n-Alkyl lipid concentrations and distributions in aquatic plants and their individual δD variations  

作　　者：Hu LIU Zhonghui LIU Cheng ZHAO Weiguo LIU 

机构地区：[1]State Key L aboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China [2]University of Chinese Academy of Sciences, Beijing 100049, China [3]Department of Earth Sciences, The University of Hong Kong, Hong Kong 999077, China [4]State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China

出　　处：《Science China Earth Sciences》2019年第9期1441-1452,共12页中国科学（地球科学英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant No. 41573005);the National Basic Research Programme of China (Grant No. 2013CB955901);the Key Program of the Chinese Academy of Sciences (Grant No. QYZDY-SSWDQC001);the State Key Laboratory of Loess and Quaternary Geology (Grant No. SKLLQG1632)

摘　　要：Aquatic plants are major input sources of autochthonous organic matter in lake sediments, but investigations on fatty acid(FA) and n-alkane distributions in aquatic plants are currently limited, greatly hindering the applications of their isotope geochemistry in lacustrine environments. Here, the reported n-alkyl lipid distributions of aquatic plants in globally studied lakes,together with newly obtained aquatic plant n-alkyl lipid data in Chinese lakes(Yunnan and Inner Mongolia), are used to understand their distribution characteristics. The results show that aquatic plants have predominantly mid-chain lipids(C23–C25 n-alkanes and C22–C24 FAs), differing from that of terrestrial plants(dominant by long-chain lipids), but the long-chain n-alkanes(e.g., C27 and C29) and long-chain FAs(e.g., C26 and C28) also show high abundances in most samples. Submerged plants have high concentrations of long-chain n-alkanes(avg. 47 μg g-1) and long-chain FAs(avg. 170 μg g-1), close to those in terrestrial plants, indicating that submerged plants may make large contributions of long-chain n-alkyl lipids to lake sediments, while the contributions of long-chain n-alkyl lipids derived from algae to lake sediments may be small because of their low concentrations(avg. 2 μg g-1 for n-alkanes and 9 μg g-1 for FAs). We find that lipid molecular proxies(including ACL14-32 and ATR14-18) can be reliably used to distinguish the FAs sourced from algae and other plants, and Paq′ values can be utilized to distinguish the nalkane sources between submerged plants and terrestrial plants. Aquatic plants do not have significant δD differences among different chain-length n-alkanes and FAs for each sample, suggesting that the offset between δD values of different chain-length n-alkyl lipids in lake sediments can help determine sedimentary lipid input sources and infer paleohydrological changes.Aquatic plants are major input sources of autochthonous organic matter in lake sediments, but investigations on fatty acid（FA） and n-alkane distributions in aquatic plants are currently limited, greatly hindering the applications of their isotope geochemistry in lacustrine environments. Here, the reported n-alkyl lipid distributions of aquatic plants in globally studied lakes,together with newly obtained aquatic plant n-alkyl lipid data in Chinese lakes（Yunnan and Inner Mongolia）, are used to understand their distribution characteristics. The results show that aquatic plants have predominantly mid-chain lipids(C23–C25 n-alkanes and C22–C24 FAs), differing from that of terrestrial plants（dominant by long-chain lipids）, but the long-chain n-alkanes(e.g., C27 and C29) and long-chain FAs(e.g., C26 and C28) also show high abundances in most samples. Submerged plants have high concentrations of long-chain n-alkanes(avg. 47 μg g-1) and long-chain FAs(avg. 170 μg g-1), close to those in terrestrial plants, indicating that submerged plants may make large contributions of long-chain n-alkyl lipids to lake sediments, while the contributions of long-chain n-alkyl lipids derived from algae to lake sediments may be small because of their low concentrations(avg. 2 μg g-1 for n-alkanes and 9 μg g-1 for FAs). We find that lipid molecular proxies(including ACL14-32 and ATR14-18) can be reliably used to distinguish the FAs sourced from algae and other plants, and Paq′ values can be utilized to distinguish the nalkane sources between submerged plants and terrestrial plants. Aquatic plants do not have significant δD differences among different chain-length n-alkanes and FAs for each sample, suggesting that the offset between δD values of different chain-length n-alkyl lipids in lake sediments can help determine sedimentary lipid input sources and infer paleohydrological changes.

关 键 词：N-ALKANES FATTY ACIDS Hydrogen ISOTOPES ALGAE Submerged plants 

分 类 号：Q946[生物学—植物学]