The grain size distribution of bulk sediment samples was decomposed in a core to reconstruct paleoceanographic evolution over the past 60 ka in the northern Norwegian Sea.The results show that sediments consisted of 3...The grain size distribution of bulk sediment samples was decomposed in a core to reconstruct paleoceanographic evolution over the past 60 ka in the northern Norwegian Sea.The results show that sediments consisted of 3–4 grain populations derived from the North Atlantic Current(NAC)and Barents Ice Sheet(BIS).The grain size data suggest three palaeoceanographic evolution stages:(1)an environment affected by BIS and NAC and changed with the interstadial/stadial transition in phase with the Greenland ice-core record at 60–31 ka BP,during which discharge of icebergs and the content of the coarsest population containing ice-rafted debris(IRD)in the sediments increased significantly during stadial,while the fine silt population containing volcanic glasses increased with the enhancement of NAC during the interstadial;(2)an extreme environment controlled by BIS at31–13 ka BP.BIS reached to its maximum at about 31 ka BP and the turbid plumes that formed at the leading edge of BIS contributed to a significant increase in the clayey population in sediments.Icebergs drained into the northern Norwegian Sea with periodical calving of the BIS at 31–19 ka BP.Subsequently,the ablation of the BIS discharged massive floods with clayey sediments and icebergs into the Norwegian Sea at 19–13 ka BP,resulting in a constant increase in clay and IRD in sediments;and(3)a marine environment similar to the present one under the strong influence of NAC following the complete melting of the BIS after 13 ka BP,NAC is the dominant transport agent and no IRD occurred in sediments.The fine silt populations containing volcanic glasses transported by NAC significantly increased.展开更多
We analyzed the biogenic silica(BSi)content and produced a diatom-based summer sea-surface temperature(SST)reconstruction for sediment core GC4 from the Holsteinsborg Dyb,West Greenland.Our aim was to reconstruct mari...We analyzed the biogenic silica(BSi)content and produced a diatom-based summer sea-surface temperature(SST)reconstruction for sediment core GC4 from the Holsteinsborg Dyb,West Greenland.Our aim was to reconstruct marine productivity and climatic fluctuations during the last millennium.Increased BSi content and diatom abundance suggest relatively high marine productively during the interval of AD 1000–1400,corresponding in time to the Medieval Warm Period(MWP).The summer SST reconstruction indicates relatively warm conditions during AD 900–1100,followed by cooling after AD 1100.An extended cooling period during AD 1400–1900 is characterized by prolonged low in reconstructed SST and high sea-ice concentration.The BSi values fluctuated during this period,suggesting varying marine productivity during the Little Ice Age(LIA).There is no significant correlation between the BSi content and SST during the last millennium,suggesting that the summer SST has little influence on marine productively in the Holsteinsborg Dyb.A good correspondence between the BSi content and the element Ti counts in core GC4 suggests that silicate-rich meltwater from the Greenland ice sheet was likely responsible for changes in marine productively in the Holsteinsborg Dyb.展开更多
The ocean is the largest active carbon reservoir on Earth. Organic carbon(OC), as the primary species of carbon sequestration in the ocean, plays an important role in the global carbon cycle through its deposition and...The ocean is the largest active carbon reservoir on Earth. Organic carbon(OC), as the primary species of carbon sequestration in the ocean, plays an important role in the global carbon cycle through its deposition and burial. In this study,sedimentary OC data from 5796 stations, together with relevant geochemical and sedimentological parameters in the Bohai Sea,Yellow Sea, and East China Sea(BYES) were used to summarize and elucidate the distribution and burial patterns of sedimentary OC, and assess carbon sink effect of sedimentary OC burial. The results show that the OC content in the sediments of the BYES ranges from 0.00% to 2.12%, with an average content of 0.47%±0.26%. OC content is significantly correlated with finegrained sediments, with an average OC content in mud areas being 39% higher than that in non-mud areas. Modern OC buried in the BYES are mainly deposited in 7 major mud areas, with a total sedimentary OC burial flux of approximately 8.20 Mt C yr^(–1).Among them, the burial flux of biospheric OC is 6.92 Mt C yr^(–1), equivalent to the OC consumption amount of silicate weathering of the 9 major river basins in the eastern China. In its natural state, the annually sequestered OC in the sediments of the eastern China seas is equivalent to 25.37 Mt of atmospheric CO_(2), indicating a significant carbon sink effect. The distribution and burial of terrigenous OC in the BYES are mainly influenced by the large river inputs and complex marine hydrodynamic environment,while human activities such as dam construction have significantly altered the OC burial in these coastal mud areas.展开更多
