天然海水硝酸盐氮同位素组成的蒸馏法测定     

杨志  陈敏  曹建平  邱雨生 《海洋学报》2012,34(3):72-79

建立了测定天然海水中硝酸盐氮同位素组成的蒸馏法,该方法主要是在碱性条件下利用戴氏合金将海水中的硝酸盐还原为氨,后利用稀盐酸吸收生产的氨,将得到的氨吸收液浓缩后干燥结晶,利用同位素比值质谱仪测定所得晶体的氮同位素组成。研究中开展了戴氏合金添加量及氨吸收溶液在不同条件下干燥结晶对氮同位素测值的影响研究。结果表明,戴氏合金添加量为3.0 g及60 ℃下直接干燥结晶为最佳的实验条件。所建立的氨蒸馏法氮空白值仅为(0.90±0.19) μmol,低于此前文献报道的氮空白值;氮同位素组成(δ15N)空白值为(-14.7±4.1)×10-3。运用所建立的氨蒸馏法实测得到的硝酸盐δ15N值与氨扩散法、硝酸盐直接测定法得到的数值非常吻合,进一步证明所建立氨蒸馏法的可靠性。改进后的氨蒸馏法适用于硝酸盐浓度在2~50 μmol/dm3内的天然海水硝酸盐氮同位素组成的测定,方法的标准偏差为±0.3×10-3。  相似文献   

Quantitative Recovery of Elemental Sulfur and Improved Selectivity in a Chromium-Reducible Sulfur Distillation     

Jens Gröger  Jennifer Franke  Kay Hamer  Horst D. Schulz 《Geostandards and Geoanalytical Research》2009,33(1):17-27

Chromium-reducible sulfur (CRS) distillations are intended to recover only reduced inorganic sulfur compounds (RIS) including elemental sulfur. However, the quantitative recovery of elemental sulfur is not ensured in common CRS-distillations. The new method presented here was designed to remedy this deficiency. An increase in ethanol concentration assured the quantitative recovery of elemental sulfur in various forms and, in addition, all other RIS-compounds were quantitatively recovered. Furthermore, the selectivity of the procedure was improved by an additional filtration step to eliminate zinc particles from the Cr(II)-solution. Thus, the recovery of sulfates and organic sulfur compounds was significantly decreased by a factor of up to 35, depending on the compound analysed. Exhaustive testing with a variety of pure phases, rock and soil samples demonstrated the precision and accuracy of the new method. The new protocol eliminated the constraints of previous procedures. The improved distillation efficiency for elemental sulfur ensured the quantitative recovery of all RIS-compounds in a single-step distillation.  相似文献   

Refinement of the Micro‐Distillation Technique for Isotopic Analysis of Geological Samples with pg‐Level Osmium Contents     

Nao Nakanishi  Tetsuya Yokoyama  Akira Ishikawa 《Geostandards and Geoanalytical Research》2019,43(2):231-243

In recent years, the ¹⁸⁷Re–¹⁸⁷Os isotope system has been increasingly used to study samples containing very small quantities of Os. For such samples, optimisation of measurement procedures is essential to minimise the loss of Os before mass spectrometric measurements. Micro‐distillation is a necessary purification step that is applied after the main Os chemical separation procedure, prior to Os isotope ratio measurements by negative‐thermal ionisation mass spectrometry (N‐TIMS). However, unlike the other separation steps, this procedure has not yet been optimised for small samples. In this study, we present a refined micro‐distillation method that achieved higher yields and allowed high‐precision R(¹⁸⁷Os/¹⁸⁸Os) expressed as ¹⁸⁷Os/¹⁸⁸Os measurements for small‐sized geological samples that contain only a few pg Os. The Os recovery in the micro‐distillation step was tested by changing the operating conditions including heating time and temperature, and amounts of oxidant and reductant. Recoveries were measured by the isotope dilution ICP‐MS method after the addition of ¹⁹⁰Os‐enriched spike solution. We found that the most critical factor controlling the chemical yield of Os during micro‐distillation is the extent of dilution of the reductant (HBr) by H₂O evaporated from the oxidant. A refined micro‐distillation method, in which the amount of oxidant solution is reduced from the conventional method, achieved an improved chemical yield of Os (~ 90%). This refined method was applied to the measurement of ¹⁸⁷Os/¹⁸⁸Os by N‐TIMS of varying test portions of the geological reference material BIR‐1a. The resulting ¹⁸⁷Os/¹⁸⁸Os ratios of BIR‐1a matched the literature data, with propagated uncertainties of 0.2, 1.1 and 11% digested sample quantities containing 150, 10 and 1 pg of Os, respectively.  相似文献   

Carius管溶样-负离子热表面电离质谱准确测定辉钼矿铼-锇同位素地质年龄   总被引：175，自引：30，他引：175  

杜安道赵敦敏  王淑贤孙德忠　刘敦一 《岩矿测试》2001,20(4):247-252

将样品、混合稀释剂和逆王水加入到Carius管中,于230℃溶样10h.利用蒸馏法分离Os,萃取和阴离子交换法分离Re.采用负离子热表面电离质谱精确测定了所研制的年龄标准参考物辉钼矿(HLP)的Re-Os年龄.对取自12个小瓶中17个样品所测平均年龄为221.3±0.3Ma,置信度95%.中值年龄和平均绝对偏差为221.34±0.12Ma.美国克罗拉多州立大学AIRIE小组19次单独取样所测HLP的平均年龄为221.3±1.0Ma,置信度95%.中值年龄和平均绝对偏差为221.34±0.24Ma.  相似文献   

