Helium isotope investigation on magnetic reversal boundaries of loess-paleosol sequence at Luochuan, central Chinese Loess Plateau

Extraterrestrial particles have higher 3He/4He ratios than those of terrestrial sediments ( > 100 Ra versus < 0.03 Ra, where Ra is the 3He/4He ratio normalized to the atmospheric value of 1.4×10?6). The inter- planetary dust particles (IDPs), which are very rich in 3He, continuously bombard the Earth and can accumulate in deposits. IDPs sedimentation rate changes can significantly influence 3He concentration in the Earth surface sediments. Since IDPs are not easy to detect in terrestrial deposits, measuring helium isotopes is a helpful approach to examine changes in IDPs. Helium concentration and helium isotopic composition magnetic substances and the quartz particles were examined for helium concen- tration and helium isotopic ratio. Results show that the 3He/4He ratio and the 3He concentrations of the magnetic substances are clearly higher than those of the bulk samples and the quartz particles, and, the 3He/4He ratio of the extracted magnetic substances is also higher than that of the average level of the Earth’s crust. The higher helium content in the magnetic fractions can be explained by an influx of IDPs.     

氦原子基态能量的微扰法研究

用微扰法作了一些简化处理，具体计算了氦原子基态能量到二级修正，并与实际结果进行了比较．     

金属辐照氦脆的统计理论

在非平衡统计断力学的基础上研究了辐照条件下金属的氦脆断裂问题；明确了高温氦脆（ＨＴＨＥ）的微观机理，建立了晶界上氦泡形核和长大模型，推导出氦泡形核和长大速率公式。应用氦泡演化方程得到氦泡密度分布函数和材料寿命，所得计算结果与实验值一致。     

高放废物处置库因格井预选区水化学—同位素分析

因格井坳陷是中国高放废物地质处置库黏土岩重要预选场址之一。选取研究区19组水样作为研究对象,利用Piper三线图和Gibbs图等方法,探讨该区域的地下水化学特征和氢氧同位素特征,主要结论是:研究区的地表水和地下水的水化学类型主要是Cl-SO_4-Na-Ca型或Cl-SO_4-Na型,水化学类型差别不大;pH大多落在7~9之间,TDS值均小于100 g·L~(-1),两者符合中国黏土岩选址的基本标准;地下水主要接受大气降水的补给,地表水的补给作用不明显,初步认为,就水文地质条件而言,因格井坳陷预选区适合建造高放废物处置库。     

In situ simultaneous determination of trace elements, U-Pb and Lu-Hf isotopes in zircon and baddeleyite

This paper describes a combined method of simultaneously measuring U-Pb and Lu-Hf isotopes as well as trace elements in Phalaborwa baddeleyite and 91500, GJ-1, TEMORA-1 and SK10-2 zircons by means of Neptune MC-ICPMS and Agilent Q-ICPMS connected to a 193 nm excimer laser ablation system. Material ablated by laser was carried in different proportions into Q-ICPMS for U-Pb isotopic and trace elemental and MC-ICPMS for Lu-Hf isotopic compositions. Experiments indicate that different proportions of ablated material for the Q-ICPMS and MC-ICPMS （6：4, 5：5 and 4：6 respectively） do not show any bias for the zircon/baddeleyite U-Pb age, Lu-Hf isotope and trace elemental compositions within analytical errors. Using 40-60 μm spot size, the obtained U-Pb ages of Phalaborwa baddeleyite, 91500, GJ-1, TEMORA and SK10-2 zircons are 2065±15 （2σ, n=20）, 1063±6 （2σ, n=-19）, 613±6 （2σ, n=20）, 416±5 （2σ, n=20） and 32.6±0.5 （2σ, n=20） Ma, respectively. The ^176Hf/^177Hf ratios are 0.281231±24 （2SD, n=20）, 0.282310±35 （2SD, n=19）, 0.282028±34 （2SD, n=20）, 0.282687±34 （2SD, n=20） and 0.282752±53 （2SD, n=20）, respectively. The obtained trace elemental compositions are identical to the reference values. Therefore, this kind of technique makes it possible to simultaneously obtain the U-Pb age, Lu-Hf isotopes and trace elemental compositions of zircon and baddeleyite, which could be an important tool in solving problems in earth sciences.     

东太平洋多金属结核U、Th同位素深度分布特征与生长速率

研究了东太平洋多金属结核中Ｕ、Ｔｈ同位素的深度分布与生长速率。表明,东太平洋多金属结核中的＾２３４Ｕ／＾２３８Ｕ）Ａ．Ｒ．与海水接近,证实了Ｕ的海水来源;２３４Ｕ及２３８Ｕ的活度并不随深度增加而减小,而是在次表层和更深层出现极大值。２３６７站核中＾２３２Ｔｈ的活度在次表层有最大值,之后随深度的增加而降低,反映了结核生长过程中成岩作用的影响;１７９７站南结核中＾２３２Ｔｈ表层有最大值,其它各层的变化     

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.     

氦原子基态能量与波函数研究

在用变分法研究氦原子基态能量和波函数过程中,放弃选用两个相同类氢原子基态波函数乘积作为氦原子基态尝试波函数的传统作法,而是采用另一种形式的尝试波函数,并对计算结果作了讨论,得出与传统方法相同的结果．这为研究复杂原子结构,提供了一个可供参考的方法     

西南太平洋新喀里多尼亚斜坡近三万年来沉积速率的演变——根据放射性碳测定和氧同位素曲线推断

取自新喀里多尼亚西南和东北斜坡岩心的第四纪半深海沉积物的放射性碳测定和δ~(1?)O曲线得出如下成果:台地周围软泥和钙质浮游生物残骸的放射性碳测定的年龄比由δ~(1?)O曲线给出的沉积物年龄老。最近16000a以来,特别是新喀里多尼亚西南斜坡沉积速率大大降低,这可能是由于第四纪因海侵而发育的堤礁的影响。     

基于分子筛13X的氢同位素分离

液氮温度下用分子筛13X在自行设计的单塔变压吸附装置上进行氢氘同位素气体的分离研究,考察了流量、压力与吸附床长度对分离效果的影响,在气体总压0.40 MPa、总流量63.86 cm3/min与吸附床长度1.0 m时氢氘分离因子可达到1.27.结合平衡吸附和动态分离之间的差异,表明吸附法能够有效分离氢同位素气体的机理是基于动力学效应.