Glacial–interglacial variability in Atlantic meridional overturning circulation and thermocline adjustments in the tropical North Atlantic

Santos, Raquel A. Lopes dos; Prange, Matthias; Castañeda, Isla S.; Schefuß, Enno; Mulitza, Stefan; Schulz, Michael; Niedermeyer, Eva M; Damsté, Jaap S. Sinninghe; Schouten, Stefan

doi:10.1016/j.epsl.2010.10.030

Cited by 127 publications

(116 citation statements)

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“…Indeed, several studies have shown that TEX 86 is frequently not reflecting surface but subsurface (0-200 m) conditions (cf. Huguet et al, 2007;Lopes dos Santos et al, 2010). Kim et al (2008) has shown that the correlation of TEX 86 with 0-200 m temperatures is similarly high as with SST.…”

Section: Implications For the Tex 86 Paleothermometermentioning

confidence: 95%

Intact polar and core glycerol dibiphytanyl glycerol tetraether lipids in the Arabian Sea oxygen minimum zone. Part II: Selective preservation and degradation in sediments and consequences for the TEX86

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Hopmans

Reichart

et al. 2012

Geochimica et Cosmochimica Acta

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The TEX 86 is a proxy based on a ratio of pelagic archaeal glycerol dibiphytanyl glycerol tetraether lipids (GDGTs), and used for estimating past sea water temperatures. Concerns exist that in situ production of GDGTs lipids by sedimentary Archaea may affect its validity. In this study, we investigated the influence of benthic GDGT production on the TEX 86 by analyzing the concentrations and distributions of GDGTs present as intact polar lipids (IPLs) and as core lipids (CLs) in three sediment cores deposited under contrasting redox conditions across a depth range from 900 to 3000 m below sea level in and below the Arabian Sea oxygen minimum zone (OMZ). Direct analysis of IPLs with crenarchaeol as CL via HPLC/ESI-MS 2 revealed that surface sediments in the OMZ were relatively depleted in the phospholipid hexose, phosphohexose (HPH)-crenarchaeol compared to suspended particulate matter from the water column, suggesting preferential and rapid degradation of this IPL. In sediment cores recovered from deeper, more oxic environments, concentrations of HPH-crenarchaeol peaked at the surface, probably due to in situ production by ammonia-oxidizing Archaea, followed by a rapid decrease with increasing depth. No surface maximum was observed in the sediment core from within the OMZ. In contrast, the glycolipids, monohexose-crenarchaeol and dihexose-crenarchaeol, did not change in concentration with depth in the sediment, indicating that they were relatively well preserved and likely mostly derived from fossil pelagic GDGTs. These results suggest that phospholipids are more sensitive to degradation, while glycolipids might be preserved over longer time scales, in line with previous incubation and modeling studies. Furthermore, in situ produced IPL-GDGTs did not accumulate as IPLs, and did not influence the CL-TEX 86 . This suggests that in-situ produced GDGT lipids were more susceptible to degradation than fossil CL and IPL and did not accumulate as CL. In agreement, no significant changes of TEX 86 with sediment depth in the core lipids were observed. However, consistent differences between IPL-derived TEX 86 and CL-TEX 86 were found. These could be explained by a different composition of CL-GDGT of the glyco-and phospholipids, in combination with dissimilar degradation rates of phospholipids vs. glycolipids. We also observed consistent differences in both IPL-derived and CL-TEX 86 between the different cores, equivalent to 3°C when converted to temperature, despite the proximity of the core locations. These differences may potentially be due to a larger addition of GDGTs produced in deeper, colder waters to the (sub)surface-derived GDGTs for the deeper core sites.

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Section: Implications For the Tex 86 Paleothermometermentioning

confidence: 95%

Intact polar and core glycerol dibiphytanyl glycerol tetraether lipids in the Arabian Sea oxygen minimum zone. Part II: Selective preservation and degradation in sediments and consequences for the TEX86

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Geochimica et Cosmochimica Acta

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“…In contrast, cold TEX 86 temperatures are observed in surface sediments and SPM at high-nutrient/highproductivity sites such as upwelling systems (e.g., refs. [30][31][32][33].…”

Section: Cellular Energy Balance and The Synthesis Of Gdgts: The Redumentioning

confidence: 99%

“…Culture studies have shown that the average number of cyclopentyl moieties in GDGTs can increase with growth temperature in marine Archaea (19)(20)(21)(22); however, TEX 86 values of suspended particulate material (SPM) through the water column do not reflect in situ temperatures either in trend or in magnitude (23)(24)(25)(26)(27)(28)(29). TEX 86 -calculated temperatures in sinking particles and core-top sediments are often colder than mean annual average, especially in highly productive regions such as upwelling systems (30)(31)(32)(33). TEX 86 -calculated temperatures also often reach their maximum values below 200 m, and at these depths, TEX 86 can yield temperatures that are greater than local sea surface temperatures (23,26,28,34).…”

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Influence of ammonia oxidation rate on thaumarchaeal lipid composition and the TEX ₈₆ temperature proxy

