Preliminary analysis of grain-size populations with environmentally sensitive terrigenous components in marginal sea setting

Grain-size data have been widely used to determine sediment transport patterns and to reconstruct the sedi-mentary environment. Because the natural occurring sediments deposited in the geologic periods and modern times are mostly mixtures of materials transported from multi-sources or/and by different sedimentary processes, the grain size of bulk samples is an incomplete, approxi-mate index for sedimentary environment changes[1,2]. Thus, further studies on the quantitative reconstruction of th…     

Spatial variability and representation of seabed sediment grain sizes： An example from the Zhoushan-Jinshanwei transect, Hangzhou Bay,China

Grain size analysis was undertaken for the 2-cm interval sub-samples of eight short cores collected along the Zhoushan-Jinshanwei transect in Hangzhou Bay, using a Malvern Mastersizer 2000 laser particle size analyzer. The result indicates that there are different vertical distribution patterns of mean grain size for the short cores. In the study area, the thickness of the seabed moving layer on an annual temporal scale is much larger than that of the deposited layer,i.e. the sedimentary environment is highly dynamic. As a result, the vertical distributions of mean grain size within the short cores represent different types of sedimentary records formed in the same environment, rather than signals of long-term environmental evolution. The seabed sediment consists mainly of silts in the study area, and the vertically-averaged value of mean grain size has a tendency of convergence when the thickness over which the mean value is derived increases. Such patterns indicate that the grain size composition of the deposit is controlled mainly by the source of material supply; nevertheless, to some degree hydraulic sorting is effective, which has resulted in the differences in distribution patterns along the transect between the grainsize values of the surficial sediment and the vertically-averaged values. For long-term sediment transport modeling for an environment associated with strong tidal action and silty sediment, it may be more appropriate to use the vertically-averaged grain size than the value for thesurficial sediment, as the model input.     

Pollen indication to source plants in the eastern desert of China

Pollen analysis is one of the important resources for the reconstruction of palaeoclimate and palaeovegetation. The relationship between modern pollen and vegetation is the foundation of pollen analysis. Owing to its complexity and importance, many polynologists and plant-ecologists have been studying on it[1―17]. In 1963, M. B. Davis gave the definition of R-values[2] that have carried forward the quantitative relationship between pollen and vegetation. However, R-value is changeable for d…     

Magnetic properties of highroad-side pine tree leaves in Beijing and their environmental significance

This is a report on magnetic properties of highroad-side tree (Pinus pumila Regel) leaves collected along an expressway linking Beijing City and the Capital International Airport and further focus on their environmental contributions. A series of rock magnetic experiments show that the primary mag-netic mineral of leaf samples was identified to be magnetite,in the pseudo-single domain (PSD) grain size range 0.2―5.0 μm. On the other hand,magnet-ite concentration and grain size in leaves are ascer-tained to decrease with increasing of sampling dis-tance to highroad asphalt surface,suggesting that high magnetic response to traffic pollution is localized within a distance of some two meters away from highroad asphalt surface. Although magnetic suscep-tibility is ordinarily regarded as a simple,rapid and low-cost method for monitoring traffic pollution,saturation isothermal remanent magnetization (SIRM) can be treated as a valid proxy for monitoring air par-ticulate matter (PM) when samples are magnetically weak. It is believed that a synthetic rock magnetic study is an effective method for determining concen-tration and grain size of ferromagnets in the atmos-pheric PM,and then it should be a rapid and feasible technique for monitoring atmospheric pollution.     

