Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Volume 11, issue 23
Biogeosciences, 11, 6755–6768, 2014
https://doi.org/10.5194/bg-11-6755-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
Biogeosciences, 11, 6755–6768, 2014
https://doi.org/10.5194/bg-11-6755-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 08 Dec 2014

Research article | 08 Dec 2014

Dependence of the cyclization of branched tetraethers on soil moisture in alkaline soils from arid–subhumid China: implications for palaeorainfall reconstructions on the Chinese Loess Plateau

H. Wang2,1, W. Liu3,1, and C. L. Zhang4 H. Wang et al.
  • 1State Key Laboratory of Loess and Quaternary Geology, IEE, CAS, Xi'an, 710075, China
  • 2University of Chinese Academy of Sciences, Beijing 100049, China
  • 3School of Human Settlement and Civil Engineering, Xi'an Jiaotong University, Xi'an 710049, China
  • 4State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China

Abstract. The use of branched glycerol dialkyl glycerol tetraethers (bGDGTs) in loess–palaeosol sequences (LPSs) has shown promises in continental palaeotemperature reconstructions. Thus far, however, little is known about the effect of soil moisture on their distributions in the water-limited Chinese Loess Plateau (CLP). In this study, the relationships between environmental variables and the cyclization of branched tetraethers (CBT) were investigated in arid–subhumid China using 97 surface soils in the CLP and its vicinity, as well as 78 soils with pH > 7 which have been previously published. We find that CBT correlates best with soil water content (SWC) or mean annual precipitation (MAP) for the overall data set. This indicates that CBT is mainly controlled by soil moisture instead of soil pH in alkaline soils from arid–subhumid regions, where water availability is a limiting factor for the producers of bGDGTs. Therefore, we suggest that CBT can potentially be used as a palaeorainfall proxy on the alkaline CLP. According to the preliminary CBT–MAP relationship for modern CLP soils (CBT = −0.0021 × MAP + 1.7, n = 37, r = −0.93), palaeorainfall history was reconstructed from three LPSs (Yuanbao, Lantian, and Mangshan) with published bGDGT data spanning the past 70 ka. The CBT-derived MAP records of the three sites consistently show precession-driven variation resembling the monsoon record based on speleothem δ18O, supporting CBT as a reasonable proxy for palaeorainfall reconstruction in LPS. The direct application of CBT as a palaeorainfall proxy in corroboration with the bGDGT-based temperature proxy may enable us to further assess the temperature/hydrological association for palaeoclimate studies on the CLP.

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The relationships between environmental variables and the cyclization of branched tetraethers (CBT) were investigated in surface soils in the Chinese Loess Plateau (CLP) and its vicinity. We find that CBT is not sensitive to soil pH but correlates best with soil moisture in these alkaline soils from arid-subhumid regions. Therefore, we suggest that CBT can potentially be used as a palaeorainfall proxy on the CLP and applied it to three loess-paleosol sequences published before.
The relationships between environmental variables and the cyclization of branched tetraethers...
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