Microbial glycerol dialkyl glycerol tetraethers from river water and soil near the Three Gorges Dam on the Yangtze River

Sources of organic matter in Changjiang (Yangtze River) bed sediments: Preliminary insights from organic geochemical proxies

“…Due to the diversity of environmental conditions and physicochemical properties of these soils (such as temperature, soil pH and moisture availability), different soil types may potentially be distinguished on the basis of their br GDGTs signatures, serving as a means of establishing the provenance of the soil OC contributing to the riverine load. However, recent studies have revealed that br GDGTs transported by rivers are not necessarily exclusively derived from the surrounding soils, but may also be produced in situ Kim et al, 2012;Yang et al, 2013;Zell et al, 2013;De Jonge et al, 2014). Thus initial soil br GDGT signals may be modified, confounding assessment of provenance and resulting in unreliable br GDGT-based paleotemperature reconstruction and pH reconstruction from fluvial-influenced sediments (Zell et al, 2013;De Jonge et al, 2014).…”

“…GDGTs are membrane lipids synthesized by archaea and bacteria (Langworthy et al, 1982;De Rosa and Gambacorta, 1988;Damsté et al, 2007) and can be divided into two groups: branched, and isoprenoid GDGTs (br GDGTs and iso GDGTs). The br GDGTs are thought to be produced primarily by anaerobic bacteria and are ubiquitous in soil (Weijers et al, 2007), lake sediments (Blaga et al, 2009;Powers et al, 2010;Pearson et al, 2011), peat , and estuarine and ocean margin sediments (Hopmans et al, 2004;Zhu et al, 2011), as well as rivers Yang et al, 2013;Zell et al, 2013;De Jonge et al, 2014). It has been reported that the degree of methylation (MBT index) of br GDGTs is related to mean air temperature (MAT) and soil pH and the degree of cyclisation (CBT index) is related to soil pH (Weijers et al, 2007).…”

Tracing tetraether lipids from source to sink in the Rhône River system (NW Mediterranean)

“…However, a subsequent study in the Amazon deep-sea fan sediments showed that an increased input of brGDGTs from a particular area of the drainage basin might obscure the representativeness of the entire river basin (Bendle et al, 2010). In addition, in situ production in rivers (e.g., Yang et al, 2013;Zell et al, 2013aZell et al, ,b, 2014aDe Jonge et al, 2014), in lakes (e.g., Tierney and Russell, 2009;Zell et al, 2013a;Buckles et al, 2014), and in marine/estuarine environments (e.g., Peterse et al, 2009a;Zhu et al, 2011;Strong et al, 2012;Zell et al, 2014b) may alter the original brGDGT signal of soils carried by the particles transported by rivers. Hence, the interpretation of the MBT/CBT (hereafter the term of the MBT'/CBT will be used) in marine environments is much more complex than initially anticipated.…”

Sources and distributions of branched tetraether lipids and crenarchaeol along the Portuguese continental margin: Implications for the BIT index

“…Castañeda et al, 2010;Fietz et al, 2011;Schmidt et al, 2010;Smith et al, 2012). Similarly, brGDGTs are also not exclusively produced in soil but also in lakes (Bechtel et al, 2010;Buckles et al, 2014;Loomis et al, 2011;Sinninghe Damsté et al, 2009;Tierney and Russell, 2009;Tierney et al, 2010Tierney et al, , 2012Zink et al, 2010) and rivers (De Jonge et al, 2014;Kim et al, 2012;Yang et al, 2013;Zell et al, 2013aZell et al, ,2013bZhang et al, 2012;Zhu et al, 2011). Furthermore, brGDGTs are also produced in the marine environment, but in much lower concentrations than in continental Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/csr settings, therefore the marine production does not have a strong influence on the BIT index (e.g.…”