Numerical simulation of large wood deposition patterns and responses of bed morphology in a braided river using large wood dynamics model

This study discusses the reproducibility of a numerical model for simulating the morphodynamics involved in the transport of large pieces of wood in a braided river, considering the root wad effect and jam formation. The developed numerical model can simulate the behaviour of large pieces of wood using a two-dimensional depth-averaged Eulerian flow model that calculates the water flow and bed morphology. A Lagrange-type wood transport model is used herein, and the applicability of the combined model is discussed through a comparison with obtained experimental results. From the simulation results, we calculate the total braiding index and estimate the deposition patterns of wood pieces for comparison with the experimental results. We then analyse the bed morphology responses and wood deposition patterns in terms of the root wad effect and input supply. Moreover, we discuss the advantages and limitations of the proposed model to predict the large wood dynamics considering the bed morphology. © 2019 John Wiley & Sons, Ltd.     

空间乳胶室探测器的研制

"实践八号"乳胶室探测器是我国首次用于空间观测高能电子及伽玛射线的乳胶 室探测器.介绍"实践八号"乳胶室探测器的设计原理、数据分析方法、设计过程和初步 观测结果等."实践八号"乳胶室探测器空间观测时间为15天,可探测的粒子能量范围为 100GeV～5TeV.     

Flux‐Free Fusion of Silicate Rock Preceding Acid Digestion for ICP‐MS Bulk Analysis

We present a new method for the decomposition of silicate rocks by flux‐free fusion in preparation for whole‐rock trace element determination (Sc, Rb, Sr, Y, Zr, Nb, Cs, Ba, rare earth elements and Hf) that is especially applicable to zircon‐bearing felsic rocks. The method was verified by analyses of RMs of mafic (JB‐1a, JB‐2, JGb‐1) and felsic rocks (JG‐3, JR‐3, JSd‐1, GSP‐2, G‐2). Pellets of powdered sample (up to 500 mg) without flux were weighed and placed in a clean platinum crucible. The samples were then fused in a Siliconit® tube furnace and quenched to room temperature. The optimum condition for the fusion of granitic rock was determined to be heating for 2–3 min at 1600 °C. The fused glass in the platinum crucible after heating was decomposed using HF and HClO₄ in a Teflon® beaker. Decomposed and diluted sample solutions were analysed using a quadrupole inductively coupled plasma‐mass spectrometer. Replicate analyses (n = 4 or 5) of the RMs revealed that analytical uncertainties were generally < 3% for all elements except Zr and Hf (～ 6%) in JG‐3. These higher uncertainties may be attributed to sample heterogeneity. Our analytical results for the RMs agreed well with recommended concentrations and recently published concentrations, indicating complete decomposition of our rock samples during fusion.     

Sulfur Isotope Study on Hg and Sb Deposits in Japan

Abstract. Sulfur isotope ratios of cinnabar from Hg deposits and stibnite, jamesonite and berthierite from Sb deposits in Japan are examined in order to understand metallogeneses of Hg and Sb deposits in Japanese island arcs. The studied Hg and Sb deposits include the Hg deposit at Yamato‐suigin (Honshu) and the Sb deposit at Ichinokawa (Shikoku) in the Southwest Japan arc. In addition, Hg deposits including Itomuka and Ryushoden in central Hokkaido and Hg and Sb mineralizations in Northeast Japan arc are examined. The δ³⁴S values of cinnabar from the Hidaka‐Kitami district, central Hokkaido, including the Itomuka and Ryushoden deposits range widely, from ‐10 to +16 %o, the highest values encountered at the Samani deposit. The δ³⁴S values of cinnabar from other areas in Japan range from ‐12 to +5 %o, having δ³⁴S values higher than +2 %o from southwestern Hokkaido (Meiji deposit), Shikoku (Suii deposit) and Kyushu (Hasami and Yamagano deposits). On the other hand, the δ³⁴S values of stibnite from all areas in Japan range from ‐14 to +5 %o, having positive δ³⁴S values higher than +2 %o up to +5 %o from southwestern Hokkaido (Yakumo, Toyotomi and Teine deposits) and eastern‐central Honshu (Hachiman and Daikoku deposits). The variation in δ³⁴S values of Hg and Sb deposits may reflect the variation in δ³⁴S values of country rocks or variation in mixing ratio of sulfur extracted from the country rocks, sulfur derived from seawater sulfate, and sulfur derived from magmatic emanations. The relatively high δ³⁴S values of cinnabar and stibnite higher than +2 %o from southwestern Hokkaido, eastern‐central Honshu and Kyushu are probably caused by contribution of volcanic emanation from arc magmas having positive σδ³⁴S values, whereas the positive δ³⁴S values of cinnabar higher than +2 %o from Suii deposit in Shikoku may be attributed to structurally substituted sulfate in limestone country rocks and/or sulfur derived from seawater sulfate. However, the wide range of the δ³⁴S values of cinnabar from the Hidaka‐Kitami district, central Hokkaido, is difficult to explain at this moment. Other relatively low, negative δ³⁴S values of cinnabar and stibnite, berthierite from other areas in Japan may be attributed to 1) incorporation of isotopically light sedimentary sulfur or sulfur derived from ilmenite‐series silicic magma, or 2) less contribution of volcanic emanation from arc magmas having positive σδ³⁴S values.     

