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Volatiles in the mantle transition zone and their effects on big mantle wedge systems

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National Science Review 2024年第06期11卷 15-18页

作者： Yu Wang Yi-Gang Xu State Key Laboratory of Isotope geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences Southern Marine Science and Engineering Guangdong Laboratory (guangzhou)

The mantle transition zone (MTZ), located between the upper and lower mantle, is characterized by sudden seismicvelocity discontinuities at depths of 410 and 660 km where significant change in mineralogical composition occurs. As a link between the upper and lower mantle,the MTZ is a layer of special significance in Earth’s deep structure, and a critical interface in geodynamics and material circulation.

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The origin and evolution of Earth's nitrogen

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National Science Review 2024年第06期11卷 56-75页

作者： Yuan Li State Key Laboratory of Isotope geochemistry Guangzhou Institute of GeochemistryChinese Academy of Sciences Bayerisches Geoinstitut Universit?t Bayreuth

Nitrogen is a vital element for life on Earth. Its cycling between the surface(atmosphere + crust) and the mantle has a profound influence on the atmosphere and climate. However, our understanding of the origin and evolution of Earth's nitrogen is still incomplete. This review presents an overview of the current understanding of Earth's nitrogen budget and the isotope composition of different reservoirs, laboratory constraints on deep nitrogen geochemistry, and our understanding of the origin of Earth's nitrogen and the deep nitrogen cycle through plate subduction and volcanism. The Earth may have acquired its nitrogen heterogeneously during the main accretion phase, initially from reduced, enstatite-chondrite-like impactors,and subsequently from increasingly oxidized impactors and minimal CI-chondrite-like materials. Like Earth's surface, the mantle and core are also significant nitrogen reservoirs. The nitrogen abundance and isotope composition of these three reservoirs may have been fundamentally established during the main accretion phase and have been insignificantly modified afterwards by the deep nitrogen cycle, although there is a net nitrogen ingassing into Earth's mantle in modern subduction zones. However, it is estimated that the early atmosphere of Earth may have contained ～1.4 times the present-day atmospheric nitrogen(PAN),with ～0.4 PAN being sequestered into the crust via biotic nitrogen fixation. In order to gain a better understanding of the origin and evolution of Earth's nitrogen, directions for future research are suggested.

关键词： nitrogen isotopes silicate Earth atmosphere magma ocean

Unraveling the mysteries of volatile cycling and habitability on Earth and beyond

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National Science Review 2024年第06期11卷 8-9页

作者： Yi-Gang Xu Ri-Xiang Zhu Min-Han Dai State Key Laboratory of Isotope geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences State Key Laboratory of Lithosphere Evolution Institute of Geology and Geophysics Chinese Academy of Sciences State Key Laboratory of Marine Environmental Science Xiamen University

The origin and cycling of volatiles, including water, carbon dioxide, and nitrogen, are fundamental to the very existence of habitable planets. These volatile compounds, often taken for granted,are the lifeblood of planetary systems, influencing almost everything from atmospheric composition and climate regulation to deep Earth processes and the emergence of life.

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The influence of silica on reaction rates and molecular hydrogen(H_(2))generation during olivine hydrothermal alteration

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Science China Earth Sciences 2024年第1期67卷 222-233页

作者： Ruifang HUANG Weidong SUN Xing DING Yusheng ZHAO Yibing LI Xiuqi SHANG CAS Key Laboratory of Ocean and Marginal Sea Geology South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China SUSTech Academy for Advanced Interdisciplinary Studies Southern University of Science and TechnologyShenzhen 518055China Center of Deep Sea Research Institute of OceanologyChinese Academy of SciencesQingdao 266071China State Key Laboratory of Isotope geochemistry Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China Institue of Geology Chinese Academy of Geological SciencesBeijing 100037China

Hydrothermal alteration of olivine greatly influences geodynamics and the recycling of volatiles(such as water and carbon)in subduction *** is an important component of geological fluids,and its influence on the hydrothermal alteration of olivine remains poorly *** this study,we performed experiments at 300–515℃ and 3.0 kbar(1 bar=10^(5)Pa)by reacting well homogenized mixtures of olivine and silica powders with saline solutions(0.5 mol L^(−1)NaCl).Silica greatly influences the reaction pathways,reaction rates,and molecular hydrogen(H_(2))formation during olivine hydrothermal *** experiments at 300℃ and 3.0 kbar with mixtures of olivine and 10 wt%silica,olivine was replaced by serpentine and *** proportions of serpentine and talc were determined according to standard curves based on infrared spectroscopy *** 6.5%serpentine and 12%talc were produced after an experimental duration of 7 days,which had no change after a longer period(14 days).Compared to the kinetics in silica-free systems,the rates of olivine hydrothermal alteration in experiments with 10 wt%silica are much *** overall reaction is:4.5Forsterite+5.5SiO_(2),aq+4H_(2)O=Serpentine+*** the addition of more silica(20 wt%and 40 wt%),olivine was transformed into *** rates of reaction were much faster,e.g.,for experiments with olivine and 20 wt%silica,43%of talc was produced after 14 days,which increased to 77%for experiments with 40 wt%silica over the same *** overall reaction is:3Forsterite+5SiO_(2),aq+2H_(2)O=*** experiments at 400–505℃ and 3.0 kbar,the promoting effect of silica on olivine hydrothermal alteration was also observed,which is closely associated with a decrease in Gibbs free energies of olivine hydrothermal *** 300℃ and 3.0 kbar,silica decreased H_(2)formed during olivine hydrothermal alteration by around an order of magnitude,resulting in an increase in oxygen *** on measured H_(2),we calibrated ox

