Suspended particulate barite crystals were detected in the water columns at four different stations near the 90°E ridge in the Indian Ocean.Four distinct morphological types of marine barites were distinguished:e...Suspended particulate barite crystals were detected in the water columns at four different stations near the 90°E ridge in the Indian Ocean.Four distinct morphological types of marine barites were distinguished:euhedral-subhedral crystals,oval or round crystals,rhombic crystals,and irregular crystals.The barite crystals in the study area are typically fine,with a dominant size of 1–3μm.The vertical distribution of barites is significantly affected by the formation and sedimentation processes.Barites begin to appear at a depth of 30 m and are formed primarily from the surface to the depth of 2000m with a concentration peak at the depth of 200m,where particles are coarser than those in the other layers.The barites begin to settle and dissolve once formed in the water column,resulting in finer barite particles and lower particle concentrations.The formation of barite crystals is related to biological processes associated with the decomposition of barium-rich skeletons in the microenvironment of decaying organic matter that is affected by the primary productivity and dissolved oxygen content in the water column.The dissolving process of barite crystals showed similar variation with the concentration of dissolved barium in ocean water,and the substitution of strontium for barite in crystals promotes the selective dissolution of barite and exerts an important impact on its morphology.It is approximately 33%of barites in the amount and 22%in the concentration to settle to the bottom of the water column compared to that observed in the main barite formation zone.展开更多
The southern sea area of the Huludao City, Liaoning Province might be polluted by heavy metals because it is close to the Jinzhou Bay, one of the heaviest sea area polluted by heavy metals in China. The undisturbed mo...The southern sea area of the Huludao City, Liaoning Province might be polluted by heavy metals because it is close to the Jinzhou Bay, one of the heaviest sea area polluted by heavy metals in China. The undisturbed modern sediment core can be used to analyze the accumulation and source of the pollutants using 137 Cs and 210 Pb ex . Thirty-five samples of surface sediment and two core sediments were collected from the southern sea area of Huludao City. The concentrations of copper (Cu), lead (Pb), chrome (Cr), zinc (Zn), arsenic (As) and mercury (Hg) in the surface sediments as well as Cu, Pb, Zn, Cr, 137 Cs and 210 Pb ex in the core sediments were determined to research the spatial distribution and accumulation characteristics, and to analyze the sources and the potential risks of heavy metals. The results show that the pollution levels of Zn and Hg are serious, and 26 stations are at moderate or heavy ecological risks. The concentrations of the heavy metals increase from east to west, as well as from open sea to offshore marine area. The concentrations of heavy metals are not high in the sediments adjacent to the Jinzhou Bay, and the influence caused by the seawater exchange with the Jinzhou Bay is little. The concentrations of the heavy metals in the core sediments show low-high-low characteristic, and it coincides with the pollution history of Huludao City. The atmospheric deposition of heavy metals from the Huludao Zinc Plant is likely to be the main source of pollution without direct discharge of wastewater. The high concentrations of heavy metals appear on the upper sediment of 20 cm. The shallow sediment with high heavy metal contents might be exposed to surface when it was disturbed by the ocean engineering and big storm surge, then cause risk to the safety of aquaculture and human healthy.展开更多
The semi-enclosed Bohai Sea has received large amount of pollutants from surrounding rivers and sewage channels along the densely populated and industrializing Bohai coasts,as well as the offshore oil exploration in t...The semi-enclosed Bohai Sea has received large amount of pollutants from surrounding rivers and sewage channels along the densely populated and industrializing Bohai coasts,as well as the offshore oil exploration in the sea.The concentrations of heavy metals copper,cobalt,nickel,zinc,lead,chromium and cadmium in 25 surface sediment samples from the central Bohai Sea are obtained by ICP-MS analysis.The speciation of these heavy metals is extracted and their distribution,fractionation,pollution status and sources are presented.High concentrations of copper,cobalt,nickel,zinc and chromium are found in the sediments off the coastal area of the Bohai Bay and the central Bohai Sea mud,while high concentrations of cadmium and lead are found in the sediments in the whole study area.The residual fraction is the dominant form of copper,cobalt,nickel,zinc and chromium in the surface sediments,while cadmium and lead have large proportions in the nonresidual fractions.The