简介:InordertoexplorethefeasibilityofusingX-raytomeasuremoisturecontentinthedryingprocessandhaveafurtherstudyontheeffectofprecisionofmoisturecontentwhenscanningthroughdifferentgraindirections,X-rayscanningmethodandweightingmethodwereusedtomeasureaveragemoisturecontentofCunninghamialanceolataduringhotairdrying.Theresultsshowthatthemoisturecontentvaluesoftwomethodswereveryclosetooneanother,thedeterminationcoefficientsofbothwerehighlycorrelatedwithavalueover0.99,andtheabsolutedeviationwasbelow2%;whenscanningalongradialdirectionandlongitudinaldirection,theprecisionsofaveragemoisturecontentwerehigherthanthatofthetangentialdirection,butthedeviationcanbenegligibleintheactualmeasurement;inthepracticalapplication,theeffectofgraindirectiononprecisionofmoisturecontentmeasurementcouldnotbetakenintoaccountwhenusingX-raytomeasurethemoisturedistributionofwood.
简介:KafangTownship,XinxianCountyofHenanProvinceislocatedinthehinterlandoftheDabieMountainborderingHenanandHubeiprovinces.Thistown...
简介:TheabsorptionandenrichmentofheavymetalelementsbyleavesofPopulus×euramericanacv.’Neva’wereanalyzedthroughcontentassessingofheavymetalelementsinsoilsofthreeforestlandsatFangshanDistrictinthesouthernsuburbofBeijing.TheseforestlandswithP.×euramericanacv.’Neva’plantationwerearoundwiththevarioussourcesofpollutionsuchascementmill,stonemill,sewageandgarbage.SomeofheavymetalelementssuchasCd,Pb,Cu,andZnwerefoundinthesoilsamplesandleavesofP.×euramericanacv.’Neva’grownonthethreeforestlandswhichwereinvestigated.TheresultsofinvestigationshowedthatthesoilsofthreeforestlandswerepollutedwithPb,Cd,CuandZninvaryingdegrees.ThecontentsofPb,CuandZninsoilsweresignificantlydifferentamongthethreeforestlands,whereastheaveragecontentofCd(0.0776mg·kg-1)waslessbutthatofPb,Cu,andZn(37.61,26.25and90.3mg·kg-1)weremorethantheaveragebackgroundvalueofBeijing.ThecontentsofPb,Cd,CuandZninleavesofP.×euramericanacv.’Neva’weredifferentamongthreeforestlands.Withthechangesofheavymetalcontentsinsoilsamples,therewasnoregularityonthechangesofdifferentheavymetalcontentsinleavesofP.×euramericanacv.’Neva’grownondifferentforestland.P.×euramericanacv.’Neva’canabsorbandaccumulatePb,Cd,CuandZninsoilbutshoweddifferentcapacitiesofabsorptionandaccumulationwiththeorderofCd>Zn>Cu>Pb.Especially,itsabsorptionandaccumulationcapacityforCdwasstrongwithmaximumenrichmentfactorhigherthan16andshowedhighaccumulationonlowbackground,whereasitsenrichmentcapacitiesforPbandCuwererelativelypoorerwithaverageenrichmentfactoroflessthan1.Atdifferentforestlands,thereexistedgreatdifferenceonabsorptioncapacityofP.×euramericanacv.’Neva’withthesameheavymetal.
简介:用X-射线微区分析方法对I-214(PopulusdeltoidesP.nigra(Dode)Guinier)和胡杨(P.euphraticaOlive)根和叶片样品中元素浓度和分布研究的结果表明,与盐胁迫处理和对照的I-214相比较,胡杨根系中具有”次生液泡”,因而Cl,Na,K和Mg离子浓度较低,而Ca离子浓度较高.在不耐盐的I-214杨中由于不具有”次生液泡”,Cl和K离子浓度较高.胡杨中的这种结构一方面可以做为Cl离子的储存场所,另一方面可以防止Cl离子在细胞核中积聚.在盐胁迫处理条件下,相对细胞壁而言胡杨表现出较强的防止细胞核中积聚Cl离子的能力,表明胡杨在离子选择吸收和区隔化方面具有较强的功能,这将有助于解释胡杨所具有的较强的耐盐性
简介:从1999年8至10月,2000年的4至6月,2002年8月至2003年9月,在平均树高为26米的长白山阔叶红松林内,用红外气体分析仪(2250D,LI-CORInc.和LI-COR,820)测定了不同高度的二氧化碳浓度。根据测定的数据,分析了阔叶红松林二氧化碳廓线的日变化和季节变化动态。结果表明:CO2浓度的垂直分布在白天和夜间是不同的,在接近地面处CO2浓度始终最大。从季节CO2廓线看出,在植物生长季节林冠处CO2浓度有明显的成层现象,不同高度(60~2.5m)的CO2浓度3月份变化较小差值为10mmol穖ol-1,而在7月份变化较大,差值为60mmol穖ol-1。7月份林冠处(22,26,32m)CO2浓度梯度较大,浓度差为8mmol穖ol-1。计算位于涡度相关仪器之下的40米高空气柱中CO2贮存状况表明,年际贮存是负值,但对NEE的贡献很小。图4参11。