关键词： Olivine hydrothermal alteration Silica Serpentinization Hydrogen Serpentine

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Extractable and kerogen-bound hopanoids from typical Eocene oil shales in China

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Energy Geoscience 2024年第2期5卷 171-179页

作者： Changbo Zhai Zhirong Zhang John K.Volkman Hong Lu Yan'e Chen SINOPEC Key Laboratory of Petroleum Accumulation Mechanisms Wuxi Institute of Petroleum GeologySINOPEC2060 Lihu RoadWuxiJiangsu213126China SINOPEC Petroleum Exploration and Production Research institute 31 Xueyuan RoadBeijing100083China State Key Laboratory of Organic geochemistry Guangzhou Institute of GeochemistryChinese Academy of ScienceGuangzhou510640GuangdongChina

This study conducted a comparative analysis of extractable hopanoid hydrocarbons and those released via stepwise pyrolysis of typical Eocene immature oil shales in China,namely the Huadian,Maoming,and Fushun *** the Huadian and Maoming shales exhibit immature indicators in extractable and kerogen-bound hopanoids(notably,high abundance of C_(29)to C_(32)17β,21β-hopanes and unsaturated hopenes).In contrast,the Fushun oil shale's hopanoids from extracts and pyrolyzates suggest a higher maturity *** absence of neohopenes in the pyrolyzates of the shales underpins that the kerogenbound hopanoid skeletons resist ***,the Huadian oil shale's asymmetric distribution of C_(29)and C_(30)hopenes and neohopenes hints at the presence of an additional *** unsaturated hopenes,such as hop-20(21)-enes,identified in pyrolyzates of the three kerogens at various pyrolysis temperatures,reveal the occurrence of double bonds in kerogen-bound hopanoid skeletons without methyl *** absence of hop-20-(21)-ene in extracts suggests that it might act as an intermediate of these novel hopenes during the epimerization of hopanoid skeletons within *** extractable and pyrolytic hopanoids'stereochemical alignment indicates that epimerization may occur in both ring systems and alkyl side chains of kerogen-bound hopanoid *** stepwise pyrolysis proves to be a quick screening method for geological hopanoids without causing any significant alteration to the original skeletons even when cracking multiple covalent bonds is necessary.

关键词： Hopanoid Hopane Hopene Neohopene Stepwise pyrolysis Kerogen Eocene oil shale

Low-latitude hydroclimate changes related to paleomagnetic variations during the Holocene in coastal southern China

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Frontiers of Earth Science 2024年第2期18卷 324-335页

作者： Tingwei ZHANG Xiaoqiang YANG Jian YIN Qiong CHEN Jianfang HU Lu WANG Mengshan JU Qiangqiang WANG School of Earth Science and Engineering/Guangdong Provincial Key Laboratory of Geodynamics and Geohazards/Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Sun Yat-sen UniversityGuangzhou 510275China institute of Cultural Heritage Shandong UniversityQingdao 266237China State Key Laboratory of Organic geochemistry Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China College of Urban and Environmental Sciences Peking UniversityBeijing 100871China institute of Oceanology Chinese Academy of SciencesQingdao 266071China

The variations in precipitation have displayed a complex pattern in different regions since the *** formation processes may have a significant impact on precipitation,especially during the tropical marine processes and summer monsoon which convey abundant water vapor to coastal southern China and inland ***,we use two 7500 year sedimentary records from the Pearl River Delta and the closed Maar Lake,respectively,in coastal southern China to reconstruct the mid-to-late-Holocene humidity variability and explore its possible relationship with cloud cover modulated by the Earth’s magnetic fields(EMF).Our proxy records document an apparent increase in wetness in coastal southern China between 3.0 and 1.8 kyr *** apparent increase in humidity appears to be consistent with the lower virtual axial dipole moments and,in turn,with a lower *** correlation suggests that the EMF might have been superimposed on the weakened monsoon to regulate the mid-to-late-Holocene hydroclimate in coastal southern China through the medium of galactic cosmic rays,aerosols,and cloud ***,further investigations are needed to verify this interaction.

