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Provenance of colorless and brown volcanic glass in late Pleistocene tephra layers in the Western Philippine Sea
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作者 Fuqing JIANG Zhishun ZHANG +6 位作者 Zhaohui ZHANG Guoliang ZHANG Peng HUANG Xiaojing ZHOU Zhifang XIONG Congying li tiegang li 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2024年第5期1438-1449,共12页
Tephra layers in the western Philippine Sea,characterized by abundant volcanic glass shards,may provide crucial evidence on the eruption history of volcanoes and tectonic evolution of the western Pacific.A 220-ka sedi... Tephra layers in the western Philippine Sea,characterized by abundant volcanic glass shards,may provide crucial evidence on the eruption history of volcanoes and tectonic evolution of the western Pacific.A 220-ka sediment core from the Benham Rise in the western Philippine Sea offers new insights into the provenance of four intercalated tephra layers(T1–T4,in chronological order)containing either colorless or brown glass shards.Relative to primitive mantle,all glass shards are enriched in large-ion lithophile elements,such as Rb,Cs,and Pb,and depleted in high field-strength elements,such as Th,Nb,and Ta,indicating a subduction-related origin.The colorless glass shards are characterized by high SiO_(2)(>78%)and light rare earth element(LREE)contents as well as high La/Sm ratios(>9),low FeO and MgO contents(<1%),low Sr/Y(<15)and high Ba/Th ratios(>100),pointing to a rhyolitic composition and a medium-K calc-alkaline serial affinity.In contrast,the brown glass shards are characterized by lower SiO_(2)(<63%)and LREE contents,higher FeO,MgO,and CaO contents,lower La/Sm(<6)and Ba/Th(<75),and similar Sr/Y ratios(<15),indicating derivation from medium to high-K calc-alkaline andesite magma.Brown glass shards from layers T3(152 ka)and T4(172 ka)were correlated with volcanic deposits from the Taal and Laguna Caldera in the Maccolod Corridor,respectively,while the colorless glass shards from layers T1(36.5 ka)and T2(61.2 ka)were likely sourced from the Irosin Caldera in the Bicol Arc.Establishing the provenance of late Pleistocene tephra layers in the western Philippine Sea is helpful to complement a Philippine volcanic history and establish a regional tephrochronostratigraphy. 展开更多
关键词 volcanic glass PROVENANCE chemical composition Philippine Sea late Pleistocene
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Revisiting the dependence of thermocline-dwelling foraminiferal B/Ca on temperature and [CO32-], and its application in reconstruction of the subsurface carbonate system in the tropical western Pacific since 24 ka 被引量:1
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作者 Jingteng Guo tiegang li +2 位作者 Zhifang Xiong Xiaohua Qiu Fengming Chang 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2019年第9期71-86,共16页
The B/Ca ratio of planktonic foraminifer shells has been used as a proxy for reconstructing past ocean carbonate chemistry. However, recent studies have revealed significant uncertainties associated with this proxy, s... The B/Ca ratio of planktonic foraminifer shells has been used as a proxy for reconstructing past ocean carbonate chemistry. However, recent studies have revealed significant uncertainties associated with this proxy, such as whether seawater temperature or [CO^2-3 ] is the dominant control on the partition coefficient (KD) of planktonic foraminiferal B/Ca. To address these uncertainties and thus improve our understanding of the planktonic foraminiferal B/Ca proxy, we analysed B/Ca ratios in the tests of Neogloboquadrina dutertrei (300- 355 μm) and Pulleniatina obliquiloculata (355- 400 μm) in surface sediment samples from the tropical western Pacific and South China Sea. The relationship between these B/Ca ratios and bottom water calcite saturation states (Δ[CO^2-3 ]) is weak, thus suggesting only a small dissolution effect on the B/Ca of the two species. The correlation coefficients (R2) between the B/Ca ratios of N. dutertrei and P. obliquiloculata and environmental parameters (e.g., temperature, salinity, phosphate, DIC and ALK) in the tropical western Pacific and South China Sea are not high enough to justify using B/Ca ratios as a palaeoenvironmental proxy in the study areas. The significant correlation between KD values of N. dutertrei and P. obliquiloculata and carbonate system parameters (e.g.,[CO^2-3 ], DIC, ALK, pH and [HCO^-3 ]) in the study area reflect chemical links between the KD denominator and these variables. Based on our surface sediment calibration, an empirical relationship