Glycerol dialkyl glycerol tetraethers and TEX86 index in sinking particles in the western North Pacific

Abstract

temperature was lower than the SST from May to December and corresponded to the 30 temperature at the thermocline, whereas it was higher than the SST from December to 31May. The annual average sinking flux of the GDGTs decreased with increasing depth. 32The GDGT half-depth, the depth range over which half of the GDGT is lost, was 33 calculated to be 3108-3349 m, implying that GDGTs were well preserved during 34 sinking in the water column. The flux-weighted average TEX 86 -based temperatures 35were constant with depth and roughly corresponded to mean annual SST. These findings 36 support a previously proposed hypothesis that the GDGTs produced in surface waters 37 are preferentially delivered to the deeper water column by grazing and repackaging in 38 larger particles. The constant TEX 86 at different depths indicates that TEX 86 is not 39 affected by degradation in the water column. The preservation efficiency of GDGTs was 40 1.0-1.3% at the water-sediment interface. Despite the significant degradation of the 41GDGTs, there was a small difference in TEX 86 levels between sinking particles and the 42 surface sediment. 43 44

Archaeal and bacterial assemblages in the Oxygen Minimum Zone of the upwelling ecosystem off Central Chile as determined by organic biomarkers

“…The seasonal contrast in the iGDGTs abundance observed off Concepción is also consistent with previous reports. A higher abundance of iGDGTs during winter in the North Sea was reported by Wuchter et al (2005) and Herfort et al (2006), suggesting that Thaumarchaeota thrive in winter due to lack of competition with phytoplankton for NH 3 (Yamamoto et al 2012). Similarly, we found the highest abundance of core iGDGTs in suspended particulate matter collected in austral-winter (June 2010, Fig.…”

A four-year record of U K′ 37 - and TEX 86 -derived sea surface temperature estimates from sinking particles in the filamentous upwelling region off Cape Blanc, Mauritania

“…In contrast, only six marine sediment-trap time series have been published for TEX 86 (Fallet et al, 2011;Huguet et al, 2007;McClymont et al, 2012;Turich et al, 2013;Wuchter et al, 2006;Yamamoto et al, 2012), and only some of these also include alkenone data for comparison. Wuchter et al (2006) observed a strongly seasonally varying GDGT flux and TEX 86 -temperatures corresponding to SST in a shallow trap (500 m water depth), and more seasonally averaged signals in deeper traps.…”

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

“…It has been shown that highest GDGT fluxes are closely linked to highest organic matter, opal (diatom frustules) and lithogenic particle fluxes (Mollenhauer et al, 2015;Yamamoto et al, 2012). 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).…”

“…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).…”