The flux of settling particles in the ocean has been widely explored since 1980s due to its important role in biogenic elements cycling,especially in the transport of particulate organic carbon(POC)in the deep sea.How...The flux of settling particles in the ocean has been widely explored since 1980s due to its important role in biogenic elements cycling,especially in the transport of particulate organic carbon(POC)in the deep sea.However,research in the seamount area of the oligotrophic subtropical Northwest Pacific Ocean is lacking.In this work,two sediment traps were deployed at the foot and another two at the hillside of Niulang Guyot from August2017 to July 2018.The magnitude and composition of particle fluxes were measured.The main factors influencing the spatial variations of the fluxes were evaluated.Our results indicated a low particulate flux from Niulang Guyot area in the Northwest Pacific Ocean,reflecting low primary productivity of the oligotrophic ocean.The total mass flux(TMF)decreased from 2.57 g/(m^(2)·a)to 0.56 g/(m^(2)·a)with increasing depth from 600 m to 4850 m.A clear seasonal pattern of TMF was observed,with higher flux in summer than that in winter.The peak flux of 26.52 mg/(m^(2)·d)occurred in August at 600 m,while the lowest value of 0.07 mg/(m^(2)·d)was shown in February at 4850 m.The settling particles at the deep layers had similar biochemical composition,with calcium carbonate(CaCO_(3))accounting for up to 90%,followed by organic matter and opal,characteristics of Carbonate Ocean.The POC flux decreased more rapidly in the twilight layer because of faster decomposition,remineralization,and higher temperature.A small fraction of POC was transported into the deep ocean by biological pump.Particle fluxes were mainly controlled by the calcareous ballasts besides the primary productivity of the surface water.The advection may be another important factor affecting the flux in the seamount area.The combination of settled matters rich in foraminiferal tests with topography and currents may be the reason for regulating the local abundance of benthos on seamounts.Our results will fill in the knowledge gap of sedimentation flux,improve the understanding of ecosystem in Niulang Guyot area,and eventually provide data support for the optimization of regional ecological modeling.展开更多
Based upon cruise observations broadly covering the tropical North Pacific during July-November 2017,together with data obtained from the World Ocean Circulation Experiment Hydrographic Program,this study examined the...Based upon cruise observations broadly covering the tropical North Pacific during July-November 2017,together with data obtained from the World Ocean Circulation Experiment Hydrographic Program,this study examined the distribution of dissolved inorganic nitrogen(DIN,nitrate(NO_(3)^(-))+nitrite(NO_(2)^(-))),dissolved inorganic phosphorus(DIP)and related N^(*)(nitrogen-anomaly,N^(*)=N-16P+2.9,where N and P are the concentrations of DIN(>1.0μmol/L)and DIP(>0.1μmol/L)),used as an index of N2fixation,in the upper 1000 m of the water column.Nutrient concentrations displayed distinct spatial variability in the upper ocean but became relatively constant at a depth of 1000 m:they were high at low latitudes and in the eastern region,with an obvious nutricline at~150 m(DIN,~32.0μmol/L;DIP,~2.4μmol/L)and then generally increased with depth;they decreased markedly(DIN,~1.2μmol/L;DIP,~0.1μmol/L;at~150 m)at high latitudes and in the western region,where a nutricline was not apparent.The N^(*)index showed significant meridional and zonal variation,with the most negative values located at low latitudes and in the eastern region(~10°N,~150°-170°E),while becoming positive towards the northwest(the north of~18°N,~160°E westward).A N^(*)concentration larger than 2.0μmol/L which often used as an indicator of N2fixation,was observed between 155°E and 165°E;N^(*)values were 2.0μmol/L to6.0μmol/L at~15°-28°N,i.e.,much higher than those in the southern sector(0-2.0μmol/L at~5°-10°N).Zonally,N^(*)decreased gradually from west(-2.0μmol/L to 4.0μmol/L,~145°-165°E)to east(-2.0μmol/L to-8.0μmol/L,~155°W)along~10°N,which was consistent with the distribution of Trichodesmium abundance and N2fixation rates.Furthermore,since such region was also supplied with aeolian deposition,high N^(*)was probably not only induced by N2fixation but also influenced by iron and/or nitrogen deposition.展开更多
