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nitrogen isotopes from the Neoproterozoic Liulaobei Formation,North China:Implications for nitrogen Cycling and Eukaryotic Evolution

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Journal of Earth Science 2022年第5期33卷 1309-1319页

作者： Ting Yang Xinqiang Wang Dongtao Xu Xiaoying Shi Yongbo Peng School of Earth Science and Resources China University of GeosciencesBeijing100083China State Key Laboratory of Biogeology and Environmental Geology China University of GeosciencesBeijing100083China International Center for Isotope Effect Research Nanjing UniversityNanjing210023China School of Earth Sciences and Engineering Nanjing UniversityNanjing210023China

The nitrogen isotope compositions(δ^(15)N )of sedimentary rocks can provide information about the nutrient N cycling and redox conditions that may have played important roles in biological evolution in Earth’s *** considerableδ^(15)N data for the Precambrian have been published,there is a large gap during the Early Neoproterozoic that restrains our understanding of the linkages among N cycling,ocean redox changes and biological evolution during this key ***,we report bulkδ^(15)N and organic carbon isotope(^(δ)13C_(org))compositions as well as the total nitrogen(TN)and total organic carbon(TOC)contents from the Tonian fossiliferous Liulaobei Formation in the southern part of the North China ***δ^(15)N in the study section is dominated by very stable values centering around+4.3‰,which is moderately lower than that in modern sediments(~+6‰).These positiveδ^(15)N values were attributed to partial denitrification under low primary productivity(scenario 1)and/or denitrification coupled with dissimilatory nitrate reduction to ammonium(DNRA)(scenario 2).In either case,the availability of fixed nitrogen may have provided the nutrient N required to facilitate facilitated eukaryotic *** study highlights the pivotal role of nutrient N in the evolution of eukaryotes.

关键词： Neoproterozoic Tonian Liulaobei Formation nitrogen isotopes eukaryotic evolution nutrient limitation geochemistry

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Carbon and nitrogen isotopes analysis and sources of organic matter in the upper reaches of the Chaobai River near Beijing,China

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Science China Earth Sciences 2013年第2期56卷 217-227页

作者： LU FengYun LIU ZhuQing JI HongBing Key Laboratory of Metropolitan Eco-Environment Processes College of Resource Environment and TourismCapital Normal University College of Water Conservancy & Civil Engineering China Agricultural University The State Key Laboratory of Environmental Geochemistry Institute of GeochemistryChinese Academy of Sciences

The carbon and nitrogen isotopes in the surface sediments,plants,and soil in the upper reaches of the Chaobai River have been *** results showed 27.75‰-21.58‰ and 1.32‰-6.74‰ for carbon and nitrogen isotopic ratios in the surface sediments,*** sources of sedimentary organic matter in this area are soil organic matter,aquatic vascular plants,and riverine plankton,respectively,and a significant contributor to sediment in the Chaohe River,the Baihe River,and the Miyun Reservoir areas is soil organic ***,part of sedimentary organic matter in the Miyun Reservoir is attributed to the input from the Chaohe River and the Baihe River,the other is from C4 vegetation growing around individual point stations at the Miyun *** with the situation in Hebei Province,the contribution of soil organic matter decreased significantly and river plankton and aquatic vascular plants increased significantly in Beijing municipal *** study reveals that the source of organic matter has a close relationship with the soil erosion.

关键词： carbon isotopes nitrogen isotopes organic matter Chaobai River material source

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Tracing nitrate sources in one of the world's largest eutrophicated bays(Hangzhou Bay):insights from nitrogen and oxygen isotopes

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Acta Oceanologica Sinica 2024年第6期43卷 86-95页

作者： Zhi Yang Jianfang Chen Haiyan Jin Hongliang Li Zhongqiang Ji Yangjie Li Bin Wang Zhenyi Cao Qianna Chen Key Laboratory of Marine Ecosystem Dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China

