Rare earth elements in bottom sediments of major rivers around the Yellow Sea: implications for sediment provenance

Rare earth elements (REEs) of 91 fine-grained bottom sediment samples from five major rivers in Korea (the Han, Keum, and Yeongsan) and China (the Changjiang and Huanghe) were studied to investigate their potential as source indicator for Yellow Sea shelf sediments, this being the first synthetic report on REE trends for bottom sediments of these rivers. The results show distinct differences in REE contents and their upper continental crust (UCC)-normalized patterns: compared to heavy rare earth elements (HREEs), light rare earth elements (LREEs) are highly enriched in Korean river sediments, in contrast to Chinese river sediments that have a characteristic positive Eu anomaly. This phenomenon is observed also in primary source rocks within the river catchments. This suggests that source rock composition is the primary control on the REE signatures of these river sediments, due largely to variations in the levels of chlorite and monazite, which are more abundant in Korean bottom river sediments. Systematic variations in I LREE pound/I HREE pound ratios, and in (La/Yb)-(Gd/Yb)(UCC) but also (La/Lu)-(La/Y)(UCC) and (La/Y)-(Gd/Lu)(UCC) relations have the greatest discriminatory power. These findings are consistent with, but considerably expand on the limited datasets available to date for suspended sediments. Evidently, the REE fingerprints of these river sediments can serve as a useful diagnostic tool for tracing the provenance of sediments in the Yellow Sea, and for reconstructing their dispersal patterns and the circulation system of the modern shelf, as well as the paleoenvironmental record of this and adjoining marginal seas.

Manganese abnormity in holocene Sediments of the Bohai Sea

Manganese abnormity has been observed in the Holocene sediments of the mud area of Bohai Sea. On the basis of grain size, chemical composition, heavy mineral content and accelerator mass spectrometry (AMS) C-14 dating of foraminifer, relationships between manganese abnormity and sedimentation rates, material source, hydrodynamic conditions are probed. Manganese abnormity occurred during the Middle Holocene when sea level and sedimentation rates were higher than those at present. Sedimentary hiatus was not observed when material sources and hydrodynamic conditions were quite similar. Compared with the former period, the latter period showed a decrease in reduction environment and an inclination toward oxidation environment with high manganese content, whereas provenance and hydrodynamic conditions showed only a slight change. From the above observations, it can be concluded that correlation among manganese abnormity, material source, and hydrodynamic conditions is not obvious. Redox environment seems to be the key factor for manganese enrichment, which is mainly related to marine authigenic process.

Mineral provinces and matter provenance of the surficial sediments in the western Philippine Sea: implication for modern sedimentation in West Pacific marginal basin

The characteristics and distribution patterns of detrital minerals (0.063 similar to 0.125 mm) in marine sediments provide a significant indicator for the identification of the origin of sediment. The detrital mineral composition of 219 surface sediment samples was analysed to identify the distribution of sediments within the western Philippine Sea. The area can be divided into three mineral provinces: ( 1) province east of the Philippine Trench, the detrital minerals in this province are mainly composed of calcareous or siliceous organisms, with the addition of volcanogenic minerals from an adjacent island arc; (II) middle mineral province, clastic minerals including feldspar, quartz and colorless volcanic glass, sourced from seamounts with intermediate-acid volcanic rock, or erupting intermediate-acid volcano; (III) province west of the Palau-Kyushii Ridge, the matter provenance within this province is complex; the small quantity of feldspar and quartz may be sourced from seamounts or erupting volcano with intermediate - acid composition, with a component of volcanic scoria sourced from a volcano erupting on the Palau-Kyushu Ridge. it is suggested that, ( I) Biogenic debris of the study area is closely related to water depth, with the amount of biogenic debris controlled by carbonate lysocline. (2) Volcaniclastic matter derived from the adjacent island are can be entrained by oceanic currents and transported towards the abyssal basin over a short distance. The weathering products of volcanic rocks of the submarine plateau ( e. g. I Benham Plateau) and adjacent ridges provide an important source of detrital sedimentation, and the influence scope of them is constrained by the intensity of submarine weathering. (3) Terrigenous sediments from the continent of Asia and the adjacent Philippine island arc have little influence on the sedimentation of this study area, and the felsic mineral component is probably sourced from volcanic seamounts of intermediate-acid composition.

