基于湖泊碎屑堆积反演湖泊环境演化是干旱、半干旱地区全球变化研究的主要内容之一。但是大部分指标方法仅具有定性特点且敏感程度受制于背景环境等因素,影响了对湖泊环境演变与水文气候变化过程的深入了解。因此,从结构涌现秩序的理念...基于湖泊碎屑堆积反演湖泊环境演化是干旱、半干旱地区全球变化研究的主要内容之一。但是大部分指标方法仅具有定性特点且敏感程度受制于背景环境等因素,影响了对湖泊环境演变与水文气候变化过程的深入了解。因此,从结构涌现秩序的理念出发,基于粒度参数指标体系,开发了可用于描述体系结构演化的指标——体系结构量化指数(又称结构异常指数),尝试重建东亚季风边缘区农牧交错带封闭湖泊黄旗海约3 600~1 500 cal a BP年间湖面水位波动。结果显示,在轨道驱动的夏季太阳辐射降低的背景下,黄旗海湖面逐渐降低,期间存在百年尺度的剧烈波动。与基于孢粉重建的山西公海降水量、贵州董哥洞和湖北和尚洞等洞穴石笋氧同位素记录,以及ENSO活跃程度等记录对比分析发现,这种百年尺度的波动与太阳活动驱动的亚洲季风区夏季风降水和ENSO活动密切相关。太阳辐射减弱、夏季风降水减弱、ENSO活动增强,反之亦然。本研究揭示了太阳活动与ENSO、夏季风强度之间的关系,验证了湖泊碎屑沉积结构异常指数能在百年-千年尺度上较好地反演封闭湖泊水位变化。从已有的研究推断,这种反演具有定量属性,这对于内陆湖泊全球变化研究具有重要意义。展开更多
Enhanced weathering(EW)of ultramafi c rocks from the Muslim Bagh Ophiolite,Pakistan,has been studied in laboratory experiments to explore carbon sequestration as a climate change mitigation strategy for coastal and op...Enhanced weathering(EW)of ultramafi c rocks from the Muslim Bagh Ophiolite,Pakistan,has been studied in laboratory experiments to explore carbon sequestration as a climate change mitigation strategy for coastal and open sea environments.The research focused on a cost-eff ective ex situ experiment to examine the eff ects of EW reaction pathways arising from the interactions among rock powder,seawater and CO_(2).The experimental fi ltrates from diff erent milled peridotite samples exhibit a decrease in the Mg/Ca ratio as the specifi c surface area increases,which accelerates reaction rates.This suggests that the leached Mg from the original rock may have been consumed in the formation of brucite,serpentine and carbonates during EW.Similar reaction pathways are also responsible for the chemical alterations observed in amphibolite,albeit to varying degrees.On the other hand,the experimental residues showed an increase in loss on ignition compared to the original rock,indicating that EW has facilitated the incorporation of H 2 O and CO_(2) into secondary mineral structures through various reaction pathways,leading to the formation of brucite,serpentine and carbonates.Thermal gravimetric analysis of the experimental residues confi rms the presence of these minerals based on their decomposition temperatures.Additionally,XRD analysis identifi ed a range of carbonates in the residues of both peridotite and amphibolite samples,validating the occurrence of carbonation reactions.SEM images reveal textural changes in both samples,supporting the formation of secondary minerals through EW,consistent with observations from the petrographic study of untreated samples.Control experiments on CO_(2) absorption in seawater showed a decrease in pH,highlighting ocean acidifi cation from increased CO_(2) emissions.However,when rock powder was added to the seawater-CO_(2) mixture,the pH increased.This suggests that the EW of ultramafi c rock powders can sequester CO_(2) while raising seawater pH through the formation of secondary minerals.This research could serve as an analog for EW applications,considering the worldwide abundance of ultramafi c rocks and the availability of coastal and open ocean environments.However,further research is required to understand the behavior of other elements and their impacts on ocean chemistry in EW processes before applying CO_(2) sequestration strategies.展开更多
