Water recovery rate and isotopic signature of cryogenic vacuum extracted spiked soil water following oven-drying at different temperatures     

Mingyi Wen  Bingcheng Si  Yanwei Lu  Hongxiu Wang 《水文研究》2021,35(6):e14248

Extracting water from soils is often a critical step for obtaining soil water isotope information. Cryogenic vacuum extraction (CVE), the most widely used laboratory-based removal technique, produces biased isotope composition and the mechanisms causing the biases remain uncertain. Here, we conducted spiking tests on soil samples oven-dried at 105 and 205°C, respectively. The recovery rate and isotopic composition of the extracted water were analysed. Our results show that conventional oven-drying (105°C) was not sufficient to liberate tightly bound water from soils but oven-drying at temperatures above 205°C was. Part of the tightly bound water in soil was extracted by CVE, because the extraction capacity of CVE (heating at 95°C) was equivalent to oven-drying at temperature between 105 and 205°C. Moreover, the two pretreatments yielded markedly differences in water recovery rates. And with increasing ratios of clay contents to water contents, the recovery rates of the pretreated soil at 105°C trended upward above 100%, but that of 205°C trended downward below 100%. Further, the ²H and ¹⁸O signatures of the extracted water from the soil pretreated at 205°C were both depleted relative to reference water, but the pretreatment at 105°C showed enriched ¹⁸O and depleted ²H. This suggests that oxygen isotope exchange may have occurred between tightly bound water and soil minerals, resulting in enriched ¹⁸O in water for the 105°C pretreatments. For the 205°C pretreatment, pre-existing soil water was completely removed and relative to spiking water, isotopic signatures of the extracted water followed equilibrium fractionation law due to incomplete extraction. Therefore, our results suggested that the biased isotopic signatures of water extracted by CVE may be partially due to incomplete extraction and mixture of added water with the residual tightly bound water that pre-exists before spiking.  相似文献   

真空-堆载联合预压法在软基加固中的应用   总被引：14，自引：3，他引：11  

李就好 《岩土力学》1999,20(4):geMap1

根据太沙基有效应力原理,分析了真空预压和堆载预压加固软基的基本原理。通过现场试验观测和理论分析,认为真空-堆载联合预压法适用于深厚软基的加固处理。  相似文献   

Limits on the chirality of interstellar and intergalactic space     

Maurice Goldhaber  Virginia Trimble 《Journal of Astrophysics and Astronomy》1996,17(1-2):17-21

We raise the question of whether velocities of left and right circularly-polarized photons might be different (for reasons other than the well-known Faraday effect). Such a difference could manifest itself either in the time profiles of pulsed or bursting astronomical sources or in the rotation of the direction of polarization of linearly polarized radiation from them. The existing observations of pulsars, gamma ray bursters, and quasar jets are used to set limits to the difference in speed, between 10^-17and 10^-32  相似文献   

论喀斯特塌陷的水动力因素   总被引：9，自引：0，他引：9  

何宇彬  徐超 《水文地质工程地质》1993,20(5):39-42

对覆盖喀斯特区的塌陷形成模式的研究,得出塌陷的过程是潜蚀、吸蚀、气爆3种力的作用过程。引起塌陷的机理应是巨厚灰岩Ⅲ水动力带喀斯特管流水水动力场的变化,从而研究预防和治理措施也必须从这一主要方面入手,才能达到治本的效果。  相似文献   

几种纤维矿物粉尘的真空有机吸附及表面基团变化     

宋功保  石荣铭  董发勤  冯启明  李国武 《岩石矿物学杂志》2000,19(3):264-271

利用真空有机吸附和红外光谱分析法,研究了几种纤维矿物粉尘对不同偶极矩的正己烷（偶极矩为０）、乙醚（偶极矩为１．１６）和吡啶（偶极矩为２．１９）的吸附特征及这种有机试剂对表面基团的影响。研究发现：纤维矿物粉尘对有机试剂的吸附能力并不完全与有机试剂的偶极矩大小成正比;部分纤维矿物粉尘对正己烷的吸附为化学吸附,吸附解吸后出现了１２６２￣１２６７ｃｍ＾－１、１３１１ｃｍ＾－１的新的ＩＲ谱带,它们应是部分纤  相似文献   