ecological risk assessment shows that the sediments in the study area are unpolluted with respect to the heavy metals of cobalt,nickel and chromium and unpolluted to moderately polluted with respect to copper,zinc,cadmium and lead.Cobalt,nickel and chromium mainly have natural origin and their concentrations significantly vary with the composition of the sediments.The contents of copper,zinc,lead and especially cadmium in sediments are suggested to be influenced by pollutants of human activities.The heavy metals in the surface sediments at most sampling stations are mainly come from the Huanghe River; the heavy metals in the sediments in the northernmost part of the study area are significantly affected by the sediment from the Luanhe River; while in the Bohai Bay and the central region they were affected by the sediment from the Haihe River and aerosol deposition.展开更多
We used the X-ray diffraction method to determine systematically the mineral phases in bulk sediment samples and acid undissolved residuals of the fine-grained fraction of the surface sediments from the 49.6°E hy...We used the X-ray diffraction method to determine systematically the mineral phases in bulk sediment samples and acid undissolved residuals of the fine-grained fraction of the surface sediments from the 49.6°E hydrothermal field at the Southwest Indian Ridge(SWIR)and discussed the mineral sources of the surface sediments.The results showed that the surface sediments in this region were composed of calcareous ooze,and calcite was the dominant mineral.The sediments also contained quartz,feldspar,clay minerals,pyroxene,sphalerite,barite,serpentine,and magnetite.The quartz,feldspar,and clay minerals were exogenous minerals that mainly originated from the Namib and Kalahari deserts in southern Africa.The pyroxene,serpentine,magnetite,sphalerite,calcite,and barite were endogenous minerals from weathering of seafloor basement rocks and seafloor hydrothermal activities.The sulfide particles in the sediments were mainly deposited from upwelling plumes.展开更多
The grain-size of suspended particulate matter （SPM） in the Huanghe Estuary and its adjacent sea area was investigated with an in situ laser particle size analyzer （LISST-100） in November 2006.The spatial distribu...The grain-size of suspended particulate matter （SPM） in the Huanghe Estuary and its adjacent sea area was investigated with an in situ laser particle size analyzer （LISST-100） in November 2006.The spatial distribution of the grain-size parameters was very complicated.The results show that （1） the mean particle size of SPM ranged from 3.00Φ to 6.41Φ,with an average value of 4.66Φ;（2） the frequency distribution patterns of the SPM grain-size showed three different types,which were mono-mode,dual-mode and tri-mode,respectively;（3） C-M chart suggested that the transportation-processes of the SPM not only included suspended mode,but also the bed load transportation mode.The bed load transportation mode mainly occurred at the bottom layer.The characteristics and space distribution of SPM grain-size might be mainly controlled by sediment discharge of the Huanghe River,hydrodynamics condition,surface sediment types,and biological process within the study area.展开更多
Diversion of the Yellow River is a unique geological event in offshore China,causing changes of the sedimentary environment in eastern China Seas.The last diversion took place in AD 1855,with the estuary diverted from...Diversion of the Yellow River is a unique geological event in offshore China,causing changes of the sedimentary environment in eastern China Seas.The last diversion took place in AD 1855,with the estuary diverted from the Yellow Sea into the Bohai Sea.The identification of the river diversion events in the shelf sediments would not only provide the definite ages for the sediments,but also give a clue for better understanding of the sedimentation in that area.In this study,210 Pb,grain size,geochemical element,and foraminiferal data in core H205 from the north Yellow Sea were systematically investigated.A high-resolution sedimentary record was established,which was coupled with the Yellow River diversion and runoff changes.The results show that the foraminiferal composition and foraminiferal abundance of the sediments from the north Yellow Sea had good response to the Yellow River diversion in 1855.Before the change,shallow water assemblages dominated the foraminifera,and the abundance of each foraminiferal species was very low.After the diversion event,the abundance of most foraminifera increased sharply,with a maximum increase of 16 times,and the assemblage was still dominated by shallow water species.Furthermore,the changes in foraminiferal abundance in the core sediments corresponded well with the discharge fluctuation of the Yellow River since 1855.When the Yellow River began entering the Bohai Sea,the Yellow River water,which is rich in nutrients,along with the coastal currents affected the north Yellow Sea,increased the primary productivity in the north Yellow Sea,which is the main reason for the abrupt increase and fluctuation of foraminiferal abundance in this area.At the meantime,the East Asian winter monsoon could also promote the development of nearshore foraminiferal species by enhancing the coastal currents.展开更多