Hurley

Elling

Könneke

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Archaeal membrane lipids known as glycerol dibiphytanyl glycerol tetraethers (GDGTs) are the basis of the TEX 86 paleotemperature proxy. Because GDGTs preserved in marine sediments are thought to originate mainly from planktonic, ammonia-oxidizing Thaumarchaeota, the basis of the correlation between TEX 86 and sea surface temperature (SST) remains unresolved: How does TEX 86 predict surface temperatures, when maximum thaumarchaeal activity occurs below the surface mixed layer and TEX 86 does not covary with in situ growth temperatures? Here we used isothermal studies of the model thaumarchaeon Nitrosopumilus maritimus SCM1 to investigate how GDGT composition changes in response to ammonia oxidation rate. We used continuous culture methods to avoid potential confounding variables that can be associated with experiments in batch cultures. The results show that the ring index scales inversely (R 2 = 0.82) with ammonia oxidation rate (ϕ), indicating that GDGT cyclization depends on available reducing power. Correspondingly, the TEX 86 ratio decreases by an equivalent of 5.4°C of calculated temperature over a 5.5 fmol·cell −1 ·d −1 increase in ϕ. This finding reconciles other recent experiments that have identified growth stage and oxygen availability as variables affecting TEX 86 . Depth profiles from the marine water column show minimum TEX 86 values at the depth of maximum nitrification rates, consistent with our chemostat results. Our findings suggest that the TEX 86 signal exported from the water column is influenced by the dynamics of ammonia oxidation. Thus, the global TEX 86 -SST calibration potentially represents a composite of regional correlations based on nutrient dynamics and global correlations based on archaeal community composition and temperature.T he glycerol dibiphytanyl glycerol tetraether (GDGT) membrane lipids of Archaea are abundant in marine water columns and sediments. The major source of GDGTs to ocean sediments is thought to be planktonic, ammonia-oxidizing Archaea (AOA) affiliated with the phylum Thaumarchaeota (formerly Marine Group I Crenarchaeota) (1, 2). Thaumarchaeota play a primary role in the nitrogen cycle, performing the first and rate-limiting step of nitrification-namely, the oxidation of ammonia to nitrite (3-5). Accordingly, Thaumarchaeota are most abundant at the base of, or below, the euphotic zone (6-9). Based on the phylogeny of their ammonia monooxygenase gene, the planktonic Thaumarchaeota are divided into two distinct clusters, the Water Column Cluster A that is most abundant in the epi-and upper mesopelagic (above ∼200 to ∼500 m, depending on location) and the Water Column Cluster B that dominates thaumarchaeal assemblages in the deeper mesopelagic and bathypelagic (7-10). These clusters putatively represent thaumarchaeal ecotypes adapted to high and low ammonium flux, respectively (11,12).Thaumarchaeota produce GDGTs containing from zero to four cyclopentane rings (GDGT-0 to GDGT-4) or four cyclopentane rings and one additional cyclohexane ring (e.g., in crenarchaeol;...

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“…A lack of production of sinking particles that can incorporate GDGTs formed in deeper waters prohibits that surface-sediment TEX 86 values are 230 biased towards deep-water temperatures (Basse et al, 2014;Mollenhauer et al, 2015;Yamamoto et al, 2012). Still, particular environmental settings (e.g., upwelling regions, regions with oxygen-depleted deep waters, fresh-water surface waters) might favor the transport of a subsurface temperature signal to the sediments (Kim et al, 2012a(Kim et al, , 2012bLopes dos Santos et al, 2010;Mollenhauer et al, 2015). Also for polar oceans it has been suggested that reconstructed temperatures reflect subsurface temperatures, as today Thaumarchaeota are virtually absent in the 235 upper 0-45 m of Antarctic low-salinity surface waters (Kalanetra et al, 2009).…”

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Oligocene TEX<sub>86</sub>-derived seawater temperatures from offshore Wilkes Land (East Antarctica)

Hartman

Sangiorgi

Salabarnada

et al. 2017

Preprint

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Abstract. Today, the temperature of the surface waters near the Antarctic coast is a determining factor in the formation of Antarctic Bottom Water (AABW) through sea-ice production, sea-ice extent, and the extent of the ice shelf. O variability is due to large glacial-interglacial bottom-water temperature shifts, the Oligocene Antarctic ice volume was less sensitive to climate change than previously assumed. 45Clim. Past Discuss., https://doi

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Glacial–interglacial variability in Atlantic meridional overturning circulation and thermocline adjustments in the tropical North Atlantic

Cited by 127 publications

References 49 publications

Intact polar and core glycerol dibiphytanyl glycerol tetraether lipids in the Arabian Sea oxygen minimum zone. Part II: Selective preservation and degradation in sediments and consequences for the TEX86

Intact polar and core glycerol dibiphytanyl glycerol tetraether lipids in the Arabian Sea oxygen minimum zone. Part II: Selective preservation and degradation in sediments and consequences for the TEX86

Influence of ammonia oxidation rate on thaumarchaeal lipid composition and the TEX ₈₆ temperature proxy

Oligocene TEX<sub>86</sub>-derived seawater temperatures from offshore Wilkes Land (East Antarctica)

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Glacial–interglacial variability in Atlantic meridional overturning circulation and thermocline adjustments in the tropical North Atlantic

Cited by 127 publications

References 49 publications

Intact polar and core glycerol dibiphytanyl glycerol tetraether lipids in the Arabian Sea oxygen minimum zone. Part II: Selective preservation and degradation in sediments and consequences for the TEX86

Intact polar and core glycerol dibiphytanyl glycerol tetraether lipids in the Arabian Sea oxygen minimum zone. Part II: Selective preservation and degradation in sediments and consequences for the TEX86

Influence of ammonia oxidation rate on thaumarchaeal lipid composition and the TEX 86 temperature proxy

Oligocene TEX&lt;sub&gt;86&lt;/sub&gt;-derived seawater temperatures from offshore Wilkes Land (East Antarctica)

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Influence of ammonia oxidation rate on thaumarchaeal lipid composition and the TEX ₈₆ temperature proxy

Oligocene TEX<sub>86</sub>-derived seawater temperatures from offshore Wilkes Land (East Antarctica)