Two sediment cores, KCES1 and ODP797,which were recovered from the Sea of Japan(JS), were measured for alkenone-derived sea surface temperatures(UK037-SSTs). Our results revealed that the SSTs closely follow the glaci...Two sediment cores, KCES1 and ODP797,which were recovered from the Sea of Japan(JS), were measured for alkenone-derived sea surface temperatures(UK037-SSTs). Our results revealed that the SSTs closely follow the glacial-interglacial cycles during the last 170 ka,except in the last glacial maximum(LGM), during which the SST was higher than in the Holocene. The anomalous high temperature in the LGM is considered as an effect of the intrusion of a low salinity water mass into the JS when the sea level was almost below 130 m. On the glacialinterglacial to orbital timescale, the UK037-SSTs record in the JS correlated well with the benthic foraminiferal d18 O record and solar insolation, which suggests the dominant control of solar insolation and its related sea ice development on the SST in the JS. On the sub-orbital/millennial timescale, reduced SST corresponds to an enhanced east asian winter monsoon(EAWM) during the last glacial period(MIS3 and MIS4), indicating the dominant control of sea ice expansion due to the enhanced EAWM on the SST in the JS. In contrast, during the last interglacial period(MIS5), the SST in the JS was controlled by variations in the east Asian summer monsoon. These results highlight the key role of solar insolation and associated glacialinterglacial conditions in the variations of the SST in the JS since the last 170 ka.展开更多
Methane(CH_(4))and carbon dioxide(CO_(2))are the two most important greenhouse gases(GHGs).To examine the variation characteristics of CH_(4)and CO_(2)in the coastal South China Sea,atmospheric CH_(4)and CO_(2)measure...Methane(CH_(4))and carbon dioxide(CO_(2))are the two most important greenhouse gases(GHGs).To examine the variation characteristics of CH_(4)and CO_(2)in the coastal South China Sea,atmospheric CH_(4)and CO_(2)measurements were performed in Bohe(BH),Guangdong,China,in summer 2021.By using an adaptive data analysis method,the diurnal patterns of CH_(4)and CO_(2)were clearly extracted and analysed in relation to the sea breeze(SB)and land breeze(LB),respectively.The average concentrations of CH_(4)and CO_(2)were 1876.91±31.13 ppb and 407.99±4.24 ppm during SB,and 1988.12±109.92 ppb and 421.54±14.89 ppm during LB,respectively.The values of CH_(4)and CO_(2)during SB basically coincided with the values and trends of marine background sites,showing that the BH station could serve as an ideal site for background GHG monitoring and dynamic analysis.The extracted diurnal variations in CH_(4)and CO_(2)showed sunrise high and sunset low patterns(with peaks at 5:00–7:00)during LB but mid-morning high and evening low patterns(with peaks at 9:00)during SB.The diurnal amplitude changes in both CH_(4)and CO_(2)during LB were almost two to three times those during SB.Wind direction significantly modulated the diurnal variations in CH_(4)and CO_(2).The results in this study provide a new way to examine the variations in GHGs on different timescales and can also help us gain a better understanding of GHG sources and distributions in the South China Sea.展开更多
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
Paleomagnetic records from globally distributed locations are essential for fully understanding geomagnetic field variations,particularly non-dipole field fluctuations[1].Paleomagnetic studies on historical time scale...Paleomagnetic records from globally distributed locations are essential for fully understanding geomagnetic field variations,particularly non-dipole field fluctuations[1].Paleomagnetic studies on historical time scales have demonstrated the existence of persistent geomagnetic flux patches,such as the Canadian(North America)and Siberian(East Asia)flux lobes,which may result from an organizing structure imposed on the geomagnetic field by lower mantle heterogeneity[2].Holocene paleomagnetic secular variations,reconstructed from the Alaskan margin of the Subarctic Pacific Ocean(SPO)[3]and revealed by dynamo modeling[4],further suggest that time-varying flux expulsions on the core-mantle boundary recurrently occur in high-latitude locations(Fig.la).展开更多
基金The Basic Scientific Research Operation Fee of the Third Institute of Oceanography,the Ministry of Natural Resources under contract No.2018006the project of the Chinese Arctic and Antarctic Administration of the State Oceanic Administration under contract No.CHINARE2016-03-02the Shandong Provincial Natural Science Foundation under contract No.ZR2019BD054。
文摘The grain size distribution of bulk sediment samples was decomposed in a core to reconstruct paleoceanographic evolution over the past 60 ka in the northern Norwegian Sea.The results show that sediments consisted of 3–4 grain populations derived from the North Atlantic Current(NAC)and Barents Ice Sheet(BIS).The grain size data suggest three palaeoceanographic evolution stages:(1)an environment affected by BIS and NAC and changed with the interstadial/stadial transition in phase with the Greenland ice-core record at 60–31 ka BP,during which discharge of icebergs and the content of the coarsest population containing ice-rafted debris(IRD)in the sediments increased significantly during stadial,while the fine silt population containing volcanic glasses increased with the enhancement of NAC during the interstadial;(2)an extreme environment controlled by BIS at31–13 ka BP.BIS reached to its maximum at about 31 ka BP and the turbid plumes that formed at the leading edge of BIS contributed to a significant increase in the clayey population in sediments.Icebergs drained into the northern Norwegian Sea with periodical calving of the BIS at 31–19 ka BP.Subsequently,the ablation of the BIS discharged massive floods with clayey sediments and icebergs into the Norwegian Sea at 19–13 ka BP,resulting in a constant increase in clay and IRD in sediments;and(3)a marine environment similar to the present one under the strong influence of NAC following the complete melting of the BIS after 13 ka BP,NAC is the dominant transport agent and no IRD occurred in sediments.The fine silt populations containing volcanic glasses transported by NAC significantly increased.
