褶皱变形区正负向构造单元页岩气差异富集特征     

张梦琳  李郭琴  寇一龙  李柯  陈佳  徐剑良  何嘉  梁霄  樊骐铖 《地质论评》2024,70(S1):272-274

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黑龙江拜泉地区硒元素在土壤-植物系统中的迁移富集规律     

梁帅  朱建新  戴慧敏  宋运红  刘凯  韩晓萌  翟富荣 《地质与资源》2021,30(4):456-464,478

以拜泉地区1:5万土地质量地球化学调查数据为基础,开展硒地球化学特征及生态效应研究,探讨硒元素在土壤-植物系统中的迁移富集规律.研究表明:拜泉地区根系土硒含量均值为0.25×10-6,属中等富硒土壤,黄豆和水稻富硒占比相对较高;水溶态硒和离子交换态硒含量之和约为5％,一定程度上制约硒的有效量.土壤理化性质对硒全量、硒形...  相似文献   

An Efficient Procedure for Isolating Microsatellite DNAs from Sea Cucumber (Apostichopus japonicus)   总被引：1，自引：0，他引：1  

HU Jingjie  ZHAN Aibin  LU Wei  HU Xiaoli  and BAO Zhenmin* Laboratory of Marine Genetics  Breeding 《中国海洋大学学报(英文版)》2007,6(1):12-15

1 Introduction Microsatellite DNAs, also called simple sequence re-peats (SSRs), are stretches of DNA, consisting of tan-demly repeating mono-, di-, tri-, tetra- or penta-nucleotide units. They are evenly distributed throughout the ge-nomes of most eukaryotic species (Tohn et al., 2000). Their high information content about the divergence of genome, which is directly related to the number of alleles at each locus, and the ease of PCR assays make them ex-cellent molecular markers (Powell …  相似文献   

湖水同位素平衡研究中分馏系数和富集系数计算形式的组合选择   总被引：3，自引：1，他引：2       下载免费PDF全文

曾承  余俊清 《盐湖研究》2005,13(1):7-11

湖泊自生碳酸盐δ18O(δ18Oc)是研究湖泊水体同位素平衡和气候变化的重要环境同位素指标。由于δ18Oc与湖水δ18O(δ18Ow)密切相关,前人建立了δ18Ow的计算公式,这方面的研究对于δ18Oc环境意义的正确判读十分重要。δ18Ow计算公式中的平衡分馏系数α和平衡富集系数ε各有几种计算形式,当两个参数同时出现时,其计算形式须正确组合:当α>1时,ε=α-1或ε=1-1/α;当α<1时,ε=1-α或ε=1/α-1。其中"α>1,ε=α-1"组合最常用。  相似文献   

海洋环境中氟喹诺酮类抗生素(FQs)分析的样品前处理与检测技术          下载免费PDF全文

温丽联  宋金明  李学刚  马骏  戴佳佳  袁华茂  段丽琴  王启栋 《海洋科学》2023,47(9):103-118

氟喹诺酮类(FQs)药物是一种广泛使用的人工合成类抗生素,存在于水体、沉积物等各种环境介质中,并在水生生物体内得到富集,对人类健康和全球生态系统的可持续发展有重要的影响。环境中FQs残留的分析检测是了解其环境生物地球化学行为和潜在生态环境风险的基础,本文系统总结了近几年海洋水体、沉积物和生物体样品中FQs的残留特征、样品前处理与检测技术,在此基础上,前瞻分析了海洋环境中FQs残留分析检测技术的发展趋势。分析表明,FQs的分离富集和测定必须充分考虑FQs的物理化学性质和样品成分的复杂性。海水样品准备应注意过滤膜的选择和pH的调节;沉积物和生物体的样品准备应考虑水分、萃取溶剂、基质效应和pH的影响,并使用超声萃取。固相萃取、QuEChERS萃取、磁性固相萃取是分离富集FQs较常用的方法,吸附剂、淋洗溶液和洗脱溶液的选择和优化是提高样品回收率的关键。FQs的检测大多通过液质联用或液相色谱结合荧光检测器进行,其中色谱柱的选择、离子对试剂的添加和进样pH值的调整都是优化的关键因素。研究指出海洋领域FQs在线自动SPE技术的开发以及新型萃取吸附剂的研制应在未来研究中被重点关注。  相似文献   

