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The shift of biogeochemical cycles indicative of the progressive marine ecosystem collapse across the Permian-Triassic boundary:An analog to modern oceans

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Science China Earth Sciences 2018年第10期61卷 1379-1383页

作者： shucheng xie State Key Laboratory of Biogeology and Environmental Geology China University of Geosciences

Global warming,the most severe faunal mass extinction and the shift of biogeochemical cycles were observed in the ocean across the Permian-Triassic boundary about 252 million years ago,providing an analog to understanding the modern *** with the progressive global warming,the biogeochemical cycle was documented to show a shift from the decoupled processes of carbon,nitrogen and sulfur prior to the mass extinction to the coupled biogeochemical processes during faunal mass *** coupled biogeochemical cycle was further observed to shift from the coupled C-N processes during the first episode of the faunal mass extinction to the coupled C-N-S processes during the second episode,diagnostic of the progressive development of more deteriorated marine environmental conditions and the more severe biotic crisis across the Permian-Triassic *** biogeochemical cycles could thus be an indication to the progressive collapse of marine ecosystems triggered by the global warming in Earth *** modern oceans,the coupled C-N cycle triggered by the global warming was observed in some *** these local C-N processes develop and expand to the global oceans,the coupled C-N-S processes might be brought into existence and the marine ecosystems are inevitable to suffer from complete collapse as observed at 252 million years ago.

关键词： Microbes Mass extinction Permian-Triassic boundary Euxinia Global warming Geobiology

Linking minerals to bacterial genes

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National Science Review 2023年第1期10卷 103-104页

作者： shucheng xie State Key Laboratory of Biogeology and Environmental Geology China University of Geosciences (Wuhan)

The biogeochemical roles of microbes in the Earth system are relatively well known [1],but their biogeophysical roles in Earth history are yet to be *** bacteria(MTB) may have been the earliest organisms to sense Earth’s magnetic field and to form intracellular nanocrystals of magnetic minerals,so-called magnetotaxis and magnetosomes,respectively[2].These magnetos ome minerals are highly resistant to diagenesis and generally well-preserved in sediments or sedimentary rocks as magnetofossils[3],making excellent archives of the biogeophysical activity of microbes.

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Comparison of paleotemperature reconstructions using microbial tetraether thermometers of the Chinese loess-paleosol sequence for the past 350000 years

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Science China Earth Sciences 2017年第6期60卷 1159-1170页

作者： TANG ChangYan YANG Huan DANG XinYue xie shucheng State Key Laboratory of Biogeology and Environmental Geology School of Earth Sciences China University of Geosciences Wuhan 430074 China

The recently proposed global and local calibrations for the mean annual air temperature(MAT) reconstruction on the basis of 5-and 6-methyl brGDGTs have rarely been applied to the Chinese LPS yet, leaving the applicability of these calibrations unclear. Here, we used the improved chromatography method to analyze 198 loess-paleosol samples from the Weinan section in the southern CLP for the past 350 kyr. The 6-methyl brGDGTs comprise a major proportion of total brGDGTs, pointing to alkaline conditions for most soil samples from the Weinan LPS. The decoupled profile variation of MBT′6ME and MBT′_(5ME) suggests their response to different enviromental factors, possibly soil pH(or soil moisture) and temperature, respectively. This discrimination further corraborates that temperature and monsoonal precipitation were not in phase during the last four deglaciations on the CLP. Temperature estimates for the six calibrations tested show similar trends but remarkably differ in amplitudes. The soil moisture appears to affect the global MBT′/CBT calibration, the global MATmr calibration(a calibration based on the multiple linear regression) and the Chinese local SSM(Stepwise Selection Method) calibration, resulting in a significant underestimation of late Holocene temperature. In contrast, the dry climate has no effect on the global MBT′5ME calibration. Of the six calibrations,only the Chinese local SSM calibration and global MATmr calibration produce temperature variation amplitude over the past 350 ka that is consistent with other independent proxy data. The recently proposed local calibrations based on 5-and 6-methyl brGDGTs for North China yield the amplitude of temperature changes that is much larger than the results determined by other *** the six calibrations have their own weakness in the MAT reconstruction, due partly to the inconsistency between the brGDGT distribution in the Weinan LPS and the modern soils used to establish these calibrations.

