Lake Water Depth Controlling Archaeal Tetraether Distributions in Midlatitude Asia: Implications for Paleo Lake‐Level Reconstruction

Abstract

Lake‐level reconstructions, related to terrestrial hydrological changes, are important for our understanding of past and future climates. Currently, however, reliable lake‐level proxies are still limited. Here we report distributions of archaeal tetraether lipids in 70 surface sediment samples collected from 55 lakes in midlatitude Asia. We have found that among various lake physico‐chemical characteristics, the relative abundances of crenarchaeol and Hydroxylated isoprenoid glycerol dialkyl glycerol tetraethers (%cren and %OH‐GDGTs) are best correlated with lake water depth, due to a preference of Thaumarchaeota, the producer of these biomarkers, for a niche in subsurface lake water. This supports the recent hypothesis based on single‐lake investigations that %cren and %OH‐GDGTs are potentially novel lake‐level proxies. Our results also suggest that %OH‐GDGTs is less affected by soil input than %cren. Nevertheless, other confounding factors should be well constrained and local/site‐specific calibrations are needed before the two molecular proxies are used quantitatively in down‐core applications.

Microbial Membrane Tetraether lipid-inferred paleohydrology and paleotemperature of Lake Chenghai during the Pleistocene-Holocene transition

“…It is also worth noting that the crenarchaeol'/crenarchaeol ratios were not only relatively higher during the H1 cold event, but also showed a minor reversal during the YD cold event. These results are consistent with group I.1b Thaumarchaeota being an important source of isoGDGTs in some small lakes and to the nearshore area of large lakes (Wang et al, 2019).…”

“…suggesting that %cren may be less sensitive to water depth variation when the lake-level is relatively high (Wang et al, 2019). It is also worth noting that the crenarchaeol'/crenarchaeol ratios were not only relatively higher during the H1 cold event, but also showed a minor reversal during the YD cold event.…”

“…Furthermore, mixing of the water column will be much more frequent at lowstand conditions (Filippi and Talbot, 2005), and therefore periodically or permanently oxic, high nutrient availability water and enhanced nitrogen cycling would be likely result in a relatively lower production of crenarchaeol. Therefore, the cren% value measure in lacustrine sediments has been proposed to be a potential proxy for lake level change, with high values indicating highstand and deep lake status, while low values reflecting lowstand and shallow lake status (Wang et al, 2014a;Wang et al, 2017a;Wang et al, 2019).…”

“…Although TEX 86 and cren% show great potential as paleotemperature and paleo-lake-level proxies, they may be significantly biased when a substantial amount of soil and/or methanogenic archaea isoGDGTs are identified in the same lacustrine sediment (Weijers et al, 2006;Blaga et al, 2009;Powers et al, 2010;Wang et al, 2019). BIT index values are generally >0.90 in soils, whereas values are close to zero for large lake sediments (Hopmans et al, 2004;Weijers et al, 2006).…”

“…However, the index may not be a reliable proxy for past temperature in small lakes (Blaga et al, 2009;Powers et al, 2010;Sinninghe Damsté et al, 2012a). In addition, the proportion of crenarchaeol in isoGDGTs has been suggested to be a lake-level proxy due to a preference of the producer of this compound for a niche above the oxycline in the upper part of the water column in lacustrine systems (Wang et al, 2014a;Wang et al, 2017a;Wang et al, 2019). In this study, we present an isoGDGT record from Lake Chenghai in the southwest China.…”