Noble gases in a section across the vapor dominated geothermal field of Larderello,Italy     

Emanuel Mazor 《Pure and Applied Geophysics》1978,117(1-2):262-275

Noble gases were studied in six wells, located on a 4.5 km south to north section across the Larderello field. Depth of wells, flow and gas/steam ratios are known to increase from south to north. Exploitation progressed in the same direction. The following noble gas patterns are observable: (a) Atmospheric Ar, Kr and Xe reflect productions of gas-depleted water at Colombaia 2 and progressively more gas-enriched steam towards the Gabbro wells. (b) Radiogenic⁴He and⁴⁰Ar are observed in increasing concentrations from south to north. (c) The radiogenic and atmospheric gases reveal a positive correlation, indicating that the recharging water enters deep into the system, and gets well mixed with the radiogenic gases prior to the steam separation. (d) Gas contents and relative abundances of radiogenic argon decrease with production, thus supplying markers for the degree of exploitation in a well and a guide for optimum well spacing. (e) Excess neon over argon is observed and discussed in terms of crustal origin versus possible fractionation of atmospheric noble gases due to pertial steam separation.  相似文献   

水体蒸发过程中稳定同位素的分形机制   总被引：1，自引：0，他引：1  

章新平  田立德  刘晶淼 《地理学报(英文版)》2005,15(3):375-384

The variations of stable isotopes in atm ospheric vapor and precipitation are caused by stableisotopic fractionation during phase changes in w ater cycle. The isotopic fractionation m ainlyhappens in the m ass transportation of stable isotopes from free w…  相似文献   

共沸蒸馏置换干燥法制备纳米氧化镁粉体的研究   总被引：2，自引：0，他引：2       下载免费PDF全文

王宝和  张伟  张文博  范方荣 《盐湖研究》2006,14(3):34-38

以六水氯化镁和尿素为原料,采用均匀沉淀法制备出氢氧化镁沉淀,利用不同共沸蒸馏置换干燥法除去沉淀中的湿分,再将干燥的氢氧化镁粉体经马弗炉煅烧得到纳米氧化镁粉体;通过透射电子显微镜和X射线衍射仪的表征与分析,研究不同共沸蒸馏置换干燥法对纳米氧化镁粉体形貌、颗粒尺寸和团聚情况的影响;探讨了共沸蒸馏置换干燥的基本原理、操作方法和置换剂的选择原则。  相似文献   

结晶膜蒸馏处理吸收炼矿烟气酸性废水的研究     

王鹤  李滦宁  张凤君  张孝生  王顺义  沙娜  戴宁 《吉林大学学报(地球科学版)》2006,(Z1)

采用天然碳酸钙中和烟气吸收酸性废水,研究中空纤维结晶膜蒸馏技术对中和后废水处理的效果。考察了料液温度、起始浓度、流速、pH值等因素对膜通量的影响。在选定的条件下对水样进行连续膜蒸馏处理。结果表明,在料液温度50℃,料液速度为18.5mL/min,pH值为7,运行18h后,浓缩溶液开始出现结晶,结晶效果较好。截留率均接近100%。  相似文献   

稠油油藏蒸汽驱中后期剩余油分布特征及提高采收率方式研究     

石兰香  李秀峦  王宏远  罗池辉  刘鹏程 《现代地质》2022,36(6):1585-1593

针对中国浅层及中深层稠油油藏,利用数值模拟研究方法,研究了不同稠油油藏的蒸汽驱开发规律和蒸汽驱中后期的剩余油分布特征,明确了稠油油藏蒸汽驱中后期的提高采收率方式。研究结果表明:浅层稠油油藏与中深层稠油油藏蒸汽驱的开发规律基本一致。驱替阶段生产效果好、产量高且稳定、油汽比高、含水率低;蒸汽突破后的开发阶段也是蒸汽驱开发的重要阶段,但是该阶段油汽比明显低于驱替阶段,表明该阶段蒸汽热效率明显降低。不同稠油油藏的剩余油分布特征类似,均表现出明显的垂向动用差异特征,即油层上部动用程度高,剩余油饱和度低,油层下部动用程度低,剩余油饱和度高,下部油层是剩余油挖潜的主要对象。从下到上逐层上返开发和多介质辅助是提高蒸汽驱中后期采收率的有效方式。研究结果对同类油藏开发具有重要意义。  相似文献   

偏硼酸锂熔矿-超声提取-电感耦合等离子体发射光谱法测定岩石水系沉积物土壤样品中硅铝铁等10种元素   总被引：10，自引：7，他引：3  

王龙山  郝辉  王光照  胡建平 《岩矿测试》2008,27(4):287-290

采用偏硼酸锂熔矿分解样品,超声波振动提取,电感耦合等离子体发射光谱法同时测定同一份溶液中的硅、铝、铁、钙、镁、钾、钠、磷、锰、钛等组分。通过对岩石、水系沉积物和土壤国家一级标准物质测定验证,方法的准确度、精密度能够满足样品中各元素定量分析的要求。  相似文献