应用宇宙成因核素10Be和26Al估算剥蚀面的暴露时间及剥蚀速率和剥蚀厚度

宇宙成因核素10 Be和2 6Al的浓度记录着岩层剥蚀面的暴露时间和岩石剥蚀速率等信息。利用数学换算法分析影响10 Be和2 6Al浓度的因素 ,并利用10 Be和2 6Al的半衰期的近似倍数关系建立联立方程组 ,从理论上得到了年轻地质体中遭受快速埋藏的剥蚀面的暴露时间和剥蚀速率的估算公式。在此基础上 ,对整个剥蚀区不同位置剥蚀速率进行了分析。通过分析可以更准确地估算出整个剥蚀区不同位置的剥蚀厚度 ,从而可恢复剥蚀面的古地貌。     

In-situ cosmogenic 36Cl denudation rates of carbonates in Guizhou karst area

This study quantifies surface denudation of carbonate rocks by the first application of in-situ cosmogenic36Cl in China. Concentrations of natural Cl and in-situ cosmogenic36Cl in bare carbonates from Guizhou karst areas were measured with isotope dilution by accelerator mass spectrometer. The Cl concentration varied from 16 to 206 ppm. The 36Cl concentrations were in range of (0.8-2.4)106 atom g-1 , resulting in total denudation rates of 20-50 mm ka-1 that averaged over a 104-105 a timescale. The 36Cl-denudation rates showed roughly a negative correlation with the local mean temperature. This preliminary observation may suggest the variations of proportions of chemical weathering and physical erosion in denudation process, depending upon local climatic conditions.     

Uprising period and elevation of the Wenyu granitic pluton in the Xiaoqinling District, Central China

Xiaoqinling District is an important gold-producing area in China. It ranks second to Jiaodong with regard to gold deposits. The uprising period of the Wenyu granitic pluton and the wall-rocks of the deposit, as well as the mineralizing depth and reserved place of gold ore bodies, are significant to ore exploration. Fission-track （FT） analysis of zircons and apatites of granitic rocks from the Wenyu granitic pluton shows that apatite FT （AFT） data modeling indicates a rapid cooling rate of 20℃/Ma from 138 to 120 Ma after emplacement at 138 Ma. Thermal evolution and inversion curves suggest a secondary phase of fast cooling and up- rising from 45 to 35 Ma, and 35 Ma, respectively, with a cooling rate of 6.7℃/Ma and a denudation quantity of -4.3 km. The last cooling phase took place from 〈4 Ma, with an average cooling rate of -11.3℃/Ma and a denudation amount of 1.3 km. Total exhumation quantity of 5.6 km and uprising elevation of 7.3 km are similar to the estimated results of fluid inclusions from the Dongtongyu and Wenyu gold deposits. The 39Ar/40Ar dating of sericite from the fault planes of the Xunmadao-Xiaohe and Taiyao faults demonstrate two uprising activities of the ore-host metamorphic complex. The Huashan and Wenyu granitic plutons inten- sively occurred during 77 and 45 Ma, respectively. These data sets are valuable for understanding the uplifting process and for preserving gold ore bodies in the Xiaoqinling area, as well as for further studies on tectonic evolutions of the Taihua Complex and the Qinling-Dabie Orogen.     

New evidence for enhanced cosmogenic isotope production rate in the atmosphere ≈37 kaBP from the Guliya ice core

A³⁶Cl peak was found in the predicted section of Guliya ice core, from the Qinghai-Tibetan Plateau, at about 37 kaBP. This cannot be interpreted by means of changes in the accumulation rate, but by the enhanced cosmogenic isotope production rate in the atmosphere. Compared with the records of¹⁰Be and³⁶Cl in the other regions, the peaks of the cosmogenic isotopes are global and can be considered as time marks. An intriguing fact is that the peaks coincided with cold periods.     

稻壳基活性炭修饰碳糊电极对多巴胺的测定

利用稻壳基活性炭与石墨粉直接混合法制备活性炭修饰碳糊电极， 在pH=7.63的 磷酸缓冲溶液中， 用微分脉冲技术的吸附伏安法测定多巴胺， 该电极对多巴胺在2× 10^-7~1×10^－３ mol/L范围内分三段成线性响应， 检出限为7.5×10^－８ mol/L， 抗坏血酸等十余种共存物质基本不干扰. 该电极具有良好的稳定性及重 现性.     

