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Baxter, Allix J; Hopmans, Ellen C; Russell III, James M; Sinninghe Damsté, Jaap S (2019): Bacterial GMGTs in East African lake sediments: Their potential as palaeotemperature indicators. PANGAEA, https://doi.pangaea.de/10.1594/PANGAEA.901011 (dataset in review), Supplement to: Baxter, AJ et al. (accepted): Bacterial GMGTs in East African lake sediments: Their potential as palaeotemperature indicators. Geochimica et Cosmochimica Acta

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Abstract:
Glycerol monoalkyl glycerol tetraethers (GMGTs) are a group of membrane spanning lipids produced by some species of archaea and bacteria. They differ from the more commonly studied glycerol dialkyl glycerol tetraethers (GDGTs) in having an additional covalent carbon-carbon bond connecting the two alkyl chain. The relative abundance and distribution of bacterial branched GMGTs (brGMGTs) in surface sediments from a set of East African lakes were studied. The abundance of brGMGTs relative to the brGDGTs is positively correlated to measured mean annual air temperature (MAAT), although with a significant amount of scatter. BrGMGT abundance was not correlated to lake water pH. Seven major brGMGTs that vary in degree of methylation were identified, with m/z 1020, 1034 and 1048. Further, the mass chromatograms of the m/z 1020 and 1034 brGMGTs show an interesting distribution of peaks, which likely relates to the occurrence of distinct brGMGT isomers. This structural complexity is higher than previously observed in peats and marine sediments. Principal component analysis of the fractional abundance of bacterial tetraether lipids revealed the brGMGTs behave similarly to one another but differently from both the 5- or 6-methyl brGDGTs. This suggests the brGMGTs are produced by a common source organism and are methylated at a different position. The distribution of the seven brGMGTs showed considerable correlation with MAAT. This variability was captured in a new proxy index (the brGMGTI), which showed a strong positive linear relationship with MAAT. Lacustrine brGMGTs show potential to be applied to ancient settings to provide information about paleoclimate.
Keyword(s):
GDGTs; GMGT; H-GDGT; lakes; membrane lipids; palaeotemperature; sediments; tetraethers
Coverage:
Median Latitude: 1.006029 * Median Longitude: 33.529232 * South-bound Latitude: -4.872000 * West-bound Longitude: 29.617000 * North-bound Latitude: 6.893000 * East-bound Longitude: 39.908000
Minimum DEPTH, water: 0.2 m * Maximum DEPTH, water: 180.0 m
Event(s):
Albert_Lake * Latitude: 1.683000 * Longitude: 30.917000 * Elevation: 615.0 m * Device: Multiple investigations (MULT)
Bandara_Lake * Latitude: -0.157000 * Longitude: 37.449000 * Elevation: 2938.0 m * Device: Multiple investigations (MULT)
Batoda_Lake * Latitude: 0.300000 * Longitude: 29.883000 * Elevation: 4017.0 m * Device: Multiple investigations (MULT)
Parameter(s):
#NameShort NameUnitPrincipal InvestigatorMethodComment
1Event labelEventBaxter, Allix J
2Latitude of eventLatitudeBaxter, Allix J
3Longitude of eventLongitudeBaxter, Allix J
4Elevation of eventElevationmBaxter, Allix J
5LakeLakeBaxter, Allix J
6CountryCountryBaxter, Allix J
7DEPTH, waterDepth watermBaxter, Allix JGeocode
8Lake surface areaLake aream2Baxter, Allix J
9Temperature, air, annual meanMAAT°CBaxter, Allix J
