifu, Japan. The system consists of three types of independent interferometers: (1) an EW linear strainmeter of the Michelson type with unequal arms, (2) an NS-EW differential strainmeter of the Michelson type with equal arms and (3) a NS absolute strainmeter of the Fabry–Perot type. These are configured in L-shaped vacuum pipes, each of which has a length of 100 m. (1) and (2) are highly sensitive (order of 10⁻¹³ strain) and have wide dynamical range (10⁻¹³–10⁻⁶). Observations with strainmeters (1) and (2) started on June 11, 2003. (3) is a new device for absolute-length measurements of the order of 10⁻⁹ of a long-baseline (100 m) Fabry–Perot cavity by the use of phase-modulated light. This third strainmeter will be ready for operation before the end of 2004. The laser source of strainmeters (1) and (2) is a frequency-doubled YAG laser with a wavelength of 532 nm. The laser frequency is locked onto an iodine absorption line and a stability of 2 × 10⁻¹³ is attained. The light paths of the laser strainmeter system are enclosed in SUS304 stainless steel pipes. The inside pressure is kept to be 10⁻⁴ Pa. Consequently, quantitative measurement of crustal strains of the order of 10⁻¹³ can be attained by employing the laser strainmeter system of (1) and (2) at Kamioka. This resolving power corresponds to that of a superconducting gravimeter. Using the laser strainmeter system, we expect to determine parameters related to fluid core resonance, core modes and core undertone as well as other geodynamic signals such as slow strain changes caused by silent earthquakes or slow earthquakes.  相似文献   

Elastic properties of a single-crystal forsterite Mg2SiO4, up to 1,200 K     

Isao Suzuki  Orson L. Anderson  Yoshio Sumino 《Physics and Chemistry of Minerals》1983,10(1):38-46

Elastic moduli of forsterite were measured between 300 and 1,200 K (? 1.6 times the Debye temperature) by the Rectangular Parallelepiped Resonance method. All the moduli decrease regularly with temperature. A summary of the results is as follows:

Elastic moduli C _ij in GPa  相似文献   

38.

High potential activity of extracellular alkaline phosphatase in deep waters of the central Pacific   总被引：1，自引：0，他引：1  

Isao Koike  Toshi Nagata 《Deep Sea Research Part II: Topical Studies in Oceanography》1997,44(9-10)

We found high potential activities of alkaline phosphatase associated with particles (0.2 μm or greater size fraction) in deep waters (1000–4000 m) of the central Pacific Ocean. The potential enzyme activity at depth (0.03 – 0.3 nM h⁻¹) was up to 50% of that at the surface (0–125 m). In contrast, activities of α- and β-d-glucosidase in the deep layer were low (generally less than 1 % of those in the upper layer), yielding up to two orders of magnitude difference in the ratio of alkaline phosphatase and α- and β-d-glucosidase activities with depth. It is unlikely that the phosphatase is actively produced by microorganisms inhabiting the deep-sea environment, where labile organic carbon supply is limited and phosphate concentration is high (2.4 – 3.0 AM). Instead, deep-water phosphatase is probably supplied by rapidly sinking particles and their subsequent fragmentation and dissolution. Different distributions of phosphatase and glucosidase indicate that sinking particles of phytoplankton origin are an important source of alkaline phosphatase enzymes in the deep sea.  相似文献   

39.

Fine scale distribution of nitrous oxide in marine sediments   总被引：1，自引：0，他引：1  

Isao Koike  Kazuki Terauchi 《Marine Chemistry》1996,52(3-4)

Vertical profiles of nitrous oxide and other inorganic nitrogen compounds in the sediments in Tokyo Bay and its vicinity were measured using the whole core squeezing method. Within the bay area, vertical profiles of nitrous oxide in the interstitial waters showed one or two distinctive peaks around the depth of 2–4 cm, which corresponded to the peaks of nitrite and nitrate. In situ formation of nitrous oxide through nitrification was suggested in those sediments, which was possibly activated by the presence of benthic animals. On the other hand, at the deep sediment off Tokyo Bay the profiles of nitrous oxide, nitrite and nitrate gave a monotonous single peak, indicating less bioturbated condition. Denitrification or dissimilatory nitrate reduction might be important for the formation of nitrous oxide peaks in the latter type of sediment.  相似文献   

40.

Silicate to Nitrate Ratio of the Upper Sub-Arctic Pacific and the Bering Sea Basin in Summer: Its Implication for Phytoplankton Dynamics   总被引：2，自引：0，他引：2  

Isao Koike  Hiroshi Ogawa  Toshi Nagata  Rumi Fukuda  Hideki Fukuda 《Journal of Oceanography》2001,57(3):253-260

Consumption of silicate and nitrate (Si:N molar ratio) in the upper layer of the pelagic subarctic Pacific in summer was evaluated by a regression analysis of silicate vs. nitrate concentrations at the upper 100 m depth. Based on data of three cruises, the pelagic subarctic Pacific can be classified into two groups. First group is characterized by roughly 1:1 consumption of silicate and nitrate, and occupies rather larger area of subarcfic Pacific, i.e., the Gulf of Alaska and the Western Subarctic gyre (averaged slope of Si:N linear regression: 1.21, n = 10 and 1.45, n = 9, respectively). Second group is the regions of the Bering Sea basin and the Oyashio region, and showed higher silicate consumption compared to that of nitrate (averaged slope of Si:N linear regression: 2.14, n = 9 and 2.36, n = 3, respectively). The Si:N difference observed is possibly attributed to relative contribution of diatoms production among the phytoplankton assemblages in the regions, i.e., dominance of diatoms production in the regions of the second group. Higher accumulation of ammonium at the bottom of euphotic layer in the summer Bering Sea basin would also contribute to increase consumption ratio of Si:N amounts.  相似文献   

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