Eutrophication caused by inputs of excess nitrogen(N) has become a serious environmental problem in Hangzhou Bay(China),but the sources of this nitrogen are not well *** this study,the August 2019 distributions of salinity,nutrients [nitrate(NO_(3)^(-)),nitrite,ammonium,and phosphate],and the stable isotopic composition of NO_(3)^(-)(δ^(15)N and δ^(18)O) were used to investigate sources of dissolved inorganic nitrogen(DIN) to Hangzhou B *** distributions of nitrate,salinity,and nitrate δ^(18)O indicate that the Qiantang River,the Changjiang River,and nearshore coastal waters may all contribute nitrate to the *** on the isotopic compositions of nitrate in these potential source waters and conservative mixing of nitrate in our study area,we suggest that the NO_(3)^(- )in Hangzhou B ay was likely derived mainly from soils,synthetic N fertilizer,and manure and ***-member modeling indicates that in the upper half of the bay,the Qiantang River was a very important DIN source,possibly contributing more than 50% of DIN in the bay head *** the lower half of the bay,DIN was sourced mainly from strongly intruding coastal *** coming directly from the Changjiang River made a relatively small contribution to Hangzhou Bay DIN in August 2019.

关键词： nitrogen isotopes oxygen isotopes nitrogen cycle nitrate sources Hangzhou Bay

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Isotopic constraints confirm the significant role of microbial nitrogen oxides emissions from the land and ocean environment

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National Science Review 2022年第9期9卷 186-194页

作者： Wei Song Xue-Yan Liu Benjamin Z.Houlton Cong-Qiang Liu School of Earth System Science Tianjin University Department of Global Development and Department of Ecology and Evolutionary Biology Cornell University

nitrogen oxides(NOx,the sum of nitric oxide(NO) and N dioxide(NO2)) emissions and deposition have increased markedly over the past several decades,resulting in many adverse outcomes in both terrestrial and oceanic ***,because the microbial NOxemissions have been substantially underestimated on the land and unconstrained in the ocean,the global microbial NOxemissions and their importance relative to the known fossil-fuel NOxemissions remain *** we complied data on stable N isotopes of nitrate in atmospheric particulates over the land and ocean to ground-truth estimates of NOxemissions *** considering the N isotope effect of NOxtransformations to particulate nitrate combined with dominant NOxemissions in the land(coal combustion,oil combustion,biomass burning and microbial N cycle) and ocean(oil combustion,microbial N cycle),we demonstrated that microbial NOxemissions account for 24 ± 4%,58 ± 3% and 31 ± 12% in the land,ocean and global environment,*** amounts of microbial NOxemissions in the land(13.6 ± 4.7 Tg N yr-1),ocean(8.8 ± 1.5 Tg N yr-1) and globe(22.5 ± 4.7 Tg N yr-1) are about 0.5,1.4 and 0.6 times on average those of fossil-fuel NOx emissions in these *** findings provide empirical constraints on model predictions,revealing significant contributions of the microbial N cycle to regional NOx emissions into the atmospheric system,which is critical information for mitigating strategies,budgeting N deposition and evaluating the effects of atmospheric NOxloading on the world.

关键词： nitrogen isotopes nitrate NOx emission nitrogen deposition microbial N cycle

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Variation in δ^(15)N of a lacustrine sedimentary sequence in the Nanling Mountains and its potential implication for climatic conditions over the past ~16000 years

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Chinese Journal of Oceanology and Limnology 2013年第5期31卷 1098-1106页

作者：钟巍曹家元薛积彬欧阳军 School of Geographic Sciences South China Normal University

Although extensive studies have been performed on nitrogen isotopes in lake sediments, understanding the complexity of the δ15N variation related to past environmental and climatic conditions still remains unclear. Supported by multi-proxy records including litho-units, organic carbon isotopes, ration of total organic carbon and total nitrogen, organic matter content, bulk dry density, the accumulation rate of organic matter, median grain size, magnetic susceptibility, and Rb/Sr and Ca/Mg ratios obtained from a sedimentary sequence in a small lake （i.e., Dahu Swamp） in the eastern Nanling Mountains in South China, we deduce that variation in the δ15N values results primarily from the sources of organic matter, which are significantly influenced by climatic conditions over the past -16 000 years. A low （or high） lake level resulting from dry （or wet） conditions would lead to more （or fewer） vascular plant remains in the sediments and stronger （or weaker） denitrification associated with hypolimnetic anoxia, resulting in lower （or higher） 615N values. In addition, dry （or wet） conditions would favor weakened （or strengthened） biogeochemical activity in the catchment, which could result in less （or more） external input of δ15N-enriched OM, thus leading to decreased （or increased） δ15N values. Our results indicate that the lake sediment δ15N record in the Nanling Mountains has the potential to provide valuable insight into past East Asian monsoon climate- driven environmental changes.