For a long time,most studies about pyrite have focused on sediments while only a few have focused on pyrite in water.In this study,a method that combines the scanning electron microscopy(SEM)and the energy dispersive ...For a long time,most studies about pyrite have focused on sediments while only a few have focused on pyrite in water.In this study,a method that combines the scanning electron microscopy(SEM)and the energy dispersive X-ray spectrometry(EDS)was used to compare pyrite particles suspended in water to those in associated bottom sediments,both obtained from the mixing zone of the Yangtze Estuary.It was found that the pyrite particles in the two media have similar morphologies and size distributions.The particle morphology mainly includes two types,single crystal and aggregate,and the particle size mainly ranges from 0.5 to 2μm.The pyrite particles in water exhibit an increase in relative content towards the sea,and their transport and deposit processes are mainly affected by hydrodynamic conditions.It is concluded that the pyrite particles in the suspended matter mainly derived from the resuspension of sediments,which are products of the early diagenesis.Precursor minerals may appear during the formation of pyrite,but are generally restricted by the diagenetic environment and local microenvironment.展开更多
Three cores(ZY-1,ZY-2 and ZY-3) retrieved from the Central Yellow Sea mud(CYSM) were analyzed in sensitive grain size and AMS 14 C dating to reconstruct the history of the East Asian Winter Monsoon(EAWM) since the Mid...Three cores(ZY-1,ZY-2 and ZY-3) retrieved from the Central Yellow Sea mud(CYSM) were analyzed in sensitive grain size and AMS 14 C dating to reconstruct the history of the East Asian Winter Monsoon(EAWM) since the Middle Holocene in the study area.The results show that these data provide a continuous history of the EAWM over the past 7.2 ka and that the EAWM can be divided into three periods:strong and highly fluctuating during 7.2-4.2 ka BP;moderate and relatively stable during 4.2-1.8 ka BP;and weakened during 1.8-0 ka BP.Compared with the East Asian Summer Monsoon(EASM) recorded in the previous studies,the evolutionary history of the EAWM broadly follows the orbital-derived winter insolation with a similar long-term step-decreased trend as the EASM.At the centennial scale,however,the EAWM intensified events correlate well with the EASM weakened events and the North Atlantic climatic variations(Bond events 0 to 5) within the dating error,most likely forced by the reduction of solar irradiance through changes in the oceanic-atmospheric circulation patterns.展开更多
Sea surface temperature (SST) records in the South Yellow Sea during the last 6200 years are reconstructed by the unsaturation index of long-chain alkenones (K 37 U ') in sediment core ZY2 from the central mud are...Sea surface temperature (SST) records in the South Yellow Sea during the last 6200 years are reconstructed by the unsaturation index of long-chain alkenones (K 37 U ') in sediment core ZY2 from the central mud area.The SST records varied between 14.1 and 16.5°C (15.6°C on average),with 3 phases:(1) A high SST phase at 6.2-5.9 cal ka BP;(2) A low and intensely fluctuating SST phase at 5.9-2.3 cal ka BP;and (3) A high and stable SST phase since 2.3 cal ka BP.Variation of the SST records is similar to intensity of the Kuroshio Current (KC),and corresponds well in time to global cold climate events.However,the amplitude of the SST response to cooling events was significantly different in different phases.The SST response to global cooling event was weak while the KC was strong;and the SST response was strong while the KC was weak.The difference in amplitude of the SST response is possibly caused by the modulation effect of the Yellow Sea Warm Current which acts as a shelf branch of the KC and a compensating current induced by the East Asia winter monsoon.The warm waters brought by the Yellow Sea Warm Current cushion the SST decrease induced by climate cooling,and both the Kuroshio and East Asian winter monsoon play important roles in the modulation mechanism.The SST records display a periodicity of 1482 years.The same period was found in the KC records,indicating that variation of the SST records in the central South Yellow Sea is strongly affected by KC intensity.The same period was also found in Greenland ice cores and North Atlantic and Arabian Sea sediment cores,showing a regional response of marine environmental variability in the East China Seas to that in the global oceans.展开更多
基金supported by the COMRA Major Project(No.DY135-S1-01-09)the Opening Foundation of Key Laboratory of Submarine Geosciences and Prospecting Techniques,Ocean University of China(No.SGPT-2019OF-02).