This research investigated eight stations in Clarion-Clipperton Fracture Zone(CCFZ)in the eastern tropical Pacific in 2017 to study the spatial distribution characteristics of nutrients and chlorophyll a(Chi a)concent...This research investigated eight stations in Clarion-Clipperton Fracture Zone(CCFZ)in the eastern tropical Pacific in 2017 to study the spatial distribution characteristics of nutrients and chlorophyll a(Chi a)concentration,and compared nutrient concentrations and molar ratios with those of other investigations 20 years ago in the same area.The study found that dissolved inorganic nutrient(N,P and Si)concentrations were lowest in the upper layer,and increased from surface to some depths,then they decreased a little to the bottom.N was the limited nutrient factor for the growth of phytoplankton community.Although nutrient concentrations and molar ratios have no obvious changes in 2017 comparing those in 1998-2003,supplemented from the equatorial Pacific,nutrient concentrations in the study area were higher than those in seamounts in the North Pacific and Station ALOHA.Furthermore,this study used Generalized Additive Models(GAMs)to infer the underlying bottom-up factors controlling phytoplankton abundance(Chi a concentration),showing that depth,salinity and PO^-P concentration were major factors controlling the growth of phytoplankton community.Furthermore,this study can provide basic data and theoretical support for the development of polymetallic nodule area and its long-term impact assessment on the environment.展开更多
Resource exploitation in the Clarion-Clipperton Zone(CCZ)is of major research interest worldwide,but its influence on the environment is poorly understood,especially due to the lack of baseline values for metals in th...Resource exploitation in the Clarion-Clipperton Zone(CCZ)is of major research interest worldwide,but its influence on the environment is poorly understood,especially due to the lack of baseline values for metals in the surrounding sediment.This work aimed to establish the baseline values of 17 metals(Ba,Ca,K,Mg,Mn,Na,Ag,As,B,Cd,Co,Cr,Cu,Hg,Ni,Pb,and Zn)using normalization,the cumulative frequency curve method considering a total of 172 samples taken from 8 multitube cores and 1 box sediment core collected in the western CCZ during the COMRA-45 cruise campaign from August to September 2017.The baseline values of the evaluated metals were as follows:1932 mg/kg for Ba,29512 mg/kg for Ca,18150 mg/kg for K,17120 mg/kg for Mg,6747 mg/kg for Mn,28546 mg/kg for Na,0.571 mg/kg for Ag,5.00 mg/kg for As,94.4 mg/kg for B,0.626 mg/kg for Cd,104 mg/kg for Co,76.1 mg/kg for Cr,370 mg/kg for Cu,0.028 mg/kg for Hg,190 mg/kg for Ni,27.5 mg/kg for Pb and 156 mg/kg for Zn.Our findings would fill the baseline value gap in the study area and further improve accuracy of environmental impact assessments on the impact of resource exploitation.展开更多
The fluidic oscillator is an instrument that can continuously generate a spatially sweeping jet entirely based on its internal geometry without any moving parts.However,the traditional fluidic oscillator has an inhere...The fluidic oscillator is an instrument that can continuously generate a spatially sweeping jet entirely based on its internal geometry without any moving parts.However,the traditional fluidic oscillator has an inherent limitation,that is,the spreading angle cannot be controlled independently,rather by the jet volume flow rate and internal geometry.Accordingly,two types of fluidic oscillators based on the master-slave design are developed in current study to decouple this correlation.In both designs,the master layer inherits the similar oscillation mechanisms of a sweeping jet,and the slave layer resembles a steady jet channel.The difference between the two designs is that Design A has a short diverging exit in the slave layer,but Design B adds a long interaction chamber in the exit channel to intensify flow instability.The external flow fields and governing oscillation properties of these two designs are experimentally explored with time-resolved Particle Image Velocimetry(PIV),while the internal flow dynamics and driving oscillation mechanisms are numerically investigated.By fixing the total volume flow rate,the jet spreading angle of Design A can be increased smoothly from 0°to above 100°by increasing the proportion of master layer’s flow rate from 0 to 100%.For Design B,the control authority of the master layer is significantly enhanced by adding the interaction chamber in the slave layer.In addition,the added chamber causes notable jet oscillation even when the master layer has none input.展开更多
基金The Global Change and Air-sea Interaction II Project under contract Nos GASI-04-HYST-01 and GASI-01-NPACSTsumthe Eastern Pacific Eco-environment Monitoring and Protection Project under contract No.DY135-E2-5-02+1 种基金the Fund of COMRA-45 Cruise under contract No.DY-HC-135-45the Scientific Research Foundation of Third Institute of Oceanography,Ministry of Natural Resources of the People’s Republic of China under contract No.2017014。
