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Responses of Nutrients to the Precipitation Variation and Land Use in Subtropical Monsoonal Small Mountainous Rivers:A Case Study of Baixi Watershed

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Journal of Ocean University of China 2024年第2期23卷 383-391页

作者： TIAN Yuan GAO Fei CAO Ke LV Shenghua DUAN Xiaoyong YIN Ping Qingdao Institute of Marine geology China Geological SurveyMinistry of Natural ResourcesQingdao 266237China laboratory for Marine geology Laoshan LaboratoryQingdao 266237China

Small mountainous rivers are characterized by large instantaneous fluxes and susceptible to extreme weather events,which can rapidly transport materials into the sea and have a significant impact on the ecological environment of estuaries and bays.In order to investigate the seasonal characteristics of nutrients in small mountainous rivers in the subtropical monsoon region and the output pattern to the sea during heavy precipitation,surveys on the mountainous rivers were carried out in Baixi watershed in August 2020(wet season),March 2021(dry season)and June 2021(Meiyu period).The results showed that the dissolved inorganic nitrogen(DIN)of the rivers has an average concentration of 752μg L^(−1)in the wet season and 1472μg L^(−1)in the dry season.The concentrations of dissolved inorganic phosphorus(DIP)in wet season and dry season were 63μg L^(−1)and 51μg L^(−1),respectively.Influenced by the changes of land use in sub-watersheds,DIN concentrations in the mainstream increased from 701μg L^(−1)in the upper reaches to 1284μg L^(−1)in the middle reaches.Two rainstorms during the Meiyu period in the watershed caused the pulse runoff in the river.The maximum daily runoff reached 70 times that before rains.The maximum daily fluxes of DIN and DIP were 109 and 247 times that before rains,respectively.In view that the watershed experienced several rainstorms in the wet season,the river,with pulse runoff,carries a large amount of nutrients into the sea in a short time,which will have a significant impact on the environment of Sanmen bay and its adjacent sea.

关键词： small mountainous river uneven precipitation rainstorm pulse runoff nitrogen and phosphorus

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Assessment of Different Digestion Procedures for Mo Isotope Measurements of Black and Grey Shales Using the Double Spike Technique

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Journal of Earth Science 2022年第1期33卷 76-81页

作者： Jin Li Xiangkun Zhu Suohan Tang MNR Key laboratory of Isotope geology MNR Key Laboratory of Deep-Earth DynamicsInstitute of GeologyChinese Academy of Geological SciencesBeijing 100037China

This study investigates the behavior of Mo and Mo isotopes (δ^(98)Mo) in shales following leaching with HCl and HNO_(3) with the aim of simplifying the shale dissolution procedure.Up to 6%of the Mo was lost and the Mo isotopes were unaffected when shales were leached using 9 M HCl after ashing.Bulk sample digestion or leaching by 4 M or more concentrated HCl after ashing were all found to be acceptable and reliable approaches to the analysis of Mo isotopes in shales.After black shale (CAGS-BS) was leached with 2 M HCl,1 M HCl,and 9 M HNO_(3),the Mo concentration ([Mo]) in the leachate was lower and δ^(98)Mo was heavier than that obtained from bulk digestion.A Mo isotope mass-balance model showed that the δ^(98)Mo in the residues was lighter than the δ^(98)Mo from the bulk digestion of CAGS-BS and of crustal igneous rocks.No more Mo was lost,nor did Mo isotope fractionation,if the double spike was added before rather than after ashing and followed by bulk digestion or leaching with 9 M HCl.For efficiency,leaching using 4 M or more concentrated HCl after ashing is preferred for Mo isotope measurements.

关键词： Mo isotopes double spike ashing bulk digestion leaching

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Calcification of planktonic foraminifer Neogloboquadrina pachyderma(sinistral) controlled by seawater temperature rather than ocean acidification in the Antarctic Zone of modern Sothern Ocean

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Science China Earth Sciences 2022年第9期65卷 1824-1836页

作者： Qianwei SONG Bingbin QIN Zheng TANG Yanguang LIU Zhihua CHEN Jingteng GUO Zhifang XIONG Tiegang LI Key laboratory of Marine geology and Metallogeny First Institute of OceanographyMinistry of Natural ResourcesQingdao 266061China laboratory for Marine geology Pilot National Laboratory for Marine Science and TechnologyQingdao 266237China