基金The Open Research Fund of State Key Laboratory of Estuarine and Coastal Research under contract No.SKLECKF201708the Project of Laboratory for Marine Geology,Pilot National Laboratory for Marine Science and Technology(Qingdao)under contract No.MGQNLM201707+2 种基金the National Natural Science Foundation of China under contract Nos 41776193,41876215,41876070 and 41406209the Natural Science Foundation of Zhejiang Province under contract Nos LY17D060001 and LQ15D020001the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)under contract No.2018SDKJ0104-3.
文摘We analyzed the biogenic silica(BSi)content and produced a diatom-based summer sea-surface temperature(SST)reconstruction for sediment core GC4 from the Holsteinsborg Dyb,West Greenland.Our aim was to reconstruct marine productivity and climatic fluctuations during the last millennium.Increased BSi content and diatom abundance suggest relatively high marine productively during the interval of AD 1000–1400,corresponding in time to the Medieval Warm Period(MWP).The summer SST reconstruction indicates relatively warm conditions during AD 900–1100,followed by cooling after AD 1100.An extended cooling period during AD 1400–1900 is characterized by prolonged low in reconstructed SST and high sea-ice concentration.The BSi values fluctuated during this period,suggesting varying marine productivity during the Little Ice Age(LIA).There is no significant correlation between the BSi content and SST during the last millennium,suggesting that the summer SST has little influence on marine productively in the Holsteinsborg Dyb.A good correspondence between the BSi content and the element Ti counts in core GC4 suggests that silicate-rich meltwater from the Greenland ice sheet was likely responsible for changes in marine productively in the Holsteinsborg Dyb.
基金supported by the Laoshan Laboratory (Grant No.LSKJ202204200)the Chinese Offshore Investigation and Assessment Project (Grant No.908~ZC~I~05)+2 种基金the National Natural Science Foundation of China-Shandong Joint Fund for Marine Science Research Centers (Grant No.U1606401)the National Natural Science Foundation of China Shiptime Sharing Project (Grant Nos.42049902,42149902)the Taishan Scholar Program of Shandong (Grant No.tspd20181216)。
文摘The ocean is the largest active carbon reservoir on Earth. Organic carbon(OC), as the primary species of carbon sequestration in the ocean, plays an important role in the global carbon cycle through its deposition and burial. In this study,sedimentary OC data from 5796 stations, together with relevant geochemical and sedimentological parameters in the Bohai Sea,Yellow Sea, and East China Sea(BYES) were used to summarize and elucidate the distribution and burial patterns of sedimentary OC, and assess carbon sink effect of sedimentary OC burial. The results show that the OC content in the sediments of the BYES ranges from 0.00% to 2.12%, with an average content of 0.47%±0.26%. OC content is significantly correlated with finegrained sediments, with an average OC content in mud areas being 39% higher than that in non-mud areas. Modern OC buried in the BYES are mainly deposited in 7 major mud areas, with a total sedimentary OC burial flux of approximately 8.20 Mt C yr^(–1).Among them, the burial flux of biospheric OC is 6.92 Mt C yr^(–1), equivalent to the OC consumption amount of silicate weathering of the 9 major river basins in the eastern China. In its natural state, the annually sequestered OC in the sediments of the eastern China seas is equivalent to 25.37 Mt of atmospheric CO_(2), indicating a significant carbon sink effect. The distribution and burial of terrigenous OC in the BYES are mainly influenced by the large river inputs and complex marine hydrodynamic environment,while human activities such as dam construction have significantly altered the OC burial in these coastal mud areas.