between the KD of N. dutertrei and temperature is proposed in the tropical western Pacific. We also generated a record of B/Ca ratios in N. dutertrei (300 -355 μm) from Core MD06-3052 in the tropical western Pacific over the past 24 ka to evaluate the application of the revised B/Ca proxy method. Based on the reconstructed empirical relationship for B/Ca and subsurface seawater ALK, we estimated subsurface seawater carbonate system parameters in the tropical western Pacific since 24 ka. In general, the estimated subsurface seawater pH and [CO^2-3 ] show an increase with time, and the record of subsurface seawater pCO2 shows a decrease with time, in the tropical western Pacific over the past 24 ka. The consistent trends in subsurface seawater pCO2 and opal flux during deglaciation may imply that the reported increase in subsurface water pCO2 in the study area was promoted by enhanced upwelling in the Southern Ocean. 展开更多
关键词 PLANKTONIC FORAMINIFERA B/Ca carbonate chemistry tropical western PACIFIC South China Sea
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NGS-metabarcoding revealing novel foraminiferal diversity in the Western Pacific Magellan Seamount sediments 被引量:1
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作者 Junfeng SHI Yanli LEI +1 位作者 Haotian li tiegang li 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2021年第5期1718-1729,共12页
Seamount is a unique deep-sea ecosystem widely distributed in the world.Its biodiversity is vibrant due to its specific geographical and hydrological conditions.However,the diversity and features of foraminifera in su... Seamount is a unique deep-sea ecosystem widely distributed in the world.Its biodiversity is vibrant due to its specific geographical and hydrological conditions.However,the diversity and features of foraminifera in such an environment have rarely been studied.We extracted environmental DNA(eDNA)in sedime nts and amplified the partial small subunit ribo somal DNA(SSU rDNA)of fo raminife ra to understand the foraminiferal diversity from four sites in Magellan Seamount(Western Pacific Ocean).Partial S SU rDNA sequencing was conducted and 912979 foraminiferal reads were obtained and gathered into 266 operational taxonomic units(OTUs).In the available dataset,a high proportion of rare OTUs and low identity OTUs in each studied sample showed that the Magellan Seamount foraminiferal community might have a high genetic novelty.The relative abundance of foraminifera varied between replicates probably due to the existence of bias in amplification process and patchiness of the deep-sea floor.It showed that the Magellan Seamount has a relatively high benthic foraminiferal diversity characterized mainly by monothalamiids(76.37%of total reads)in association with rotaliids(19.03%of total reads),including planktic foraminiferal sequences(38.58%of rotaliids;7.36%of total reads).The remaining reads were assigned to miliolids(0.83%of total reads)and textulariids(0.66%of total reads),and 3.11%of total reads are unassigned to a specific family.The co mparative analysis with foraminiferal assemblage s from coastal and deep-sea environme nts indicated that seamounts could aggregate species from a nearby deep-sea. 展开更多
关键词 metabarcoding Magellan Seamount FORAMINIFERA Western Pacific Ocean
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Morphotype dependence of Globigerinoides ruber(white)and Trilobatus sacculifer Mg/Ca ratios in the western tropical Pacific:implications for reconstructing the mixed-layer depth
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作者 Qi Jia tiegang li +1 位作者 Zhifang Xiong Bingbin Qin 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2023年第11期35-43,共9页
Planktonic foraminifer Globigerinoides ruber(white)and Trilobatus sacculifer are the most frequently used mixedlayer dwelling species for reconstructing past oceanic environments.Specifically,the Mg/Ca ratios of these... Planktonic foraminifer Globigerinoides ruber(white)and Trilobatus sacculifer are the most frequently used mixedlayer dwelling species for reconstructing past oceanic environments.Specifically,the Mg/Ca ratios of these two foraminiferal species have been used for reconstructing tropical/subtropical changes in sea surface temperature(SST).However,these two species have different morphotypes,of which the spatial and temporal differences in Mg/Ca ratios and their influencing factors are still unclear.Our objective is to investigate the potential differences between the Mg/Ca ratios of these different morphotypes of G.ruber(white)and T.sacculifer in the western Philippine Sea(WPS)and determine their implications for the reconstruction of SST and upper-ocean structure.Mg/Ca measurements are made on two basic morphotypes of G.ruber(white)[sensu stricto(s.s.)and sensu lato(s.l.)]and T.sacculifer[with(w)and without(w/o)a sac-like final chamber]on samples of Site MD06-3047B from the WPS.Our results reveal that Mg/Ca ratios of different G.ruber morphotypes show consistent differences;and those of T.sacculifer morphotypes show staged variations since MIS 3.It is suggested to select a single morphotype for reconstructing SST changes using the Mg/Ca ratios of G.ruber and T.sacculifer in the WPS.Furthermore,the Mg/Ca ratios between G.ruber s.s.and G.ruber s.l.