Neutron Activation Analysis,Atomic Absorption and X‐Ray Fluorescence Spectrometry Review for 2006–2007     

L. Paul Bédard 《Geostandards and Geoanalytical Research》2008,32(4):399-403

These mature analytical techniques do not show any change in publication level from the previous two years and AAS remains dominant in terms of the number of publications. The last two years have seen fewer technical improvements than in the previous review period. Some interesting papers dealing with uncertainty and quality assurance in INAA were published during 2006–2007. It is suggested that photon activation should be reconsidered because the source of electron accelerators has recently improved. A technique to preconcentrate Se for INAA determination has also been proposed. In the case of AAS, papers on analyte preconcentration continue to be more abundant than those relating to instrumental modification. Sample preparation for AAS is also active and ultrasound‐assisted leaching shows some promising applications. There were an unusual number of reviews concerned with AAS and those important to geological samples are cited here. A technique to preconcentrate Cr in water is presented and a new device to determine As and Se is showing some potential uses. Confocal X‐ray mapping continues to show interesting developments. One group developed a technique to perform XRF inside an oyster and an interesting application of μ‐XRF mapping of sediments is presented. Determination of platinum‐group elements (at μg g¹ concentrations) can be carried out very quickly with an improved XRF technique.  相似文献   

降雪对荒漠生物土壤结皮光合生理特性的影响     

司守霞  李宜轩  回嵘  刘立超  谢敏  王艳莉 《中国沙漠》2018,38(3):560-567

生物土壤结皮（BSC）广泛分布在干旱、半干旱区,对荒漠生态系统的稳定、平衡等具有重要意义。初步探讨了降雪量对腾格里沙漠东南缘藻类、地衣和藓类结皮叶绿素荧光参数、光合色素、丙二醛（MDA）及可溶性蛋白含量的影响。结果表明：结皮光合生理特性对降雪量的响应有显著差异。适量降雪激发3种结皮PSⅡ反应中心,引起光合色素、可溶性蛋白合成升高,MDA含量降低;过量降雪导致藻类和地衣结皮光合电子传递受阻,光合色素、可溶性蛋白合成减少,MDA含量升高,产生光抑制现象。适量冬季降雪对结皮具有一定的促进作用,而藓类结皮更能适应极端降雪环境,但相关分子机制还需深入研究。  相似文献   

兼养对雨生红球藻细胞生长的促进作用及藻株差异性   总被引：1，自引：0，他引：1  

龙元薷  刘建国  张立涛 《海洋科学》2014,38(12):1-7

结合叶绿素荧光技术,对比研究了不同雨生红球藻藻株在兼养(光照+乙酸钠)培养过程中细胞生长和光合作用的共性与差异性反应。结果表明:兼养明显提高红球藻细胞密度和比生长速率;乙酸钠不仅为红球藻提供异养的有机碳源,而且还明显导致藻细胞光自养的光合综合性能指数发生改变,兼养对细胞生长促进作用的贡献在前期主要来自于其中的异养部分,而在后期却明显来自于自养部分;兼养对细胞生长的促进作用在藻株之间存在一定差异,不同藻株对乙酸钠的适应能力和最适质量浓度也存在明显差异,藻株H0可适应的乙酸钠质量浓度较高,而藻株H6对乙酸钠需求和适应性相对较低。上述结果意味着规模化培养红球藻过程中,针对不同藻株采用适宜乙酸钠兼养方式可有效缩短培养周期,提高生产效率。  相似文献   

The effects of elevated-CO₂ on physiological performance of Bryopsis plumosa     

YILDIZ Gamze  DERE &#;&#;kran 《海洋学报(英文版)》2015,34(4):125-129

An increase in the level of atmospheric carbon dioxide (CO2) and the resultant rise in CO2 in seawater alter the inorganic carbon concentrations of seawater. This change, known as ocean acidification, ...  相似文献   

