Research output: Contribution to journal › Article › peer-review
Salinity-controlled isomerization of lacustrine brGDGTs impacts the associated MBT5ME' terrestrial temperature index. / Wang, Huanye; Liu, Weiguo; He, Yuxin et al.
In: Geochimica et Cosmochimica Acta, Vol. 305, 15.07.2021, p. 33-48.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Salinity-controlled isomerization of lacustrine brGDGTs impacts the associated MBT5ME' terrestrial temperature index
AU - Wang, Huanye
AU - Liu, Weiguo
AU - He, Yuxin
AU - Zhou, Aifeng
AU - Zhao, Hui
AU - Liu, Hu
AU - Cao, Yunning
AU - Hu, Jing
AU - Meng, Bowen
AU - Jiang, Jiawei
AU - Kolpakova, Marina
AU - Krivonogov, Sergey
AU - Liu, Zhonghui
N1 - Funding Information: Three anonymous reviewers and the editor are thanked for their constructive comments. This research was supported by the Chinese Academy of Sciences (XDB40000000, XDA2007020202), Hong Kong Research Grants Council (17325516), the Second Tibetan Plateau Scientific Expedition and Research (STEP) program (2019QZKK0101), West Light Foundation of the Chinese Academy of Sciences (XAB2019A03), and the Youth Innovation Promotion Association, CAS (2019403). Lake investigations in southern Siberia and Mongolia were supported by RSF (17-77-10086), RFBR (21-55-53037, 19-05-00403 a, 19-29-05085, 18-35-00072 mol_a, 18-33-20038 mol_a), and the State assignment of the Institute of Geology and Mineralogy SB RAS. Publisher Copyright: © 2021 Elsevier Ltd
PY - 2021/7/15
Y1 - 2021/7/15
N2 - Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are microbial molecular fossils ubiquitous in natural environments. The correlation between the Methylation Index of brGDGTs (the MBT5ME' paleothermometer) and temperature offers an important tool for reconstructing past terrestrial temperatures. However, factors other than temperature could also affect the distribution of brGDGTs in lacustrine systems, hampering the quantitative application of this paleothermometer. Here we investigated brGDGT distributions in contemporary sediments collected from 52 lakes in mid-latitude Asia. Combined with published brGDGT data from other lakes across the globe, we have found a strong salinity control on the relative abundance of 5-methyl brGDGTs versus their late-eluting isomers (including 6-methyl, 7-methyl, and unknown isomers). This allows the development of novel indices based on the isomerization of brGDGTs for tracing past lake water salinity. We also demonstrate that salinity-controlled isomerization of pentamethylated and hexamethylated brGDGTs can significantly impact the MBT5ME' paleothermometer, potentially leading to an overestimation of past temperature, but the temperature signal can be extracted out of the MBT5ME' index after correcting the salinity effect. As demonstrated in application to a Lake Qinghai (China) sediment core spanning the last 18 kyr, our finding could facilitate the simultaneous retrieval of reliable temperature and salinity records using brGDGTs in lacustrine settings, in particular for lakes that have experienced large salinity changes during the geological past.
AB - Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are microbial molecular fossils ubiquitous in natural environments. The correlation between the Methylation Index of brGDGTs (the MBT5ME' paleothermometer) and temperature offers an important tool for reconstructing past terrestrial temperatures. However, factors other than temperature could also affect the distribution of brGDGTs in lacustrine systems, hampering the quantitative application of this paleothermometer. Here we investigated brGDGT distributions in contemporary sediments collected from 52 lakes in mid-latitude Asia. Combined with published brGDGT data from other lakes across the globe, we have found a strong salinity control on the relative abundance of 5-methyl brGDGTs versus their late-eluting isomers (including 6-methyl, 7-methyl, and unknown isomers). This allows the development of novel indices based on the isomerization of brGDGTs for tracing past lake water salinity. We also demonstrate that salinity-controlled isomerization of pentamethylated and hexamethylated brGDGTs can significantly impact the MBT5ME' paleothermometer, potentially leading to an overestimation of past temperature, but the temperature signal can be extracted out of the MBT5ME' index after correcting the salinity effect. As demonstrated in application to a Lake Qinghai (China) sediment core spanning the last 18 kyr, our finding could facilitate the simultaneous retrieval of reliable temperature and salinity records using brGDGTs in lacustrine settings, in particular for lakes that have experienced large salinity changes during the geological past.
KW - brGDGTs
KW - Isomerization
KW - MBT
KW - Salinity
KW - Temperature
UR - http://www.scopus.com/inward/record.url?scp=85110414681&partnerID=8YFLogxK
U2 - 10.1016/j.gca.2021.05.004
DO - 10.1016/j.gca.2021.05.004
M3 - Article
AN - SCOPUS:85110414681
VL - 305
SP - 33
EP - 48
JO - Geochmica et Cosmochimica Acta
JF - Geochmica et Cosmochimica Acta
SN - 0016-7037
ER -
ID: 33988021