基于硼氮共掺杂荧光碳点定量分析吡罗昔康

以邻苯二胺、谷氨酸及硼酸为前驱体,通过简单的一步水热法成功制备水溶性极好的硼氮共掺杂荧光碳点(B,N-CDs)。该B,N-CDs粒径约为20 nm,在吡罗昔康(PRX)的存在下,由于B,N-CDs和PRX之间存在强烈的电子或能量转移导致发生了强烈的荧光淬灭效应。据此,应用荧光碳点B,N-CDs作为荧光探针成功构建了高选择性、高灵敏性的PRX检测荧光传感器。实验数据显示,该传感器具有响应速度快、线性范围宽和检测限低等优点。检测PRX的线性范围为2×10~(-5)～1.5×10~(-4) mol/L,LOD为5.7×10~(-8) mol/L。该传感器用于实际样品检测得到了较好的回收率(94.3%～103.3%),充分说明B,N-CDs在药物检测领域具有很好的潜在应用价值。     

The modeling analysis of microwave emission from stratified media of non-uniform lunar cratered terrain surface for Chinese Chang-E 1 observation

In China’s first lunar exploration project,Chang-E 1,the multi-channel (3.0,7.8,19.35,37 GHz) microwave radiometers were aboard the satellite,with the purpose of measuring microwave brightness temperature from lunar surface and surveying the global distribution of lunar regolith layer thickness,and global evaluation of 3He content.To analyze the modeling of microwave radiative transfer from three-layered media of lunar surface,some factors,such as the cratered lunar surface roughness,scattering of regolith particulate medium with temperature profile,are discussed.Based on the statistics of the lunar cratered terrain and using Monte Carlo (MC) method,the cratered lunar surfaces are numerically generated.The triangulated network is utilized to divide the undulated lunar surface into discrete triangle meshes with the size 10 m as a digital surface topography.The reflectivities of each plane mesh are calculated,and the average reflectivity for all MC-realized lunar surfaces is obtained.It is found that under the spatial resolution of 30 km×30 km of Chang-E 1 radiometer observation,the lunar surface can be well modeled as a flat surface.It makes the predominance of the parameters,such as the regolith layer thickness and stratified structures,to be studied.Using the radiative transfer equation of stratified media with dense scatterers,the scattering coefficient of the regolith particulate medium is found negligible,and the emission is mainly governed by the absorptive property of the medium.Brightness temperature of multi-layered media,i.e.lunar soil,regolith layer with temperature profile and underlying rock media,are derived and calculated,and relevant main factors to affect the modeling and emission simulation are analyzed.     

Distribution,ecology, and oxygen and carbon isotope characteristics of modern planktonic foraminifers in the Makarov Basin of the Arctic Ocean

The Arctic region, with magnificent ice cover on the surface of the Arctic Ocean and adjacent seas, is not only extremely sensitive to but also has strong amplification effects on climate change. Observations during the past decades have documented substantial retreat and thinning of the Arctic sea-ice cover, a process that is accelerating. Its feedback and impact on the global climate has become an important subject of current climate change research. Calcite tests of planktonic foraminifers are major constituents in pelagic sediments, and they provide valuable materials for the reconstruction of past oceanographic conditions. However, research is still sparse in the Arctic sea area because of limited availability of the materials for investigation. Here, we present a study of modern foraminifers from the plankton tow samples taken in the Makarov Basin of the Arctic Ocean during the fourth Arctic expedition of China. We have analyzed ecological information stored in the modern planktonic foraminifers and in their stable isotope signals, and established a relationship between the distribution of the main taxa and the environment. Our main observations are as follows:(1) in the Makarov Basin, the polar species Neogloboquadrina pachyderma(sinistral coiling) dominates the [150 lm planktonic foraminiferal assemblages.(2) The planktonic foraminifers live mainly in the upper halocline at a water depth of 50–100 m and less in the depth interval of 100–200 m.(3) Temperature change in the halocline can affect the absolute abundance of planktonic foraminifers and their distribution in the water column. The warmer halocline is more favorable to the development of planktonic foraminifers.(4) A lighter d18O value(2.11 %) of N. pachyderma(sin.) is recorded in the depth interval of 100–200 m, which is likely related to the isotopically light brines separated out during sea ice freezing. The relatively heavy d18O value(1.68 %–2.68 %, average 2.27 %) in the depth interval of 50–100 m may be influenced by the low salinity water with the relatively heavy d18O value formed during the sea-ice melting in the surface layer.     