Extraterrestrial phenomena have influenced Earth’s processes throughout geological history.Evaluating the impact of extraterrestrial material on the environment is crucial for understanding the evolution of Earth and...Extraterrestrial phenomena have influenced Earth’s processes throughout geological history.Evaluating the impact of extraterrestrial material on the environment is crucial for understanding the evolution of Earth and life.This study incorporates the investigation of micrometeorites(MMs),abundant cosmic materials on Earth,to understand their influence on the chemical composition and biogeochemistry of the ocean.Comprehensive etching and flux analyses reveal that∼95%of cosmic spherules(CSs)entering seawater are etched or wholly dissolved,supplying nutrients to phytoplankton.Barred spherules show the highest degree of etching(∼19%),followed by porphyritic(∼17%),glass(∼15%),cryptocrystalline(∼12%),scoriaceous(∼10%),G-type(∼9%),and I-type(∼6%).Annually,∼3080 tonnes(t)of olivine from MMs dissolve into seawater,contributing∼495 t of Mg^(2+),∼1110 t of Fe^(2+),and∼1928 t of silicic acid.This signifies that over the Indian Ocean’s∼40 Myr history,∼23 Gt of olivine from CSs has dissolved,providing nutrients to seawater and sequestering∼7 Gt of CO_(2).The world ocean during this time has sequestered∼35 Gt of CO_(2),with fluctuations influenced by extraterrestrial activity.For instance,the Veritas event,lasting∼1.5 Myr,sequestered∼6 Gt of CO_(2)from the atmosphere.A robust flux calculation based on∼2 t of deep-sea sediments from 3610 MMs provides a more accurate estimate of the time-averaged flux of∼229 t yr^(−1).These comprehensive analyses reveal MM’s original characteristics,post-deposition processes,geological record and their overall impact on Earth’s marine environments,thereby contributing to our knowledge of the interconnection between terrestrial and extraterrestrial processes.展开更多
To explore the geochemical characteristics and genesis of the elements in ferromanganese nodules from the Northwest Pacific,this study analyses the mineral composition,elemental content,occurrence phase and genetic me...To explore the geochemical characteristics and genesis of the elements in ferromanganese nodules from the Northwest Pacific,this study analyses the mineral composition,elemental content,occurrence phase and genetic mechanisms of samples by X-ray diffraction(XRD),inductively coupled plasma-optical emission spectrometry(ICP-OES),inductively coupled plasma-mass spectrometry(ICP-MS)and phase analysis methods.The results show that ferromanganese nodules are mainly hydrogenetic,and Mn/Fe content ratio ranges from 0.95 to 2.05.The major minerals are vernadite(δ-MnO_(2))and amorphous ferric oxyhydroxide(FeOOH),and the secondary minerals include todorokite,birnessite,quartz and plagioclase.Ferromanganese nodules contain high contents of Co(0.24%-0.42%),Cu(0.23%-0.73%),Ni(0.33%-0.86%)and rare earth elements(REEs,1192-1990μg/g),which have positive Ce and negative Y anomalies but no Eu anomaly.A cluster analysis suggests that the elements in ferromanganese nodules can be divided into three groups:hydrogenetic components,including Fe,Ti,Zr,P,Pb,Co,Ba,Sr,V and REEs;diagenetic components,including Mn,Ni,Mg,Zn and Cu;and detrital components,including Al,Na,K and Ca.According to chemical leaching,ferromanganese nodules can be divided into four phases:Na,Ca,Mg and Sr are mainly enriched in the carbonate phase;Mn,Co,Ni and Ba are mainly enriched in the Mn-oxide phase;Fe,P,Ti,Cu,Pb,V,Zn,Zr and REEs are mainly enriched in the Fe-oxide phase;and Al and K are mainly enriched in the residual phase.A combination of the two different methods reveal selective enrichment of metal elements from seawater by ferromanganese nodules,featuring multisource mineralization.Moreover,through ion exchange and adsorption,approximately 71.2%of REEs are enriched in the Fe-oxide phase,15.4%in the Mn-oxide phase and 12.4%in the residual phase,while REE contents in the carbonate phase are relatively low.In addition,under the oxic conditions of seawater,the oxidation of soluble Ce^(3+)to insoluble CeO_(2)together with Fe-Mn minerals results in Ce enrichment in ferromanganese nodules.This study provides a reference for the metallogenesis of ferromanganese nodules from the Northwest Pacific.展开更多
