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Hydrogen isotopic composition of plant leaf wax in response to soil moisture in an arid ecosystem of the northeast Qinghai-Tibetan Plateau, China

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Journal of Arid Land 2014年第5期6卷 592-600页

作者： Yuan YAO weiguo liu School of Human Settlements and Civil Engineering Xi'an Jiaotong University State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences

The hydrogen isotopic composition of plant leaf wax（δDwax） is used as an important tool for paleohydrologic reconstruction. However, the understanding of the relative importance of environmental and biological factors in determining δDwax values still remains incomplete. To identify the effects of soil moisture and plant physiology on δDwax values in an arid ecosystem, and to explore the implication of these values for paleoclimatic reconstruction, we measured δD values of soil water（δDwater） and δDwax values in surface soils along two distance transects extending from the lakeshore to wetland to dryland around Lake Qinghai and Lake Gahai on the northeast Qinghai-Tibetan Plateau. The results showed that the δDwater values were negatively correlated with soil water content（SWC）（R^2=0.9166）, and ranged from –67‰ to –46‰ with changes in SWC from 6.2% to 42.1% in the arid areas of the Gangcha（GCh） and Gahai（GH） transects. This indicated that evaporative D-enrichment in soil water was sensitive to soil moisture in an arid ecosystem. Although the shift from grasses to shrubs with increasing aridity occurred in the arid area of the GH transect, the δDwax values in surface soils from the arid areas of the two transects still showed a negative correlation with SWC（R^2=0.6835）, which may be due to the controls of primary evaporative D-enrichment in the soil water and additional transpirational D-enrichment in the leaf water on the δDwaxvalues. Our preliminary research suggested that δDwax values can potentially be applied as a paleo-humidity indicator on the northeast Qinghai-Tibetan Plateau.

关键词： hydrogen isotope D-enrichment soil water content northeast Qinghai-Tibetan Plateau

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Distributions and hydrogen isotopic compositions of plant leaf wax from Orinus kokonorica along a general aridity gradient around Lake Qinghai, China

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Chinese Journal Of Geochemistry 2014年第3期33卷 236-243页

作者： YAO Yuan liu weiguo School of Human Settlements and Civil Engineering Xi'an Jiaotong University State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences

To quantitatively analyze the response of distributions and hydrogen isotopic compositions(δD) of plant leaf wax to moisture, and to better understand their implications for paleoclimatic reconstruction, we measured average chain length(ACL) and δD values of n-alkanes and n-fatty acids(n-FAs) from Orinus kokonorica, a typical and representative plant in Lake Qinghai area, along a distance transect extending from lakeshore to wetland to dryland in the arid ecosystem. The results showed that the ACL values of n-alkanes and n-FAs were negatively correlated with soil water content(SWC) with R2=0.593 and R2=0.924, respectively. This is as a result of plant's response to water loss with more abundance in long-chain n-alkyl lipids under increasing aridity by analyzing relationships between the molecular ratios of long-chain n-alkyl lipids(n-alkanes and n-FAs) from O. kokonorica and SWC. The δD values of C29 n-alkane and C28 n-FA were also negatively correlated with SWC with R2=0.778 and R2=0.760, respectively, which may due to enhanced D-enrichment in leaf water by evapotranspiration(soil water evaporation and leaf water transpiration) with increasing aridity. Our results demonstrated that moisture exerts a significant control on the ACL and δD values from O. kokonorica in an arid ecosystem. This preliminary study on a modern single plant(O. kokonorica) sets a foundation for comprehending these values as quantitative proxies for paleo-humidity reconstruction.

关键词：同位素组成青海湖地区植物叶干旱土壤水分蒸发访问控制列表正构烷烃梯度

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n-Alkyl lipid concentrations and distributions in aquatic plants and their individual δD variations

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Science China Earth Sciences 2019年第9期62卷 1441-1452页

作者： Hu liu Zhonghui liu Cheng ZHAO weiguo liu State Key L aboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi'an 710061 China University of Chinese Academy of Sciences Beijing 100049 China Department of Earth Sciences The University of Hong Kong Hong Kong 999077 China State Key Laboratory of Lake Science and Environment Nanjing Institute of Geography and Limnology Chinese Academy of Sciences Nanjing 210008 China