关键词： hydroclimate variations Earth’s magnetic field coastal southern China the Holocene epoch

Assessment of tree-ring mercury radial translocation and age effect in Masson pine:Implications for historical atmospheric mercury reconstruction

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Journal of Environmental Sciences 2024年第4期138卷 266-276页

作者： Xu Liu Xun Wang Dingyong Wang College of Resources and Environment Southwest UniversityChongqing 400715China State Key Laboratory of Environmental geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China

The tree ring has been regarded as an emerging archive to reconstruct historical atmospheric mercury(Hg)trends,but with the large knowledge gaps in the *** this study,we comprehensively evaluated the Hg source,radial translocation and age effect of Masson pine(Pinus massoniana)tree ring at *** in Chongqing,to assess the suitability of such tree ring as the archive of atmospheric *** showed that distinct variabilities among Masson pine tree-ring Hg concentration *** Hg concentration significantly increased along with stem height(P<0.05),indicating the Hg in tree rings mainly derived from foliage uptake atmospheric *** found a distinct age effect that the tree ring of young trees had the higher Hg ***,we used the advection-diffusion model to demonstrate how Hg concentration shifted by the advection or/and diffusion in tree *** modeling results showed that the advection induced radial translocation during the young growth period of tree was a plausible mechanism to result in the tree-ring Hg record largely different from the trend of anthropogenic Hg emissions in *** finally suggest that in further Hg dendrochemistry,better discarding the tree-ring Hg profile of the young growth period to reduce impacts of the radial translocation and age effect.

关键词： Masson pine Tree-ring mercury Radial translocation Tree age effect

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Effects of zero-valent iron added in the flooding or drainage process on cadmium immobilization in an acid paddy soil

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Journal of Environmental Sciences 2024年第4期138卷 19-31页

作者： Hanbing Meng Shiwen Hu Zebin Hong Wenting Chi Guojun Chen Kuan Cheng QiWang Tongxu Liu Fangbai Li Kexue Liu Yang Yang guangzhou institute of geochemistry Chinese Academy of SciencesGuangzhou 510640China National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and ManagementInstitute of Eco-environmental and Soil SciencesGuangdong Academy of SciencesGuangzhou 510650China School of Resources and Planning Guangzhou Xinhua UniversityGuangzhou 510310China University of Chinese Academy of Sciences Beijing 100049China

Zero-valent iron(ZVI)is a promising material for the remediation of Cd-contaminated paddy ***,the effects of ZVI added during flooding or drainage processes on cadmium(Cd)retention remain ***,Cd-contaminated paddy soil was incubated for 40days of flooding and then for 15 days of drainage,and the underlying mechanisms of Cd immobilization coupled with Fe/S/N redox processes were *** addition of ZVI to the flooding process was more conducive to Cd *** potential available Cd was detected by adding ZVI before flooding,which may be due to the increase in paddy soil pH and newly formed secondary Fe ***,the reductive dissolution of Fe minerals promoted the release of soil colloids,thereby increasing significantly the surface sites and causing Cd ***,the addition of ZVI before flooding played a vital role in Cd retention after soil *** contrast,the addition of ZVI in the drainage phase was not conducive to Cd retention,which might be due to the rapid decrease in soil pH that inhibited Cd adsorption and further immobilization on soil *** findings of this study demonstrated that Cd availability in paddy soil was largely reduced by adding ZVI during the flooding period and provide a novel insight into the mechanisms of ZVI remediation in Cd-contaminated paddy soils.

关键词： Paddy soil Zero-valent iron Cadmium Flooding and drainage Remediation

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Laboratory studies on the infectivity of human respiratory viruses:Experimental conditions,detections,and resistance to the atmospheric environment

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Fundamental Research 2024年第3期4卷 471-483页

作者： Yaohao Hu Shuyi Peng Bojiang Su Tao Wang Juying Lin Wei Sun Xiaodong Hu Guohua Zhang Xinming Wang Ping'an Peng Xinhui Bi State Key Laboratory of Organic geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China University of Chinese Academy of Sciences Beijing 100049China Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control Guangzhou 510640China

The environmental stability of infectious viruses in the laboratory setting is crucial to the transmission potential of human respiratory *** experimental techniques or conditions used in studies over the past decades have led to diverse understandings and predictions for the stability of viral infectivity in the atmospheric *** this paper,we review the current knowledge on the effect of simulated atmospheric conditions on the infectivity of respiratory viruses,mainly focusing on influenza viruses and coronaviruses,including severe acute respiratory syndrome coronavirus 2 and Middle East respiratory syndrome ***,we summarize the impact of the experimental conditions on viral stability;these involve the methods of viral aerosol generation,storage during aging and collection,the virus types and strains,the suspension matrixes,the initial inoculum volumes and concentrations,and the drying ***,we summarize and discuss the detection methods of viral infectivity and their ***,we integrate the results from the reviewed studies to obtain an overall understanding of the effects of atmospheric environmental conditions on the decay of infectious viruses,especially aerosolized ***,this review highlights the knowledge gaps in predicting the ability of viruses to maintain infectivity during airborne transmission.

关键词： Respiratory viruses Viral infectivity Laboratory simulation Atmospheric environmental condition Airborne transmission