Geochemical character and material source of sediments in the eastern Philippine Sea

Based upon analyses of grain-size, rare earth element (REE) compositions, elemental occurrence phases of REE, and U-series isotopic dating, the sediment characteristics and material sources of the study area were examined for the recently formed deep-sea clays in the eastern Philippine Sea. The analytical results are summarized as follows. (1) Low accumulation rate, poor sorting and roundness, and high contents of grains coarser than fine silt indicate relatively low sediment input, with localized material source without long distance transport. (2) The REE Contents are relatively high. Shale-normalized patterns of REE indicate weak enrichment in heavy REE (HREE), Ce-passive anomaly, and Eu-positive anomaly. (3) Elemental occurrence phases of REE between the sediments with and without crust are similar. REE mainly concentrate in residual phase and then in ferromanganese oxide phase. The light REE (LREE) enrichment, Ce-positive anomaly, and Eu-positive anomaly occur in residual phase. Ferromanganese oxide phase shows the characteristics of relatively high HREE content and Ce-passive anomaly. (4) There are differences in each above mentioned aspect between the sediments with and without ferromanganese crust. (5) Synthesizing the above characteristics and source discriminant analysis, the study sediments are deduced to mainly result from the alteration of local and nearby volcanic materials. Continental materials transported by wind and/or river (ocean) flows also have minor contributions.

Effective dielectric response of composites witli graded material

The effective dielectric response of linear composites containing graded material is investigated under an applied electric field Eo. For the cylindrical inclusion with gradient dielectric function, epsilon(i)(r) = b + cr, randomly embedded in a host with dielectric constant epsilon(m), we have obtained the exact solution of local electric potential of the composite media regions, which obeys a linear constitutive relation D = epsilonE, using hypergeometric function. In dilute limit, we have derived the effective dielectric response of the linear composite media. Furthermore, for larger volume fraction, the formulas of effective dielectric response of the graded composite media, are given.

Organic geochemical studies of sinking particulate material in China sea area(I) - Organic matter fluxes and distributional features of hydrocarbon compounds and fatty acids

Sinking particulate material collected from Nansha Yongshu reef lagoon and the continental shelf of the East China Sea by sediment traps has been analyzed and studied for the first time using organic geochemical method. The results show that about half of the sinking particulate organic matter in the two study areas are consumed before reaching the depth of 5 m to the sea floor and the degree of this consumption in Yongshu reef lagoon is larger than that in the continental shelf of the East China Sea. The distributions of hydrocarbons and fatty acids indicate that the minor difference of biological sources of sinking particulate organic matter exists between Yongshu reel lagoon and the continental shelf of the East China Sea, but they mainly come from marine plankton. Stronger biological and biochemical transformations of sinking particulate organic matter are also observed and the intensity of this transformation in Yongshu reef lagoon is greater than that in the continental shelf of the East China Sea. It is found that the occurrence of C-25 highly branched isoprenoid (HBI) diene may be related to the composition of diatom species.