Aquatic plants are major input sources of autochthonous organic matter in lake sediments, but investigations on fatty acid(FA) and n-alkane distributions in aquatic plants are currently limited, greatly hindering the applications of their isotope geochemistry in lacustrine environments. Here, the reported n-alkyl lipid distributions of aquatic plants in globally studied lakes,together with newly obtained aquatic plant n-alkyl lipid data in Chinese lakes(Yunnan and Inner Mongolia), are used to understand their distribution characteristics. The results show that aquatic plants have predominantly mid-chain lipids(C23–C25 n-alkanes and C22–C24 FAs), differing from that of terrestrial plants(dominant by long-chain lipids), but the long-chain n-alkanes(e.g., C27 and C29) and long-chain FAs(e.g., C26 and C28) also show high abundances in most samples. Submerged plants have high concentrations of long-chain n-alkanes(avg. 47 μg g-1) and long-chain FAs(avg. 170 μg g-1), close to those in terrestrial plants, indicating that submerged plants may make large contributions of long-chain n-alkyl lipids to lake sediments, while the contributions of long-chain n-alkyl lipids derived from algae to lake sediments may be small because of their low concentrations(avg. 2 μg g-1 for n-alkanes and 9 μg g-1 for FAs). We find that lipid molecular proxies(including ACL14-32 and ATR14-18) can be reliably used to distinguish the FAs sourced from algae and other plants, and Paq′ values can be utilized to distinguish the nalkane sources between submerged plants and terrestrial plants. Aquatic plants do not have significant δD differences among different chain-length n-alkanes and FAs for each sample, suggesting that the offset between δD values of different chain-length n-alkyl lipids in lake sediments can help determine sedimentary lipid input sources and infer paleohydrological changes.

关键词： n-Alkanes Fatty acids Hydrogen isotopes Algae Submerged plants

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Influence factors of methane hydrate formation from ice:Temperature,pressure and SDS surfactant

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Chinese Journal of Chemical Engineering 2019年第2期27卷 405-410页

作者： weiguo liu Yanghui Li Xiaohu Xu Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology

A series of experiments of forming hydrate from ice powders in different conditions have been carried out with constant volume method to evaluate the influence factors such as pressure, temperature, and SDS surfactant. The change of temperature and pressure were collected as a function of elapsed time, which were used to calculate the gas consumption and hydrate saturation during hydrate formation(pVT method). Based on the experimental results and the analysis, it is concluded that:(1) Both initial pressure and temperature have effect on the hydrate formation and temperature plays a more important role in the process;(2) heating and secondary pressurization will promote the gas hydrate formation and enhance the hydrate saturation as a result. Meanwhile, the promotion of heating seems to be more obvious than that of secondary pressurization;(3) different concentrations of SDS surfactant have clearly influence on the saturation of gas hydrate and there is an optimal concentration to promote the hydrate formation.

关键词： Methane hydrate Ice Heating Secondary pressurization Surfactant

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A Comparison of Different Preservation Methods for Nitrogen Isotopes of Soil Extractable NO3^-

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Pedosphere 2018年第6期28卷 943-951页

作者： liu Junchi liu weiguo HU Jing State Key Laboratory of Loess and Quaternary Geology Institute of Earth EnvironmentChinese Academy of SciencesXi'an 710075(China) Key Laboratory of Vertebrate Evolution and Human Origin of Chinese Academy of Sciences Institute of Vertebrate Paleontology and PaleoanthropologyChinese Academy of SciencesBeijing 100044(China) University of Chinese Academy of Sciences Beijing 100049(China) School of Human Settlement and Civil Engineering Xi'an Jiaotong UniversityXi'an 710049(China)

Nitrogen(N) isotope ratio(δ^(15)N) of soil extractable NO_3^- plays a pivotal role in the study of N biogeochemical circulation in ecosystems. However, the NO_3^-concentration and its isotope composition of soil samples are unstable, making sample storage critical for preserving the N isotope composition of extracted soil NO_3^-. Nevertheless, studies on the appropriate selection of storage methods after soil sampling are scarce. In this study, we compared two commonly used methods for storing soil samples and investigated the stability of N isotopes of soil NO_3^-. The results demonstrated that no significant changes in the NO_3^-concentration and δ^(15)N value occurred in the samples stored at-18?C. However, the soil NO_3^-concentration markedly increased, and NO_3^-δ^(15)N value significantly changed after air-drying storage. Meanwhile, we also found that NO_3^-and its δ^(15)N were well preserved in the filtered soil extracts after 1 month. In contrast, the NO_3^-concentration gradually decreased and the^(15)N in NO_3^-was gradually enriched in the bactericidal agent-containing soil mixture solution during the storage period. Overall, our results indicated that N isotopes of NO_3^-could be effectively preserved in frozen-stored soil samples or filtered soil extracts. For field investigations conducted in remote areas and continued for a long-time period(and lacking a refrigerant supply), soil extraction/filtration using a CaSO_4-saturated solution may be a superior preparation and storage method for analyzing N isotopes of soil NO_3^-.

