GDGT distribution in a stratified lake and implications for the application of TEX86in paleoenvironmental reconstructions.
We investigated the relationship between distributions of GDGTs, GDGT-based proxies and environmental factors in a stratified lake in northwestern Norway. More than 90% of isoGDGTs were produced at the bottom of the oxycline, indicating a predominance of ammonia-oxidizing Group I.1a of Thaumarchaeota, supported by high crenarchaeol/caldarchaeol ratios. Dissolved oxygen content, rather than temperature, exercised a primary control on TEX86values. In spite of low BIT value in surface sediment, the reconstructed lake surface temperature was "cold" biased. MBT values in streams and lake surface water were significantly smaller than those in the catchment soil, suggesting in situ production of brGDGTs in streams. A rapid transition of MBT vs. temperature/pH relationships occurring at the bottom of oxycline indicated the differential production of various brGDGTs with D.O. and depths. Only within the oxycline were CBT-based pH values close to in situ pH. Our results confirm earlier studies calling for caution in applying TEX86as a surface temperature proxy, or MBT and/or CBT for reconstructing pH, in anoxic or euxinic lakes, estuaries and ocean basins. We propose that caldarchaeol/crenarchaeol ratio, an indicator of contributions from methanogenic archaea, together with the BIT and TEX86proxies, can help reconstruct past levels of stratification.
Institute of Marine Chemistry and Environment, Ocean College, Zhejiang University, 1 Zheda Road, Zhoushan, 316021, China.|Climate System Research Center, Department of Geosciences, University of Massachusetts, 627 North Pleasant Street, Amherst, MA 01003-9354, USA.
Zhaohui
Z
Zhang
Department of Geological Sciences, Stockholm University, Svante Arrhenius väg 8, SE-106 91 Stockholm, Sweden.
Rienk H
RH
Smittenberg
Climate System Research Center, Department of Geosciences, University of Massachusetts, 627 North Pleasant Street, Amherst, MA 01003-9354, USA.
Raymond S
RS
Bradley
FEMS Microbiol Ecol. 2011 Nov;78(2):314-26
21696407
Syst Appl Microbiol. 2009 Dec;32(8):571-82
19716251
Proc Natl Acad Sci U S A. 2004 Jul 27;101(30):11111-6
15258285
Environ Microbiol. 2012 Jan;14(1):23-40
21210935
Proc Natl Acad Sci U S A. 2015 Sep 1;112(35):10979-84
26283385
Science. 2000 Dec 8;290(5498):1947-51
11110658
Environ Microbiol. 2015 Oct;17(10):3847-56
25818237
Environ Microbiol. 2013 Jun;15(6):1717-33
23253149
J Lipid Res. 2002 Oct;43(10):1641-51
12364548
ISME J. 2008 Apr;2(4):429-41
18200070
Appl Environ Microbiol. 2012 Mar;78(5):1480-90
22226949
Environ Microbiol. 2016 Dec;18(12 ):4324-4336
26950522
FEMS Microbiol Ecol. 2007 Dec;62(3):242-57
17991018
Proc Natl Acad Sci U S A. 2007 Apr 24;104(17):7104-9
17420469
FEMS Microbiol Lett. 2004 Oct 1;239(1):51-6
15451100
Environ Microbiol. 2010 Jan;12(1):172-91
19788414
Environ Microbiol. 2007 Apr;9(4):1001-16
17359272
Proc Natl Acad Sci U S A. 2016 Jul 12;113(28):7762-7
27357675
Nat Rev Microbiol. 2008 Mar;6(3):245-52
18274537
Appl Environ Microbiol. 2002 Jun;68(6):2997-3002
12039760