[Δ(Mg/Ca)_(G.ruber s.s.-s.l.)]downcore MD06-3047B covaries with indexes of summer monsoon.Combining with the core-top results,showing regional variation of differences in theΔ(Mg/Ca)_(G.ruber s.s.-s.l.)over the western tropical Pacific,we propose thatΔ(Mg/Ca)_(G.ruber s.s.-s.l.)may tend to reflect summer mixed layer depth. 展开更多
关键词 MORPHOTYPES Globigerinoides ruber(white) Trilobatus sacculifer Mg/Ca ratios mixed-layer depth
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Sea surface temperature evolution in the Yellow Sea Warm Current pathway and its teleconnection with high and low latitude forcing during the mid-late Holocene 被引量:2
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作者 Zhong PI Fengming CHANG +1 位作者 tiegang li Yikun CUI 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2022年第1期93-109,共17页
Sea surface temperature(SST)in the Yellow Sea Warm Current(YSWC)pathway is sensitive to the East Asian Winter Monsoon(EAWM)and YSWC.However,the role of the YSWC in the evolution of regional SST remains unclear.Here,we... Sea surface temperature(SST)in the Yellow Sea Warm Current(YSWC)pathway is sensitive to the East Asian Winter Monsoon(EAWM)and YSWC.However,the role of the YSWC in the evolution of regional SST remains unclear.Here,we present new U 37 k′based SST and grain size sequences spanning the last 6092 years in the sediment core Z1,which was retrieved from the central Yellow Sea muddy area.Overall,U 37 k′-SST gradually increased since 6.1 ka BP,with a series of centennial-scale fl uctuations.Its variation was mainly caused by EAWM when YSWC was weak between 6.1 and~3.9 ka BP,as shown by the end-member content of grain size.However,after YSWC was fully developed,i.e.,since~3.9 ka BP,it exerted critical eff ects on SST evolution in its pathway.The 1010-and 538-year cycles of the SST sequence indicated a basic control of solar activity on the oceanic conditions in the Yellow Sea.It is suggested that the variation of total solar irradiance was amplifi ed by thermohaline circulation and then transmitted to the Yellow Sea through the EAWM.Meanwhile,the tropical Pacifi c signal of El Niño was transmitted to the YSWC through the Kuroshio Current.The dual properties of warm water transported by YSWC to compensate the EAWM and driving by Kuroshio Current closely linked the variation of SST in the YSWC pathway to the Northern Hemisphere high latitude climate and the tropical Pacifi c.These fi ndings highlight the signifi cance of YSWC on regional SST evolution and its teleconnection to high and low latitude forcing,which grains a better understanding of the long-term evolution of SST in the middle latitude Yellow Sea. 展开更多
关键词 Yellow Sea Warm Current U 37 k′-SST East Asian Winter Monsoon Kuroshio Current high and low latitude forcing
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Productivity in the Southern Ocean Antarctic Zone during the Northern Hemisphere Glaciation(NHG)and its link to atmospheric pCO_(2)
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作者 Yiming WU Jingteng GUO +4 位作者 Xiangyu ZHAO Wenshen XIAO Heng liU Zhifang XIONG tiegang li 《Science China Earth Sciences》 SCIE EI CAS CSCD 2024年第7期2242-2252,共11页
A decrease in atmospheric CO_(2)partial pressure(pCO_(2))is considered an important prerequisite for the onset and intensification of Northern Hemisphere Glaciation(NHG).However,how the ocean sequestered missing CO_(2... A decrease in atmospheric CO_(2)partial pressure(pCO_(2))is considered an important prerequisite for the onset and intensification of Northern Hemisphere Glaciation(NHG).However,how the ocean sequestered missing CO_(2)during the NHG is still uncertain.Changes in surface productivity and deep ventilation in the Southern Ocean(SO)have been proposed to explain the variations in atmospheric pCO_(2)over the last eight glacial cycles,but it is unclear whether these mechanisms contributed to the decrease in atmospheric pCO_(2)during the NHG.Using titanium-normalized