The Effect of Pore Size of Nanoporous Material for Lithium Ion Batteries

1 Results 3-dimensionally ordered mesoporous materials have been used as electrode materials for lithium ion batteries to improve their electrochemical performance by decreasing the polarization during cycling.Our synthesize nanoporous TiO2 particles without substrate present enhanced cycle performance compared with that of previous reports[1]. Here we report our results referring to that nanoporous TiO2 materials with different pore sizes exhibit different electrochemical performance.The detail procedure to synthesize nanoporous TiO2 can be found in reference[1].The nanoporous titania particles with different pore sizes of 80 nm,250 nm and 1 μm were synthesized by adopting polystyrene (PS) colloidal crystal particles with average particle size of 100,600 nm and 1.7 μm as template,differently.It is obvious to find in Fig.1 that all the nanoporous titania present good cycle performance at each rate.The titania with pore size of 250 nm present the highest capacity.The surface area and dispersion of conductive additives have great impacts on the capacity of materials with different pore size.     

Variation of soil △δ ~(13)C values in Xifeng loess-paleosol sequence and its paleoenvironmental implication

The loess-paleosol sequence on the Chinese Loess Plateau provides abundant information of paleoclimate and paleoenvironment[1―3]. The carbon isotopic compo- sitions of the C3 and C4 plants are different: from ?32‰ to ?20‰ (mean value is ?27‰) for C3 p…     

Microstructural study and numerical simulation of phase decomposition of heat treated Co–Cu alloys

The influence of heat treatment on the phase decomposition and the grain size of Co–10 at% Cu alloy were studied. Few samples were aged in a furnace for either 3 or 5 h and then quenched in iced water. The materials and phase compositions were investigated using energy dispersive spectrometry and X-ray diffraction techniques. X-ray diffraction analysis showed that the samples contained Co, Cu, Cu O, Co Cu2O3, Co Cu O2 phases in different proportions depending on the heat treatment regimes. The formation of dendrite Co phase rendered the spinodal decomposition while the oxidations prevent the initiation of the spinodal decomposition even for a deep long aging inside the miscibility gap.Since the Bragg reflections from different phases of Co–Cu alloy significantly overlap, the crystal structural parameters were refined with FULLPROF program. The shifts in the refined lattice constants(a, b and c), the space group and the grain size were found to be phase- and heat treatment-dependant. Two-dimensional computer simulations were conducted to study the phase decomposition of Co–Cu binary alloy systems.The excess free energy as well as the strain energy, without a priori knowledge of the shape or the position of the new phase, was precisely evaluated. The results indicate that the morphology and the shape of the microstructure agree with SEM observation.     

Influence of Microstructure and Sintering Routes on Transport Properties of Apatite Materials for Fuel Cells

1 Results Oxy-apatite materials are thought as zirconia-substitutes in Solid Oxide Fuel Cells due to their fast ionic conduction. However, the well known difficulties related to their densification prevent them from being used as such. This study presents strategies to obtain oxy-apatite dense materials and the influence of elaboration route on transport properties. Particular emphasis is put on the microstructure effect on ion conduction. By the combined use of freeze-drying and conventional or spark plasma sintering, dense samples with composition La9.33 xSi6O26 3x/2 (0≤x≤0.67) have been obtained in a wide range of temperatures, leading to very different microstructures[1]. The structural and transport properties of such samples have been then evaluated as a function of sintering conditions and lanthanum content. We show that,for lanthanum content higher than 9.6 per formula, the parasitic phase La2SiO5 is observed leading to a degradation of conduction properties. We also show that the conductivity is strongly dependent on the grain size, the highest values of conductivities being obtained for the samples sintered at 1 700 ℃. The whole study gives further insight into the understanding of electrical properties of grain boundaries in apatite compounds.     