关键词： 5-methyl brGDGTs 6-methyl brGDGTs Paleotemperature Loess-paleosol sequences

Distinct distribution revealing multiple bacterial sources for 1-Omonoalkyl glycerol ethers in terrestrial and lake environments

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Science China Earth Sciences 2015年第6期58卷 1005-1017页

作者： YANG Huan ZHENG FengFeng XIAO WenJie xie shucheng State Key Laboratory of Biogeology and Environmental Geology China University of Geosciences State Key Laboratory of Marine Geology Tongji University

The 1-O-monoalkyl glycerol ethers （MAGEs） were initially viewed as the biomarkers for sulfate-reducing bacteria （SRB） me- diating anaerobic oxidation of methane in the marine environments. However, limited information is known about their distri- bution in terrestrial and other aquatic settings including soils, fresh water lakes, and cave sediments, which may obscure our understanding of their biological sources. Here we found that MAGEs were ubiquitous but differed obviously in distributional pattern among those environments. The surface soils are dominated generally by iC15：0-MAGE, followed by nCI6：o-MAGE whereas the lake sediments show the opposite, resulting in significantly higher iC15：0/nC16：0 ratios in soils than in lake sedi- ments. The cave deposits are characterized by considerably higher proportions of branched MAGEs than the former two envi- ronments. The logarithm of iC15：0/aC15：0 ratio shows a significant negative correlation with soil pH, likely reflecting an adapta- tion of microbial cell membrane to change in the ambient proton concentration. The MAGE profiles in cultured bacteria cannot fully explain the MAGE distribution in all the samples analyzed. Therefore, MAGEs in soil, lake sediments, and cave deposits likely have additional biological source（s） other than SRB and cultured MAGE-producing bacteria. The difference in MAGE pattern among environments is likely to be attributed to change in microbial communities.

关键词： 1-O-monoalkyl glycerol ethers soil lake sediments cave deposits biological sources

Flooding impact on the distribution of microbial tetraether lipids in paddy rice soil in China

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Frontiers of Earth Science 2013年第3期7卷 384-394页

作者： Asma AYARI Huan YANG shucheng xie State Key Laboratory of Biogeology and Environmental Geology China University of Geosciences Wuhan 430074 China

Isoprenoid and branched glycerol dialkyl glycerol tetraethers （GDGTs） lipids were studied in flooded and non-flooded paddy soil in Wuhan, central China, to examine the response of the GDGTs distribution to the soil flooding. Samples were collected before and after the soil flooding in four specific months. Both core （CL） and intact polar （IPL） GDGTs were quantified. Increase in the abundance of archaeol and caldarchaeol may be indicative of the occurrence of methanogens in the flooded soil. A negative correlation was observed between the ratio of IPL branched GDGT-IIa to GDGT-Ia and the soil pH. The rise of the soil pH in the acid soil is known to be controlled by the redox conditions resulting from flooding. Thus, the branched GDGTs distribution may be controlled by the water content in the paddy soil. In addition, we suggest that the anoxic conditions resulting from flooding may also control the abundance of branched GDGTs relative to crenarchaeol, which in turn results in the increase of branched and isoprenoidal tetraethers （BIT） values, the index for the terrestrial input to the marine sediments.

关键词： glycerol dialkyl glycerol tetraethers (GDGTs) soil flooding soil pH redox conditions GDGTs distribution branched and isoprenoidal tetraethers (BIT)

Characterstics of seasonal variations of leaf n-alkanesand n-alkenes in modern higher plants in Qingjiang, Hubei Province, China

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Chinese Science Bulletin 2008年第17期53卷 2659-2664页

作者： CUI JingWei HUANG JunHua xie shucheng State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Wuhan 430074 China Key Laboratory of Biogeology and Environmental Geology of Ministry of Education China University of Geosciences Wuhan 430074 China

On the basis of GC and GC-MS analyses, the seasonal variation of leaf lipids is observed in five plant species in Qingjiang in Hubei Province. The CPI values (carbon preference index) of n-alkanes decrease gradually from May to November, though the carbon number distributions and the predominant carbon number in an individual species keep unchanged. The declined CPI values might be caused by the leaf fading, which is further supported by a comparison of the defoliated leaves with the fresh leaves. This observation infers the CPI values of n-alkanes in Quaternary sediments can be used as a tool to index the humification, and thus the climatic and the environmental conditions. The plants analyzed here show a remarkable difference in n-alkanes abundance, suggesting their differential contribution to the n-alkanes identified in sediments. The abundance and the compound species of the n-alkenes detected in the plant leaves change greatly with the seasons due to the influence of temperature, with the least compounds being identified in August.