基金supported by the National Natural Science Foundation of China(41076038,40710069004,40606016 and 41006036)the Project of Global Change and Air Sea Interaction
文摘Two sediment cores, KCES1 and ODP797,which were recovered from the Sea of Japan(JS), were measured for alkenone-derived sea surface temperatures(UK037-SSTs). Our results revealed that the SSTs closely follow the glacial-interglacial cycles during the last 170 ka,except in the last glacial maximum(LGM), during which the SST was higher than in the Holocene. The anomalous high temperature in the LGM is considered as an effect of the intrusion of a low salinity water mass into the JS when the sea level was almost below 130 m. On the glacialinterglacial to orbital timescale, the UK037-SSTs record in the JS correlated well with the benthic foraminiferal d18 O record and solar insolation, which suggests the dominant control of solar insolation and its related sea ice development on the SST in the JS. On the sub-orbital/millennial timescale, reduced SST corresponds to an enhanced east asian winter monsoon(EAWM) during the last glacial period(MIS3 and MIS4), indicating the dominant control of sea ice expansion due to the enhanced EAWM on the SST in the JS. In contrast, during the last interglacial period(MIS5), the SST in the JS was controlled by variations in the east Asian summer monsoon. These results highlight the key role of solar insolation and associated glacialinterglacial conditions in the variations of the SST in the JS since the last 170 ka.
基金supported by the Basic Scientific Fund for National Public Research Institutes of China(No.2018Q01)the Natural Science Foundation of Shandong Province(China)(No.ZR202102190358)+2 种基金the National Natural Science Foundation of China(No.41821004)the international cooperation project on Indo-Pacific Ocean environmental variability and air-sea interactions(China)(No.GASIIPOVAI-05)the Aoshan Talents Cultivation Excellent Scholar Program supported by Qingdao National Laboratory for Marine Science and Technology(China)(No.2017ASTCP-ES04).
文摘Methane(CH_(4))and carbon dioxide(CO_(2))are the two most important greenhouse gases(GHGs).To examine the variation characteristics of CH_(4)and CO_(2)in the coastal South China Sea,atmospheric CH_(4)and CO_(2)measurements were performed in Bohe(BH),Guangdong,China,in summer 2021.By using an adaptive data analysis method,the diurnal patterns of CH_(4)and CO_(2)were clearly extracted and analysed in relation to the sea breeze(SB)and land breeze(LB),respectively.The average concentrations of CH_(4)and CO_(2)were 1876.91±31.13 ppb and 407.99±4.24 ppm during SB,and 1988.12±109.92 ppb and 421.54±14.89 ppm during LB,respectively.The values of CH_(4)and CO_(2)during SB basically coincided with the values and trends of marine background sites,showing that the BH station could serve as an ideal site for background GHG monitoring and dynamic analysis.The extracted diurnal variations in CH_(4)and CO_(2)showed sunrise high and sunset low patterns(with peaks at 5:00–7:00)during LB but mid-morning high and evening low patterns(with peaks at 9:00)during SB.The diurnal amplitude changes in both CH_(4)and CO_(2)during LB were almost two to three times those during SB.Wind direction significantly modulated the diurnal variations in CH_(4)and CO_(2).The results in this study provide a new way to examine the variations in GHGs on different timescales and can also help us gain a better understanding of GHG sources and distributions in the South China Sea.
基金the support of Chinese Arctic and Antarctic Administrationsupported by the Impact and Response of Antarctic Seas to Climate Change (Grant No. IRASCC2020-2022-No.01-03-02)+2 种基金the Basic Scientific Fund for National Public Research Institutes of China (Grant Nos. 2019S04, 2017Y07, 2019Q09)the National Natural Science Foundation of China (Grant Nos. 42076232, 41976080, 42006075)the Taishan Scholars Project Funding (Grant No. TS20190963)。
文摘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.
基金the National Natural Science Foundation of China(41874078,41806063,and U1606401)the National Key Research&Development Program of China(2016YFA061903)+4 种基金National Program on Global Change and AirSea Interaction(GASI-GEOGE-03)the Open Fund of the Key Laboratory of Marine Geology and Environment,Chinese Academy of Sciences(MGE2018KG05)Laboratory for Marine Geology,Pilot National Laboratory for Marine Science and Technology(Qingdao)(MGQNLM201818),SIGEPAX(03F0704A)State Key Laboratory of Marine Geology,Tongji University(MGK1826)Shenzhen Science and Technology Program(KQTD20170810111725321)。
文摘Paleomagnetic records from globally distributed locations are essential for fully understanding geomagnetic field variations,particularly non-dipole field fluctuations[1].Paleomagnetic studies on historical time scales have demonstrated the existence of persistent geomagnetic flux patches,such as the Canadian(North America)and Siberian(East Asia)flux lobes,which may result from an organizing structure imposed on the geomagnetic field by lower mantle heterogeneity[2].Holocene paleomagnetic secular variations,reconstructed from the Alaskan margin of the Subarctic Pacific Ocean(SPO)[3]and revealed by dynamo modeling[4],further suggest that time-varying flux expulsions on the core-mantle boundary recurrently occur in high-latitude locations(Fig.la).