Observation of small-scale processes over shelf break in the East China Sea

The turbulent dissipation along with temperature and salinity was measured on board R/V Dong Fang Hong 2 over the shelf break of the East China Sea from March 7 to 9, 2004. Applying the Turner angle, it is found that the ＇diffusive＇ double diffusion, salt-fingering, and stable stratification coexist in the upper water column of about 50 m. Below that depth, there exists weak salt-fingering. The turbulent dissipation rates are enhanced along the ray paths of M2 internal tides emanating from the shelf break with values ranging from 1.0×10^-9 W·kg^-1 to 1.2×10^-6 W·kg^-1. The corresponding diapycnal mixing rates are from 1×10^-6 m^2· s^-1 to 1×10^-2 m^2· s^-1. The spatially averaged mixing rate over the whole observation section is 2.3×10^-3 m^2· s^-1, which is much larger than 1×10^-5 m^2·s^-1 of the background diapycnal mixing rate in the open ocean.     

Rapid denudation of the Himalayan orogen in the Nyalam area,southern Tibet,since the Pliocene and implications for tectonics–climate coupling

The Himalayan orogen characterized by very high variability in tectonic and climatic processes,and is thus regarded as a natural laboratory for investigating the coupling of tectonics and climate,as well as the influence of this coupling on geomorphological processes.This study uses apatite fission track(AFT)dating of samples from a45-km-long section crossing the Great Himalaya Crystalline Complex(GHC)in the Nyalam area,southern Tibet,to constrain the timing and rate of late Cenozoic denudation.The AFT ages can be divided into two groups:(1)15–6 Ma,to the north of Nyalam town,for which the bestfit line of elevation-age has a gentle slope of 0.05,and for which a denudation rate of 0.27 mm/a is calculated;and(2)3–1 Ma,south of Nyalam town,for which the best-fit line has a steep slope of 0.64,and for which a denudation rate of 1.32 mm/a is calculated.The whole AFT ages has a positive correlation with sample elevation(i.e.,older ages are found at higher elevations),and the geographical location of the point of inflexion of the two fitted lines corresponds closely to the junction of Poqu River near Nyalam town.By integrating the AFT data with thermotectonic modeling,it can be inferred that the GHC has experienced two different periods of denudation:(1)slow denudation during middle to late Miocene(15–6 Ma)is recorded in the northern part of the GHC;and(2)rapid denudation from the Pliocene to the Pleistocene(3–1 Ma)is recorded in the southern part of the GHC.An abrupt change in denudation rate occurred between the two periods,with the Pliocene–Pleistocene denudation rate being five times higher than that during the Miocene.This abrupt change in denudation rate during Pliocene pervaded the Himalayan orogen,and was roughly synchronous with a marked change in global climate at 4–3 Ma,and intensification of the Asian monsoon.Importantly,the later period of rapid denudation in the study region closely coupled to the mean annual precipitation,while there is no clear evidence for large-scale faulting activity and associated uplift during this period.Therefore,climate(precipitation)is inferred to be the main cause of the rapid denudation of the Himalayan orogen since the Pliocene.     

Effects of gadolinium addition on the microstructure and mechanical properties of Mg-9Al alloy

This research aims to study the significance of Gd addition (0wt%-2wt%) on the microstructure and mechanical properties of Mg-9Al alloy. The effect of Gd addition on the microstructure was investigated via X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The Mg-9Al alloy contained two phases, α-Mg and β-Mg17Al12. Alloying with Gd led to the emergence of a new rectangular-shaped phase, Al₂Gd. The grain size also decreased marginally upon Gd addition. The ultimate tensile strength and microhardness of Mg-9Al alloy increased by 23% and 19%, respectively, upon 1.5wt% Gd addition. We observed that, although Mg-9Al-2.0Gd alloy exhibited the smallest grain size (181 μm) and the highest dislocation density (5.1×1010 m-2) among the investigated compositions, the Mg-9Al-1.5Gd alloy displayed the best mechanical properties. This anomalous behavior was observed because the Al₂Gd phase was uniformly distributed and present in abundance in Mg-9Al-1.5Gd alloy, whereas it was coarsened and asymmetrically conglomerated in Mg-9Al-2.0Gd.     