contents and mass accumulation rates of biogenic opal and total organic carbon from the International Ocean Discovery Program(IODP)Expedition 374 Site U1524A,we reconstruct the productivity in the Ross Sea,Antarctica,from 3.3 Ma to 2.4 Ma.The productivity records exhibit a long-term decreasing trend and several distinct phased evolutionary features.Specifically,the local productivity fluctuated dramatically during 3.3-3.0 Ma,decreased gradually during 3.0-2.6 Ma,and remained relatively constant during 2.6-2.4 Ma.By comparing productivity with its potential influences,we infer that the phased and long-term evolutions of productivity were mainly controlled by changes in deep ocean ventilation.Sea ice expansion might have decreased productivity during 3.3-3.0 Ma by light attenuation.Changes in eolian dust input have little effect on productivity.Further analysis revealed no coupling linkage between productivity and atmospheric pCO_(2),indicating that the productivity in the SO Antarctic Zone(AZ)was not the main factor controlling the atmospheric CO_(2)decrease during the NHG.To improve our understanding of the role of SO processes in the NHG,further studies should focus on the potential influences of deep ocean ventilation on atmospheric pCO_(2)in the AZ,and similar studies should also be extended to the sea area in the Subantarctic Zone. 展开更多
关键词 Ross Sea Biogenic opal Total organic carbon Deep ocean ventilation Sea ice Ocean carbon cycle
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Responses of benthic foraminifera to changes of temperature and salinity:Results from a laboratory culture experiment 被引量:2
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作者 Shuaishuai DONG Yanli LEI +1 位作者 tiegang li Zhimin JIAN 《Science China Earth Sciences》 SCIE EI CAS CSCD 2019年第2期459-472,共14页
The effects of temperature and salinity on intertidal foraminiferal community under laboratory conditions are poorly understood. We designed a two-factor crossed experiment in which foraminiferal communities were cult... The effects of temperature and salinity on intertidal foraminiferal community under laboratory conditions are poorly understood. We designed a two-factor crossed experiment in which foraminiferal communities were cultured at different temperatures (6, 12, and 18℃) and salinities (15, 20, 25, and 30 psu) for 10 weeks. In total, 2616 living (stained) specimens were obtained and analyzed. Foraminiferal abundance ranged from 9 to 202 individuals/10 g wet weight of sediment. The highest abundance was obtained at 12℃, 25 psu and the lowest at 6℃, 15 psu. Statistical results demonstrated that temperature affected foraminiferal community more significantly than salinity. Most foraminiferal community parameters (abundance, species richness, Margalef index, and Shannon-Wiener diversity) were significantly positively correlated to temperature, but not to salinity, whereas Pielou's evenness was significantly negatively correlated to both temperature and salinity. The interactive effect of temperature and salinity on foraminiferal abundance was significant. In addition, with increasing temperature, the species composition shifted from hyaline Rotaliida to porcellaneous Miliolida. The abundance of dominant species (e.g., Ammonia aomoriensis, A. beccarii, and Quinqueloculina seminula) showed significant positive correlations to temperature. Our study indicated that the intertidal foraminiferal community responds sensitively and rapidly to the changes of salinity and, especially,temperature by shifting foraminiferal species composition and altering the community parameters. 展开更多
关键词 Benthic foraminifera Community parameter Temperature SALINITY Culture experiment Intertidal zone
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The evolution of the Kuroshio Current over the last 5 million years since the Pliocene: Evidence from planktonic foraminiferal faunas 被引量:1
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作者 Jia WANG Fengming CHANG +3 位作者 tiegang li Hanjie SUN Yikun CUI Tianhao liU 《Science China Earth Sciences》 SCIE EI CAS CSCD 2020年第11期1714-1729,共16页