Genetic analysis and gene fine mapping for a rice novel mutant （rl9〈t）） with rolling leaf character

Much attention has been paid to leaf shape of rice in the process of ideotype breeding[1]. Several authors have reported that the rolling of leaf in some degree helps keep it erect, consequently optimizing canopy light transmission condition, which is good for dry matter accumulation and for high yield[2―6]. Rice as a polymorphic crop has many types of vari- ety with different morphologies. In terms of leaf shape, different cultivars with rolling leaf have been identifiedin rice germplasm. Le…     

Hardness of Mn2V2O7 thin films and its influential factors

Mn2V2O7 thin films were deposited onto amorphous glass substrates using a chemical bath deposition method and different deposition time. X-ray diffraction (XRD) analysis was used to define the structure of the films. Their roughness, thickness, and surface properties were evaluated through atomic force microscopy (AFM). The hardness of the films was measured using a nanohardness tester. The film thickness, average grain size, and roughness were positively correlated with each other. These three parameters were observed to increase with the deposition time. The film thickness and average grain size were inversely correlated with the hardness and rough-ness. In addition, the number of crystallites per unit area and the dislocation density were observed to be positively correlated with the hardness and roughness. This study was designed to elucidate and formalize the underlying reasons for these relationships.     

Magnetostratigraphy of borehole EY02-2 in the southern Yellow Sea and its paleoenvironmental significance

Various media are used for the study of paleoenvi- ronment. Among them, ice-core, loess and marine sediments are the most important for long time re- cording[1]. In all kinds of researches of paleoenviron- ment, age determination of the sediments is the m…     

Variation of Zr/Rb ratios on the Loess Plateau of Central China during the last 130000 years and its implications for winter monsoon

To find a new index of winter monsoon without effects of chemical weathering and pedogenesis is an important task in loess research. Chemical analysis of five grain size fractions (i.e. >32 μm, 32–20 μm, 20–8 μm, 8–2 μm and <2 μm) show that Zr is enriched in coarser grain size, while Rb is concentrated in finer fractions. An excellent correlation occurs between Zr/Rb ratios and mean grain size in loess units (L₁LL₁ and L₁LL₂) from Huanxian and Xifeng sections, reflecting that Zr/Rb ratios increase when grain size is coarser. Due to immobility of the two elements during the postdepositional process, Zr/Rb ratios can eliminate the effect of weathering and pedogenesis and serve as an excellent proxy on winter monsoon variation. The Zr/Rb ratio curves of the Huanxian, Xifeng and Luochuan sections during the last 130000 years show that the winter monsoon strength was very weak during MIS 3, which corresponded to the intensity during MIS 5.     

Stepwise advance of the Mu Us Desert since late Pliocene: Evidence from a red clay-loess record

Analyses of paleomagnetic polarity reversals, magnetic susceptibility and grain size on the red clay-loess sequence, about 280 m thick, at Jingbian show that this sequence contains most of the stratigraphic units recorded in the standard red clay-loess sections of the Loess Plateau over the past 3.5 Ma. Using sand particle percentage ( > 63 μm%) of the eolian sequence as a proxy indicator of desert extent and aridity in the dust source regions, it is found that during the past 3.5 Ma, there are three important climatic events indicating the advance of the Mu Us Desert. The events occurred at about 2.6, 1.1 and 0.6 MaBP, respectively. The stepwise advance of the Mu Us Desert may be linked closely to increase in global ice volume and uplift of the Tibetan Plateau in the late Cenozoic.     

Dynamic control on grain-size distribution of terrigenous sediments in the western South China Sea: Implication for East Asian monsoon evolution

High-resolution oxygen isotope stratigraphy of Core MD05-2901, which is located off eastern Vietnam in the western South China Sea （SCS）, was established and indicated that the core spans a time period of the past 450 ka. Based on the bulk density, fractional porosity and lithogenic content of the sediments, terrigenous mass accumulation rate （TMAR） was obtained, which is 4.9-6.0 g cm^-2 ka^-1 on average during interglacial stages, higher than that during glacial stages, i.e. 1.9-5.0 g cm^-2 ka^-1, which is different from northern and southern SCS which show higher TMAR in glacial stages. By principle component analysis of grain size distribution of all the samples, two main control factors （F1 and F2） were obtained, which are responsible for about 80% variance of granularity. The contents of grain size population 1.26-2.66 μm% and 10.8-14.3 μm% which are sensible to F1 show high-frequency fluctuation, and correlate well with the summer insolation at 15^o N. They exhibit a distinct cyclicity with frequencies near 23 ka and 13 ka, in contrast to a strong frequency peak near 100 ka obtained in proxies 4.24-7.42 μm% and 30.1-43.7 μm% controlled mainly by F2. The sedimentary character of this part of the SCS was controlled by variations of input flux from two main source areas, namely the southwest and north SCS, which were transported by different circulations of surface current forced by East Asian summer monsoon and winter monsoon respectively. We believe that the East Asian summer monsoon has fluctuated with high frequency and been forced by changes in solar insolation in low latitude associated with precession and half precession, while ice-volume forcing is probably a primary factor in determining the strength and timing of the East Asian winter monsoon but with less important insolation forcing.     

