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101.
Hydrological and sediment fluxes were monitored for a 1 yr period in a tropical headwater catchment where a 3 yr old logging road caused substantial Hortonian overland flow (HOF) and intercepted subsurface flow (ISSF). On a 51·5 m road section, ISSF became an increasingly important component of total road runoff, up to more than 90% for large storms. The proportion of ISSF contributed by road cuts along more or less planar slopes compared with ISSF from a zero‐order basin (convergent slopes) truncated by the road declined with increasing rainfall. During the monitored storms that generated ISSF along the road, on average, 28% of sediment export and 79% of runoff from the road section were directly attributable to ISSF. Estimates of total sediment export from the road surface (170 t ha?1 yr?1) and suspended sediment export from the logging‐disturbed catchment (4 t ha?1 yr?1) were exceptionally high despite 3 yr of recovery. ISSF caused not only additional road‐generated sediment export, but also exacerbated HOF‐driven erosion by creating a poor foundation for vegetation recovery on the road surface. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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Hirata Takashi Zaima Nobuhiro Yamashita Kyoko Noguchi Ryoko XUE Changhu Sugawara Tatsuya 《中国海洋大学学报(英文版)》2005,4(3):193-197
In this report, we reviewed recent literature on physiologically active substances from sea cucumbers (SCs) and their activities together with results obtained from our study. Preventive properties against lipid metabolism were reported in rats using a whole SC preparation with no particular constituent specified. Administration of the preparation lowered serum and hepatic cholesterol levels and improved the HDL/LDL ratio. These functions may be attributed to the stimulatory effect of the extract on the secretion of cholesterol in feces. Novel fucosylated chondroitin sulfates (FCSs) from Ludwigothurea grisea significantly induced fibroblast growth factor 2-dependent angiogenesis in human umbilical vein endothelial cells (HUVECs). The proangiogenetic activity seemed attributable to the action of the sulfated fucose branches on the polysaccharide. SCs contain mycosporine-like amino acids (MAAs) that are capable of absorbing UV. A biogenetic precursor of MAAs was first reported in SCs. The anti-proliferative effects of a branched chain fatty acid from a sea cucumber on prostate cancer cells was reported with the activity of 5-lipoxygenase. Glycosphingolipid constituents in SCs have been systematically analyzed over the past ten years. The results showed that the gangliosides in several SCs differed from those of mammals in that a sialic acid of SC gangliosides directly binded to glucose of cerebroside. Neuritogenic activity of the glycosphingolipids was demonstrated in vitro experiments and may lead to the development of therapeutic products for neurological disorders. Our study also showed that sphingoid bases, the hydrolyzed products of glycosphingolipids from SCs, induced significant apoptosis in several tumor cell lines. 相似文献
104.
Intermineral oxygen three‐isotope systematics of silicate minerals in equilibrated ordinary chondrites 下载免费PDF全文
David McDougal Daisuke Nakashima Travis J. Tenner Noriko T. Kita John W. Valley Takaaki Noguchi 《Meteoritics & planetary science》2017,52(11):2322-2342
High‐precision oxygen three‐isotope ratios were measured for four mineral phases (olivine, low‐Ca and high‐Ca pyroxene, and plagioclase) in equilibrated ordinary chondrites (EOCs) using a secondary ion mass spectrometer. Eleven EOCs were studied that cover all groups (H, L, LL) and petrologic types (4, 5, 6), including S1–S4 shock stages, as well as unbrecciated and brecciated meteorites. SIMS analyses of multiple minerals were made in close proximity (mostly <100 μm) from several areas in each meteorite thin section, to evaluate isotope exchange among minerals. Oxygen isotope ratios in each mineral become more homogenized as petrologic type increases with the notable exception of brecciated samples. In type 4 chondrites, oxygen isotope ratios of olivine and low‐Ca pyroxene are heterogeneous in both δ18O and Δ17O, showing similar systematics to those in type 3 chondrites. In type 5 and 6 chondrites, oxygen isotope ratios of the four mineral phases plot along mass‐dependent fractionation lines that are consistent with the bulk average Δ17O of each chondrite group. The δ18O of three minerals, low‐Ca and high‐Ca pyroxene and plagioclase, are consistent with equilibrium fractionation at temperatures of 700–1000 °C. In most cases the δ18O values of olivine are higher than those expected from pyroxene and plagioclase, suggesting partial retention of premetamorphic values due to slower oxygen isotope diffusion in olivine than pyroxene during thermal metamorphism in ordinary chondrite parent bodies. 相似文献
105.
Marryanna Lion Yoshiko Kosugi Satoru Takanashi Shoji Noguchi Masayuki Itoh Masanori Katsuyama Naoko Matsuo Siti‐Aisah Shamsuddin 《水文研究》2017,31(24):4338-4353
To evaluate water use and the supporting water source of a tropical rainforest, a 4‐year assessment of evapotranspiration (ET) was conducted in Pasoh Forest Reserve, a lowland dipterocarp forest in Peninsular Malaysia. The eddy covariance method and isotope signals of rain, plant, soil, and stream waters were used to determine forest water sources under different moisture conditions. Four sampling events were conducted to collect soil and plant twig samples in wet, moderate, dry, and very dry conditions for the identification of isotopic signals. Annual ET from 2012 to 2015 was quite stable with an average of 1,182 ± 26 mm, and a substantial daily ET was observed even during drought periods, although some decline was observed, corresponding with volumetric soil water content. During the wet period, water for ET was supplied from the surface soil layer between 0 and 0.5 m, whereas in the dry period, approximately 50% to 90% was supplied from the deeper soil layer below 0.5‐m depth, originating from water precipitated several months previously at this forest. Isotope signatures demonstrated that the water sources of the plants, soil, and stream were all different. Water in plants was often different from soil water, probably because plant water came from a different source than water that was strongly bound to the soil particles. Plants showed no preference for soil depth with their size, whereas the existence of storage water in the xylem was suggested. The evapotranspiration at this forest is balanced and maintained using most of the available water sources except for a proportion of rapid response run‐off. 相似文献
106.
