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Molecular fossil and paleovegetation records of paleosol S4 and adjacent loess layers in the Luochuan loess section, NW China

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Science China Earth Sciences 2008年第3期51卷 321-330页

作者： ZHANG HuCai YANG MingSheng ZHANG WenXiang LEI GuoLiang chang fengqin PU Yang FAN HongFang Key Laboratory of Western China’s Environmental Systems Ministry of EducationCollege of Earth and Environment SciencesLanzhou UniversityLanzhou 730000China State Key Laboratory of Lake and Environment Sciences Nanjing Institute of Geography and LimnologyChinese Academy of SciencesNanjing 210008China

Using gas chromatography-mass spectrometry (GC-MS) technique, a series of biomarkers were identi- fied, including n-alkanes, n-alkane-2-ones, isoprenoid etc. from the loess-paleosol samples collected from the S4 and adjacent L5, L4 of the Luochuan loess section, Northwestern China. Based on these data, especially n-alkanes and high-resolution magnetic susceptibility and grain size data, the pa- leoenvironment and paleovegetation history during S4 was reconstructed. The CPI (Carbon Predomi- nance Index) and correlation between n-alkanes and magnetic susceptibility and grain size data dem- onstrated that the molecular fossils in paleosol and loess layers can reflect the vegetation condition during the loess-paleosol formation, if the allochthonous organic inputs could be excluded reasonably. The ACL (average chain length) index is correlated well with paleomagnetic susceptibility and grain size variations, displaying their good synchrony with warm and humid climate. However, it relatively lagged behind the paleomagnetic susceptibility and the grain size variations when the climate began to deteriorate. During the formation period of paleosol, the n-alkanes was dominated by C31 homologue, indicating that the primary organic input originated from herbs. Our study also demonstrated that the herbs were more flourish than wood plants in Loess Plateau, especially in the Luochuan area during the warm and humid phase, and there was no typical forest vegetation developed in the studied period.

关键词： paleoenvironment Paleosol S4 Luochuan loess section biomarker paleovegetation

NiCo_(2)O_(4) hollow microsphere-mediated ultrafast peroxymonosulfate activation for dye degradation

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Chinese Chemical Letters 2021年第8期32卷 2495-2498页

作者： Pengjia Ding Jianrui Niu fengqin chang Zhuang He Thomas Wagberg Zaixing Li Guangzhi Hu College of Environmental Science and Engineering Hebei University of Science and TechnologyShijiazhuang 050018China Institute for Ecological Research and Pollution Control of Plateau Lakes School of Ecology and Environmental ScienceYunnan UniversityKunming 650504China Department of Physics Umea UniversityUmeå90187Sweden

Morphology and dispersity are key factors for activating peroxymonosulfate(PMS).In this study,we designed a recyclable open-type NiCo_(2)O_(4) hollow microsphere via a simple hydrothermal method with the assistance of an NH_(3) *** physical structure and chemical properties were characterized using techniques such as scanning electron microscope(SEM),transmission electron microscope(TEM),X-ray diffraction(XRD),N2 adsorption and X-ray photoelectron spectroscopy(XPS).The test results confirm that the inner and outer surfaces of open-type NiCo_(2)O_(4) hollow-sphere can be efficiently utilized because of the hole on the surface of the catalyst,which can minimize the diffusion resistance of the reactants and *** optimized conditions,the total orga nic carbon(TOC) removal efficiency of rhodamine B(RhB) can reach up to 80% in 40 min,which is almost 50% shorter than the reported *** reactive radicals were identified and the proposed reaction mechanism was well ***,the disturbances of HCO_(3)^(-),NO_(3)^(-),Cl^(-)and H_(2) PO_(4)^(-)were further *** a result,HCO_(3)-and NO_(3)-suppressed the reaction while Cl-and H_(2) PO4-had a double effect on reaction.

关键词： Open-type sphere Hollow NiCo_(2)O_(4) Vesicle Inner and outer surface Ultra peroxymonosulfate activation

Self-supported porous copper oxide nanosheet arrays for efficient and selective electrochemical conversion of nitrate ions to nitrogen gas

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Journal of Materials Science & Technology 2023年第6期137卷 104-111页

作者： Xue Li Xue Zhao Jiapei Lv Xiuxiu Jia Shuxing Zhou Yimin Huang fengqin chang Hucai Zhang Guangzhi Hu Institute for Ecological Research and Pollution Control of Plateau Lakes School of Ecology and Environmental ScienceYunnan UniversityKunming 650504China College of Chemistry and Molecular Sciences Wuhan UniversityWuhan 430072China State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental SciencesBeijing 100012China Hubei Key Laboratory of Low Dimensional Optoelectronic Materials and Devices Hubei University of Arts and ScienceXiangyang 441053China Department of Physics UmeåUniversityS-90187 UmeåSweden