文摘Suspended particulate barite crystals were detected in the water columns at four different stations near the 90°E ridge in the Indian Ocean.Four distinct morphological types of marine barites were distinguished:euhedral-subhedral crystals,oval or round crystals,rhombic crystals,and irregular crystals.The barite crystals in the study area are typically fine,with a dominant size of 1–3μm.The vertical distribution of barites is significantly affected by the formation and sedimentation processes.Barites begin to appear at a depth of 30 m and are formed primarily from the surface to the depth of 2000m with a concentration peak at the depth of 200m,where particles are coarser than those in the other layers.The barites begin to settle and dissolve once formed in the water column,resulting in finer barite particles and lower particle concentrations.The formation of barite crystals is related to biological processes associated with the decomposition of barium-rich skeletons in the microenvironment of decaying organic matter that is affected by the primary productivity and dissolved oxygen content in the water column.The dissolving process of barite crystals showed similar variation with the concentration of dissolved barium in ocean water,and the substitution of strontium for barite in crystals promotes the selective dissolution of barite and exerts an important impact on its morphology.It is approximately 33%of barites in the amount and 22%in the concentration to settle to the bottom of the water column compared to that observed in the main barite formation zone.
基金Under the auspices of National Natural Science Foundation of China (No. 40806045)Ocean Public Welfare Scientific Research Project,State Oceanic Administration People's Republic of China (No. 201105005)
文摘The southern sea area of the Huludao City, Liaoning Province might be polluted by heavy metals because it is close to the Jinzhou Bay, one of the heaviest sea area polluted by heavy metals in China. The undisturbed modern sediment core can be used to analyze the accumulation and source of the pollutants using 137 Cs and 210 Pb ex . Thirty-five samples of surface sediment and two core sediments were collected from the southern sea area of Huludao City. The concentrations of copper (Cu), lead (Pb), chrome (Cr), zinc (Zn), arsenic (As) and mercury (Hg) in the surface sediments as well as Cu, Pb, Zn, Cr, 137 Cs and 210 Pb ex in the core sediments were determined to research the spatial distribution and accumulation characteristics, and to analyze the sources and the potential risks of heavy metals. The results show that the pollution levels of Zn and Hg are serious, and 26 stations are at moderate or heavy ecological risks. The concentrations of the heavy metals increase from east to west, as well as from open sea to offshore marine area. The concentrations of heavy metals are not high in the sediments adjacent to the Jinzhou Bay, and the influence caused by the seawater exchange with the Jinzhou Bay is little. The concentrations of the heavy metals in the core sediments show low-high-low characteristic, and it coincides with the pollution history of Huludao City. The atmospheric deposition of heavy metals from the Huludao Zinc Plant is likely to be the main source of pollution without direct discharge of wastewater. The high concentrations of heavy metals appear on the upper sediment of 20 cm. The shallow sediment with high heavy metal contents might be exposed to surface when it was disturbed by the ocean engineering and big storm surge, then cause risk to the safety of aquaculture and human healthy.
