Materials and Methods Introduction Results and Discussion Acknowledgements References Cited DeLong, E.F., Archaeal mysteries of the deep revealed. Proc. Natl Acad. Sci. USA 103, 6417– Herfort, L., Schouten, S., Boon, J.P., Sinninghe Damsté, J.S., Application of the TEX86 temperature proxy to the southern North Sea. Org. Geochem. 37, 1715–1726. Hopmans, E.C., Weijers, J.W.H., Schefuß, E., Herfort, L., Sinninghe Damsté, J.S., Schouten, S., A novel proxy for terrestrial organic matter in sediments based on branched and isoprenoid tetraether lipids. Earth Planet. Sci. Lett. 224, 107–116. Huguet, C., Kim, J.-H., Sinninghe Damsté, J.S., Schouten, S., Reconstruction of sea surface temperature variations in the Arabian Sea over the last 23 kyr using organic proxies (TEX86 and UK” 37). Paleoceanography 21 PA3003. 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Wuchter, C., Schouten, S., Wakeham, S.G., Sinninghe Damsté, J.S., Temporal and spatial variation in tetraether membrane lipids of marine crenarchaeota in particulate organic matter: implications for TEX86 paleothermometry. Paleoceanography 20, PA3013. Zhang, C.L., Wang, J., Wei Y., Zhu, Y., Huang L., Dong H., Production of branched tetraether lipids in the lower Pearl River and estuary: effects of exraction methods and impact on bGDGT proxies. Fron. Micro. Doi: /fmicb Zhu, C., Weijers, J., Wagner T., Pan J., Chen J., Pancost R.D., Sources and distributions of tetraether lipids in surface sediments across a large river-dominated continental margin. Org. Geo 42, 376 – 386. We thank Dai L., Li Y., Zhong D., Hong Y.,Wong C., and Shao L. for helping with the sampling and analysis of greatly appreciated for helping with the field experiments during the cruise. This research was supported by the South China Sea-Deep program of the National Science Foundation of China ( ) and the State Key Laboratory of Marine Geology of Tongji University. some of the samples collected for this study. Captain Deng was Sediment and suspended particulate matter samples were collected from the lower Pearl River and the Pearl River Estuary, in China SE. Conclusions LC-MS/MS analysis 3. Comparisons of TEX 86 -derived temperatures to satellite-based water surface temperatures in the lower Pearl River and estuary. Detection was performed using the Agilent 6460 triple-quadrupole spectrometer MS with an atmospheric pressure chemical ionization (APCI) ion source. Lipid extraction and fractionation followed the procedure described in Zhang et al. (2012). The GDGTs were analyzed on an Agilent 1200 liquid chromatography equipped with an automatic injector coupled to QQQ 6460 MS and Mass Hunter LC-MS manager software using a procedure modified from Schouten et al. (2007). Sampling Jinxiang Wang Chuanlun Zhang (Department of Marine Sciences, Univ. of Georgia, Athens, 30602, USA & State Key Laboratory of Marine Geology, Tongji Univ., Shanghai, , China) PP43B-2029 The TEX 86 temperature proxy is based on archaeal glycerol dialkyl glycerol tetraethers (GDGTs), which are abundant in river system (Hopmans et al., 2004; Herfort et al., 2006; Zhu et al., 2011). The biological sources are non-hyperthermophilic cren- and euryarchaeota, a major group of prokaryotes in today’s oceans and lakes (Karner et al., 2001; Powers et al., 2004).The relative distribution of these isoprenoidal GDGTs varies with growth temperature and linear regressions of core-top TEX 86 values to SST enable the use of the TEX 86 as a temperature proxy (Kim et al., 2008, 2010; Schouten et al., 2002, 2007; Wuchter et al., 2005). Although, the TEX 86 is increasingly used for reconstructing ancient SSTs, a number of issues remain unresolved (Huguet et al., 2006; Pearson et al., 2007). It appears that the TEX 86 can be biased due to additional production of GDGTs below the mixed layer (Huguet et al., 2007; Lee