文摘The flux of settling particles in the ocean has been widely explored since 1980s due to its important role in biogenic elements cycling,especially in the transport of particulate organic carbon(POC)in the deep sea.However,research in the seamount area of the oligotrophic subtropical Northwest Pacific Ocean is lacking.In this work,two sediment traps were deployed at the foot and another two at the hillside of Niulang Guyot from August2017 to July 2018.The magnitude and composition of particle fluxes were measured.The main factors influencing the spatial variations of the fluxes were evaluated.Our results indicated a low particulate flux from Niulang Guyot area in the Northwest Pacific Ocean,reflecting low primary productivity of the oligotrophic ocean.The total mass flux(TMF)decreased from 2.57 g/(m^(2)·a)to 0.56 g/(m^(2)·a)with increasing depth from 600 m to 4850 m.A clear seasonal pattern of TMF was observed,with higher flux in summer than that in winter.The peak flux of 26.52 mg/(m^(2)·d)occurred in August at 600 m,while the lowest value of 0.07 mg/(m^(2)·d)was shown in February at 4850 m.The settling particles at the deep layers had similar biochemical composition,with calcium carbonate(CaCO_(3))accounting for up to 90%,followed by organic matter and opal,characteristics of Carbonate Ocean.The POC flux decreased more rapidly in the twilight layer because of faster decomposition,remineralization,and higher temperature.A small fraction of POC was transported into the deep ocean by biological pump.Particle fluxes were mainly controlled by the calcareous ballasts besides the primary productivity of the surface water.The advection may be another important factor affecting the flux in the seamount area.The combination of settled matters rich in foraminiferal tests with topography and currents may be the reason for regulating the local abundance of benthos on seamounts.Our results will fill in the knowledge gap of sedimentation flux,improve the understanding of ecosystem in Niulang Guyot area,and eventually provide data support for the optimization of regional ecological modeling.
基金The Eastern Pacific Environment Monitoring and Protection Project under contract No.DY135-E2-5-02the Global Change and Air-Sea Interaction Project+1 种基金the National Natural Science Foundation of China under contract No.42103077the Natural Science Foundation of Fujian Province of China under contract No.2020J05077。
文摘Based upon cruise observations broadly covering the tropical North Pacific during July-November 2017,together with data obtained from the World Ocean Circulation Experiment Hydrographic Program,this study examined the distribution of dissolved inorganic nitrogen(DIN,nitrate(NO_(3)^(-))+nitrite(NO_(2)^(-))),dissolved inorganic phosphorus(DIP)and related N^(*)(nitrogen-anomaly,N^(*)=N-16P+2.9,where N and P are the concentrations of DIN(>1.0μmol/L)and DIP(>0.1μmol/L)),used as an index of N2fixation,in the upper 1000 m of the water column.Nutrient concentrations displayed distinct spatial variability in the upper ocean but became relatively constant at a depth of 1000 m:they were high at low latitudes and in the eastern region,with an obvious nutricline at~150 m(DIN,~32.0μmol/L;DIP,~2.4μmol/L)and then generally increased with depth;they decreased markedly(DIN,~1.2μmol/L;DIP,~0.1μmol/L;at~150 m)at high latitudes and in the western region,where a nutricline was not apparent.The N^(*)index showed significant meridional and zonal variation,with the most negative values located at low latitudes and in the eastern region(~10°N,~150°-170°E),while becoming positive towards the northwest(the north of~18°N,~160°E westward).A N^(*)concentration larger than 2.0μmol/L which often used as an indicator of N2fixation,was observed between 155°E and 165°E;N^(*)values were 2.0μmol/L to6.0μmol/L at~15°-28°N,i.e.,much higher than those in the southern sector(0-2.0μmol/L at~5°-10°N).Zonally,N^(*)decreased gradually from west(-2.0μmol/L to 4.0μmol/L,~145°-165°E)to east(-2.0μmol/L to-8.0μmol/L,~155°W)along~10°N,which was consistent with the distribution of Trichodesmium abundance and N2fixation rates.Furthermore,since such region was also supplied with aeolian deposition,high N^(*)was probably not only induced by N2fixation but also influenced by iron and/or nitrogen deposition.
基金The Eastern Pacific Ecoenvironment Monitoring and Protection Project under contract No.DY135-E2-5-02the Global Change and Air-sea Interaction II under contract No.GASI-01-NPAC-STsumthe Scientific Research Foundation of the Third Institute of Oceanography,Ministry of Natural Resources of China under contract No.2019017.
