TY - JOUR
T1 - The influence of soil chemistry on branched tetraether lipids in mid- and high latitude soils
T2 - Implications for brGDGT- based paleothermometry
AU - De Jonge, C.
AU - Kuramae, E. E.
AU - Radujković, D.
AU - Weedon, J. T.
AU - Janssens, I. A.
AU - Peterse, F.
N1 - Funding Information:
We thank Klaas Nierop, Antoinette van den Dikkenberg and Dominika Kasjaniuk for laboratory assistance at the University of Utrecht, as well as Tom Van der Spiet at the University of Antwerp. David Naafs and an anonymous reviewer are thanked for their feedback that has further improved this manuscript. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement n° 707270/WISLAS). FP acknowledges funding from NWO-Vidi (#192.074). This is publication number XXXX of the Netherlands Institute of Ecology (NIOO-KNAW).
Funding Information:
We thank Klaas Nierop, Antoinette van den Dikkenberg and Dominika Kasjaniuk for laboratory assistance at the University of Utrecht, as well as Tom Van der Spiet at the University of Antwerp. David Naafs and an anonymous reviewer are thanked for their feedback that has further improved this manuscript. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement n? 707270/WISLAS). FP acknowledges funding from NWO-Vidi (#192.074). This is publication number XXXX of the Netherlands Institute of Ecology (NIOO-KNAW).
Publisher Copyright:
© 2021 The Author(s)
PY - 2021/10/1
Y1 - 2021/10/1
N2 - Branched glycerol dialkyl glycerol tetraethers (BrGDGTs) are a suite of orphan bacterial membrane lipids commonly used as paleo-environmental proxies for mean annual air temperature (MAT) and pH. Recent calibrations between the Methylation of Branched Tetraethers index (MBT′5ME) and MAT, based on modern surface soils (including peats), show a considerable amount of scatter, especially in mid- and high latitude soils, suggesting that brGDGT signals are influenced by additional environmental and/or biological controls at these sites. Here we test the impact of soil chemical gradients and bacterial community changes (16S rDNA sequence-based) on brGDGT distributions at two grasslands sites (Ossenkampen [NL], ForHot [IS]), and one agricultural site (Craibstone [UK]). In addition to the variation in soil chemistry, the ForHot site experiences belowground warming. Of the studied edaphic parameters, soil pH is the primary factor that explains simultaneous changes in both the bacterial community composition and the brGDGT distribution. Variations in the MBT′5ME at two sites without soil warming indeed correlate strongly to soil pH (r = 0.9–1.0, pH = 4.5–7.3), whereas pH explains part of the variation in the MBT′5ME at the site with soil warming (mean soil temperature ranging between 5 and 14 °C). At all sites, soil pH is positively related with the same brGDGTs (Ib, IIb, IIIb, IIIc, IIa′, IIb′, IIc′, IIIa′, IIb′, IIIc′) and influences the ratio between main brGDGT compounds Ia, IIa and IIIa, impacting the MBT′5ME values. This change in brGDGT distributions coincides with a change in the composition of the bacterial community at all sites. The bacterial clades that vary at the three experimental sites (specifically Acidobacteria subgroups 1, 2, 3, 6, 22) have previously been shown to also respond to soil pH on a global scale. As soil pH changes on geological timescales, the impact of changing pH on the MBT′5ME paleothermometer should be considered when performing paleoclimate studies.
AB - Branched glycerol dialkyl glycerol tetraethers (BrGDGTs) are a suite of orphan bacterial membrane lipids commonly used as paleo-environmental proxies for mean annual air temperature (MAT) and pH. Recent calibrations between the Methylation of Branched Tetraethers index (MBT′5ME) and MAT, based on modern surface soils (including peats), show a considerable amount of scatter, especially in mid- and high latitude soils, suggesting that brGDGT signals are influenced by additional environmental and/or biological controls at these sites. Here we test the impact of soil chemical gradients and bacterial community changes (16S rDNA sequence-based) on brGDGT distributions at two grasslands sites (Ossenkampen [NL], ForHot [IS]), and one agricultural site (Craibstone [UK]). In addition to the variation in soil chemistry, the ForHot site experiences belowground warming. Of the studied edaphic parameters, soil pH is the primary factor that explains simultaneous changes in both the bacterial community composition and the brGDGT distribution. Variations in the MBT′5ME at two sites without soil warming indeed correlate strongly to soil pH (r = 0.9–1.0, pH = 4.5–7.3), whereas pH explains part of the variation in the MBT′5ME at the site with soil warming (mean soil temperature ranging between 5 and 14 °C). At all sites, soil pH is positively related with the same brGDGTs (Ib, IIb, IIIb, IIIc, IIa′, IIb′, IIc′, IIIa′, IIb′, IIIc′) and influences the ratio between main brGDGT compounds Ia, IIa and IIIa, impacting the MBT′5ME values. This change in brGDGT distributions coincides with a change in the composition of the bacterial community at all sites. The bacterial clades that vary at the three experimental sites (specifically Acidobacteria subgroups 1, 2, 3, 6, 22) have previously been shown to also respond to soil pH on a global scale. As soil pH changes on geological timescales, the impact of changing pH on the MBT′5ME paleothermometer should be considered when performing paleoclimate studies.
KW - Biomarker lipid proxy development
KW - branched GDGT
UR - http://www.scopus.com/inward/record.url?scp=85111559923&partnerID=8YFLogxK
U2 - 10.1016/j.gca.2021.06.037
DO - 10.1016/j.gca.2021.06.037
M3 - Article
AN - SCOPUS:85111559923
SN - 0016-7037
VL - 310
SP - 95
EP - 112
JO - Geochimica et Cosmochimica Acta
JF - Geochimica et Cosmochimica Acta
ER -