et al., 2008), by seasonality in crenarchaeotal growth (Herfort et al., 2006; Menzel et al., 2006; Schouten et al., 2002) and by the ecology of planktonic cren- and euryarchaeota due to their presence in different water depths of the ocean and the theoretical possibility of GDGT synthesis by marine euryarchaeota (Delong, 2006; Wuchter et al., 2005). Additionally, archaea living in sediments of continental margins and the deep-sea may contribute to the GDGT pool and thus influence the TEX 86 vale (Lipp et al., 2008; Shah et al., 2008). In coastal settings, fluvial input of terrestrial isoprenoidal GDGTs may bias the TEX 86 (Herfort et al., 2006). Here we present results of TEX 86 from GDGTs analysis at lower Pearl River and estuary, by comparing the results with available satellite-based water surface temperatures. Estuary Lower Pearl River Liu et al., LC-MS/MS profiles of archaeal lipids Filters-PLFilters-CL Sediments-PL Sediments-CL 2. Basic information on water depth, temperature, chemistry, nutrients, and particulates on filters. Sample Water Temp. Chemistry SPM Core Lipids Polar Lipds % PL (PL+CL) depth pH SALTDSDOPO 4 3- SiO 4 2- NH 4 + NO 2 - NO 3 - DOCDICiGDGTs (m) (℃)(℃)(﹪)(﹪) (g/l)(mg/l)(µmol/l) (mg/l) (μg/g spm) (%) PR-F n.c. PR-F PR-F PR-F PR-F PR-F PR-F PR-F PR-F PR-F PR-F-11S PR-F-11D n.c. PR-F-12S PR-F-12D PR-F-13S PR-F-13D PR-F-14S PR-F-14D Comparisons of TEX 86 -derived temperatures to the satellite-based water surface temperatures and measured monthly mean air temperatures of the lower Pearl River drainage basin. Greater abundances of PL-GDGTs and CL-GDGTs were found in the lower Pearl River. The TEX 86 H temperature for CL-GDGTs reflect the annual mean surface water temperature; whereas, the TEX 86 H temperatures for PL-GDGTs have the potential to respond to seasonal variation. In situ production of P-GDGTs in surface sediments may complicate the TEX 86 H – derived temperatures in the estuary. Caution needs to be excised when interpreting low TEX 86 H – derived temperature as winter signals in paleo – coastal climate studies. Two different compositions of GDGTs were separated by the interface, which was located in the boundary the lower Pearl River and estuary. Most of the PL-GDGTs where produced in the in- situ environments. TEX 86 H temperature for C-GDGTs ranged from 21.2 ℃ to 26.9 ℃ for suspended particles, which were close to satellite-based annual mean water temperature (average 24.6±0.1 ℃ ); whereas the TEX 86 temperatures for P-GDGTs have the potential to respond to satellite-based July mean water surface temperature. The in situ production of PL-GDGTs in the sediments contributed to the good correlation between TEX 86 H of PL-GDGTs derived temperature and satellite-based winter mean water surface temperature. Terrestrial input of PL-GDGTs may be one of the maim reasons to cause the TEX 86 H of PL-GDGTs derived temperature to be higher than satellite-based annual mean water temperature. TEX 86 H of CL and PL derived temperatures in soil highly correlated with monthly average air temperature in July. The TEX 86 H of CL-GDGTs derived temperatures have more stability than that of PL-GDGTs derived temperatures in sediments and filters. TEX 86 H derived temperature is not affected by extraction method when calculations are performed using the CL-GDGTs; Yet, it’s better to use the B-D method to do extraction when calculations are performed using the PL-GDGTs. BD Protocol Silica column Polar Fraction Apolar Fraction Acid Hydrolysis LC-MS AR GDGT (0) #9 AR GDGT (0) Crenarchaeol #1 GDGT (0) #12B AR GDGT (0) Crenarchaeol #12S GDGT (0) Crenarchaeol #14 Lower Pearl River Estuary SCS Crenarchaeol GDGT (0) Sedi - #9 Soil - #1 Soil - #19 Sedi - #1 Sedi - #12 Sedi - #14 Factors Affecting TEX 86 H – derived Temperature in the Lower Pearl River and Estuary of China