Landslide detection based on height and amplitude differences using pre- and post-event airborne X-band SAR data

Natural Hazards - The recognition of landslides and making their inventory map are considered to be urgent tasks not only for damage estimation but also for planning rescue and restoration...     

Organic matters and acid‐sulfate alteration in Itomuka mercury mine,Hokkaido, Japan: Implications for the transportation and deposition mechanisms of Hg

In order to examine the transportation and deposition mechanisms of Hg, we investigated the ore and hydrothermal alteration minerals and solid organic matters from Itomuka mercury mine located in the eastern part of central Hokkaido. In addition to the ore minerals, native mercury and cinnabar, quartz, marcasite, alunite, kaolinite, and minor amounts of pyrite and smectite were identified in the Hg ore by powder X‐ray diffraction (XRD) analysis. This mineral assemblage of acid sulfate alteration was likely developed under the conditions of low temperature (≤100°C) and low pH (≤2) in the steam‐heated environment. The H₂SO₄ was produced above the water table by the oxidation of H₂S separated from deep, near‐neutral fluids by boiling. The dominance of native mercury over cinnabar in Hg ore indicates that the greater part of mineralized Hg was transported as Hg⁰ in aqueous solution and vapor with low sulfur fugacity. The solid organic matters found in the Hg ore were analyzed with SEM‐EDS, micro‐XRD, and micro‐Fourier transform infrared (FTIR) spectroscopy, and these results suggest that the organic matters contributed to keeping the low fO₂ of the Hg‐bearing fluid and transportation of Hg as Hg⁰ in S‐poor condition. Because the solubility of Hg in acidic fluid is low, neutral to alkaline fluid seems to have leached Hg from the basement sedimentary rocks of Hidaka Group which also supplied the organic matters to the fluid. The oxidation and cooling of Hg‐bearing solution and vapor triggered the deposition of liquid Hg as a primary phase.     

中国东部岩石圈地幔的演化——地幔岩捕虏体微量元素的证据

对中国东部赋存于新生代玄武岩中的地幔岩捕虏体的全岩和单斜辉石等作了主元素和微量元素分析，证实了二辉橄榄岩及其单斜辉石在主元素有连续变化的趋势，反映了具部分熔融后残留相的性质。方辉橄榄岩及其中的单斜辉石的主元素，Ｎｄ／Ｙｂ，Ｔｉ／Ｚｒ和Ｓｒ／Ｚｒ值与二辉橄榄岩的同类矿物是不连续过渡。     

A Proposed Method to Estimate In Situ Dissolved Gas Concentrations in Gas‐Saturated Groundwater

Gas‐saturated groundwater forms bubbles when brought to atmospheric pressure, preventing precise determination of its in situ dissolved gas concentrations. To overcome this problem, a modeling approach called the atmospheric sampling method is suggested here to recover the in situ dissolved gas concentrations of groundwater collected ex situ under atmospheric conditions at the Horonobe Underground Research Laboratory, Japan. The results from this method were compared with results measured at the same locations using two special techniques, the sealed sampler and pre‐evacuated vial methods, that have been developed to collect groundwater under its in situ conditions. In gas‐saturated groundwater cases, dissolved methane and inorganic carbon concentrations derived using the atmospheric sampling method were mostly within ±4 and ±10%, respectively, of values from the sealed sampler and pre‐evacuated vial methods. In gas‐unsaturated groundwater, however, the atmospheric sampling method overestimated the in situ dissolved methane concentrations, because the groundwater pressure at which bubbles appear (P_critical) was overestimated. The atmospheric sampling method is recommended for use where gas‐saturated groundwater can be collected only ex situ under atmospheric conditions.