关键词： nitrogen isotopes lacustrine sediments climate changes Nanling Mountains

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Coupled δ^(15)N_(TN) and δ^(13)C_(TOC) Insights into Methane Seepage Activities in Bulk Marine Sediments of the Qiongdongnan Basin, South China Sea

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Journal of Ocean University of China 2022年第6期21卷 1495-1503页

作者： MIAO Xiaoming FENG Xiuli HU Limin LI Jingrui LIU Xiting WANG Nan XIAO Qianwen WEI Jiangong College of Marine Geosciences Ocean University of Chinathe Key Laboratory of Submarine Geosciences and Prospecting TechniquesQingdao 266100China Deep-Sea Multidisciplinary Research Center&Laboratory for Marine Geology Qingdao National Laboratory for Marine Science and TechnologyQingdao 266037China MLR Key Laboratory of Marine Mineral Resources Guangzhou Marine Geological SurveyGuangzhou 510075China Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou) Guangzhou 511458China

Recently,methane seepage related to the dissociation of natural gas hydrates has attracted much attention,which has a significant impact on the study of the global carbon and nitrogen *** on the detailed geochemical analyses of sediments(core Q6)from the Qiongdongnan Basin,South China Sea,three methane seepage activities were identified and the exact horizons of anaerobic oxidation of methane(AOM)were ***,organic carbon isotopic(δ^(13)C_(TOC))levels ranged from−23.6‰–−20.6‰PDB;nitrogen isotopes(δ^(15)N_(TN))of the same sedimentary samples ranged from 1.8‰–5.3‰.We also found obvious simultaneous negative excursions of organic carbon isotopes(δ^(13)C_(TOC))and nitrogen isotopes(δ^(15)N_(TN))in the horizons of methane *** with the normal sediments,their maximum negative excursions were 2.6‰and 2.5‰,*** discuss in detail the various characteristics ofδ^(15)N_(TN) andδ^(13)C_(TOC) levels in sediments and their coupling responses to methane seepage *** believe that the methane seepage events changed the evolution trajectory ofδ^(15)N_(TN) andδ^(13)C_(TOC) levels in sediment records,which resulted in the simultaneous negative *** phenomenon is of great significance to reveal the historical dissociation of natural gas hydrates and their influence on the deep-sea carbon and nitrogen pool.

关键词： methane seepage TS/TOC nitrogen isotopes organic carbon isotopes South China Sea

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Influencing factors and significance of organic and inorganic nitrogen isotopic compositions in lacustrine sedimentary rocks

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Geoscience Frontiers 2023年第2期14卷 27-39页

作者： Juan Chen Jianfa Chen Lipeng Yao Qingyong Luo Shengbao Shi Jianping Chen Lei Zhu Zeya Chen Key Laboratory of Environment Change and Resources Use in Beibu Gulf(Nanning Normal University) Ministry of EducationNanning 530001China State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum(Beijing)Beijing 102249China Research Institute of Petroleum Exploration and Development PetroChinaBeijing 100083China

Comprehensive nitrogen biogeochemical cycle has been reconstructed for representative lacustrine organic-rich sedimentary rock in China,namely the Triassic Yanchang Formation(YF,199–230 Ma)in Ordos and the Cretaceous Qingshankou Formation(QF,86–92 Ma)in Songliao basins,by evaluating the organic and inorganic nitrogen isotopic compositions rather than only organic or bulk nitrogen isotopic *** results indicate that the nitrogen isotope values of bulk rock(δ^(15)N_(bulk))in the non-metamorphic stage are significantly different from that of kerogen,which challenge the conceptual framework of sedimentary nitrogen isotope ***δ^(15)N_(bulk)from the YF and QF were lower than their respective the nitrogen isotope values of kerogen(δ^(15)N_(ker)),with offsets up to5.1‰,which have the inverse relationship for the metamorphosed *** evolution did not significantly modify the d15N of bulk rock and *** d15N of sediments from the YF(δ^(15)N_(bulk),1.6‰–5.6‰)were lower than that of rock from the QF(δ^(15)N_(bulk),10.2‰–15.3‰).The nitrogen isotope values of silicate incorporated nitrogen(δ^(15)N_(sil))were slightly lower than those of the d15Nker in the YF and obviously lower for the *** fact that different nitrogen cycles occur in the YF and QF due to the different depositional redox conditions leads to different isotopic *** YF water environment dominated by oxic conditions is not conducive to the occurrence of denitrification and anammox,and no abundant N2 loss leads to the relatively lightδ^(15)N_(bulk).In the stratified water for the QF,redox transition zone promotes denitrification and anammox,resulting in the heavyδ^(15)N_(bulk)of rock and promotes the DNRA,resulting in heavyδ^(15)N_(ker)and lowδ^(15)N_(sil).

