学科分类
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3 个结果
  • 简介:Fivehumicfractionswereobtainedfromauniformly^15N-labelledsoilbyextractionwith0.1molL^-1Na4P2O7,0.1molL^-1NaOH,andHF/HCl-0.1molL^-1NaOH,consecutively,andanalyzedby^13Cand^15NCPMASNMR(crosspolarizationandmagicanglespinningnuclearmagneticresonace).Comparedwiththoseofnativesoilshumicfractionsstudiedasawholecontainedmorealkyls,methoxylsandO-alkyls,being27%-36%,17%-21%and36%-40%,respectively,butfeweraromaticsandcarboxyls(bein14%-20%and13%-90%,respectively),Amongthosehumicfractions,thehumicacid(HA)andfulvicacid(FA)extractedby0.1molL^-1Na4P2O7containedslightlymorecarboxylsthancorrespondinghumicfractionsextractedby0.1molL^-1NaOH,andtheHAextactedby0.1molL^-1NaOHaftertreatmentwithHF/HClcontainedtheleastaromaticsandcarboxyls.Thedistributionofnitrogenfunctionalgroupsofsoilhumicfractionsstudiedwasquitesimilartoeachotherandalsoquitesimilartothatofhumicfractionfromnativesoils.Morethan75%oftotalNineachfractionwasinamidefrom,with9%-13%presentasaromaticand/oraliphaticaminesandtheremainderasheerocyclicN.

  • 标签: 芳香族化合物 腐殖质 赋存形态 土壤成分
  • 简介:Theannualseriesofδ13CweremeasuredintreeringsofthreeCryptomeriafortuneidisks(CF-1,CF-2,andCF-3)collectedfromWestTianmuMountain,ZhejiangProvince,China,accordingtocross-datingtreeringages.Therewasnoobviousdecreasingtrendoftheδ13CannualtimeseriesofCF-2before1835.However,from1835to1982thethreetreeringδ13Cannualseriesexhibitedsimilardecreasingtrendsthatweresignificantly(P≤0.001)correlated.Thedistributioncharacteristicsofascatterdiagrambetweenestimatedδ13CseriesofCF-2frommodelingandtheatmosphericCO2concentrationextractedfromtheLawDomeicecorefrom1840to1978wereanalyzedandacurvilinearregressionequationforreconstructingatmosphericCO2concentrationwasestablishedwithR2=0.98.Also,atestofindependentsamplesindicatedthatbetween1685and1839thereconstructedatmosphericCO2concentrationusingtheδ13CseriesofCF-2hadacloserelationshipwiththeLawDomeandSipleicecores,withastandarddeviationof1.98.ThegeneralincreasingtrendofthereconstructedatmosphericCO2concentrationcloselyreflectedthelong-termvariationofatmosphericCO2concentrationrecordedbothbeforeandaftertheIndustrialRevolution.Between1685and1840theevaluatedatmosphericCO2concentrationwasstable,butafter1840itexhibitedarapidincrease.Givenalongerδ13Cannualtimeseriesoftreerings,itwasfeasibletorebuildarepresentativetimeseriestodescribetheatmosphericCO2concentrationforanearlierperiodandforyearsthatwerenotintheicecorerecord.

  • 标签: 大气CO2浓度 温室效应 全球变暖 气候
  • 简介:绿化混凝土是一种新型的建筑材料,具有高透水性、高透气性和较强的耐冲刷力和防护性能。本文概述了绿化混凝土的研究现状,并对重要的技术环节进行了讨论。绿化混凝土实现了经济效益、生态效益和社会效益的统一,具有广阔的应用前景。

  • 标签: 绿化混凝土 岩石开挖裸露面 护坡 改性