A new method for the speciation of Fe and Mn at mineral surfaces is proposed using X-ray absorption fine structure in conversion electron yield mode (CEY-XAFS). This method generally reflects information on the species at the sub-μm scale from the particle surface due to the limited escape depth of the inelastic Auger electron. The surface sensitivity of this method was assessed by experiments on two samples of granite showing different degrees of weathering. The XANES spectra of the Fe-K and Mn-K edge clearly gave different information for CEY and fluorescence (FL) modes. These XANES spectra of Fe and Mn show a good fit upon application of least-squares fitting using ferrihydrite/MnO2 and biotite as the end members. The XANES spectra collected by CEY mode provided more selective information on the secondary phases which are probably present at the mineral surfaces. In particular, CEY-XANES spectra of Mn indicated the presence of Mn oxide in unweathered granite despite a very small contribution of Mn oxide being indicated by FL-XANES and selective chemical-extraction analyses. Manganese oxide could not be detected by micro-beam XANES (beam size: 5 × 5 μm2) in unweathered granite, suggesting that Mn oxide thinly and ubiquitously coats mineral surface at a sub-μm scale. This information is important, since Mn oxide can be the host for various trace elements. CEY-XAFS can prove to be a powerful tool as a highly sensitive surface speciation method. Combination of CEY and FL-XAFS will help identify minor phases that form at mineral surfaces, but identification of Fe and Mn oxides at mineral surfaces is critical to understand the migration of trace elements in water-rock interaction. 相似文献
107.
Ashraf Ali Seddique Harue Masuda Muneki Mitamura Keiji Shinoda Toshiro Yamanaka Takaaki Itai Teruyuki Maruoka Kenji Uesugi Kazi Matin Ahmed Dipak Kumar Biswas 《Applied Geochemistry》2008,23(8):2236-2248
Continuous core sediments (to a depth of 90.1 m) taken at a transitional area of Holocene and Pleistocene deposits in Sonargaon, Bangladesh were characterized for their mineralogy and chemistry. Among the sediments of the lower part of the Holocene aquifer (depth: 18–29 m), where most domestic wells are installed, As is mostly fixed in biotite and organic phases. A positive correlation of As concentration with those of Al and Fe but not that of total organic C clearly suggests that biotite is a primary source of As. Although microbial reduction–dissolution of As-containing Fe oxyhydroxides is thought to cause As-enriched groundwater in the Ganges–Brahmaputra–Meghna delta plain, the authors conclude that chemical weathering of biotite is the primary formation mechanism and prevailing reducing conditions contribute to the expansion of As-enriched groundwater in the study area. 相似文献
108.
109.
Li?ZhangEmail author Joseph?R.?Smyth Takaaki?Kawazoe Steven?D.?Jacobsen Shan?Qin 《Contributions to Mineralogy and Petrology》2018,173(7):52
Ni, Co, and Zn are widely distributed in the Earth’s mantle as significant minor elements that may offer insights into the chemistry of melting in the mantle. To better understand the distribution of Ni2+, Co2+, and Zn2+ in the most abundant silicate phases in the transition zone and the upper mantle, we have analyzed the crystal chemistry of wadsleyite (Mg2SiO4), ringwoodite (Mg2SiO4), forsterite (Mg2SiO4), and clinoenstatite (Mg2Si2O6) synthesized at 12–20 GPa and 1200–1400 °C with 1.5–3 wt% of either NiO, CoO, or ZnO in starting materials. Single-crystal X-ray diffraction analyses demonstrate that significant amounts of Ni, Co, and Zn are incorporated in octahedral sites in wadsleyite (up to 7.1 at%), ringwoodite (up to 11.3 at%), olivine (up to 2.0 at%), and clinoenstatite (up to 3.2 at%). Crystal structure refinements indicate that crystal field stabilization energy (CFSE) controls both cation ordering and transition metal partitioning in coexisting minerals. According to electron microprobe analyses, Ni and Co partition preferentially into forsterite and wadsleyite relative to coexisting clinoenstatite. Ni strongly prefers ringwoodite over coexisting wadsleyite with \({D}_{\text{Ni}}^{\text{Rw}/\text{Wd}}\)?=?4.13. Due to decreasing metal–oxygen distances with rising pressure, crystal field effect on distribution of divalent metal ions in magnesium silicates is more critical in the transition zone relative to the upper mantle. Analyses of Ni partitioning between the major upper-mantle phases implies that Ni-rich olivine in ultramafic rocks can be indicative of near-primary magmas. 相似文献
110.
Habibie Muhammad Iqbal Noguchi Ryozo Shusuke Matsushita Ahamed Tofael 《GeoJournal》2021,86(2):777-807
GeoJournal - Maize is one of the potential crops can help in regional food production with self-sufficiency of foods in the drought prone areas of East Java in Indonesia. The purpose of this... 相似文献