关键词：环境变化 n-烷烃 n-烯烃平均碳链长度高等植物

Paleoaltimetry proxies based on bacterial branched tetraether membrane lipids in soils

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Frontiers of Earth Science 2015年第1期9卷 13-25页

作者： Huan YANG Wenjie XIAO Chengling JIA shucheng xie State Key Laboratory of Biogeology and Environmental Geology China University of Geosciences Wuhan 430074 China State Key-Laboratory of Marine Geology Tongji University Shanghai 200092 China

The MBT/CBT （Methylation Index of Branched Tetraethers/Cyclisation ratio of Branched Tetraether） proxy, a terrestrial paleothermometer based on bacterial branched glycerol dialkyl glycerol tetraethers CoGDGTs）, was employed to indicate altimetry; however, the mechanistic control on this proxy is still ambiguous. Here, we investigated the bGDGTs＇ distribution and associated environmental factors along an altitude transect of Mt. Shennongjia in China in order to determine the applicability of bGDGT-based proxies to altimetry reconstruction. The MBT index exhibits only a weak correlation with estimated mean annual air temperature （MATe, estimated according to the meteorological record and lapse rate） or altitude. Likewise, MBT shows weak or no relationship with temperature or altitude at four other mountains （Mts. Meghalaya, Jianfengling, Gongga, and Rungwe）. It is notable that mean annual air temperature （MAT） or altitude estimated by the MBT/CBT proxy largely relies on CBT, rather than on MBT, which was generally acknowledged. The poor relationship between MBT and MATe for Mt. Shennongjia can be ascribed to the insensitive response of bGDGT-I to temperature. Our data fxom this mountain imply that care should be taken if the MBT/CBT proxy is employed as an indication of paleoaltimetry. We propose that the fractional abundance of bGDGTs may be a better paleoaltimeter than the MBT/ CBT proxy, because specific bGDGT subsets that might show the most sensitive response to temperature can be preferentially selected using a statistical method and used to establish local calibration. This local calibration was applied to Mt. Shennongjia and apparently improves the accuracy of temperature and altimetry reconstruction. The differential response of bGDGTs to temperature among mountains suggests that local calibrations are needed to better constrain the altimetry.

关键词： branched glycerol dialkyl glycerol tetraethers,soil pH paleoaltimetry temperatures

Deining the discipline of geobiology

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National Science Review 2014年第4期1卷 483-485页

作者： Michael J.Benton shucheng xie School of Earth Sciences University of Bristol State Key Laboratory of Biogeology and Environmental Geology China University of Geosciences

One of the fundamental questions in science,but also for any intelligentperson,is‘What is the diference between life and non-life?’Philosophers havedebated this for centuries,and alchemists and novelists have explor... 详细信息

关键词： Deining the discipline of geobiology

Spurious Thermoluminescence Characteristics of the Ediacaran Doushantuo Formation(ca. 635–551 Ma) and Its Implications for Marine Dissolved Organic Carbon Reservoir

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Journal of Earth Science 2015年第6期26卷 883-892页

作者： Haiyang Wang Chao Li Chaoyong Hu shucheng xie State Key laboratory of Biogeology and Environment Geology China University of Geosciences School of Earth Sciences China University of Geosciences

The Ediacaran Doushantuo Formation（ca. 635–551 Ma） deposited immediately after the last Neoproterozoic glaciations and recorded the most prominent negative excursions of carbonate carbon isotopic composition（δ^（13）C（carb））. These excursions have been interpreted as a result of widespread remineralization of a large dissolved organic carbon（DOC） reservoir in the Ediacaran deep oceans. However, there is no direct evidence so far found in rocks for the proposed DOC reservoir, which devalues such an interpretation. Here, we conducted a detailed study on the glow-curves characteristics and signal origins of spurious thermoluminescence（TL） of the Doushantuo Formation at Jiulongwan in Yangtze Gorges area, South China, through sequential tests under CO2, N2 and air. Spurious TL intensities for test samples before and after removing soluble organic matter via accelerated solvent extraction（ASE） are nearly identical. Further, significant positive correlation between the spurious TL intensity and total inorganic carbon（TIC） content（R^2=0.7） indicate that the Doushantuo spurious TL with the characteristic peak at 393.5 °C from the sequential test is chemiluminescence（CL） which is derived from the oxidation of a type of non-volatile organic matter strongly associated with carbonate mineral lattice（termed as “X-OM”）. A most likely explanation is that the X-OM is a type of dissolved organic matter which co-precipitated with carbonate minerals into sediments in the Ediacaran Doushantuo Ocean. Furthermore, a significant exponential negative correlation（R^2=0.55） is observed between the CL data and the isotopic difference between carbonate and coexisting bulk organic matter（i.e., Δ^（13）C（carb-org）, a proxy for remineralization degree of DOC reservoir in proposed DOC hypothesis）, suggesting that the X-OM was derived from the oxidation of the DOC reservoir in the Ediacaran Ocean. We thus propose that the X-OM and its CL detected in our study may have recorded the evolution of the possi

关键词： Doushantuo Formation spurious thermoluminescence chemiluminescence carbonates,dissolved organic carbon.