Magnetic characteristics and its environmental implications of core YSJD-86GC sediments from the southern South China Sea

Sediments of core YSJD-86GC （referred to as 86GC） collected from the southern South China Sea were selected for environmental magnetic studies. Combined with the published chronological framework, sediment magnetic properties were revealed for the study area since the MIS3 stage. The rock magnetic results indicate that low-coercivity magnetite is the main magnetic mineral within the sediments. Also, a certain amounts of hematite are present. The King plot and Day plot, which reflect the magnetic particle size, show that fine-grained pseudo-sin- gle-domain phase magnetic particles dominate the magnetic minerals in the sediments. Comparison of magnetic parameters and geochemical indicators show that magnetic properties of core 86GC sediments reflect a terrigenous input. Simultaneously, magnetic characteristics of the stud- ied sediment are influenced by the quantity of terrigenous sediment input, oxidation-reduction conditions of the provenance area, and the transportation environment and distance. Sea level fluctuation caused by global climate change was the main factor for variation in concentration of magnetic minerals and magnetic particle size of thestudied core sediments. Thus, variation of sediment magnetic properties in the study area can be used as an indirect indicator of sea level fluctuation.     

中国东部海区bGDGTs的含量分布及其与环境因子的关系

【目的】近海是接受陆源输入的主要地带,沉积物中的有机质有可能记录了流域环境与气候变化的信息。本文以中国东部海区表层沉积物中陆源细菌来源的支链类甘油二烷基甘油四醚脂(branched Glycerol Dialkyl Glycerol Tetraethers,bGDGTs)为研究对象,分析其作为流域环境与气候变化指标的可行性。【方法】使用高效液相色谱-质谱联用仪(HPLC-MS)分析海域表层沉积物中bGDGTs的含量和分布,并进一步统计分析其与环境因子的关系。【结果】中国东部海区沉积物中bGDGTs的绝对含量呈现出区块状分布,在东海基本上随离岸距离的增加而降低,而在南黄海最高值出现在南黄海中心泥质区。支链和类异戊二烯指数(BIT)值除在长江口外上升流区外,基本呈现出随离岸距离的增加而降低的趋势。【结论】bGDGTs主要来源于陆源输入;有机质主要富存于细颗粒沉积物,且有海洋自生bGDGTs的贡献;相对于陆源输入,海洋自生bGDGTs以环状为主;除特殊环境,BIT仍可以作为衡量陆源输入相对多寡的指标;东部海区沉积物中的甲基化指数/环化指数(MBT/CBT)不能作为构建流域古气候变化的指标。     

浙江近岸海域表层沉积物中磷的存在形态及其分布特征

运用SEDEX方法分析了浙江近岸海域表层沉积物中总磷(TP)及磷在各提取相的含量和分布.研究结果表明,表层沉积物中TP含量为432.2～846.1 mg/kg,平均为(533.2±90.1) mg/kg;弱吸附态磷(Ads-P)、铁结合态磷(Fe-P)、自生磷灰石及钙结合态磷(Ca-P)、碎屑态磷(De-P)和有机磷(OP)平均含量分别为6.2,93.2,12.4,295.0和66.5 mg/kg,分别占TP的1.2％,17.7％,2.4％,56.7％,和12.7％.沉积物的Ads-P、Ca-P和OP与其粒度和有机碳含量呈显著正相关,De-P则呈负相关.各站位沉积物中磷在不同提取相中的含量差异较大,与沉积物的陆源输入、沉积物粒径及沉积海域的水动力条件等因素有关.     