Electrochemical techniques have shown advantages for the removal of low-concentration ***,copper oxide nanosheets were grown on self-supporting nickel foam(NF)to prepare electrodes(CuO/NF),which realized the rapid and highly selective conversion of nitrate pollutants in sewage into nontoxic and harmless N_(2).The CuO/NF afforded 100%NO_(3)^(-)removal within 100 min and 99.53%selectivity for N_(2)at-50 mA without producing a lot of by-products(NO_(2)-,NH_(4)^(+),and N_(2)H_(4)).Furthermore,81.8%of NO_(3)^(-)was removed under the given conditions after six experimental *** results suggest that the cat-alyst has excellent electrochemical *** performance of CuO/NF for the electrocatalytic removal of NO_(3)^(-)in simulated wastewater(which contained Cl^(-) and SO_(4)^(2-))was almost *** of the high efficiency,high stability,and low cost of CuO/NF,this catalyst is practical for the removal of nitrate for wastewater purification.

关键词： Electrocatalysis Nitrate reduction Copper oxide nanosheet Selective conversion Nitrogen gas

Discovery of bacteriopheophytin-a in lacustrine deposits from Lake Zigetang on the central Tibetan Plateau and its paleoenvironmental significance

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Science China Earth Sciences 2017年第12期60卷 2171-2180页

作者： LI HuaYong ZHANG HuCai chang fengqin ZHENG Qian ZHANG WenXiang LEI GuoLiang LEI YanBin PU Yang JI JunFeng Key Laboratory of Plateau Lake Ecology and Global change Yunnan Provincial Key Laboratory of Plateau Geography Process and Environment ChangesCollege of Tourism and Geography ScienceYunnan Normal UniversityKunming 650500China School of Resource Environment and Tourism Anyang Normal UniversityAnyang 455000China College of Urban and Environment Sciences Central China Normal UniversityWuhan 430079China Key Laboratory for Subtropical Mountain Ecology(Ministry of Science and Technology and Fujian Province Funded) Fujian Normal UniversityFuzhoa 350007China Laboratory of Tibetan Environment changes and Land Surface Processes Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100085China School of Remote Sensing Nanjing University of Information Science&TechnologyNanjing 210044China Institute of Surface Geochemistry Department of Earth SciencesNanjing UniversityNanjing 210093China

Lake Zigetang is located on the central Tibetan Plateau(TP) and represents a rare but typical meromictic lake in *** lake's stable meromixis sustains microflora communities, and changes in these communities are relatively independent of climate. Therefore, these communities can be used as paleoclimate proxies. In this paper, the stratification properties and their relationships with the microflora of Lake Zigetang were analyzed. We found that water depth and climate conditions were two important factors for maintaining meromixis in Lake Zigetang. Generally, stratification was enhanced during warm periods, while temperature differences between the mixolimnion and monimolimnion were decreased during cold periods. The presence of anoxygenic phototrophic bacteria(APB) was demonstrated by the discovery of bacteriopheophytin-a(Bph-a) in the *** bacterial community is mainly concentrated at the bottom of the chemocline and the top of the monimolimnion, where it forms a thin APB layer. Moreover, total APB productivity is mainly affected by the light intensity penetrating to the APB layer,which exponentially increases as the thermocline becomes shallow. Therefore, high Bph-a values in the lake corresponded to a shallow thermocline and warm periods, low Bph-a values corresponded to cold periods, and zero changes indicated that the water was completely mixed and reflected an extreme cold climate or low lake level period. Thus, Bph-a can be used as a climate proxy to reconstruct the history of lake stratification and climate changes.

关键词： Lake Zigetang Tibetan Plateau Meromictic lakes Thermocline Anoxygenic phototrophic bacteria

Geochemical fractionation of rare earth elements in lacustrine deposits from Qaidam Basin

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Science China Earth Sciences 2009年第11期52卷 1703-1713页

作者： ZHANG HuCai ZHANG WenXiang chang fengqin YANG LunQing LEI GuoLiang YANG MingSheng PU Yang LEI YangBin Key Laboratory of Western China’s Environments MOECollege of Earth Sciences and EnvironmentsLanzhou UniversityLanzhou 730000China State Key Laboratory of Lake Science and Environment Nanjing Institute of Geography and LimnologyChinese Academy of SciencesNanjing 210008China Key Laboratory of Boyang Lake MOESchool of Environmental and Chemical EngineeringNanchang UniversityNanchang 330031China