天山南北山前盆地中-新生代沉积记录及其动力学分析

It has been long known that intense multiple Mesozoic-Cenozoic intracontinental deformations have controlled the grand scale basin-range structural evolution of the Tianshan and its adjacent basins. So it is important to study the sedimentary records of the piedmont basins along the two sides of the Tianshan synthetically for the continental geodynamic research.We carried out a magnetostratigraphy study on Cretaceous- Tertiary succession and U-Pb dating analysis of detrital zircons from the representative sandstone samples of the Mesozoic-Cenozoic deposits in Kuqa Subbasin, northern Tarim Basin, combining our previous results of multiple depositional records from different profiles including paleocurrent data, conglomerate clast, sandstone framswork grains, detrital heavy minerals and geochemistry analysis, so the multiple intracontinental tectonic processes of Tianshan and their depositional response in the Kuqa Subbasin can be revealed. The results show that the tectonic evolution of the Tianshan Orogen and the sedimentary processes of the Kuqa Subbasin can be divided into four periods: early Triassic(active period), from middle Triassic to late Jurassic(placid period), from early Cretaceous to Tertiary Paleocene(active period) and from Neogene to present (intensely active period). Simultaneously，the depositional records reveal the provenance types and tectonic attributes in different periods. As follows, the lower Triassic with a dominant age ranging from 250 to 290Ma of the Zircons, which were principally derived from alkali feldspar granites and alkaline intrusion obviously, relative to the magma activity in Permian. In middle Triassic-late Jurassic, the two samples collected from the Taliqike formation and the Qiakemake formation respectively show the age peak at 350～450Ma, which was relative to the subduction of the Tarim Block to Yili-Central Tianshan Plate. In this period the provenance of the Kuqa deposits was the Central Tianshan arc orogenic belts distantly with little height predominance.During early Cretaceous-Paleogene, two major zircons age spectra at 240~330Ma and 370~480Ma have been acquired, with some other not dominant age ranges, indicating complicated provenance types. In Neogene, the detrital zircons age dating ranges from 460 to 390 Ma primarily. What’s more, the newer chronology of the stratigraphy and the older source age, indicating that Tianshan was uplifted and exhumated further strongly. Further study on the heavy mineral and the detrital zircons age dating of the Mesozoic-Paleogene representative profiles in southern Junggar Basin, combined with the published results of the sandstone framework grains, we consider that it occurred obvious sedimentary and tectonic changes occurred in the inside of Jurassic, from late Jurassic to early Cretaceous and form early Cretaceous to late Cretaceous. On this faces, there are remarkable changes of the steady minerals and unstable minerals, the sandstone maturity and the age spectra of the detrital zircons. Compared the sedimentary records from the two sides of the Tianshan, We find that they are different obviously since Middle Jurassic. It can be concluded that Tianshan have uplifted highly enough to influence the paleo-climatic. According to the current strata division, the structural activity apparently showed a migration from north to south. That is to say, the South Tianshan uplift later than the north, especially from late Jurassic to early Cretaceous , but it was uplifted and exhumated more strongly. Furthermore, correlating the depositional records and tectonic styles in the Kuqa-South Tianshan basin-range conjugation site in the east with the west, the obvious differentiation between the west and the east from the Cretaceous especially in Tertiary along the Tianshan-Kuqa belt was revealed, probably showing earlier uplifting in the east while greater exhumation depth and sediment rates in the west. In addition, the contacting style of Kuqa subbasin to the Tianshan Orogenic belts and the basement structure are also inconsistent at different basin-range conjugation sites. It is probably controlled by a series of N-S strike adjusting belts within the Kuqa subbasin, or probably correlated with the material difference at the complicated basin-range boundary. The research on the Mesozoic-Cenozoic tectonic-depositional response in the piedmont basins along the two sides of the Tianshan shows that the basin-filling process was controlled by the intracontinental multicyclic basin-range interactions, especially affected by the intense tectonic differentiations of basin-range system, which can’t be illuminated using a single evolutionary model.