关键词： nitrogen isotopes Bulk rock Kerogen Extracted organic matter Thermal maturation nitrogen biogeochemical cycle

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nitrogen isotope stratigraphy of the Early Cambrian successions in the Tarim Basin:Spatial variability of nitrogen cycling and its implication for paleo-oceanic redox conditions

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Acta Geochimica 2024年第4期43卷 785-801页

作者： Bi Zhu Xuefeng Li Lu Ge Yongquan Chen Institute of Earth’s Critical Zone School of Earth Sciences and EngineeringHohai UniversityNanjing 210098China Research Institute of Exploration and Development Tarim Oil Field CompanyPetroChinaKorlaChina

The Early Cambrian represents a critical time period characterized by extraordinary biological innovations and dynamic redox conditions in *** isotopic signatures of ancient sediments have the potential to elucidate the evolutionary path of marine redox states and the biogeochemical nitrogen cycle within the water column of the Early Cambrian *** existing research on this topic has predominantly focused on South China,the exploration of other continental margins has been limited,leaving contradictory hypotheses *** this study,pairedδ^(15)N andδ^(13)C org analyses were performed on the Lower Cambrian successions from the Shiairike section(inner ramp)and Well Tadong 2(deep shelf/basin)in the northwestern and eastern Tarim Basin,*** data from the Shiairike section reveal a discernible shift in the operation of different nitrogen cycles for the black chert-shale unit,also referred to as the black rock series in Chinese literature,of the Yurtus Formation(Fortunian stage to lower Stage 3).Oscillatingδ^(15)N values for its lower part are suggestive of alternating anaerobic assimilation of NH 4+and denitrification/*** is likely attributed to a shallow,unstable chemocline consistent with the upwelling and incursion of deep,anoxic waters during a major *** contrast,aerobic nitrogen cycling,indicated by positiveδ^(15)N values of>2‰,dominated the upper part alongside a reduction in upwelling *** the other hand,theδ^(15)N signatures of Xishanbulake and Xidashan Formations of Well Tadong 2,which encompass a time interval from the Cambrian Fortunian Age to Age 4,are indicative of N_(2)fixation by diazotrophs as the major nitrogen *** two studied intervals,although not time-equivalent,exhibit separated states of nitrogen cycling at least during the deposition of the Yurtus black rock *** spatially different nitrogen cycling of the studied sections is compatible with a redox-stratified ocean dur

关键词： nitrogen isotopes Early Cambrian Tarim Black rock series

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Relative importance of climatic and edaphic factors as drivers of plantδ^(15)N along a longitudinal transect

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Ecosystem Health and Sustainability 2022年第1期8卷 94-108页

作者： Xianzhao Liu Tianhao Wang and Qing Su School of Geosciences and Spatial Information Hunan University of Science and TechnologyXiangtanHunanChina

Many studies have shown that climatic and edaphic factors influence the variations in nitrogen isotopes(δ^(15)N)in terrestrial ***,the relative importance of co-varying climatic and edaphic controls on plantδ^(15)N remains somewhat *** address this issue,regional-scale plant(***)and soil samples were collected along a longitudinal transect across the temperate grasslands in northern *** influences of climatic and edaphic factors on the plantδ^(15)N were disentangled using the variable importance in projection(VIP)*** found that the climatic and edaphic variables explained 52.4%and 31.2%,respectively,of the variation in plantδ^(15)*** mean annual precipitation(MAP),soil N,and mean annual temperature(MAT)were the most important variables,but the soil water content(SWC),aridity index(AI),and soil clay content were also important *** soil pH and soil C:N ratios were identified as unimportant ***,a high-performance model for simulating plantδ^(15)N values was constructed based on the important variables(VIP>0.8).Further investigations should focus on the effects of the interaction between the climatic and edaphic variables on the N cycles in the temperate grasslands to provide more reliable predictions of plantδ^(15)N.

关键词： Relative importance nitrogen isotopes climatic variables edaphic variables L.chinensis

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