关键词： air-drying freezing ion exchange isotopic fractionation nitrogen isotope tracing soil extraction soil storage

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Compound-specific δD and its hydrological and environmental implication in the lakes on the Tibetan Plateau

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Science China Earth Sciences 2018年第6期61卷 765-777页

作者： Hu liu Hong YANG Yunning CAO weiguo liu State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi 'an 710061 China University of Chinese Academy of Sciences Beijing 100049 China Laboratory for Terrestrial Environments Department of Science and Technology College of Arts and Sciences Bryant University Smithfield Rhode Island 02917 USA

The hydrogen isotopic composition(δD) of n-alkanes in lacustrine sediments is widely used in palaeoenvironmental studies, but the heterogeneous origins and relative contributions of these lipids provide challenges for the interpretation of the increasing dataset as an environment and climatic proxy. We systematically investigated n-alkane δD values from 51 submerged plants(39 Potamogeton, 1 Myriophyllum, and 11 Ruppia), 13 algae(5 Chara, 3 Cladophora, and 5 Spirogyra) and 20 terrestrial plants(10 grasses and 10 shrubs) in and around 15 lakes on the Tibetan Plateau. Our results demonstrate that δD values of C_(29) nalkane are correlated significantly with the lake water δD values both for algae(R^2=0.85, p0.05), suggesting that the n-alkane δD values of the algae and submerged plants record the signal of D enrichment in lake water relative to precipitation only in closed lakes in arid and semi-arid area. For each algae and submerged plant sample, we find uniformed δD values of different chain length n-alkanes, implying that, in combination with other proxies such as Paq and Average Chain Length, the offset between the δD values of different chain length n-alkanes can help

关键词： n-Alkane Hydrogen isotope composition Submerged plant Algae Tibetan Plateau

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Efect of operating parameters on sulfide biotransformation to sulfur

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Journal of Environmental Sciences 2013年第12期25卷 2417-2421页

作者： weiguo liu Cunzhen Liang Jiaqing Chen Ling Zhu College of Resources and Environmental Engineering Wuhan University of Technology Department of Environmental Engineering Beijing Institute of Petrochemical Technology

A laboratory-scale bioreactor with polyethylene semi-soft packing was constructed and utilized to determine the efficlency of sulfide biotransformation to sulfur under various operating parameters. Sodium sulfide dissolved in tap water was pumped into the bioreactor as sulfide for biological desulfurization. The sulfide, sulfur and sulfate-S in the effluent and the sulfide purged as gas-phase HzS were determined to investigate the effects of operating parameters, such as pH, DO, hydraulic retention time （HRT）, temperature and salinity, on the sulfide oxidation products. The activity of bacteria was highest at pH 7.8-8.2. The maximal sulfide removal load was 7.25 kg/（m^3·day）, with a 322.07 mg/L influent sulfide concentration and 4.80 mg/L DO. The increase of DO value corresponds to a decrease in the sulfur yield. The reactor had the highest sulfide removal load and sulfur yield at 2.55 mg/L DO. HRT had little effect on desulfurization efficiency when the sulfide removal load was kept constant. The most effective desulfurization temperature was 33℃. The sulfide removal load decreased from 2.85 to 0.51 kg/（m^***） with increasing salinity from 0.5% to 2.5% （m/m）.

