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铁还原细菌矿化产物及其对铁建造沉积的指示意义

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岩石学报 2024年第4期40卷 1299-1310页

作者：韩晓华潘永信中国科学院地质与地球物理研究所地球与行星物理院重点实验室北京100029 中国科学院大学地球与行星科学学院北京100049

铁还原细菌是微生物诱导矿化的典范之一,它可以利用有机质或氢气作为电子供体还原三价铁,并在细胞外矿化形成多种含铁矿物,比如磁铁矿、菱铁矿、蓝铁矿和绿锈等矿物,从而广泛参与自然界中铁元素的生物地球化学循环过程。本文主要介绍铁... 详细信息

铁还原细菌是微生物诱导矿化的典范之一,它可以利用有机质或氢气作为电子供体还原三价铁,并在细胞外矿化形成多种含铁矿物,比如磁铁矿、菱铁矿、蓝铁矿和绿锈等矿物,从而广泛参与自然界中铁元素的生物地球化学循环过程。本文主要介绍铁还原细菌矿化产物的矿物特征、形成条件和影响因素。此外,通过实验室内建立严格厌氧的环境体系,以与微量元素共沉淀的水合氧化铁为底物,本研究分别利用Feap2+和铁还原细菌Shewanella oneidensis MR-4合成非生物成因和生物成因的磁铁矿,结果发现微量元素的存在会改变磁铁矿的形貌和粒径。结合前人提出的微生物可能参与铁建造沉积的过程,本文评估了微量元素作为识别矿物成因指标的有效性,探讨铁还原细菌矿化产物对铁建造沉积的潜在贡献。

关键词：铁还原细菌铁建造磁铁矿菱铁矿微量元素

On the biospheric effects of geomagnetic reversals

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National Science Review 2023年第6期10卷 49-51页

作者： yongxin pan Jinhua Li Key Laboratory of Earth and Planetary Physics Institute of Geology and Geophysics Chinese Academy of Sciences

Unlike its neighbouring planets Mars and Venus,Earth has a global magnetic *** geomagnetic field effectively protects life from the solar wind and cosmic radiation,prevents atmospheric erosion and water loss,and thus Earth makes for a habitable planet [1].The geomagnetic field also provides useful clues to orientation and navigation for a diverse group of organisms,from bacteria to vertebrates.

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Link between the geomagnetic polarity reversal and global-geology events

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Chinese Science Bulletin 1999年第20期44卷 1843-1851页

作者： Rixiang Zhu Qingsong Liu yongxin pan Chinese Acad Sci Inst Geophys Beijing 100101 Peoples R China

The origin of the earth’s magnetic field is one of the five most important unsolved problems in physics, especially geomagnetic polarity reversal remains one of Nature’s most enigmatic phenomena. It is proposed that the geomagnetic polarity reversal links with some global-geology events, although it is difficult to clarify the mechanism of this correlation. The history of continental structures in eastern China would be also linked with some global-geology events.

关键词： geomagnetic reversal paleointensity global-geology event.

Magnetic properties related to thermal treatment of pyrite

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Science China Earth Sciences 2008年第8期51卷 1144-1153页

作者： WANG Lei pan yongxin LI JinHua QIN HuaFeng Paleomagnetism and Geochronology Laboratory(SKL-LE) Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Graduate University Chinese Academy of SciencesBeijing 100049China Key Laboratory of the Study of Earth’s Deep Interior Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China

Detailed rock magnetic experiments were conducted on high-purity natural crystalline pyrite and its products of thermal treatments in both argon and air atmospheres. In argon atmosphere (reducing environment), the pyrite is altered by heating to magnetite and pyrrhotite; the latter is stable in argon atmosphere, and has coercive force and coercivity of remanence of ～20 and ～30 mT, respectively. Whereas in air, the pyrite is ultimately oxidized to hematite. First order reversal curve (FORC) diagram of the end product shows that the remanence coercivity of hematite is up to ～1400 mT. The corresponding thermal transformation process of pyrite in air can be simply summarized as pyrite→ pyrrhotite→magnetite→hematite. These results are helpful for understanding of sedimentary magnetism, secondary chemical remanence and meteorolite magnetic properties.

关键词： pyrite pyrrhotite magnetite hematite thermal alteration rock-magnetic properties

Determination of the heating efficiency of magnetotactic bacteria in alternating magnetic field

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Journal of Oceanology and Limnology 2021年第6期39卷 2116-2126页

作者： Tongwei ZHANG Huangtao XU Jia LIU yongxin pan Changqian CAO Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsInnovation Academy for Earth ScienceChinese Academy of SciencesBeijing 100029China Innovation Academy for Earth Science Chinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China France-China Joint Laboratory for Evolution and Development of Magnetotactic Multicellular Organisms Chinese Academy of SciencesBeijing 100029China

Magnetotactic bacteria(MTB)intact cells have been applied in magnetic hyperthermia therapy of tumor,showing great efficiency in heating for tumor cell ***,the detailed magnetic hyperthermia properties and optimum heat production conditions of MTB cells are still poorly understood due to lack of standard measuring *** specific absorption rate(SAR)of MTB cells is often measured by home-made equipment at a limited frequency and magnetic field *** this study,we have used a commercial standard system to implement a comprehensive study of the hyperthermic response of Magnetospirillum gryphiswaldense MSR-1 strain under 7 frequencies of 144-764 kHz,and 8 field amplitudes between 10 and 45 kA/*** measurement results prove that the SAR of MTB cells increases with magnetic field frequency and amplitude within a certain *** combination with the magnetic measurements,it is determined that the magnetic hyperthermia mechanism of MTB mainly follows the principle of hysteresis loss,and the heat efficiency of MTB cells in alternating magnetic field are mainly aff ected by three parameters of hysteresis loop,saturation magnetisation,saturation remanent magnetisation,and *** when we culture MTB in LA-2 medium containing sodium nitrate as source of nitrogen,the SAR of MTB LA-2 cells with magnetosomes arranged in chains can be as high as 4925.6 W/g(in this work,all SARs are calculated with iron mass)under 764 kHz and 30 kA/m,which is 7.5 times than current commercial magnetic particles within similar size range.