Fluid-rock interaction modeling to constrain Au enrichment: Implication for the giant Jiaodong Au mineralization,eastern North China Craton     

《Gondwana Research》2024

The devolatilization model of the metasomatized lithospheric mantle without pre-enriched gold has been proposed to account for the giant gold mineralization. An excellent example is the world-class Jiaodong gold province with >5000 tonnes Au resources in the eastern North China Craton. The auriferous fluid transport and gold enrichment during wallrock alterations are two vital processes to determine the giant gold mineralization formation in this province. However, the effects of the fluid-rock interaction with alterations on the auriferous fluid transport and gold enrichment still keep poor understanding, which leads the above model to be imperfect. The giant Jiaojia goldfield in this province recorded a wallrock alteration evolution from K-feldspar alteration to pyrite-sericite-quartz alteration, and some parts of the latter can become gold orebodies when the gold grade is >1 ppm. This study conducts thermodynamic fluid-rock interaction modeling to reveal auriferous fluid transport and coupled relationship between gold enrichment and alteration mineral assemblage based on the alteration-mineralization and ore fluid characteristics of the goldfield. The modeling of fluid-rock interaction with cooling indicates the transformation of Au-Cl complexes to Au-S complexes combined with the total sulfur concentration decrease by pyrite precipitation when cooling from ∼460 °C can trigger the dispersive gold precipitation, which should hinder the gold long-range transport to lower ambient temperature. The high oxygen fugacity at >400 °C can enhance Au-Cl complexes stability, and the low pH can maintain high total sulfur concentration in the auriferous fluid, both of which facilitate the long-range gold transport to a lower-temperature environment. The auriferous fluid would acquire higher pH by the buffering of feldspars or sericite, which was beneficial for the high-efficiency precipitations of pyrite and gold. The ankerite-siderite assemblage without pyrophyllite in the pyrite-sericite-quartz alteration zone indicates that a cumulative fluid to rock mass ratio (f/r) of 3.8–4.8 should be needed for the transformation from K-feldspar alteration to pyrite-sericite-quartz alteration according to the fluid-rock interaction modeling at 300 °C and 2000 bar. In the case of auriferous fluids with ≤200 ppb Au concentration, the single fluid-rock interaction can only elevate the gold grade to ≤0.69–0.87 ppm in the pyrite-sericite-quartz alteration zone at f/r 3.8–4.8. Therefore, the fracture-induced fluid flow coupled with fluid-rock interaction is proposed to the prerequisite to elevate the gold grade to >1 ppm in the pyrite-sericite-quartz alteration zone. The metasomatized lithospheric mantle volume for the required ore fluid and Au in the Jiaodong province is estimated according to the modeling results and alteration-mineralization characteristics, which provides a link between the mantle without abnormal Au enrichment and the alteration-mineralization processes.  相似文献   

云南个旧碱性杂岩体的岩石成因及稀土元素富集机制     

王长兵  倪光清  覃勇凯  廖志凯  李炜森  李誓  张黎  官斌 《岩石矿物学杂志》2021,40(4):704-716

云南个旧碱性杂岩体由边缘相碱长正长岩和中心相霞石正长岩组成.全岩地球化学分析表明,该碱性杂岩体具有高碱、富钾、富铁、低镁、高分异的碱性-过碱性岩石特征,晚期更富集碱金属元素;LREE/HREE值为20～59,(La/Sm)N = 8～50,(Sm/Yb)N = 1.2～5.0,富集轻稀土元素,轻稀土元素较重稀土元素分馏...  相似文献