关键词： sulfide sulfur biotransformation operating parameters

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DeepFilter: A Deep Learning Based Variant Filter for VarDict

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Tsinghua Science and Technology 2023年第4期28卷 665-672页

作者： Hao Zhang Zekun Yin Yanjie Wei Bertil Schmidt weiguo liu School of Software Shandong UniversityJinan 250100China Shenzhen Research Institute of Shandong University Shenzhen 518057China Shenzhen Institute of Advanced Technology Chinese Academy of SciencesShenzhen 518055China Institute for Computer Science Johannes Gutenberg UniversityMainz 55128Germany

With the development of sequencing technologies,somatic mutation analysis has become an important component in cancer research and *** is a commonly used somatic variant caller for this *** the heuristic-based VarDict algorithm exhibits high sensitivity and versatility,it may detect higher amounts of false positive variants than callers,limiting its clinical *** address this problem,we propose DeepFilter,a deep-learning based filter for VarDict,which can filter out the false positive variants detected by VarDict *** approach trains two models for insertion-deletion mutations(InDels)and single nucleotide variants(SNVs),*** show that DeepFilter can filter at least 98.5%of false positive variants and retain 93.5%of true positive variants for InDels and SNVs in the commonly used tumor-normal paired *** code and pre-trained models are available at https://***/LeiHaoa/DeepFilter.

关键词： variant filter deep learning somatic variant

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Enhanced dielectric,ferroelectric,and optical properties in rare earth elements doped PMN-PT thin films

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Journal of Advanced Ceramics 2021年第1期10卷 98-107页

作者： Shun ZHOU Dabin LIN Yongming SU Lin ZHANG weiguo liu Thin Film and Optical Manufacturing Technology Key Laboratory of Ministry of EducationXi’an Technological UniversityXi’an 710032China Electronic Materials Research Laboratory Key Laboratory of the Ministry of Education&International Center for Dielectric ResearchSchool of Electronic Science and EngineeringFaculty of Electronic and Information EngineeringXi’an Jiaotong UniversityXi’an 710049China

Rare earth(RE=La^(3+),Sm^(3+),Pr^(3+))ion doped Pb(Mgi/3Nb2/3)O3-PbTi03(RE-PMN-PT)ferroelectric thin films with compositions near the morphotropic phase boundary were grown on the Pt/TiO_(2)/S i02/Si(100)substrate using sol-gel/spin coating *** phase structure,electrical properties,and photoluminescence performance of thin films were investigated *** highly(100)-preferred orientation was obtained in pure perovskite Sm-PMN-0.30PT thin films with an average grain size of 131 *** 2.5%Sm^(3+)doping,the PMN-0.30PT thin films exhibited a triple enhancement of dielectric permittivity with a maximum value of 3500 at 1 kHz,a low dielectric loss of 1.3%,and high remanent polarization of 17.5μC/cm^(2)at room *** visible light and near-infrared band,the transmittance rate increased with PT content and showed the highest value of 85%in 2.5%*** addition,the films presented strong red-orange emission at 599 nm,which was sensitively in temperature range of 248-273 K corresponding to the rhombohedral to monoclinic phase transition temperature.

关键词： PMN-PT rare earth doping dielectric ferroelectric photoluminescence

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Variation of soil Δδ^(13)C values in Xifeng loess-paleosol sequence and its paleoenvironmental implication

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Chinese Science Bulletin 2006年第11期51卷 1350-1354页

作者： NING Youfeng liu weiguo AN Zhisheng State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi'an 710075 China Graduate School of Chinese Academy of Sciences Beijing 100039China College of Energy and Power Engineering Xi'an Jiaotong University. Xi'an 710049 China

The carbon isotopic compositions of soil organic matter (SOM) and total carbonate (TC) in Xifeng loess-paleosol sequence have been studied. The δ 13CSOM values vary from ?23.8‰ to ?20.2‰, which are higher in interglacial than in glacial stages. Contrary to δ 13CSOM values, the δ 13CTC values vary from ?8.5‰ to ?3.6‰ and are lower in interglacial than in glacial stages. The differences (?δ 13C) be- tween the δ 13CSOM and δ 13CTC values vary from 14.1‰ to 19.4‰. Our results from the Xifeng loess- paleosol sequence indicate that the ?δ 13C values represent the ratio of primary carbonate (PC) to secondary carbonate (SC). The ?δ 13C values were high in the loess stages, and the maximal PC-to-SC ratio can reach 6:4. But in the paleosol stages, the ?δ 13C values were low, with a small proportion of PC. The ?δ 13C values in loess-paleosol sequence also indicate the contributions of the dust to the loess sediment in the Chinese Loess Plateau because the dust contains the PC.

关键词：黄土古土壤有机碳碳酸盐碳同位素

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