Neogloboquadrina pachyderma(sinistral), the dominant planktonic foraminiferal species in the mid-to-high latitude oceans, represents a major component of local calcium carbonate(CaCO) production. However, the predominant factors,governing the calcification of this species and its potential response to the future marine environmental changes, are poorly understood. The present study utilized an improved cleaning method for the size-normalized weight(SNW) measurement to estimate the SNW of N. pachyderma(sin.) in surface sediments from the Amundsen Sea, the Ross Sea, and the Prydz Bay in the Antarctic Zone of the Southern Ocean. It was found that SNW of N. pachyderma(sin.) is not controlled by deep-water carbonate dissolution post-mortem, and can be therefore, used to reflect the degree of calcification. The comparison between N. pachyderma(sin.) SNW and environmental parameters(temperature, salinity, nutrient concentration, and carbonate system) in the calcification depth revealed that N. pachyderma(sin.) SNWs in the size ranges of 200–250, 250–300, and 300–355 μm are significantly and positively correlated with seawater temperature. Moreover, SNW would increase by ~30% per degree increase in temperature, thereby suggesting that the calcification of N. pachyderma(sin.) in the modern Antarctic Zone of the Southern Ocean is mainly controlled by temperature, rather than by other environmental parameters such as ocean acidification. Importantly, a potential increase in calcification of N. pachyderma(sin.) in the Antarctic Zone to produce CaCOwill release COinto the atmosphere. In turn, the future ocean warming will weaken the ocean carbon sink, thereby generating positive feedback for global warming.

关键词： Planktonic foraminiferal SNW Sonication CaCO3 production Ocean carbon cycle Climate change

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Titanium Isotope Analysis of Igneous Reference Materials using a Double-spike MC-ICP-MS Method

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Acta Geologica Sinica(English Edition) 2022年第2期96卷 517-524页

作者： LI Jin TANG Suohan ZHU Xiangkun MA Jianxiong ZHAO Xinmiao MNR Key laboratory of Isotope geology Institute of GeologyChinese Academy of Geological SciencesBeijing 100037China State Key laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China

Ti separation was achieved by ion-exchange chromatography using Bio-Rad AG 1-X8 anion-exchange and DGA resins.For high-Fe/Ti and high-Mg/Ti igneous samples,a three-column procedure was required,whereas a two-column procedure was used for low-Fe/Ti and low-Mg/Ti igneous samples.The Ti isotopes were analysed by MC-ICP-MS,and instrumental mass bias was corrected using a ^(47)Ti-^(49)Ti double-spike technique.The ^(47)Ti-^(49)Ti double-spike and SRM 3162a were calibrated using SRM 979-Cr,certificated value ^(53)Cr/^(52)Crt rue=0.11339.Isobaric interference was evaluated by analysing Alfa-Ti doped with Na,Mg,Ca,and Mo,and results indicate that high concentrations of Na and Mg have no significant effect on Ti isotope analyses;however,Ca and Mo interferences lead to erroneousδ^(49/47)Ti values when Ca/Ti and Mo/Ti ratios exceed 0.01 and 0.1,respectively.Titanium isotopic compositions were determined for 12 igneous reference materials,BCR-2,BHVO-2,GBW07105,AGV-1,AGV-2,W-2,GBW07123,GBW07126,GBW07127,GBW07101,JP-1,and DTS-2b.Samples yieldδ^(49/47)Ti(‰)of−0.035±0.022,−0.038±0.031,0.031±0.022,0.059±0.038,0.044±0.037,0.000±0.015,0.154±0.044,−0.044±0.018,0.010±0.022,0.064±0.043,0.169±0.034,and−0.047±0.025(relative to OL-Ti,±2SD),respectively;of which isotopic compositions of DTS-2b,JP-1,GBW07101,GBW07105,GBW07123,GBW07126,and GBW07127 are reported for the first time.Standard Alfa-Ti was analysed repeatedly over a ten-month period,indicating a reproducibility of±0.047(2SD)forδ^(49/47)Ti,similar to the precisions obtained for geochemical reference materials.

关键词： Ti isotope double-spike mass bias correction MC-ICP-MS reference material

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Petrological and geochemical characteristics of mafic rocks from the Neoproterozoic Sugetbrak Formation in the northwestern Tarim Block,China

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China geology 2023年第1期6卷 85-99页

作者： Hong-zhe Xie Xiang-kun Zhu Xun Wang Yuan He Wei-bing Shen MNR Key laboratory of Isotope geology MNR Key Laboratory of Deep-Earth DynamicsInstitute of GeologyChinese Academy of Geological SciencesBeijing 100037China