10Temperature, waterTemp°CBaxter, Allix Jsurface water
11Temperature, waterTemp°CBaxter, Allix Jbottom water
12Temperature, waterTemp°CBaxter, Allix Jmean
13pHpHBaxter, Allix Jsurface water
14pHpHBaxter, Allix Jbottom water
15pHpHBaxter, Allix Jmean
16Branched glycerol dialkyl glycerol tetraether, IIIa (peak area)brGDGT IIIa peak areaBaxter, Allix J
17Branched glycerol dialkyl glycerol tetraether, IIIa' (peak area)brGDGT IIIa' peak areaBaxter, Allix J
18Branched glycerol dialkyl glycerol tetraether, IIa (peak area)brGDGT IIa peak areaBaxter, Allix J
19Branched glycerol dialkyl glycerol tetraether, IIa' (peak area)brGDGT IIa' peak areaBaxter, Allix J
20Branched glycerol dialkyl glycerol tetraether, IIb (peak area)brGDGT IIb peak areaBaxter, Allix J
21Branched glycerol dialkyl glycerol tetraether, IIb' (peak area)brGDGT IIb' peak areaBaxter, Allix J
22Branched glycerol dialkyl glycerol tetraether, Ia (peak area)brGDGT Ia peak areaBaxter, Allix J
23Branched glycerol dialkyl glycerol tetraether, Ib (peak area)brGDGT Ib peak areaBaxter, Allix J
24Branched glycerol dialkyl glycerol tetraether, Ic (peak area)brGDGT Ic peak areaBaxter, Allix J
25Branched glycerol monoalkyl glycerol tetraethers, H1048 (peak area)brGMGT H1048 peak areaBaxter, Allix J
26Branched glycerol monoalkyl glycerol tetraethers, H1034-a (peak area)brGMGT H1034-a peak areaBaxter, Allix J
27Branched glycerol monoalkyl glycerol tetraethers, H1034-b (peak area)brGMGT H1034-b peak areaBaxter, Allix J
28Branched glycerol monoalkyl glycerol tetraethers, H1034-c (peak area)brGMGT H1034-c peak areaBaxter, Allix J
29Branched glycerol monoalkyl glycerol tetraethers, H1020-a (peak area)brGMGT H1020-a peak areaBaxter, Allix J
30Branched glycerol monoalkyl glycerol tetraethers, H1020-b (peak area)brGMGT H1020-b peak areaBaxter, Allix J
31Branched glycerol monoalkyl glycerol tetraethers, H1020-c (peak area)brGMGT H1020-c peak areaBaxter, Allix J
32Branched glycerol dialkyl glycerol tetraether, IIIabrGDGT IIIa%Baxter, Allix J
33Branched glycerol dialkyl glycerol tetraether, IIIa'brGDGT IIIa'%Baxter, Allix J
34Branched glycerol dialkyl glycerol tetraether, IIabrGDGT IIa%Baxter, Allix J
35Branched glycerol dialkyl glycerol tetraether, IIa'brGDGT IIa'%Baxter, Allix J
36Branched glycerol dialkyl glycerol tetraether, IIbbrGDGT IIb%Baxter, Allix J
37Branched glycerol dialkyl glycerol tetraether, IIb'brGDGT IIb'%Baxter, Allix J
38Branched glycerol dialkyl glycerol tetraether, IabrGDGT Ia%Baxter, Allix J
39Branched glycerol dialkyl glycerol tetraether, IbbrGDGT Ib%Baxter, Allix J
40Branched glycerol dialkyl glycerol tetraether, IcbrGDGT Ic%Baxter, Allix J
41Branched glycerol monoalkyl glycerol tetraethers, H1048brGMGT H1048%Baxter, Allix J
42Branched glycerol monoalkyl glycerol tetraethers, H1034-abrGMGT H1034-a%Baxter, Allix J
43Branched glycerol monoalkyl glycerol tetraethers, H1034-bbrGMGT H1034-b%Baxter, Allix J
44Branched glycerol monoalkyl glycerol tetraethers, H1034-cbrGMGT H1034-c%Baxter, Allix J
45Branched glycerol monoalkyl glycerol tetraethers, H1020-abrGMGT H1020-a%Baxter, Allix J
46Branched glycerol monoalkyl glycerol tetraethers, H1020-bbrGMGT H1020-b%Baxter, Allix J
47Branched glycerol monoalkyl glycerol tetraethers, H1020-cbrGMGT H1020-c%Baxter, Allix J
48SumSum%Baxter, Allix JbrGDGT + brGMGT
Size:
2991 data points

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