Determination and geological implication of O-Si isotope of the sediment core in the CC area, the Pacific Ocean

Conclusions  

Cosmogenic ^10Be dating of Guxiang and Baiyu Glaciations

Guxiang and Baiyu Glaciations are two previously recognized local glaciations of the Tibetan Plateau. They have been widely used as the reference standard for classifying Late Quaternary glaciations on the Tibetan Plateau and its surrounding mountains. However, the numerical chronologies of both glaciations have been lacking. In this study, cosmogenic They dating was undertaken to define the timing of these two glaciations. The surface boulders deposited by the glaciers of the Guxiang and Baiyu Glaciations have exposure ages of 112.9±16.7-136.5±15.8 ka BP and 11.1±1.9-18.5±2.2 ka BP, respectively. It is likely that the Guxiang and Baiyu Glaciations correspond to marine isotope stages 6 and 2, respectively.     

First-principles studies of the adsorption of O2 on Al （001）

Oxidationisaubiquitousphenomenonofnature.Theeconomiclossduetooxidationisverylargeeveryyear.Theinvestigationoftheadsorptionofoxygenonthesur-facesofmetalsisofgreatimportanceforbetterunder-standingoftheoxidationmechanismbecauseitistheverybeginningstageofoxidationofmetals.Itisgenerallybe-lievedthattheprocessofO2adsorptiononmetalsisinanorderofO2?O?O-?O2-,andthefollowingstagesareoxidenucleation,growthandtheoxidefilmformation.Astheprocessofadsorptionistooquicktobeobservedbyexperiments,atheoreticals…     

Rapid solidification of acoustically levitated Al-Cu-Si eutectic alloy under laser irradiation

Al-27%Cu-5.3%Si ternary eutectic alloy was melted using a YAG laser and then solidified while being acoustically levitated. A maximum undercooling to 195 K (0.24 TL) was achieved with a cooling rate of 76 K/s. The solidification microstructure was composed of (Al+θ+Si) ternary eutectics and (Al+θ) pseudobinary eutectics. During acoustic levitation, the (Al+θ+Si) ternary eutectics are refined and the (Al+θ) pseudobinary eutectics have morphological diversity. On the surface of the alloys, surface oscillations and acoustic streaming promote the nucleation of the three eutectic phases and expedite the cooling process. This results in the refinement of the ternary eutectic microstructure. During experiments, the reflector decreases with increasing alloy temperature, and the levitation distance always exceeds the resonant distance. Because of the acoustic radiation pressure, the melted alloy was flattened, and deformation increases with increasing sound pressure. The maximum aspect ratio achieved was 6.64, corresponding to a sound pressure of 1.8×104 Pa.     

2010年夏季广西北部湾沿岸浮游植物分布特征及其与环境因子的相关性

2010年6月4日至26日在广西北部湾沿岸共设46个站位凋查分析浮游植物群落结构特征,以及浮游植物数量与环境因子的相关性。结果共鉴定出浮游植物70属149种(含变种和变型),其中硅藻41属106种,占总物种数的71.14%,占总细胞丰度的95.81%;甲藻18属32种,占总物种数的21.48%,占总细胞丰度的1.44%。浮游植物平均密度为61.10×104 cell/L,硅藻平均细胞丰度为58.54×104 cell/L,甲藻类平均细胞丰度为0.88×104cell/L。浮游植物密集区在防城港海区,此外在北海营盘附近海域有一个较高的密度区。浮游植物丰度在茅尾海和钦州港近岸较低,其余海区的浮游植物数量分布态势为近岸高、外海低。浮游植物主要优势种为尖刺拟菱形藻(Pseudo-nitzschia pungens)、中肋骨条藻(Skeletonema costatum)、拟旋链角毛藻(Chaetocerospseudocurvisetus)、菱形海线藻(Thalassionema nitzschioides)、丹麦细柱藻(Leptocylindrus danicus)。尖刺拟菱形藻、拟旋链角毛藻密集区主要在防城港海区,而中肋骨条藻密集区主要在北海海区。浮游植物数量与温度、盐度及硝酸盐、亚硝酸盐、氨盐和硅酸盐无相关性,北海海区和防城港海区浮游植物丰度与活性磷酸盐呈显著正相关,磷在以上两个海区成为浮游植物生长的限制因子。     

Distribution characteristics of ^137Cs in wind-eroded soil profile and its use in estimating wind erosion modulus