Based on the concentration and distribution pattern analysis of the rare earth elements (REEs) at the Shell Bar section from Qaidam Basin, we studied the geochemical fractionations of REE in paleolake deposits and their paleo-environmental significance. Our results show that the REE concentration in AS (acid soluble) and AR (acid residual) fractions are 20.9 μg/g and 95.4 μg/g (except element Y) individually, showing a strong REE differentiation between AS and AR fractions. However, the two types of fractions (AS & AR) have similar REE distribution patterns, which are slightly rich in light earth rare elements (LREEs), with slightly right-tilting and negative Eu anomaly. The LREE of AR is richer than that of AS. There were no significant correlations between the REE in AS, AR and other proxies. It indicated that the lacustrine deposition had different material sources and experienced varying geochemical procedures. Correlation analysis between the REE and the content of fine grain-size (changes in the lake catchment and the evolutionary processes of lake itself. Our results suggest that δCe and (La/Yb)n could be used as proxies of the reduction-oxidation conditions and furthermore the temperature change and the lake level fluctuations. Using these proxies, we reconstructed the paleoclimate and water level fluctuation history during the high lake level period lasting between 43.5 and 22.4 cal. ka BP.

关键词： Shell Bar section rare earth elements (REE) fractionation paleoclimate Qaidam Basin

Climate variability recorded by n-alkanes of paleolake sediment in Qaidam Basin on the northeast Tibetan Plateau in late MIS3

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Science China Earth Sciences 2010年第6期53卷 863-870页

作者： PU Yang ZHANG HuCai LEI GuoLiang chang fengqin YANG MingSheng ZHANG WenXiang LEI YanBin YANG LunQing PANG YouZhi State Key Laboratory of Lake Science and Environment Nanjing Institute of Geography and LimnologyChinese Academy of SciencesNanjing 210008China Graduate University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Boyang Lake MOESchool of Environmental and Chemical EngineeringNanchang UniversityNanchang 330031China

Here we combine n-alkanes preserved in a shell bar section from Qarhan paleolake, Qaidam Basin with the other sedimentary proxies to elucidate the lake evolution process during the period 39.7 to 17.5 14C ka BP (calibrated age ranges from 43.5 to 22.4 cal. ka BP). In different stages, the n-alkane homologues exhibited different distribution modes indicative of variations in the surrounding vegetation and the hydrologic condition of the lake. The n-alkanes proxies (CPIh, ACLh, Paq) have the same trends as the summer solar insolation variation, implying that the summer insolation is the most important climatic factor driving the environmental changes and also indirectly controls lake evolution on the Tibetan Plateau. CPIh and ACLh as well as the total pollen concentration appear to show a trend comparable with methane concentration record from the GRIP ice core that reflected the Dansgaard-Oeschger events. This demonstrates that the paleoclimate variations in Qarhan area generally agree with global climate change and show rapid oscillations in late MIS3. These findings provide the latest molecular fossil evidence from paleolake sediments to confirm that lake evolution on Tibetan Plateau in late MIS3 was closely associated with enhanced summer insolation.

关键词： paleolake sediment molecular fossil n-alkane paleoclimate paleoenvironment solar insolation

Branched aliphatic alkanes of shell bar section in Qarhan Lake,Qaidam Basin and their paleoclimate significance

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Chinese Science Bulletin 2007年第9期52卷 1248-1256页

作者： ZHANG HuCai chang fengqin LI Bin LEI GuoLiang CHEN Yue ZHANG WenXiang NIU Jie FAN HongFang YANG MingSheng Nanjing Institute of Geography and Limnology Chinese Academy of Sciences Nanjing 210008 China Key Laboratory of Westem China's Environments MOE College of Earth Sciences and Environments Lanzhou University Lanzhou 730000 China

Biomarkers of paleolake deposits from Qarhan Salt Lake in Qaidam Basin,northwest China were sys-tematically analyzed and the A―C series compounds of branched aliphatic alkanes with quaternary substituted carbon atom(BAQCs) were identified. The homologous distinguished three series,A―C,were identified as 5,5-diethylalkanes,6,6-diethylalkanes and 5-butyl,5-ethylalkanes series,and their relative abundance was A > B > C. Series A and C were characterized by odd carbon numbers,whereas series B was characterized by even carbon numbers. The high values of series A corresponded with the high values of series B and C. Therefore,it can be concluded that series A,B and C possess a similar biological origin. The abundance of series A was relatively low in the lower part of the section compared with that in the upper part,implying that these series originated from bacteria and/or algae more prevalent in fresh-mesohaline water,and such kinds of bacteria and/or algae are most likely to be thermophilous species. The A25/nC25 ratio differences in the section show that such branched aliphatic alkanes can be treated as one kind of environmental change proxy for paleolake evolution and may provide important information for the climate reconstruction of the Late Pleistocene.