ZY—1G型真空紫外辐射强度测试仪的研制   总被引：2，自引：0，他引：2  

王荣荣  马如森 《岩矿测试》1998,17(4):259-263

介绍了一种真空紫外辐射强度仪的研制。仪器选用ＭｇＦ２做窗口材料,使用的光电管为ＣｕＩ光电阴极（以ＫＩ和Ｃｕ为原料通过电化学方法制备）。仪器具有良好的灵敏度和重现性,对于ｘ＝４３μＡ的光电流测定１１次,ＲＳＤ＝２．１％,线性相关系数ｒ为０．９９。光谱响应范围１１０～２００ｎｍ。  相似文献   

生物纳米FeS强化灰岩去除酸矿废水中砷的研究          下载免费PDF全文

王艳香  赵峰华  孙红福  周磊 《岩石矿物学杂志》2016,35(5):893-900

通过两种还原型微生物铁还原菌JF-5和硫酸盐还原菌SRB对模拟酸矿废水中Fe~(3+)和SO~(2-)_4的还原作用合成纳米FeS,并将该生物纳米FeS包覆在灰岩表面,以提高灰岩可渗透反应墙(PRBs)对酸矿废水中砷的去除能力。通过批吸附实验研究As(Ⅴ)的静态吸附机理,柱实验研究As(Ⅴ)在包覆灰岩柱中的动态吸附和迁移,结果表明,包覆层生物FeS粒径为纳米级,并呈现一定晶形,能有效提高灰岩表面的比表面积和对As(Ⅴ)的吸附能力,红外光谱分析表明化学吸附为主要吸附机制;生物纳米FeS包覆灰岩静态吸附实验最大吸附量为187.46μg/g,达到纯灰岩吸附量(6.64μg/g)的30倍;JF-5和SRB形成的生物包覆吸附性质优于SRB和Fe(Ⅱ),二者对As(Ⅴ)的吸附能力都远大于纯灰岩对As(Ⅴ)的滞留能力。  相似文献   

西天山乌拉根大规模铅锌成矿中H_2S成因:菌生结构和硫同位素组成约束   总被引：1，自引：0，他引：1  

陈兴  薛春纪 《岩石学报》2016,32(5):1301-1314

乌拉根铅锌矿是中国西北地区目前探明金属量最大的铅锌矿床,但大规模成矿所需H2S的成因方式尚不清楚。在野外调查和矿相学观察基础上,论文通过场发射扫描电镜(FESEM)、能谱(EDS)和质谱(MS)观测分析表明,矿石中发育闪锌矿纳米莓球、丝/管状结构,它们由他形闪锌矿微晶集合而成,莓球直径30~700nm,丝/管状结构与莓球密切共生;常见与闪锌矿等矿石矿物共生的方解石纳米莓球结构,由他形方解石微晶集合而成,莓球直径20~800nm;也常见与矿石矿物共生的菱铁矿微米莓球、丝/管状结构,它们由他形菱铁矿微晶集合而成,莓球直径1~3μm,表面毛糙,丝/管状结构常出现在莓球周围并连接着莓球。这些纳/微米莓球在矿石中成群落不均匀分布,属细菌微生物成因,丝/管状结构为胞外聚合物的表现。矿石δ34SCDT变化大且显著偏负值(-27.9‰~15.0‰)。乌拉根大规模铅锌硫化物成矿所需H2S可能主要通过细菌硫酸盐还原(BSR)产生,盆地流体中烃类有机质催化下的细菌微生物硫酸盐还原反应是乌拉根铅锌大规模成矿的重要过程。  相似文献   

真空紫外四色超高温测量的参数优化     

钟先琼  向安平  杨经国 《成都信息工程学院学报》2004,19(4):588-591

利用黑体辐射定律和四色光学测温原理,在3000K～33000K的温度范围和20nm～56nm的真空紫外波段计算了非理想辐射体在四个波长处辐射强度的比率.并从测温灵敏度、测温范围和测温精度等方面对各测温参数的优化进行了讨论.  相似文献   

超临界二氧化碳钻井技术     

张琳  胥豪  牛洪波  刘晓兰 《探矿工程》2014,41(4):10-13

当温度和压力分别达到31．10℃、7．38 MPa及以上时,CO2成为超临界状态,超临界CO2具有类似于液体的密度,而其粘度又比空气和氮气大,可以驱动井下动力钻具旋转破岩,并携带岩屑,形成超临界CO2钻井技术。超临界CO2钻井具备破岩速度快、油气层保护好、驱替效率高等优势,对于非常规油气藏开发具有明显优势。超临界CO2钻井与连续管钻井技术相结合,应用于压力欠平衡钻井和压力衰竭地层前景广阔。介绍了超临界CO2物理特征、超临界CO2钻井技术流程及其技术优势,最后阐述了超临界CO2钻井技术的研究进展及发展趋势。  相似文献