The Neoproterozoic Sugetbrak Formation in the Aksu area,which is located at the northwest margin of Tarim Block,comprises mafic rocks and provides key records of the evolution of the Rodinia supercontinent.However,the genetic relationship among these mafic rocks exposed in different geographical sections are still unclear.In this study,the petrology,geochemistry,and Sr-Nd-Pb isotope geochemistry of the mafic rocks exposed in the Aksu-Wushi and Yuermeinark areas have been studied in some detail along three sections.The authors found that the mafic rocks in these three typical sections were mainly composed of pyroxene and plagioclase,containing a small amount of Fe-Ti oxides and with typical diabasic textures.All the mafic rocks in this region also showed similar geochemical compositions.They were characterised by high TiO_(2)contents(1.47%–3.59%)and low MgO(3.52%–7.88%),K_(2)O(0.12%–1.21%).Large ionic lithophile elements(LILEs)(Rb,Sr,and Cs)were significantly depleted.Meanwhile,high field strength elements(HFSEs)were relatively enriched.In the samples,light rare earth elements(LREEs)were enriched,while heavy rare earth elements(HREEs)were depleted.Based on the Zr/Nb,Nb/Y,and Zr/TiO_(2)ratios,the Aksu mafic rocks belong to a series of sub-alkaline and alkaline transitional rocks.The mafic rocks along the three typical sections showed similar initial values of^(87)Sr/^(86)Sr(I_(Sr))(0.7052–0.7097)and ε_(Nd)(t)(–0.70 to–5.35),while the Pb isotopic compositions with^(206)Pb/^(204)Pb,^(207)Pb/^(204)Pb and^(208)Pb/^(204)Pb values of 16.908–17.982,15.487–15.721,37.276–38.603,respectively.Most of the samples plot into the area near EM-Ⅰ,indicating that the magma of the mafic rocks might have derived from a relatively enriched mantle with some crustal materials involved.The geochemical element characteristics of most samples showed typical OIB-type geochemical characteristics indicating that the source region had received metasomatism of recycled materials.Combining with the regional geological background and geochemical d

关键词： Mafic rocks Sugetbrak Formation Rodinia supercotinent Neoproterozoic Sr-Nd-Pb isotopes Mantle plume Geological survey engineering Tarim Block Xinjiang

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Clay mineral distribution characteristics of surface sediments in the South Mid-Atlantic Ridge

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Journal of Oceanology and Limnology 2023年第3期41卷 897-908页

作者： Qiannan HU Chuanshun LI Baoju YANG Xisheng FANG Huahua LÜ Xuefa SHI Jihua LIU Key laboratory of Marine geology and Metallogeny First Institute of OceanographyMinistry of Natural ResourcesQingdao 266061China laboratory for Marine geology Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266237China

Clay minerals are usually considered as important indicators to identify sources in both terrigenous and marine sediments.In particular,clay minerals in metalliferous sediments(MS)have long been studied in global oceans except in South Mid-Atlantic Ridge(SMAR)due to limited explorations.Thus,32 MS and 34 non-MS(NMS)samples were analyzed to clarify the distribution characteristics and mineral compositions of clay minerals.All the sediments were collected along the SMAR between 12°S and 27°S.After removal of organic matter and carbonate,clay fractions(<2μm)were investigated by Xray diffraction(XRD)analysis.Results show that clay mineral assemblages of surface MS consist dominantly of smectite,less abundant illite,chlorite,and kaolinite in average weight percentage of 30%,21%,18%,and 16%,respectively.On the other hand,clay mineral assemblages in the NMS consist mainly of illite,less abundant kaolinite,chlorite,and very scarce smectite in average weight percentage of 47%,29%,24%,and 0.2%,respectively.The clay fractions in MS are mainly composed of amorphous or poorly crystallized Fe/Mn oxyhydroxides,clay mineral,quartz,and plagioclase.However,the counterparts in the NMS are mainly composed of well-crystallized clay minerals,quartz,and plagioclase without the presence of Fe/Mn oxyhydroxides.It is suggested that most of the illite,kaolinite,and chlorite in both MS and NMS are likely aeolian dust in origin from South Africa continent.In addition,the abundance of kaolinite dominates the clay mineral assemblage at low latitudes,where the intensive chemical weathering of continental source rocks facilitating the formation of kaolinite.In terms of smectite,it is indicated of authigenic origin in consideration of only smectite is available in several MS and the absence in NMS.Moreover,the MS samples with only smectite available are always accompanied by goethite.Therefore,it is assumed that most of smectite occurred in studied area is the results of interaction between hydrothermal Fe-oxyhydroxide,silica,and seawater.