关键词：柴达木盆地察尔汗盐湖贝壳堤剖面侧链脂族烷古气候意义

鄂陵湖晚全新世沉积物记录的黄河源区气候环境变化

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第四纪研究 2021年第4期41卷 1000-1011页

作者：蒲阳韩悦张虎才常凤琴南京信息工程大学地理科学学院江苏南京210044 云南大学生态与环境科学学院高原湖泊生态与污染治理研究院云南昆明650504

通过对青藏高原黄河源区鄂陵湖35 cm长的沉积物岩芯(NR-1)中总有机碳含量(TOC)、总氮含量(TN)、碳氮比值(C_(org)/N_(tot))以及有机碳同位素(δ^(13)C_(org))和总氮同位素(δ^(15)N_(tot))等地球化学指标的分析,并结合青海地区文献资料... 详细信息

通过对青藏高原黄河源区鄂陵湖35 cm长的沉积物岩芯(NR-1)中总有机碳含量(TOC)、总氮含量(TN)、碳氮比值(C_(org)/N_(tot))以及有机碳同位素(δ^(13)C_(org))和总氮同位素(δ^(15)N_(tot))等地球化学指标的分析,并结合青海地区文献资料记载的人口数量变化以及高原湖泊水位记录,对研究区近1500 a以来的气候环境变化进行了深入探讨。结果表明:近两百多年以来鄂陵湖沉积物中TOC和TN指标呈现明显上升的趋势,与青海东部地区人口数量变化趋势一致,表明近代人类活动已经对青藏高原最大淡水湖生态系统产生了显著的影响;而沉积物中δ^(13)C_(org)值变化与青海湖水文环境重建指标具有可比性,说明高原大型淡水湖泊沉积物δ^(13)C_(org)值可指示湖泊水位波动;此外δ^(15)N_(tot)值变化趋势与青藏高原东北部已有的古温度记录总体一致,推测鄂陵湖沉积物δ^(15)N_(tot)值可能响应了湖泊水体营养状态的变化,间接指示了湖泊夏季表层水温的波动。本研究为青藏高原腹地高海拔现代湖泊沉积物中有机碳和总氮含量及其同位素指标的解译提供了全新的思路。

关键词：黄河源区湖泊水位水文条件气候变化环境演变人口数量

Omnidirectional simulation analysis of thermomechanical coupling mechanism in inertia friction welding of Ni-based superalloy

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Chinese Journal of Aeronautics 2025年第1期38卷 202-216页

作者： chang-an LI Guoliang QIN Hao WANG School of Materials Science and Engineering Shandong UniversityJinan 250061China

The coupling between heat and pressure is the kernel of inertia friction welding(IFW)and is still not fully understood.A novel 3D fully coupled finite element model based on a plastic friction pair was developed to simulate the IFW process of a Ni-based superalloy and reveal the omnidirectional thermo-mechanical coupling mechanism of the friction *** numerical model successfully simulated the deceleration,deformation processes,and peak torsional moments in IFW and captured the evolution of temperature,contact pressure,and *** simulated results were validated through measured thermal history,optical macrography,and axial *** results indicated that interfacial friction heat was the primary heat source,and plastic deformation energy only accounted for 4%of the *** increase in initial rotational speed and friction pressure elevated the peak temperature,reaching a maximum of 1525.5K at an initial rotational speed of 2000 r/min and friction pressure of 400 *** interface heat generation could form an axial temperature gradient exceeding 320K/*** radial inhomogeneities of heat generation and temperature were manifested in a concentric ring distribution with maximum heat flux and temperature ranging from 2/5 to 2/3 *** radial inhomogeneities were caused by increasing linear velocity along the radius and an opposite distribution of contact pressure,which could reach 1.7 times the set pressure at the *** circumferential inhomogeneity of thermomechanical distribution during rotary friction welding was revealed for the first time,benefiting from the 3D *** deflection and transformation of distribution in contact pressure and Mises stress were indicators of plastic deformation and transition of quasi-steady state *** critical Mises stress was 0.5 times the friction pressure in this *** presented modeling provides a reliable insight into the thermo-mechanical coupling mechanism of IFW and lays a solid found

关键词： Inertia friction welding Thermo-mechanical coupling Inhomogeneity Numerical simulation Ni-based superalloy