A re-evaluation of the average chain length of lacustrine sedimentary n-alkanes as a paleoproxy on the Qinghai-Tibet Plateau  

作　　者：Mingda WANG Qin LI Jaime TONEY David HENDERSON Juzhi HOU 

机构地区：[1]School of Geography,Liaoning Normal University,Dalian 116029,China [2]Alpine Paleoecology and Human Adaptation(ALPHA)Group,State Key Laboratory of Tibetan Plateau Earth System,Resources and Environment,Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100101,China [3]School of Geographical and Earth Sciences,University of Glasgow,Glasgow G128QQ,Scotland,UK [4]CAS Center for Excellence in Tibetan Plateau Earth Sciences,Beijing 100101,China

出　　处：《Frontiers of Earth Science》2023年第4期905-919,共15页地球科学前沿（英文版）

基　　金：financially supported by the National Natural Science Foundation of China(Grant No.42171159);the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(No.2019QZKK0601).

摘　　要：Long-chain n-alkanes are one of the most common organic compounds in terrestrial plants and they are well-preserved in various geological archives.n-alkanes are relatively resistant to degradation and thus they can provide high-fidelity records of past vegetation and climate changes.Nevertheless,previous studies have shown that the interpretation of n-alkane proxies,such as the average chain length(ACL),is often ambiguous since this proxy depends on more than one variable.Both vegetation and climate could exert controls on the n-alkane ACL,and hence its interpretation requires careful consideration,especially in regions like the Qinghai-Tibet Plateau(QTP)where topography,biome type and moisture source are highly variable.To further evaluate the influences of vegetation and climate on the ACL in high-elevation lakes,we examined the n-alkane distributions of the surface sediments of 55 lakes across the QTP.Our results show that the ACL across a climatic gradient is significantly affected by precipitation,rather than by temperature.The positive correlation between ACL and precipitation may be because of the effect of microbial degradation during deposition.Finally,we suggest that more caution is needed in the interpretation of ACL data in different regions.

关 键 词：ACL average chain length N-ALKANES leaf wax lake sediments Qinghai-Tibet Plateau 

分 类 号：P342[天文地球—水文科学]