关键词： metalliferous sediment South Mid-Atlantic Ridge(SMAR) clay mineral smectite

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Rare earth element chemistry indicates chemical alteration of zircons during the evolution of weathering profile

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Acta Geochimica 2017年第3期36卷 433-436页

作者： Ni Su Shouye Yang Wei Yue State Key laboratory of Marine geology Tongji University laboratory for Marine geology Qingdao National Laboratory for Marine Science and Technology

Although rare earth elements(REEs)in magmatic zircons have been widely used to identify the type and compositional evolution of host rocks,REE distribution patterns during the chemical alteration of zircons need clarification.We investigated REE characteristics in zircons with different degrees of chemical weathering through systematic observation of a granodiorite-weathering profile in southeast China.Despite the relatively stable provenance of the studied profile(zircon U–Pb ages are95.2±4.8 Ma),the zircon REEs exhibited systematic differences in abundance and fractionation patterns from the bedrock to upper layers,e.g.∑PREE,(LREE/HREE)_(CN),and Ce/Ce*.This evidence suggests chemical alteration of zircons during intensive chemical weathering and an expected influence on REE variability in the weathered products due to the presence of REE-bearing minerals.

关键词：稀土元素特征化学变化风化剖面演化过程锆石元素化学中国东南部花岗闪长岩

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Linking minerals to bacterial genes

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National Science Review 2023年第1期10卷 103-104页

作者： Shucheng Xie State Key laboratory of Biogeology and Environmental geology China University of Geosciences (Wuhan)

The biogeochemical roles of microbes in the Earth system are relatively well known [1],but their biogeophysical roles in Earth history are yet to be investigated.Magnetotactic bacteria(MTB) may have been the earliest organisms to sense Earth’s magnetic field and to form intracellular nanocrystals of magnetic minerals,so-called magnetotaxis and magnetosomes,respectively[2].These magnetos ome minerals are highly resistant to diagenesis and generally well-preserved in sediments or sedimentary rocks as magnetofossils[3],making excellent archives of the biogeophysical activity of microbes.

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Test the topographic steady state in an active mountain belt

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Acta Geochimica 2017年第3期36卷 511-514页

作者： Kai Deng Shouye Yang State Key laboratory of Marine geology Tongji University laboratory for Marine geology Qingdao National Laboratory for Marine Science and Technology

Landscape evolution is the window to the link between deep earth and surface processes. One of the key issues in landscape evolution is to characterize the topographic steady state of mountain belts. The Taiwan mountain belt is an extraordinary case due to its extremely high uplift and denudation rates. The uplift of Taiwan Island is caused by the oblique collision between the Luzon Arc and the East Asian continent. In this case, the mountain building process in the north always occurs earlier than that in the south,which causes the spatial distribution of steady-state regions.The East Central Range receives much research attention with the presence of river basins that mainly distribute along the trajectory of the collision propagation. Normally, based on analyses of geomorphic parameters, the whole Central Range, or at least part of it, should be at a topographic steady state. However, the balance between uplift rates and denudation rates that exist in these regions is seldomly tested. In this contribution, we make a comprehensive literature review on the uplift and denudation rates derived from various approaches, including sediment yields, in-situ cosmogenic nuclide ^(10) Be, incision of river channels,thermochronology, and GPS observations. This literature review reveals that the topographic steady state may prevail in the northern and middle parts of the East Central Range.However, an obvious inconsistency in denudation rates calculated by different methods prevents us from better constraining the topographic steady state in some regions of this mountain range.

关键词：稳定状态山区地形测试宇宙成因核素地貌演化剥蚀速率 GPS观测地表过程

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Sediment recycling and indication of weathering proxies

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Acta Geochimica 2017年第3期36卷 498-501页

作者： Yulong Guo Shouye Yang Chao Li Lei Bi Yun Zhao State Key laboratory of Marine geology Tongji University laboratory for Marine geology Qingdao National Laboratory for Marine Science and Technology

As a result of recycling, the mineralogical and chemical compositions of riverine sediments may reflect the combined effects of the present-day weathering regime as well as previous weathering and diagenetic alteration history. River sediments can be interpreted as a mixture of non-weathered bedrock—of igneous, metamorphic, or sedimentary origin—and solids formed by the modern weathering system. The correlation between the weathering proxies chemical index of alteration and weathering index of Parker offers an approach to distinguish fine suspended particles, coarse bedload sediments, and recycled sediments under the influence of quartz dilution. Recycling of cation-depleted source rocks formed during past geological weathering episodes may have great impacts on the weathering indices of sediments from the Changjiang(Yangzte) and Zhuoshui Rivers. Special caution is required when using chemical weathering indices to investigate the intensity of chemical weathering registered in fluvial sediments. To minimize the effect of hydrodynamic sorting or sediment recycling, we suggest that the fine sediments(e.***.suspended particles and ﹤2 lm fractions of bedload sediments) in rivers better reflect the average of weatheredcrust in catchments and the terrigenous end-member in marginal seas.

关键词：河流沉积物风化过程循环利用化学成分成岩蚀变风化基岩悬浮微粒化学指标

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