文摘基于湖泊碎屑堆积反演湖泊环境演化是干旱、半干旱地区全球变化研究的主要内容之一。但是大部分指标方法仅具有定性特点且敏感程度受制于背景环境等因素,影响了对湖泊环境演变与水文气候变化过程的深入了解。因此,从结构涌现秩序的理念出发,基于粒度参数指标体系,开发了可用于描述体系结构演化的指标——体系结构量化指数(又称结构异常指数),尝试重建东亚季风边缘区农牧交错带封闭湖泊黄旗海约3 600~1 500 cal a BP年间湖面水位波动。结果显示,在轨道驱动的夏季太阳辐射降低的背景下,黄旗海湖面逐渐降低,期间存在百年尺度的剧烈波动。与基于孢粉重建的山西公海降水量、贵州董哥洞和湖北和尚洞等洞穴石笋氧同位素记录,以及ENSO活跃程度等记录对比分析发现,这种百年尺度的波动与太阳活动驱动的亚洲季风区夏季风降水和ENSO活动密切相关。太阳辐射减弱、夏季风降水减弱、ENSO活动增强,反之亦然。本研究揭示了太阳活动与ENSO、夏季风强度之间的关系,验证了湖泊碎屑沉积结构异常指数能在百年-千年尺度上较好地反演封闭湖泊水位变化。从已有的研究推断,这种反演具有定量属性,这对于内陆湖泊全球变化研究具有重要意义。
基金supported by internal grant from Sultan Qaboos University(IG/DVC/ESRC/21/01).
文摘Enhanced weathering(EW)of ultramafi c rocks from the Muslim Bagh Ophiolite,Pakistan,has been studied in laboratory experiments to explore carbon sequestration as a climate change mitigation strategy for coastal and open sea environments.The research focused on a cost-eff ective ex situ experiment to examine the eff ects of EW reaction pathways arising from the interactions among rock powder,seawater and CO_(2).The experimental fi ltrates from diff erent milled peridotite samples exhibit a decrease in the Mg/Ca ratio as the specifi c surface area increases,which accelerates reaction rates.This suggests that the leached Mg from the original rock may have been consumed in the formation of brucite,serpentine and carbonates during EW.Similar reaction pathways are also responsible for the chemical alterations observed in amphibolite,albeit to varying degrees.On the other hand,the experimental residues showed an increase in loss on ignition compared to the original rock,indicating that EW has facilitated the incorporation of H 2 O and CO_(2) into secondary mineral structures through various reaction pathways,leading to the formation of brucite,serpentine and carbonates.Thermal gravimetric analysis of the experimental residues confi rms the presence of these minerals based on their decomposition temperatures.Additionally,XRD analysis identifi ed a range of carbonates in the residues of both peridotite and amphibolite samples,validating the occurrence of carbonation reactions.SEM images reveal textural changes in both samples,supporting the formation of secondary minerals through EW,consistent with observations from the petrographic study of untreated samples.Control experiments on CO_(2) absorption in seawater showed a decrease in pH,highlighting ocean acidifi cation from increased CO_(2) emissions.However,when rock powder was added to the seawater-CO_(2) mixture,the pH increased.This suggests that the EW of ultramafi c rock powders can sequester CO_(2) while raising seawater pH through the formation of secondary minerals.This research could serve as an analog for EW applications,considering the worldwide abundance of ultramafi c rocks and the availability of coastal and open ocean environments.However,further research is required to understand the behavior of other elements and their impacts on ocean chemistry in EW processes before applying CO_(2) sequestration strategies.
基金ISRO-RESPOND GAP3332 and PMN-MOES GAP2175 Project support this work.NIO-PMN and MOES-NCPOR supported the deep-sea and Antarctica micrometeorite collections,respectively.