微量样品钕-锶-铅同位素分析方法在黄河下游悬浮颗粒物及沉积物的应用

Aim in Rb-Sr-REE-Pb isotopic analysis of river material, a single-stage, highly efficient and rapid chemical separation method of Rb-Sr-REE-Pb has been established by a combination of the SR special resin and the RE resin. At the same time, Feasibility of high precision analysis on micro-size Nd samples，which were chemically separated by using the LN resin, were systematicly studied using the NdO+ technique in thermal ionization mass spectrometer (TIMS). Results show that high precision measurement of Nd isotopic ratios can be successfully achieved on micro-sample of 1 ng size lever, by systematic experiments on isobar interferences and optimizing separation and measurement conditions. This method will greatly extend the application prospect of the NdO+ technique. Sr-Nd-Pb isotopic composition of suspending particle material (SPM) and sediment and Sr isotopic composition of river water in the low reaches of the Yellow Rriver have been systematically analysed in this study. Results can indicate followings: (1) relative stable Sr isotopic ratios around 0.7112 of river water suggest great influcence from dissolution of carbonate component of loss material on Sr isotopic composition of river water; (2) Nd isotopic compositions of SPM and sediment of the Yellow river are is similar, mean εNd value of SPM around -11.5 and mean εNd value of sediment -12.7, slightly lower than that of SPM. Nd isotopic composition of the Yellow River material is simarlar to or slightly lower than loss material (-9.5); (3) evidence of Sr and Pb isotopic compositions of both SPM and sediment reveals a mixing trend of two endmembers. Sr isotopic ratios of SPM after leaching are significantly different that those without leaching, possibly suggesting strong alteration of river water. Pb isotopic ratios of SPM remain unchangable after leaching compared with unleached SPM; (4) Pb-contents of SPM are commonly higher than those of sediments, while Pb isotopic ratios of SPM are significantly lower. Pb isotopic composition of the Yellow River is relatively constant, which can be a useful provenance indicator between the Changjiang and Yellow Rivers.

A novel zirconium-based perovskite-type membrane material for oxygen permeation

A novel zirconium-based membrane material of BaCo0.4Fe0.4Zr0.2O3-6 with cubic perovskite structure was synthesized for the first time through a method of citric and EDTA acid combined complexes. The structural stability was characterized by XRD, O-2-TPD and H-2-TPR techniques respectively. The high oxygen permeation flux of 0.873 mL/cm(2) min at 950 degreesC was obtained under He/Air gradient. Meanwhile, the single activation energy for oxygen permeation and the long-term steady operation of 200 h at 800 degreesC were achieved.

Manual de prática de coleta e herborização de material botânico.

2008

Multiplicação rápida, método simples e de baixo custo na produção de material propagativo de mandioca.

A baixa taxa de multiplicação de mandioca é um dos obstáculos à sua propagação em larga escala. De cada planta de mandioca obtém-se de 5 a 10 manivas de 20 cm de comprimento, num período médio de 12 meses, o que equivale a dizer que a taxa de propagação de mandioca varia de 1:5 a 1:10. Embora produza sementes, comercialmente a mandioca é propagada vegetativamente por meio de pedaços de caule. A propagação vegetativa tem a desvantagem de permitir a transmissão de pragas e patógenos entre as gerações sucessivas de cultivo, caso não sejam tomados cuidados com relação à qualidade do material de propagação. Essa duas características, a baixa taxa de multiplicação e a degenerescência causada pelo acúmulo de pragas, contribuem para escassez de manivas de boa qualidade à disposição de agricultores. Um método simples e barato para aumento da taxa de multiplicação, da mandioca é a multiplicação rápida a qual consiste em cortar hastes da planta de mandioca em pedaços com duas ou três gemas, e plantá-los em canteiro cobertos com plásticos transparente, para reter o calor do sol. Esses canteiros são regados frequentemente, e assim, a umidade e a temperatura elevadas induzem as manivas a brotar. Ao atingir o tamanho de 10 a 15 cm, os brotos são cortados e posto em água, para enraizar. Por sua vez, as manivas de duas ou três gemas voltam a brotar, e nisso consiste a capacidade que essa técnica tem de aumentar a taxa de multiplicação da mandioca. As taxas de multiplicação obtidas nesse trabalho variaram entre 1:140 a 1:170, isto é, um aumento de 14 a 17 vezes em relação a taxa de multiplicação convencional da mandioca (1:10). Embora esses índices estejam abaixo do potencial máximo de multiplicação apresentado na literatura ( aumento de 60 vezes), demonstram o potencial da técnica da multiplicação rápida no aumento da taxa de multiplicação da mandioca, em razão da sua simplicidade e baixo custo.