近海养殖水体溶解性有机质的荧光特征及环境指示意义     

吴峰  宋秀贤  池连宝  王文涛  俞志明 《海洋与湖沼》2022,53(3):597-606

为探究近海养殖水体溶解性有机质(dissolved organic matter,DOM)的荧光特征及环境指示意义,以山东省东营市凡纳滨对虾池塘为研究对象,利用三维荧光光谱-平行因子分析(EEMs-PARAFAC)技术对2020年9月14日至10月17日凡纳滨对虾池塘养殖水体中DOM的荧光特征进行了分析,以期揭示其来源及环境指示意义。结果表明,养殖池水体DOM有4种荧光组分,包括1种类蛋白质物质(C4)和3种类腐殖酸物质(C1、C2与C3),前者作为养殖池水体DOM特有组分,且其荧光强度高于对照池各组分。养殖池水体DOM总荧光强度、总有机碳和溶解有机碳含量于采样时期均明显高于对照池。综合3种荧光指数(FI、BIX、HIX),对照池和养殖池水体DOM以内源输入为主,自生源特征明显。对照池和养殖池水体DOM组分与营养盐(氮、磷营养盐为主)具有显著相关性,表明DOM组分的产生与利用和营养盐的消耗与生成过程相耦合。养殖池DOM组分C1和C4与chl a呈显著正相关性,表明浮游藻类是养殖水体DOM类蛋白质和类腐殖酸物质的重要来源。该研究揭示了养殖水体有机质高度积累,对养殖环境的富营养化带来潜在威胁,同时为进一步揭示养殖水体DOM的光化学性质提供了科学依据。  相似文献   

Lake Shira Level Changes in Late Holocene     

Andrey DARIN  Ivan KALUGIN  Natalya MAKSIMOVA  Tatiana MARKOVICH  Yakov RAKSHUN  Dmitryi SOROKOLETOV  Fedor DARIN  Denis RAGOZIN 《《地质学报》英文版》2014,88(Z1):3-4

正1 Introduction Meromictic Shira Lake is a good represfor detail climate modeling due to its locainformation and annually laminated bottomsediment column of 155 cm in length wahammer corer in the deepest(24 m)central in 2009.2 Sample Preparations and Measuring  相似文献   

GGR Biennial Critical Review: Analytical Developments Since 2012     

Michael Wiedenbeck  L. Paul Bédard  Roxana Bugoi  Mary Horan  Kathryn Linge  Silke Merchel  Luiz F. G. Morales  Dany Savard  A. Kate Souders  Paul Sylvester 《Geostandards and Geoanalytical Research》2014,38(4):467-512

Advances in the chemical, crystallographic and isotopic characterisation of geological and environmental materials can often be ascribed to technological improvements in analytical hardware or to innovative approaches to data acquisition and/or its interpretation. This biennial review addresses key laboratory methods that form much of the foundation for analytical geochemistry; again, this contribution is presented as a compendium of laboratory techniques. We highlight advances that have appeared since January 2012 and that are of particular significance for the chemical and isotopic characterisation of geomaterials. Prominent scientists from the selected analytical fields present publications they judge to be particular noteworthy, providing background information about the method and assessing where further opportunities might be anticipated. In addition to the well‐established technologies such as thermal ionisation mass spectrometry and plasma emission spectroscopy, this publication also presents new or rapidly growing methods such as electron backscattered diffraction analysis and atom probe tomography – a very sensitive method providing atomic scale information.  相似文献   

VUV photochemistry of small biomolecules     

Martin Schwell  Hans-Werner Jochims  François Dulieu 《Planetary and Space Science》2006,54(11):1073-1085