Meridional heat transport of the western Pacific boundary current(the Kuroshio Current)is one of the key factors in global climate change.This current is important because it controls the temperature gradient between ... Meridional heat transport of the western Pacific boundary current(the Kuroshio Current)is one of the key factors in global climate change.This current is important because it controls the temperature gradient between low latitudes and the North Pacific and so significantly influences mid-latitude atmosphere-ocean interactions.Here we reconstruct changes in hydrological conditions within the mid-latitude mainstream of the Kuroshio Current based on faunal analysis of planktonic foraminifera in core DSDP 296 from the Northwest Pacific Ocean.This approach enabled us to deduce evolutionary processes within the Kuroshio Current since the Pliocene.A total of 57 species in the coarser section(>150μm)were identified;results indicate that planktonic foraminiferal faunal evolution has mainly been characterized by three major stages,the first of which comprised mixed-layer warm-water species of Globigerinoides ruber which first appeared between 3.5 and 2.7 Ma and then gradually increased in content.Percentages of another warm-water species of G.conglobatus also gradually increased in number over this interval.Variations in warm-water species indicate a gradual rise in sea surface temperature(SST)and imply initiation of Kuroshio Current impact on the Northwest Pacific Ocean since at least 3.5 Ma.Secondly,over the period between 2.7 and 2.0 Ma,thermocline species of Globigerina calida,Neogloboquadrina humersa,Neogloboquadrina dutertrei,and Pulleniatina obliquiloculata started to appear in the section.This fauna was dominated by G.ruber as well as increasing G.conglobatus contents.These features imply a further rise in SST and its gradually enhanced influence on thermocline water,suggesting strengthening of the Kuroshio Current since 2.7 Ma.Thirdly,between 2.0 Ma and present,increasing contents of thermocline species(i.e.,G.calida,N.dutertrei and P.obliquiloculata)indicate a gradual rise in seawater temperature at this depth and also imply more intensive Kuroshio Current during this period.On the basis of comparative records from cores ODP 806 and DSDP292 from the low latitude Western Pacific,we propose that initiation of the impact of the Kuroshio Current in the Northwest Pacific and it subsequent stepwise intensifications since 3.5 Ma can be closely related to the closure and restriction of the Indonesian and Central American seaways as well as variations in the Western Pacific Warm Pool(WPWP)and equatorial Pacific region. 展开更多
关键词 PLIOCENE KUROSHIO Planktonic foraminifera Western Pacific Warm Pool
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Climate evolution of southwest Australia in the Miocene and its main controlling factors
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作者 Tianqi SUN Zhaokai XU +1 位作者 Fengming CHANG tiegang li 《Science China Earth Sciences》 SCIE EI CSCD 2022年第6期1104-1115,共12页
At present, the seasonal melting and expansion of the Antarctic ice sheet affect the location and intensification of the westerlies, as well as the precipitation and continental weathering and erosion in southwest Aus... At present, the seasonal melting and expansion of the Antarctic ice sheet affect the location and intensification of the westerlies, as well as the precipitation and continental weathering and erosion in southwest Australia. The Miocene was an important period when the Earth's climate state transitioned from a warmhouse to an icehouse and the East Antarctic Ice Sheet underwent large-scale melting and expansion. At that time, Australia was closer to the Antarctic region than it is now. This makes Australia an ideal target area for studying the coupling relationship among the atmosphere, hydrosphere, lithosphere, and cryosphere. Based on the comprehensive analysis of the siliciclastic mass accumulation rate, grain size, clay minerals, and elemental composition of the sediments at Site U1516 of the International Ocean Discovery Program Expedition 369, we reconstructed the Miocene climate evolution and the continental weathering and erosion history of southwest Australia on a tectonic time scale. Our indicators show that the climate was dry and that continental weathering and erosion were weak, with a small amount of terrestrial material transported to the ocean during the Early to Middle Miocene(22–12.7 Ma). However, as mentioned in previous studies of nearby sites, precipitation and river runoff increased prominently with enhanced continental weathering at 12.7–8 Ma, which was related to the northward migration or intensification of the westerlies, possibly due to increased sea ice in the Southern Ocean. In addition, we found that the evolution of the South Asian monsoon and the westerly belt were synchronized in the Miocene, which indicates that the South Asian monsoon system at that time may also have been affected by the high-latitude signals of the Southern Hemisphere. We speculate that the significant decrease in deep-sea temperature and the expansion of the surface sea temperature gradient in latitude and longitude until the permanent East Antarctic Ice Sheet formed(~12.8 Ma) played an important role in the transmission of Antarctic signals to low latitudes. 展开更多