文摘This research investigated eight stations in Clarion-Clipperton Fracture Zone(CCFZ)in the eastern tropical Pacific in 2017 to study the spatial distribution characteristics of nutrients and chlorophyll a(Chi a)concentration,and compared nutrient concentrations and molar ratios with those of other investigations 20 years ago in the same area.The study found that dissolved inorganic nutrient(N,P and Si)concentrations were lowest in the upper layer,and increased from surface to some depths,then they decreased a little to the bottom.N was the limited nutrient factor for the growth of phytoplankton community.Although nutrient concentrations and molar ratios have no obvious changes in 2017 comparing those in 1998-2003,supplemented from the equatorial Pacific,nutrient concentrations in the study area were higher than those in seamounts in the North Pacific and Station ALOHA.Furthermore,this study used Generalized Additive Models(GAMs)to infer the underlying bottom-up factors controlling phytoplankton abundance(Chi a concentration),showing that depth,salinity and PO^-P concentration were major factors controlling the growth of phytoplankton community.Furthermore,this study can provide basic data and theoretical support for the development of polymetallic nodule area and its long-term impact assessment on the environment.
基金The Eastern Pacific Eco-environment Monitoring and Protection Project under contract No.DY135-E2-5-02the Scientific Research Foundation of Third Institute of Oceanography,Ministry of Natural Resources of China under contract No.2017014+1 种基金the Global Change and Air-Sea InteractionⅡunder contract No.GASI-01-NPAC-STsumthe Fund of COMRA-45 Cruise under contract No.DYHC-135-45。
文摘Resource exploitation in the Clarion-Clipperton Zone(CCZ)is of major research interest worldwide,but its influence on the environment is poorly understood,especially due to the lack of baseline values for metals in the surrounding sediment.This work aimed to establish the baseline values of 17 metals(Ba,Ca,K,Mg,Mn,Na,Ag,As,B,Cd,Co,Cr,Cu,Hg,Ni,Pb,and Zn)using normalization,the cumulative frequency curve method considering a total of 172 samples taken from 8 multitube cores and 1 box sediment core collected in the western CCZ during the COMRA-45 cruise campaign from August to September 2017.The baseline values of the evaluated metals were as follows:1932 mg/kg for Ba,29512 mg/kg for Ca,18150 mg/kg for K,17120 mg/kg for Mg,6747 mg/kg for Mn,28546 mg/kg for Na,0.571 mg/kg for Ag,5.00 mg/kg for As,94.4 mg/kg for B,0.626 mg/kg for Cd,104 mg/kg for Co,76.1 mg/kg for Cr,370 mg/kg for Cu,0.028 mg/kg for Hg,190 mg/kg for Ni,27.5 mg/kg for Pb and 156 mg/kg for Zn.Our findings would fill the baseline value gap in the study area and further improve accuracy of environmental impact assessments on the impact of resource exploitation.
基金financial support from the National Natural Science Foundation of China(Nos.12072196 and 11702172)Science and Technology Commission of Shanghai Municipality(No.19JC1412900)+1 种基金Aeronautics Power Foundation(No.6141B09050393)Key Laboratory of Aerodynamic Noise Control(No.ANCL20190106)extended to this study。
文摘The fluidic oscillator is an instrument that can continuously generate a spatially sweeping jet entirely based on its internal geometry without any moving parts.However,the traditional fluidic oscillator has an inherent limitation,that is,the spreading angle cannot be controlled independently,rather by the jet volume flow rate and internal geometry.Accordingly,two types of fluidic oscillators based on the master-slave design are developed in current study to decouple this correlation.In both designs,the master layer inherits the similar oscillation mechanisms of a sweeping jet,and the slave layer resembles a steady jet channel.The difference between the two designs is that Design A has a short diverging exit in the slave layer,but Design B adds a long interaction chamber in the exit channel to intensify flow instability.The external flow fields and governing oscillation properties of these two designs are experimentally explored with time-resolved Particle Image Velocimetry(PIV),while the internal flow dynamics and driving oscillation mechanisms are numerically investigated.By fixing the total volume flow rate,the jet spreading angle of Design A can be increased smoothly from 0°to above 100°by increasing the proportion of master layer’s flow rate from 0 to 100%.For Design B,the control authority of the master layer is significantly enhanced by adding the interaction chamber in the slave layer.In addition,the added chamber causes notable jet oscillation even when the master layer has none input.