文摘Extraterrestrial phenomena have influenced Earth’s processes throughout geological history.Evaluating the impact of extraterrestrial material on the environment is crucial for understanding the evolution of Earth and life.This study incorporates the investigation of micrometeorites(MMs),abundant cosmic materials on Earth,to understand their influence on the chemical composition and biogeochemistry of the ocean.Comprehensive etching and flux analyses reveal that∼95%of cosmic spherules(CSs)entering seawater are etched or wholly dissolved,supplying nutrients to phytoplankton.Barred spherules show the highest degree of etching(∼19%),followed by porphyritic(∼17%),glass(∼15%),cryptocrystalline(∼12%),scoriaceous(∼10%),G-type(∼9%),and I-type(∼6%).Annually,∼3080 tonnes(t)of olivine from MMs dissolve into seawater,contributing∼495 t of Mg^(2+),∼1110 t of Fe^(2+),and∼1928 t of silicic acid.This signifies that over the Indian Ocean’s∼40 Myr history,∼23 Gt of olivine from CSs has dissolved,providing nutrients to seawater and sequestering∼7 Gt of CO_(2).The world ocean during this time has sequestered∼35 Gt of CO_(2),with fluctuations influenced by extraterrestrial activity.For instance,the Veritas event,lasting∼1.5 Myr,sequestered∼6 Gt of CO_(2)from the atmosphere.A robust flux calculation based on∼2 t of deep-sea sediments from 3610 MMs provides a more accurate estimate of the time-averaged flux of∼229 t yr^(−1).These comprehensive analyses reveal MM’s original characteristics,post-deposition processes,geological record and their overall impact on Earth’s marine environments,thereby contributing to our knowledge of the interconnection between terrestrial and extraterrestrial processes.
基金The Fund of Laoshan Laboratory under contract No.LSKJ202203602the National key R&D Program of China under contract No.2022YFC2803600the Taishan Scholarship from Shandong Province.
文摘To explore the geochemical characteristics and genesis of the elements in ferromanganese nodules from the Northwest Pacific,this study analyses the mineral composition,elemental content,occurrence phase and genetic mechanisms of samples by X-ray diffraction(XRD),inductively coupled plasma-optical emission spectrometry(ICP-OES),inductively coupled plasma-mass spectrometry(ICP-MS)and phase analysis methods.The results show that ferromanganese nodules are mainly hydrogenetic,and Mn/Fe content ratio ranges from 0.95 to 2.05.The major minerals are vernadite(δ-MnO_(2))and amorphous ferric oxyhydroxide(FeOOH),and the secondary minerals include todorokite,birnessite,quartz and plagioclase.Ferromanganese nodules contain high contents of Co(0.24%-0.42%),Cu(0.23%-0.73%),Ni(0.33%-0.86%)and rare earth elements(REEs,1192-1990μg/g),which have positive Ce and negative Y anomalies but no Eu anomaly.A cluster analysis suggests that the elements in ferromanganese nodules can be divided into three groups:hydrogenetic components,including Fe,Ti,Zr,P,Pb,Co,Ba,Sr,V and REEs;diagenetic components,including Mn,Ni,Mg,Zn and Cu;and detrital components,including Al,Na,K and Ca.According to chemical leaching,ferromanganese nodules can be divided into four phases:Na,Ca,Mg and Sr are mainly enriched in the carbonate phase;Mn,Co,Ni and Ba are mainly enriched in the Mn-oxide phase;Fe,P,Ti,Cu,Pb,V,Zn,Zr and REEs are mainly enriched in the Fe-oxide phase;and Al and K are mainly enriched in the residual phase.A combination of the two different methods reveal selective enrichment of metal elements from seawater by ferromanganese nodules,featuring multisource mineralization.Moreover,through ion exchange and adsorption,approximately 71.2%of REEs are enriched in the Fe-oxide phase,15.4%in the Mn-oxide phase and 12.4%in the residual phase,while REE contents in the carbonate phase are relatively low.In addition,under the oxic conditions of seawater,the oxidation of soluble Ce^(3+)to insoluble CeO_(2)together with Fe-Mn minerals results in Ce enrichment in ferromanganese nodules.This study provides a reference for the metallogenesis of ferromanganese nodules from the Northwest Pacific.