关键词 MIOCENE Southwest Australia Climate evolution Controlling factors International ocean discovery program
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Changing structure of benthic foraminiferal communities due to declining pH:Results from laboratory culture experiments
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作者 Shuaishuai DONG Yanli LEI +1 位作者 tiegang li Zhimin JIAN 《Science China Earth Sciences》 SCIE EI CAS CSCD 2019年第7期1151-1166,共16页
The ocean absorbs large amounts of CO_2 emitted from human activities, which results in a decrease in seawater p H.Marine calcifying organisms such as foraminifera, are most likely to be affected by this declining pH.... The ocean absorbs large amounts of CO_2 emitted from human activities, which results in a decrease in seawater p H.Marine calcifying organisms such as foraminifera, are most likely to be affected by this declining pH. In this study, we collected sediments from five stations of different depths(34–73 m) in a continental shelf of the Yellow Sea. The entire benthic foraminiferal communities together with sea sediments were cultured under three constant pHs(8.3, 7.8, and 7.3) for 6 and 12 weeks in the laboratory to study their responses to pH or incubation time. The microcosm's experimental results obtained showed that most of the foraminiferal community parameters(abundance, species richness, Margalef index, and Shannon-Wiener diversity) decreased significantly(p<0.05) with the decline in pH in all the tested stations. The responses of foraminifera to the decline in p H were species-specific, for instance, Protelphidium tuberculatum and Cribroelphidiumfrigidum were highly sensitive to declining pH and were finally eliminated at low pH, while some species(e.g., Lagenammina atlantica, Verneuilinulla advena, V. propinqua, Haplophragmoides applanata, and H. canariensis) could tolerate low pH and acted as pH-tolerant species. In addition, the proportion of hyaline taxa showed a significant(p<0.05) positive correlation with pH, while agglutinated type showed a negative response. Furthermore, different incubation times(6 and 12 weeks) showed significant effects on the nearshore communities other than the offshore treatments, which were, however, entirely declined after 6 weeks' incubation under low p H manipulation. Our results indicated that nearshore foraminiferal communities showed rather a resilience to the declining p H and the offshore foraminifera, especially those in the central area of the Yellow Sea Cold Water Mass were found to be more sensitive to the decline in pH in the continental shelf sediments of the Yellow Sea. 展开更多
关键词 Benthic foraminifera COMMUNITY PH Laboratory culture experiment Yellow Sea
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冰期旋回中热带西太平洋碳源汇过程、机理与效应
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作者 李铁刚 熊志方 +2 位作者 秦秉斌 贾奇 郭景腾 《科学通报》 EI CAS CSCD 北大核心 2024年第13期1742-1758,共17页
冰期旋回是第四纪地球气候变化最显著的特征,热带西太平洋通过水文循环控制全球气候演化,这是“气候演变低纬驱动”理论的核心内容.由于现代热带西太平洋CO_(2)总体上处于海-气平衡,因此基于“将今论古”的思想,长期以来学术界认为热带... 冰期旋回是第四纪地球气候变化最显著的特征,热带西太平洋通过水文循环控制全球气候演化,这是“气候演变低纬驱动”理论的核心内容.由于现代热带西太平洋CO_(2)总体上处于海-气平衡,因此基于“将今论古”的思想,长期以来学术界认为热带西太平洋相对于南大洋等高纬海区在大气CO_(2)分压(pCO_(2))冰期旋回中的作用并没那么重要,从而低估了热带西太平洋通过碳源汇演替调控全球气候的作用.在综合分析上新世以来冰期旋回中热带西太平洋碳源汇过程与机制的基础上,总结出了其气候效应模式,发现冰期时海平面降低导致更多的河流营养物进入海洋,致使近海表层有机碳生产和海底有机碳埋藏加强;同时,远洋为了“补偿”陆架珊瑚礁等钙质生物碳酸盐生产的减少,引起其深部CO32和碱度增加,致使远洋深部碳库增强;另外,开放洋区大型硅藻勃发等有机碳生产演化事件在大洋深部形成呼吸碳库,进一步“放大”了上述增强的深部碳库.这些碳循环过程表明冰期热带西太平洋扮演碳汇角色.间冰期时上述碳循环过程发生的方向或强度与冰期相反,但目前还没有证据证明间冰期热带西太平洋是否扮演碳源角色;尽管冰消期,其确实能向大气释放CO_(2).此外,叠加在冰期旋回之上的长尺度记录以及跨越冰期旋回的重大事件记录均显示,热带西太平洋可以通过全球的遥相关或洋际交换,在深部“被动”形成碳库.但这种“被动”形成的深部碳库是否也发生在冰期旋回中还有待于进一步证实.总之,热带西太平洋碳循环也同水文循环一样,通过碳源汇演替对冰期旋回中大气pCO_(2)和全球气候产生重要影响,从而丰富了“气候演变低纬驱动”理论的内涵. 展开更多
关键词 表层海洋固碳 深部海洋储碳 海平面 风尘 碳循环 上新世以来
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Short-term and oncological outcomes of natural orifice specimen extraction surgery(NOSES)for colorectal cancer in China:a national database study of 5055 patients 被引量:32
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作者 Xu Guan Xiyue Hu +46 位作者 Zheng Jiang Ye Wei Donghui Sun Miao Wu Haitao Zhou Hongliang Yao Junmin Song Guiyu Wang Junhong Hu Mingyang Ren Qing Xu Jianchun Cai Jian Peng Dan Ma Yangchun Zheng Qingsi He Bo Jiang Zejun Wang Taiyuan li Su Yan Luchuan Chen tiegang li Zhiguo Xiong Pan Chi liang Kang Gang Yu Xiaodong Deng Hong Zhang Ming Xie Jianbao Wei Hongyan Gong Xuejun Sun Weidong Zang Yongmao Song Peng He Zhengqi Wen Chunxu Zhang Yusheng Wang Yinggang Chen Guangwei Xie Mingzhang li Shaojun Yu Haiying liu Min Pu Chuangang Fu Xishan Wang on behalf of China NOSES Alliance 《Science Bulletin》 SCIE EI CSCD 2022年第13期1331-1334,M0003,共5页
