Materials and Methods

1. Factors Affecting TEX86H – derived Temperature in the Lower Pearl River and Estuary of China GDGT (0) GDGT (0) Crenarchaeol PP43B-2029 #9 GDGT (0) #1 #12S #14 Crenarchaeol Crenarchaeol Filters-CL GDGT (0) Sediments-CL AR AR AR LC-MS #12B GDGT (0) BD Protocol Jinxiang Wang (jinxiang@uga.edu), Chuanlun Zhang (archaea.zhang@gmail.com) (Department of Marine Sciences, Univ. of Georgia, Athens, 30602, USA & State Key Laboratory of Marine Geology, Tongji Univ., Shanghai, 200092, China) Acid Hydrolysis Polar Fraction Filters-PL Silica column Sediments-PL Introduction Apolar Fraction Conclusions LC-MS/MS analysis 3. Comparisons of TEX86-derived temperatures to satellite-based water surface temperatures in the lower Pearl River and estuary. The TEX86 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 TEX86 values to SST enable the use of the TEX86 as a temperature proxy (Kim et al., 2008, 2010; Schouten et al., 2002, 2007; Wuchter et al., 2005). Although, the TEX86 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 TEX86 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 TEX86 vale (Lipp et al., 2008; Shah et al., 2008). In coastal settings, fluvial input of terrestrial isoprenoidal GDGTs may bias the TEX86 (Herfort et al., 2006). Here we present results of TEX86 from GDGTs analysis at lower Pearl River and estuary, by comparing the results with available satellite-based water surface temperatures. 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). The TEX86H temperature for CL-GDGTs reflect the annual mean surface water temperature; whereas, the TEX86H temperatures for PL-GDGTs have the potential to respond to seasonal variation. In situ production of P-GDGTs in surface sediments may complicate the TEX86H – derived temperatures in the estuary. Detection was performed using the Agilent 6460 triple-quadrupole spectrometer MS with an atmospheric pressure chemical ionization (APCI) ion source. Caution needs to be excised when interpreting low TEX86H – derived temperature as winter signals in paleo – coastal climate studies. TEX86H 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 TEX86 temperatures for P-GDGTs have the potential to respond to satellite-based July mean water surface temperature. Acknowledgements Terrestrial input of PL-GDGTs may be one of the maim reasons to cause the TEX86H of PL-GDGTs derived temperature to be higher than satellite-based annual mean water temperature. 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 (91028005) and the State Key Laboratory of Marine Geology of Tongji University. some of the samples collected for this study. Captain Deng was Results and Discussion 1. 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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., 2012. Production of branched tetraether lipids in the lower Pearl River and estuary: effects of exraction methods and impact on bGDGT proxies. Fron. Micro. Doi: 10.3389/fmicb. 2011. 00274. Zhu, C., Weijers, J., Wagner T., Pan J., Chen J., Pancost R.D., 2011. Sources and distributions of tetraether lipids in surface sediments across a large river-dominated continental margin. Org. Geo 42, 376 – 386. GDGT (0) Sedi - #9 Sedi - #1 The in situ production of PL-GDGTs in the sediments contributed to the good correlation between TEX86H of PL-GDGTs derived temperature and satellite-based winter mean water surface temperature. Crenarchaeol Sedi - #12 Crenarchaeol GDGT (0) GDGT (0) Crenarchaeol Sedi - #14 Soil - #19 Soil - #1 The TEX86H of CL-GDGTs derived temperatures have more stability than that of PL-GDGTs derived temperatures in sediments and filters. Two different compositions of GDGTs were separated by the interface, which was located in the boundary the lower Pearl River and estuary. 3. Comparisons of TEX86-derived temperatures to the satellite-based water surface temperatures and measured monthly mean air temperatures of the lower Pearl River drainage basin. Most of the PL-GDGTs where produced in the in-situ environments. Materials and Methods Sampling Sediment and suspended particulate matter samples were collected from the lower Pearl River and the Pearl River Estuary, in China SE. 2. Basic information on water depth, temperature, chemistry, nutrients, and particulates on filters. Liu et al., 2009 TEX86H 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. Lower Pearl River Estuary TEX86H of CL and PL derived temperatures in soil highly correlated with monthly average air temperature in July. Greater abundances of PL-GDGTs and CL-GDGTs were found in the lower Pearl River.