Distribution of branched glycerol dialkyl glycerol tetraethers in surface soils of the Qinghai-Tibetan Plateau: implications of brGDGTs-based proxies in cold and dry regions

NWIPB OpenIR

	Distribution of branched glycerol dialkyl glycerol tetraethers in surface soils of the Qinghai-Tibetan Plateau: implications of brGDGTs-based proxies in cold and dry regions
	Ding, S. ; Xu, Y. ; Wang, Y. ; He, Y. ; Hou, J. ; Chen, L. ; He, J. -S. ; Xu, Y (reprint author), Peking Univ, Coll Urban & Environm Sci, MOE Key Lab Earth Surface Proc, Beijing 100871, Peoples R China.
	2015
发表期刊	BIOGEOSCIENCES
摘要	The methylation index of branched tetraethers (MBT) and cyclization ratio of branched tetraethers (CBT) based on the distribution of branched glycerol dialkyl glycerol tetraethers (brGDGT) are useful proxies for the reconstruction of mean annual air temperature (MAT) and soil pH. Recently, a series of 6-methyl brGDGTs were identified which were previously co-eluted with 5-methyl brGDGTs. However, little is known about 6-methyl brGDGTs in the Qinghai-Tibetan Plateau (QTP), a critical region of the global climate system. Here, we analyze 30 surface soils covering a large area of the QTP, among which 6-methyl brGDGTs were the most abundant components (average 53 +/- 17% of total brGDGT). The fractional abundance of 6-methyl brGDGTs showed a good correlation with soil pH, while the global MBT'(5ME) calibration overestimates MAT in the QTP. We therefore proposed a MBT5/6 index including both 5- and 6-methyl brGDGTs, presenting a strong correlation with MAT in QTP: MAT = -20.14 + 39.51 x MBT5/6 (n = 27; r(2) = 0.82; RMSE=1.3 degrees C). Another index, namely IBT (isomerization of branched tetraether), based on carbon skeleton isomerization of the 5-methyl to 6-methyl brGDGTs, is dependent on soil pH: pH = 6 .77-1.56 x IBT (n = 27; r(2) = 0.74; RMSE = 0.32). Our study suggests that changing the position of methyl group of brGDGTs may be another mechanism for some soil bacteria to adapt to the ambient pH change in addition to the well-known cyclization.; The methylation index of branched tetraethers (MBT) and cyclization ratio of branched tetraethers (CBT) based on the distribution of branched glycerol dialkyl glycerol tetraethers (brGDGT) are useful proxies for the reconstruction of mean annual air temperature (MAT) and soil pH. Recently, a series of 6-methyl brGDGTs were identified which were previously co-eluted with 5-methyl brGDGTs. However, little is known about 6-methyl brGDGTs in the Qinghai-Tibetan Plateau (QTP), a critical region of the global climate system. Here, we analyze 30 surface soils covering a large area of the QTP, among which 6-methyl brGDGTs were the most abundant components (average 53 +/- 17% of total brGDGT). The fractional abundance of 6-methyl brGDGTs showed a good correlation with soil pH, while the global MBT'(5ME) calibration overestimates MAT in the QTP. We therefore proposed a MBT5/6 index including both 5- and 6-methyl brGDGTs, presenting a strong correlation with MAT in QTP: MAT = -20.14 + 39.51 x MBT5/6 (n = 27; r(2) = 0.82; RMSE=1.3 degrees C). Another index, namely IBT (isomerization of branched tetraether), based on carbon skeleton isomerization of the 5-methyl to 6-methyl brGDGTs, is dependent on soil pH: pH = 6 .77-1.56 x IBT (n = 27; r(2) = 0.74; RMSE = 0.32). Our study suggests that changing the position of methyl group of brGDGTs may be another mechanism for some soil bacteria to adapt to the ambient pH change in addition to the well-known cyclization.
文献类型	期刊论文
条目标识符	http://210.75.249.4/handle/363003/37643
专题	中国科学院西北高原生物研究所
推荐引用方式 GB/T 7714	Ding, S.,Xu, Y.,Wang, Y.,et al. Distribution of branched glycerol dialkyl glycerol tetraethers in surface soils of the Qinghai-Tibetan Plateau: implications of brGDGTs-based proxies in cold and dry regions[J]. BIOGEOSCIENCES,2015.
APA	Ding, S..,Xu, Y..,Wang, Y..,He, Y..,Hou, J..,...&Xu, Y .(2015).Distribution of branched glycerol dialkyl glycerol tetraethers in surface soils of the Qinghai-Tibetan Plateau: implications of brGDGTs-based proxies in cold and dry regions.BIOGEOSCIENCES.
MLA	Ding, S.,et al."Distribution of branched glycerol dialkyl glycerol tetraethers in surface soils of the Qinghai-Tibetan Plateau: implications of brGDGTs-based proxies in cold and dry regions".BIOGEOSCIENCES (2015).