~~Distribution characteristics of ~(137)Cs in wind-eroded soil profile and its use in estimating wind erosion modulus1.Tamura, T, Jacobs, D. G, Structural implications in cesium sorp-tion, Health Physics, 1960, 6(2): 391-398. 2.Rogowshi, A. S., Tamura, T, Movement of 137Cs by runoff, erosion and infiltration on the alluvial captina silt loam, Health Physics, 1965, 11(12): 1333-3340. 3.Owens, P. N., Walling, D. E., He, Q. P., The behaviour of bomb-derived caesium-137 fallout in …     

10Be/7Be implies the contribution of stratosphere-troposphere transport to the winter-spring surface O3 variation observed on the Tibetan Plateau

10Be/7Be is a stratospheric sensitive tracer.In this paper,measurements of 10Be/7Be and surface O3 from October 2005 to May 2006 at Mt.Waliguan (hereafter WLG,100.898°E,39.287°N,3810 m,a.s.l.),China global atmospheric watch (GAW) observatory,are introduced and used to investigate the stratosphere-troposphere transport (STT) and its impact on surface O3 on the Tibetan Plateau.The results show that the magnitude of STT is weak in winter,followed by strengthening from the end of winter to the middle of spring (from mid February to mid April) with large increases in 10Be,7Be,10Be/7Be and surface O3.At the end of spring (from the end of April to mid May in this paper),the STT weakened,and the continuous increase of surface O3 at WLG is produced by tropospheric photochemistry reactions.     

Global inventory of Helium-3 in lunar regoliths estimated by a multi-channel microwave radiometer on the Chang-E 1 lunar satellite

Helium-3 (³He) implanted by solar wind in the lunar regolith is a valuable resource because of its potential as a fusion fuel. On the basis of the Apollo regolith samples, a linear relationship between ³He abundance and solar wind flux, optical maturity and TiO₂ content has been presented. China successfully launched its first lunar exploration satellite Chang-E 1 (CE-1) on October 24, 2007. A multi-channeled microwave radiometer was aboard the satellite with the purpose of measuring microwave thermal emission from the lunar surface layer. From the multi-channel brightness temperature (T_b) observed by CE-1, the global distribution of the regolith thickness was inverted from the multi-channel T_b, and was used to evaluate the total amount of ³He per unit area in the lunar regolith. The global inventory of ³He was estimated as being 6.6×10⁸ kg; 3.7×10⁸ kg for the lunar nearside and 2.9×10⁸ kg for the lunar farside.     

Interspecies and spatial diversity in the symbiotic zooxanthellae density in corals from northern South China Sea and its relationship to coral reef bleaching

Coral reef bleaching is usually characterized by expulsion of symbiotic zooxanthellae, loss of zooxanthellae pigmentation, or both. We collected 128 samples comprising 39 species of 21 genera of reef-building corals from Luhuitou and Xiaodonghai in Sanya of Hainan Island and Daya Bay of Guangdong Province, respectively, and analyzed the symbiotic zooxanthellae population density. The results show that： （1） the symbiotic zooxanthella density varies from 0.67×10^6 to 8.48×10^6 cell/cm^2, displaying significant interspecies variability, with branch corals usually having relatively less zooxanthellae （ranging from 0.67×10^6 to 2.47×10^6 cell/cm^2） than massive species （from 1.0×10^6 to 8.48×10^6 cell/cm^2）; （2） corals inhabiting within 4 m water depth have higher levels of symbiotic zooxanthellae than those living at the bottom （-7 m depth） of the reef area; （3） there is no discernable difference in the zooxanthellae density between corals from relatively high latitude Daya Bay （-22°N） and those from relatively low latitude Sanya （-18°N） at comparable sea surface temperatures （SST）; （4） in partially-bleached corals, the density of zooxanthellae shows the following order： healthy-looking part〉 semi-bleached part 〉 bleached part. Based on the above results, we suggest that （1） the zooxanthellae density difference between branching and massive coral species is the main cause that branching corals are more vulnerable to bleaching than massive corals. For example, symbiotic zooxanthellae levels are low in branching Acropora and Pocillopora corals and thus these corals are more susceptible to bleaching and mortality; （2） symbiotic zooxanthellae density can also be affected by environmental conditions, such as sediment loads, diving-related turbidity, and aquaculture-related nitrate and phosphate input, and their increase may reduce symbiotic zooxanthellae density in corals.