青藏高原北緣哈拉湖沉積記錄的近800年來的環(huán)境變化.pdf

1、蘭州大學(xué)碩士學(xué)位論文青藏高原北緣哈拉湖沉積記錄的近800年來的環(huán)境變化姓名：曹潔申請學(xué)位級別：碩士專業(yè)：環(huán)境科學(xué)指導(dǎo)教師：陳發(fā)虎張成君20050501蘭州大學(xué)瓷源環(huán)境學(xué)院2005扁碩十畢業(yè)論文AbstractAsascientific，existerltandevenpoliticalissuetheglobalwanninginthe20Centuryhasbeenattractingagrowingconcernoftheworld

2、andshouldbescientificallytestedinthecontextofclimaticchangesatagreatertime—scale(ig1000yearsor2000years)Rapidtemperatureincreaseinthe20”Centuryisinsharpcontrasttothecoolinginthe“LittleIceAge”Thuscharacteristicsofclimatic

3、changeintbe“Linle【ceAge”hasbeenwidelystudiedandfocusedonGenerallyspeakingplateauareacanprovideamoresensitiverecordofglobalchangethanlowaltitudeareaSurroundedwithhighmountains，HalaLake，alargesaltylakewiththealtitudeof4078

4、m，liesinthenorthernofQinghai—TibetPlateauDuetolittlehumanimpactsonIhelakedrainage，HalaLake，asatypicalinlandclosedlakelocatedontheChinesemonsoontransitionline，canprovidesensitivejnformationonthepastclimaticandnaturalenvir

5、onmentalchangesTherefore，HataLakeisselectedasthestudysiteonthebasisofitsaboveadvantagesforthisthsisThreeshortcoresaredrilledatHalaLakeinJuly2002Thelongestofle，HALA一3B一02，istakent。beanalyzedforthisstudv210Pband1”CsmcoreHA

6、LA一3B02ismeasuredtodeterminethemodernsedimentaryrateChronologyofthecoreindicatesitcoverednearlythepast800yearsCorrespondingly，acal800一yearpaleoenvironmenthistoryofthelakeisreconstructedbasedonthefollowingProxyrecordssuch

7、asthestableisotopeofoxygenandcarbonofcarbonatesf6”C＆6”o)’totalorganiccarboncontent(TOC)，carbonatecontentandmagneticsusceptibilityThreestagesofenvironmentalchangesoyerthepast800yearshavebeenestablishedaccordingtoouranalys

8、isFirstlyacoolwetclimatewithagraduallycoolingandwettingtrendappearedonStageCf1206AD1650AD)SecondlywarminganddryingperiodrecoveredfromthemostcoolwetstateontheearlyStageB(1650AD1890AD)andkeptitscomparativelywarn2一drystatet

9、hrou曲outtheresttimeofthisstageafter177lADFinallytheclimateonfinalstage(StageA：1890AD一2002AD)shouldbethewarmestanddriestsince1206ADMoreoveritcanbeobviouslyseenthattheperiodinHalaLakedrainageareacorresponding“1ittleIceAge”

10、isfrom1500—1735ADandthemostwarm—dryclimateperiodisthe20“’centuryIncomparisonwithrecordsfromadjacentareasandotherareasoftbewodd，HalaLakerecordshowsthesameorsimilartrendoftemperatureandeffectivehumiditywiththem，butcan’texa

11、ctlycorrespondindetailduetotimeresolutionanddifferentproxyrecordsinapplicationItisconvincinglydiscoveredthattheclimateof1920sliesinacomparativelycool—wetenvironmerJtalstateinQinghaiTibetPlateauinthemeanwhileagenerallyari