Sedimentation rates and provenance analysis in the Southwestern Okinawa Trough since the mid-Holocene

As a high-sedimentation rate depocenter along the path of the Kuroshio Current, the southwesternmost part of the Okinawa Trough is a key area to understand the Kuroshio history and sediments transpor-tation. A 34.17-m-long sediment core was obtained by the advanced piston corer of Marco Polo/IMAGES XII MARION DUFRESNE during the May 2005 from the Southern Okinawa Trough at site MD05-2908. The recovered sediments were analyzed by AMS ¹⁴C dating, coarse size fraction (>63 μm) extraction and moisture content determination in order to study its sedimentation flux and provenance. The depth-age relationship of core MD05-2908 was well constrained by 17 ¹⁴C dating points. The sediments span across the mid-Holocene (6.8 ka B.P.) and have remarkablely high sedimentation rates between 1.8 and 21.2 m ka^-1, which is well consistent with the modern observations from sediment traps. We identified five 70―200 a periods of abnormally rapid sedimentation events at 6790―6600 a B.P., 5690―5600 a B.P., 4820―4720 a B.P., 1090―880 a B.P., and 260―190 a B.P., during which the highest sedimentation rate is up to 21.2 m/ka. In general, the lithology of the sediments were dominated by silt and clay, associated with less than 5% coarse size fraction (>63 μm). As the most significant sediment source, the Lanyang River in northeastern Taiwan annually deliver about 10Mt materials to the coastal and offshore region of northeast Taiwan, a portion of which could be carried northward by currents toward the study area. Therefore, we concluded that the 5 abnormally rapid sedimentation events may be related to intensified rainfall in Taiwan and thus increased materials to our study area at that time. However, a few ex-treme-rapid sedimentation events cannot be explained by normal river runoff alone. The large earth-quakes or typhoons induced hyperpycnal discharge of fluvial sediment to the ocean may also act as a potential source supply to the Okinawa Trough.     

Spatial and temporal distribution of trace elements in Yangtze Estuary, China: Significance of diluted setting

The present study is to examine the spatial and temporal distribution of eight trace elements (Sr, Ba, B, Ga, Ni, V, Cu, and F) in various Holocene marine subfacies in the Yangtze Estuary, including its subaqueous delta by sediment borehole and vibrocore. Results demonstrate that grain size is the determinant factor in controlling the concentration of most trace elements discussed. Prodelta mud that occurs usually below the normal wave base can serve as a depository sink for trapping trace elements over the long-term time period. For example, copper concentration is 5-6 times higher than those found in the estuarine sediment. Boron, which is used to be a salinity indicator, shows a strong negative correlation with paleosalinity (using sediment phosphate method), implying desalinized water setting in the Yangtze Estuary, into which a large quantity of the Yangtze freshwater (924 × 10⁹ m³/a) has discharged. Trace element concentrations of the study area were compared with those collected from the middle and lower Yangtze River reaches, and from the east China continental shelf, including the Okinawa Trough. Result tends to show a terrigenous derivation of most geochemical components of the study area. Concentrations of strontium and barium are correlated with an increase in distance away from the estuary, rather than affected by grain size. Variation of trace elements in downcore Holocene sediment sections are fairly consistent with concentrations revealed by the modern vibrocore transect that extends from nearshore delta front, to offshore prodelta and to the delta-shelf transit zone. The overall distribution of geochemical elements discussed is capable of environmental implication to characterize the Yangtze estuarine transit between land and sea.