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  • 简介:Ananomalousisotopeeffectexistsinmanyheavyelementisotopesystems(e.g.,Sr,Gd,Zn,U).Thiseffectusedtobecalledthe‘‘odd–evenisotopeeffect’’becausetheoddmassnumberisotopesbehavedifferentlyfromtheevenmassnumberisotopes.Thismass-independentisotopefractionationdrivingforce,whichoriginatesfromthedifferenceintheground-stateelectronicenergiescausedbydifferencesinnuclearsizeandshape,iscurrentlydenotedasthenuclearfieldshifteffect(NFSE).ItisfoundthattheNFSEcandriveisotopefractionationofsomeheavyelements(e.g.,Hg,Tl,U)toanastonishingdegree,farmorethanthemagnitudecausedbytheconventionalmass-dependenteffect(MDE).Forlightelements,theMDEisthedominantfactorinisotopefractionation,whiletheNFSEisneglectable.Furthermore,theMDEandtheNFSEbothdecreaseastemperaturesincrease,thoughatdifferentrates.TheMDEdecreasesrapidlywithafactorof1/T2,whiletheNFSEdecreasesslowlywithafactorof1/T.Asaresult,evenathightemperatures,theNFSEisstillsignificantformanyheavyelementisotopesystems.Inthisreviewpaper,webeginwithanintroductionofthebasicconceptoftheNSFE,includingitshistoryandrecentprogress,andfollowwiththepotentialimplicationsoftheinclusionoftheNFSEintothekineticisotopefractionationeffect(KIE)andheavyisotopegeochronology.

  • 标签: 同位素分馏效应 同位素效应 稳定 位移 同位素年代学 重金属元素
  • 简介:土壤矿物与微生物相互作用对土壤中一系列生态过程产生重要影响。本文通过对培养液进行K、Si、Fe、Al等元素分析,测定了菌株生长与代谢产物,结合扫描电镜和透射电镜的观察,研究了钾矿物表生硅酸盐矿物分解细菌Bacillusglobis-porusQ12菌株与云母矿物(黑云母和白云母)的相互作用规律。结果表明,不同的云母矿物对B.globisporusQ12菌株的生长与代谢有不同影响;与白云母相比,黑云母更适合B.globisporusQ12菌株的生长与酸性代谢产物(如有机酸等)的合成;供试菌株能促进黑云母和白云母矿物中K、Si、Fe、Al等元素的释放。扫描电镜、透射电镜观察与能谱分析发现,B.globisporusQ12菌株能在云母矿物表面定殖,加速云母矿物的风化;菌体自身也能吸附培养液中离子和矿物碎片而形成新的矿物。

  • 标签: BACILLUS globisporus 云母 相互作用 有机酸 矿物风化