Distribution Of Mibrobial Tetraether Membrane Lipid Compounds And Its Climatic And Environmental Significance In Bosten Lake From Xin'jiang

In recent years,modern process research on glycerol dialkylglycerol tetraether compounds(GDGTs)in lake has become a hot spot in the field of biogeochemistry.The paleoenvironmental indicators based on it have become an important tool to reconstruct the paleoclimate of lakes.Bosten Lake is located in the hinterland of Eurasian continent in Xin'jiang,which is controlled by the westerly circulation.It is the largest inland freshwater lake in the arid-semi-arid zone.The lake water depth,salinity,conductivity,pH value and other water chemical factors have obvious spatial differences,which not only provides favorable conditions for the modern process research on the distribution of GDGTs and the response of water environmental factors,but also discusses the climate change based on various indicators established by them and laid the foundation for discussing the significance of climate and environment based on various indicators established by it.In view of this,this paper analyzes the distribution characteristics of GDGTs compounds in water environment factors and surface sediment samples in different lake areas of Bosten Lake,discusses the influence of water environment factors on the distribution and composition of GDGTs compounds,and further verifies the applicability of MBT/CBT and TEX₈₆ temperature indicators in Bosten Lake.Based on the work that has been carried out,the main conclusions are as follows:(1)Bacterial lipids brGDGTs are mainly GDGT-I,GDGT-II and GDGT-III without cyclopentane.Among them,GDGT-II and GDGT-III dominate in the Kaidu River Estuary and the Main Lake area.The Huangshui Bay area is dominated by GDGT-II.The pH value and conductivity of lake water have significant effects on the distribution of br GDGTs compounds.MBT(MBT')index is positively correlated with lake water pH and conductivity.(2)The archaeal lipid isoGDGTs is dominated by acyclic GDGT-0,the Yellow Water Bay area is dominant,and the Kaidu River Estuary area is almost equal to the main lake area.Crenarchaeol is dominant in the Kaidu River Estuary.The lake water depth and conductivity have significant effects on the distribution of iso GDGTs.Crenarchaeol has a significant positive correlation with water depth.The TEX₈₆ index is negatively correlated with conductivity and water depth.(3)The applicability of MBT/CBT and TEX₈₆ were applied to the surface sediments of Bosten Lake.The results showed that the basin temperature calculated by the temperature reconstruction equation proposed by Tierney et al.(2010b)is close to the measured summer temperature,which can indicate the summer temperature.Change.Using the surface water temperature(LST)reconstruction equation proposed by Powers et al.(2010a),Tierney et al.(2010a)and Casta?eda et al.(2015b),the LST calculated by the surface water temperature(LST)reconstruction equation is quite different from the measured value,considering that the LST maintains a stable trend at a certain depth(?9 m),this indicator can reflect the deep water body temperature change.The pH value of lake water calculated using the pH reconstruction equation proposed by Günther et al.(2014)is close to the measured pH value,which can indicate the change of lake water pH.