经自然腔道取标本手术(NOSES)通过无切口理念与常规手术器械的结合,表现出极佳的微创效果,并带给患者全新的就医感受.目前,尽管NOSES已广泛用于结直肠肿瘤治疗,大量研究也表明相比常规腹腔镜手术,NOSES具有恢复快、创伤小、疼痛轻等优势... 经自然腔道取标本手术(NOSES)通过无切口理念与常规手术器械的结合,表现出极佳的微创效果,并带给患者全新的就医感受.目前,尽管NOSES已广泛用于结直肠肿瘤治疗,大量研究也表明相比常规腹腔镜手术,NOSES具有恢复快、创伤小、疼痛轻等优势,但绝大多数研究均为小样本、单中心回顾性研究.本研究旨在通过分析我国5055例结直肠肿瘤NOSES患者数据,进一步探讨NOSES的短期疗效与预后.研究对象中,经直肠NOSES占整体比例的90.3%,经阴道NOSES占9.7%.NOSES术后短期并发症发生率为14.1%,吻合口瘘发生率为4.9%,腹盆腔感染率为1.9%.患者3年总生存率为93.2%,无病生存率为82.2%,局部复发率为3.6%.研究结果提示NOSES具有较好的安全性与可行性,为其应用于结直肠肿瘤治疗提供了证据. 展开更多
关键词 结直肠肿瘤 肿瘤学 并发症发生率 无病生存率 吻合口瘘 回顾性研究 总生存率 经直肠
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Testing the mantle plume hypothesis: an IODP effort to drill into the Kamchatka-Okhotsk Sea basement 被引量:7
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作者 Yaoling Niu Xuefa Shi +3 位作者 tiegang li Shiguo Wu Weidong Sun Rixiang Zhu 《Science Bulletin》 SCIE EI CAS CSCD 2017年第21期1464-1472,共9页
The great mantle plume debate(GPD) has been going on for ~15 years(Foulger and Natland, 2003;Anderson, 2004; Niu, 2005; Davies, 2005; Foulger, 2005; Campbell, 2005; Campbell and Davies, 2006),centered on whether mantl... The great mantle plume debate(GPD) has been going on for ~15 years(Foulger and Natland, 2003;Anderson, 2004; Niu, 2005; Davies, 2005; Foulger, 2005; Campbell, 2005; Campbell and Davies, 2006),centered on whether mantle plumes exist as a result of Earth's cooling or whether their existence is purely required for convenience in explaining certain Earth phenomena(Niu, 2005). Despite the mounting evidence that many of the so-called plumes may be localized melting anomalies, the debate is likely to continue. We recognize that the slow progress of the debate results from communication difficulties.Many debaters may not truly appreciate(1) what the mantle plume hypothesis actually is, and(2) none of the petrological, geochemical and geophysical methods widely used can actually provide smoking-gun evidence for or against mantle plume hypothesis. In this short paper, we clarify these issues, and elaborate a geologically effective approach to test the hypothesis. According to the mantle plume hypothesis, a thermal mantle plume must originate from the thermal boundary layer at the core-mantle boundary(CMB), and a large mantle plume head is required to carry the material from the deep mantle to the surface. The plume head product in ocean basins is the oceanic plateau, which is a lithospheric terrane that is large(1000's km across), thick(>200 km), shallow(2–4 km high above the surrounding seafloors), buoyant(~1% less dense than the surrounding lithosphere), and thus must be preserved in the surface geology(Niu et al., 2003). The Hawaiian volcanism has been considered as the surface expression of a type mantle plume, but it does not seem to have a(known) plume head product. If this is true, the Hawaiian mantle plume in particular and the mantle plume hypothesis in general must be questioned. Therefore, whether there is an oceanic plateau-like product for the Hawaiian volcanism is key to testing the mantle plume hypothesis, and the Kamchatka-Okhotsk Sea basement is the best candidate to find out if it is indeed the Hawaiian mantle plume head product or not(Niu et al., 2003; Niu, 2004). 展开更多
关键词 Mantle plume debate Geologically testing plume hypothesis Drilling into Kamchatka-Okhotsk Sea BASEMENT
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A high-performance bio-tissue imaging method using air flow-assisted desorption electrospray ionization coupled with a high-resolution mass spectrometer 被引量:3
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作者 Yiwei Lv tiegang li +9 位作者 Chengan Guo Chenglong Sun Fei Tang Luojiao Huang Zhigang Luo Xin li Ruiping Zhang Qingce Zang Jiuming He Zeper AbliZ 《Chinese Chemical Letters》 SCIE CAS CSCD 2019年第2期461-464,共4页
