• Human exposure to radon radiation geohazard in Rong Cave, Dong Van Karst Plateau Geopark, VietnamHuman exposure to radon radiation geohazard in Rong Cave, Dong Van Karst Plateau Geopark, Vietnam

    Radon concentrations in the air of Rong Cave exceeded WHO-recommended safety thresholds (UNSCEAR, 1993, 2008) except from February to April during ‘cold and dry’ weather conditions. Rong Cave’s thoron (220Rn) concentrations are far higher than the respective WHO-recommended safety level. 222Rn concentrations in Rong Cave exceed the TCVN-788...

    pdf11 trang | Chia sẻ: honghp95 | Ngày: 30/11/2020 | Lượt xem: 847 | Lượt tải: 0

  • A study on the variation of zeta potential with mineral composition of rocks and types of electrolyteA study on the variation of zeta potential with mineral composition of rocks and types of electrolyte

    In this work, streaming potential measurements are performed for five rock samples saturated with six different electrolytes. From measured streaming potential coefficients, the zeta potential is deduced. The theoretical model is then used to explain the experimental data. Based on the model, the surface site density for different rocks and th...

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  • Soil structure and soil organic matter in water-Stable aggregates under different application rates of biocharSoil structure and soil organic matter in water-Stable aggregates under different application rates of biochar

    Elevated doses of biochar with a higher level of N fertilizer application significantly increased the index of aggregate stability and the proportion of water-stable macroaggregates, especially in the size fractions from 3 to 2 mm. On the other hand, less water-stable macro-aggregates within the fraction from 0.5 to 0.25 mm were observed. Appli...

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  • Assessment of earthquake-Induced liquefaction hazard in urban areas of Hanoi city using LPI-based methodAssessment of earthquake-Induced liquefaction hazard in urban areas of Hanoi city using LPI-based method

    In this study, the LPI-based method was applied to evaluate the earthquake-induced liquefaction potential for the urban area of Hanoi city. Using a dataset of 120 boreholes logs, the “simplified procedure” to evaluate the liquefaction of soil layers in every borehole point. The Liquefaction Potential Index (LPI) was calculated for the whole s...

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  • Spatial variations of arsenic in groundwater from a transect in the Northwestern HanoiSpatial variations of arsenic in groundwater from a transect in the Northwestern Hanoi

    The arsenic concentrations of the B-B’ transect vary in a wide range: from <5 to 115 µg/L, with the lowest average concentration at Cam Yen and the highest one at Van Phuc. The As release process depends on many factors such as the extent of the reducing conditions, the sediment age, bacteria activities, etc. From the results, one can predict ...

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  • Geochemical features of Sakhalin Island mud volcanoesGeochemical features of Sakhalin Island mud volcanoes

    Deep shears are the supply channels for both fluids from sedimentary basins (hydrocarbons) and magmatic rock fluids (helium, hydrogen, carbon dioxide). The mud volcanic gas emission from sedimentary basins is enhanced during seismic activity. The presence of active mud volcanoes and mineral springs proves the activity of deep faults, through ...

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  • Study of impurity in blue spinel from the Luc Yen mining area, Yen Bai province, VietnamStudy of impurity in blue spinel from the Luc Yen mining area, Yen Bai province, Vietnam

    Impurities present in light and saturated cobalt-blue spinel samples collected from Luc Yen mining area (Vietnam) have been studied in details. By using different techniques, including EMPA, UV-VIS-NIR, ESR and XAS, the existence of impurities V, Mn, Ni, Zn, Ti, Cr, Fe, Co, and Ca were identified. Among those impurities, the oxidation state o...

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  • Improvement of the accuracy of the quasigeoid model VIGAC2017Improvement of the accuracy of the quasigeoid model VIGAC2017

    Above represented research results show, that on the base of solving the task of fitting the initial quasigeoid model VIGAC2017 to the 194 national quasigeoid heights got from the 194 GPS/first and second orders levelling quasigeoid heights by the least squares collocation, the accuracy of the this model has been increased to to 20,69 %. Tha...

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  • Inverse analysis for transmissivity and the Red river bed's leakage factor for Pleistocene aquifer in Sen Chieu, Hanoi by pumping test under the river water level fluctuationInverse analysis for transmissivity and the Red river bed's leakage factor for Pleistocene aquifer in Sen Chieu, Hanoi by pumping test under the river water level fluctuation

    The determination of the exact boundary condition kinds, boundary values and aquifer parameters values for the areas along the Red river as well as for the areas of boundary of the Pleistocene aquifer with the bed rock in the West and South-West areas of the Red river plain have a very important role in the of the natural groundwater resourc...

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  • Determination of ground displacement of 25 April 2015 Nepal earthquake by GNSS precise point positioningDetermination of ground displacement of 25 April 2015 Nepal earthquake by GNSS precise point positioning

    To monitor the effect of the earthquake with the magnitude of 7.8 on 25 April 2015 in Nepal, we collected and processed GNSS data at 17 stations around the epicenter by using the GNSS PPPC method. The GNSS station displacements are calculated precisely with an accuracy of 1cm in the horizontal and the vertical components. These displacements ...

    pdf9 trang | Chia sẻ: honghp95 | Ngày: 30/11/2020 | Lượt xem: 690 | Lượt tải: 0