浙江黄双岭萤石矿的同位素研究

文章公布了浙江黄双岭萤石矿的氢、硫、锶和铅同位素分析结果,讨论了成矿溶液和成矿物质来源,估计黄双岭萤石矿的成矿年龄大约为107Ma。     

~(211)At-Te胶体在组织中的分布及稳定性

制备了~(211)At—Te胶体注射液,测定了~(211)At—Te胶体在小白鼠体内的分布规律。腹腔注射和静脉注射给药得到了类似的结果。注射~(211)At—Te胶体~(211)At的摄取率均比注射自由砹的低。血液中的~(211)At含量变化与自由砹完全不同,它有一个缓慢增长的过程,并呈现一个不明显的峰,然后趋于平衡状态,但所有变化均波动在很小范围内。结果认为,~(211)At—Te胶体在动物体内是稳定的.     

美国Wallapai矿区Mineral Park斑岩型矿床早期矿脉中硬石膏的氧同位素组成

本文报道了美国亚利桑那Wallapai矿区Mineral Park斑岩型矿床早期矿脉(AM和AC)中硬石膏的氧同位素组成,依据包体均一温度及硫同位素温度计算成矿溶液的δ~(12)O值(纯水),运用同位素分馏理论讨论AM和AC矿脉成矿溶液的来源和演化。     

上海-南极海洋边界层大气CH4浓度及其δ13C空间分布特征

在中国第22次南极科学考察期间,用Tedlar气袋采集了"雪龙号"考察船航线上海洋边界层大气样品,在室内分析了样品中CH4浓度及其分子的δ13C值,结果表明:在28.5°N~40°S区域,海洋边界层大气CH4浓度波动较大,峰值较多,平均值为(2.97±1.51)×10-6,明显高于全球大气CH4的平均浓度(约1.8×10-6),这主要与该区域的航迹靠近陆地,受人为源的影响有关;在40°S~69.17°S航迹,远离人类活动区,洋面大气CH4的浓度较稳定,平均浓度值为(1.92±0.14)×10-6,接近于目前全球大气CH4平均浓度.航线上CH4分子的δ13C的变化范围为:-37.49‰~-24.87‰,平均为-34.5±3.0‰.在28.5°N~40°S区域,边界层大气中CH4分子的δ13C值较高且波动较大,表明洋面大气的CH4浓度受到来自富13C的化石燃料、生物质燃烧等人为源的强烈影响;在40°S~69.17°S区域,δ13C值较稳定.海洋边界层大气的CH4浓度分布与大气温度也存在相关性.     

操作条件对硼同位素分离过程的影响

根据三氟化硼-苯甲醚化学交换反应精馏体系，对硼同位素的生产过程进行了实验研究，考察了回流比的调节方式和裂解塔、络合塔产品回收率对分离效果的影响．结果表明：通过改变液相来改变回流比时，随着回流比的增加，塔顶^10B丰度逐渐减小，塔底^10B丰度逐渐增大；通过改变气相采出来改变回流比时，随着回流比的增加，塔顶、塔底^10B丰度均增加；随着产品采出率的增加，塔顶和塔底^10B丰度均降低．     

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.     

Large selenium isotopic variations and its implication in the Yutangba Se deposit, Hubei Province, China

The selenium isotopic ratios have been measured in the Yutangba Se deposit, Hubei Province, China. The results show that the δ 82/76SeNIST values vary from -12.77‰ to 4.93‰, which is the largest Se iso- topic variation found so far in natural terrestrial samples. The sample Ytb-5 of high-selenium carbona-ceous shale has the lightest Se isotopic composition with a δ 82/76SeNIST value of -12.77‰. On the basis of variations of Se isotope in the deposit along with other geological and geochemical evidence, the "redox model" is suggested to favor the explanation of the occurrence of native Se in the deposit. The application to the Yutangba Se deposit with the discovery of large Se isotopic fractionation for natural samples indicates the potential of Se isotope as a new geochemical tracer.