Mass spectrometry imaging (MSI) technology can simultaneously obtain the spatial distribution of thousands of chemical compounds and has unique advantages compared to other techniques that allow mapping the surface of... Mass spectrometry imaging (MSI) technology can simultaneously obtain the spatial distribution of thousands of chemical compounds and has unique advantages compared to other techniques that allow mapping the surface of bio-tissue. Here, we combined an air flow-assisted desorption electrospray ionization (AFADESI) MSI device with a high-resolution mass spectrometer to optimize the system parameters and achieve more accurate spatial distribution characteristics for compounds of interest while investigating bio-tissue sections. The platform set-up, required instrumentation, sample pretreatment, parameter optimization and bio-tissue characterization are described and discussed.Finally, the parameter conditions that can provide optimal ionic intensity and enhanced resolution were confirmed. The reasonable resolution and sensitivity improvements of AFADESI-MSI have been achieved through tandem a high-resolution mass spectrometer system, therefore, it would be a promising technique for the bio-tissue imaging analysis. 展开更多
关键词 MASS SPECTROMETRY imaging Air flow-assisted desorption electrospray ionization HIGH-RESOLUTION MASS SPECTROMETRY Endogenous metabolites Bio-tissue imaging
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Mid-Holocene seawater preserved in the deepest oceanic blue hole 被引量:1
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作者 Fangli Qiao Chuanjiang Huang +3 位作者 tiegang li Min Zhang Wenzheng Jiang Yanxiong liu 《Science Bulletin》 SCIE EI CSCD 2020年第23期1975-1978,M0003,共5页
南海三沙永乐蓝洞是目前已探知的最深海洋蓝洞,洞内70~100 m深的区域存在明显的温度、盐度及溶解氧等跃层结构.海水碳14测年显示该跃层之下的海水年龄约为6000~6600年,这是迄今为止在全球海洋中发现的年龄最古老的海水,对应的跃层也是... 南海三沙永乐蓝洞是目前已探知的最深海洋蓝洞,洞内70~100 m深的区域存在明显的温度、盐度及溶解氧等跃层结构.海水碳14测年显示该跃层之下的海水年龄约为6000~6600年,这是迄今为止在全球海洋中发现的年龄最古老的海水,对应的跃层也是最古老的.由于蓝洞独特的垂向几何形态,洞内的混合过程接近于分子混合,因此这些海水被很好地封存了数千年.古老海水的形成时间与中全新世发生在雷州半岛的极端冷事件时间大致相同,表明在全新世中期南海北部确实存在极端冷过程.该发现对研究全新世的海洋与气候演变具有重要科学意义. 展开更多
关键词 全球海洋 中全新世 气候演变 几何形态 跃层 全新世中期 封存 雷州半岛
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Biocalcification crisis in the continental shelf under ocean acidification
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作者 Shuaishuai Dong Yanli Lei +2 位作者 tiegang li Yifei Cao Kuidong Xu 《Geoscience Frontiers》 SCIE CAS CSCD 2023年第6期1-7,共7页
Ocean acidification(OA)is a persistent challenge for humans and is predicted to have deleterious effects on marine organisms,especially marine calcifiers such as coral and foraminifera.Benthic foraminifera is an impor... Ocean acidification(OA)is a persistent challenge for humans and is predicted to have deleterious effects on marine organisms,especially marine calcifiers such as coral and foraminifera.Benthic foraminifera is an important component of sediment in the continental shelf,while little is known about the impact of ocean acidification on benthic foraminifera both at the community and individual level and associated calcium carbonate deposition.We conducted eight months continued culture experiment under the scenario of 400,800,1200 and 1600 ppm pCO_(2)gradients on living benthic foraminifera from four stations in the continental shelf of the West Pacific Ocean.Statistic results showed OA had a negative effect on the abundance of benthic foraminifera.In contrast,the diversity increased roughly under OA conditions implying OA might stimulate the emergence of rare species and promote community diversity to some extent.In addition,we confirmed that the offshore area wasn’t the refuge for benthic foraminifera while the nearshore one had more resistance to moderate acidification.Calcareous species Protelphidium tuberculatum was the dominant species occupying on average 75%in all treatments and its shell diameter,weight and thickness showed a decrease,indicating the decrease of calcification of benthic foraminifera.A relationship between the weight of P.tuberculatum and pCO_(2)(R^(2)=0.96)was established.Based on the present work,calcareous benthic foraminifera deposited 8.57104 t calcium carbonate per year and this might reduce by nearly half and 90%under 800 and 1200 ppm scenarios,which indicates a biocalcification crisis under ongoing OA.This work shows an analogy for palaeoceanic OA and also provides new insights into the sediment of calcium carbonate in the future. 展开更多
关键词 Benthic foraminifera pCO_(2) Ocean acidification Continental shelf Calcium carbonate deposit Yellow Sea
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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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作者 Qianwei SONG Bingbin QIN +5 位作者 Zheng TANG Yanguang liU Zhihua CHEN Jingteng GUO Zhifang XIONG tiegang li 《Science China Earth Sciences》 SCIE EI CAS CSCD 2022年第9期1824-1836,共13页
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 predomin... 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. 展开更多
关键词 Planktonic foraminiferal SNW Sonication CaCO3 production Ocean carbon cycle Climate change
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