关键词： magnetotactic bacteria(MTB) hyperthermia rock magnetism alternating magnetic field(AMF)

A recording phase lag between ocean and continent climate changes: constrained by the Matuyama/Brunhes polarity boundary

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Chinese Science Bulletin 1998年第19期43卷 1593-1599页

作者： Rixiang Zhu yongxin pan Bin Guo Qingsong Liu Chinese Acad Sci Inst Geophys Beijing 100101 Peoples R China

The Matuyama/Brunhes polarity boundary (MBPB) is recorded in Chinese loess L8, which is associated with the glacial period. It is proved that loess L8 is capable of recording earth’s secular variation, and the lock-in depth in Chinese loess is no more than that of marine sediments. Comparison with the location of MBPB in Chinese loess and marine sediments, it is put forward that there is a recording phase lag between ocean and continent climate changes.

关键词： geomagnetic polarity transition paleoclimate loess.

Response of atmospheric carbon dioxide to the secular variation of weakening geomagnetic field in whole atmosphere simulations

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Earth and Planetary Physics 2021年第4期5卷 327-336页

作者： Xu Zhou XinAn Yue Han-Li Liu Yong Wei yongxin pan Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Innovation Academy for Earth Science Chinese Academy of SciencesBeijing 100029China Beijing National Observatory of Space Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China High Altitude Observatory National Center for Atmospheric ResearchBoulderCOUSA

Responses of atmospheric carbon dioxide(CO_(2))density to geomagnetic secular variation are investigated using the Whole Atmosphere Community Climate Model-eXtended(WACCM-X).Our ensemble simulations show that CO_(2) volume mixing ratios(VMRs)increase at high latitudes and decrease at mid and low latitudes by several ppmv in response to a 50%weakening of the geomagnetic *** significant changes in CO_(2) are mainly found above~90 km altitude and primarily redetermine the energy budget at~100-110 *** analysis of transformed Eulerian mean(TEM)circulation found that CO_(2) change is caused by enhanced upwelling at high latitudes and downwelling at mid and low latitudes as a result of increased Joule *** further analyzed the atmospheric CO_(2) response to realistic geomagnetic weakening between 1978 and 2013,and found increasing(decreasing)CO_(2) VMRs at high latitudes(mid and low latitudes)*** the first time,our simulation results demonstrate that the impact of geomagnetic variation on atmospheric CO_(2) distribution is noticeable on a time scale of decades.

关键词： atmospheric carbon dioxide geomagnetic fields whole atmosphere simulation upper atmosphere

Magnetic polarity ages of the fossil-bearing strata at the Sihetun section,West Liaoning:A preliminary result

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Chinese Science Bulletin 2001年第17期46卷 1473-1476页

作者： pan yongxin ZHU Rixiang John Shaw ZHOU Yaoxiu Institute of Geology and Geophysics Chinese Academy of SciencesBeijing 100101China Geomagnetism Laboratory University of LiverpoolLiverpool L69 7ZEUK The Aviatic Remote Sensing Center Ministry of Land and ResourcesBeijing 100083China

Rock-magnetic and palaeomagnetic studies have been carried out on the interval of famous fossil-bearing sedimentary rocks and its overlying basalts and underlying basalts at the Sihetun section, West Liaoning Province. Normal polarity was obtained for the sedimentary interval and the underlying basalts, while reversed polarity was found in the overlying basalts. Taking account of the new 40Ar/39Ar ages (Swisher et al., 1999), we classified the fossil-bearing sedimentary interval into the Barremian M3n zone (Early Cretaceous age). Several abnormal horizons on magnetic properties, probably corresponding to the tuffs, were observed in the fossil-bearing sedimentary interval. This implies that the massive bio-extinction may link to dramatic environmental changes that were caused by volcanic eruptions.

关键词： magnetic polarity age Jehol fauna Sihetun section.

Magnetic susceptibility variation and AMS exchange related to thermal treatment of siderite

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Chinese Science Bulletin 1999年第12期44卷 1135-1139页

作者： yongxin pan Rixiang Zhu Qingsong Liu Bin Guo Chinese Acad Sci Inst Geophys Beijing 100101 Peoples R China

Siderite is one of the common iron-bearing carbonates in deposits. Its magnetic properties are usually neglected due to its paramagnetic property at room temperature. It was shown that the magnetic susceptibility changes with temperature variation. Also it was revealed that the maximum axis (K1) of AMS ellipsoid exchange position gradually with the minimum axis (K3) during thermal treatment, and thus, AMS ellipsoids of samples change from initial prolate to oblate. It was concluded that such changes resulted from the decomposition and oxidation of siderite during heating in which siderite was transformed into magnetite, maghemite, and finally to hematite.

关键词： siderite. AMS exchange thermal treatment susceptibility.