We review our recent results on the vacuum ultraviolet (VUV) photochemistry of small biomolecules. The experimental techniques used, mass spectrometry and photofragment fluorescence spectroscopy, are described. Emphasis is laid on our mass spectrometric results obtained for five nucleic acid bases and five amino acids. Ionisation and appearance energies are determined from photoionisation mass spectrometry, many for the first time. From this, fragmentation pathways following 6-22 eV photoexciation are derived. The adiabatic ionisation energies of the biomolecules studied lie between 8.2 eV (adenine) and 9.6 eV (α-amino-isobutyric acid). We show that the nucleic acid monocations, and chemically related molecular cations, do not fragment even when formed with large internal energies (E_int) ranging from 1.80 to 5.35 eV. In contrast, amino acid monocations are unstable and rapid fragmentation occurs via rupture of the CC(OOH) bond, except for β-alanine, where rupture of the bond between the α-C and β-C is the lowest lying ionic dissociation channel. The VUV photochemistry of the prebiotic species formic acid, acetic acid and methylformate, studied in more detail previously by several techniques, including fluorescence spectroscopy, is also reviewed. Astrophysical implications of our work are discussed in the conclusion.  相似文献   

Portable X-ray fluorescence identification of the Cretaceous–Paleogene boundary: Application to the Agost and Caravaca sections,SE Spain     

《Cretaceous Research》2017

It is shown that portable X-ray fluorescence (pXRF) is a powerful tool for the identification and geochemical characterization of prospective Cretaceous–Paleogene (K–Pg) boundary sites. Field measurements in two well-known K–Pg boundary sequences, located at Agost and Caravaca, SE Spain, have been performed. A sizable enrichment around the K–Pg horizon of several elements such as K, Ti, Fe, Ni, Cr, Cu, Zn, As or Pb, together with a strong reduction in the Ca content, is found with the pXRF instrument. These observations represent a primary geochemical signature of the K–Pg boundary in distal marine sections such as those of Agost and Caravaca. Also, the intensities of the pXRF peaks correlate well with elemental composition data obtained by inductively coupled plasma-mass spectrometry (ICP-MS) on collected samples. Hence, the pXRF field measurements are shown to provide fast and useful quantitative information about K–Pg boundary sequences.  相似文献   

厚壳贻贝(Mytilus coruscus)金属硫蛋白MT-10:cDNA克隆、结构分析及铜离子胁迫下的表达   总被引：1，自引：0，他引：1  

王昊盛  宋鑫金  董文强  吴斌  陈永霞  卢玮筱  祁鹏志  郭宝英 《海洋与湖沼》2017,48(4):864-869

近年来我国沿海海域重金属污染日趋严重,软体动物尤其是双壳贝类响应重金属污染胁迫的研究发展成为目前的研究热点。金属硫蛋白是一类广泛存在于生物体内富含半胱氨酸(Cys)的小分子蛋白,具有结合金属离子的能力,能有效调节生物体细胞内的金属离子平衡,具有清除自由基,重金属解毒的功能,关于厚壳贻贝MT蛋白的研究尚未见报道。本文首次利用RT-PCR和c DNA末端快速扩增技术克隆了厚壳贻贝MT-10蛋白c DNA全长(Mc-MT-10),其包含101bp的5′UTR区,108bp的3′UTR区以及222bp的ORF区,编码73个氨基酸。经比对发现Mc-MT-10富含Cys,且具有9个软体动物中常见的CXC结构以及CKCXXXCXCX结构,系统进化树中同科或属中MT-10聚合成一个分支,显示出高度保守性。采用Q-PCR技术分析了MT-10 mRNA在Cu~(2+)胁迫下厚壳贻贝外套膜及消化腺中表达变化,结果表明Mc-MT-10 mRNA在Cu~(2+)胁迫下两种组织中的表达量急剧升高,说明Cu~(2+)能够诱导Mc-MT-10 mRNA的表达,并且表现出诱导具有阈值性特点。研究结果可为深入研究厚壳贻贝MT蛋白的功能奠定基础,为厚壳贻贝抗重金属污染新品种选育提供数据支持。  相似文献