基金The National Natural Science Foundation of China under contract Nos 41376055 and 41530966the Open Research Fund of the Key Laboratory of Marine Sedimentology and Environmental Geology,First Institute of Oceanography,State Oceanic Adiminstration,China under contract No.MASEG201204the Open Research Fund of the Key Laboratory of Submarine Geosciences and Technology of Ministry of Education,Ocean University of China under contract No.201362026
文摘The semi-enclosed Bohai Sea has received large amount of pollutants from surrounding rivers and sewage channels along the densely populated and industrializing Bohai coasts,as well as the offshore oil exploration in the sea.The concentrations of heavy metals copper,cobalt,nickel,zinc,lead,chromium and cadmium in 25 surface sediment samples from the central Bohai Sea are obtained by ICP-MS analysis.The speciation of these heavy metals is extracted and their distribution,fractionation,pollution status and sources are presented.High concentrations of copper,cobalt,nickel,zinc and chromium are found in the sediments off the coastal area of the Bohai Bay and the central Bohai Sea mud,while high concentrations of cadmium and lead are found in the sediments in the whole study area.The residual fraction is the dominant form of copper,cobalt,nickel,zinc and chromium in the surface sediments,while cadmium and lead have large proportions in the nonresidual fractions.The ecological risk assessment shows that the sediments in the study area are unpolluted with respect to the heavy metals of cobalt,nickel and chromium and unpolluted to moderately polluted with respect to copper,zinc,cadmium and lead.Cobalt,nickel and chromium mainly have natural origin and their concentrations significantly vary with the composition of the sediments.The contents of copper,zinc,lead and especially cadmium in sediments are suggested to be influenced by pollutants of human activities.The heavy metals in the surface sediments at most sampling stations are mainly come from the Huanghe River; the heavy metals in the sediments in the northernmost part of the study area are significantly affected by the sediment from the Luanhe River; while in the Bohai Bay and the central region they were affected by the sediment from the Haihe River and aerosol deposition.
基金supported by the China Ocean Mineral Resources Research and Development Association (No. DY 125-11-R-04)
文摘We used the X-ray diffraction method to determine systematically the mineral phases in bulk sediment samples and acid undissolved residuals of the fine-grained fraction of the surface sediments from the 49.6°E hydrothermal field at the Southwest Indian Ridge(SWIR)and discussed the mineral sources of the surface sediments.The results showed that the surface sediments in this region were composed of calcareous ooze,and calcite was the dominant mineral.The sediments also contained quartz,feldspar,clay minerals,pyroxene,sphalerite,barite,serpentine,and magnetite.The quartz,feldspar,and clay minerals were exogenous minerals that mainly originated from the Namib and Kalahari deserts in southern Africa.The pyroxene,serpentine,magnetite,sphalerite,calcite,and barite were endogenous minerals from weathering of seafloor basement rocks and seafloor hydrothermal activities.The sulfide particles in the sediments were mainly deposited from upwelling plumes.
基金The Ministry of Science and Technology of China under contract No. 2005CB422304the National Natural Science Foundation of China under contract No. 40976020
文摘The grain-size of suspended particulate matter （SPM） in the Huanghe Estuary and its adjacent sea area was investigated with an in situ laser particle size analyzer （LISST-100） in November 2006.The spatial distribution of the grain-size parameters was very complicated.The results show that （1） the mean particle size of SPM ranged from 3.00Φ to 6.41Φ,with an average value of 4.66Φ;（2） the frequency distribution patterns of the SPM grain-size showed three different types,which were mono-mode,dual-mode and tri-mode,respectively;（3） C-M chart suggested that the transportation-processes of the SPM not only included suspended mode,but also the bed load transportation mode.The bed load transportation mode mainly occurred at the bottom layer.The characteristics and space distribution of SPM grain-size might be mainly controlled by sediment discharge of the Huanghe River,hydrodynamics condition,surface sediment types,and biological process within the study area.
基金funded by the National Natural Science Foundation of China (NSFC) (No. 41530966)Key Project of the Ministry of Science and Technology of China (No. 2016YFA0600904)
文摘Diversion of the Yellow River is a unique geological event in offshore China,causing changes of the sedimentary environment in eastern China Seas.The last diversion took place in AD 1855,with the estuary diverted from the Yellow Sea into the Bohai Sea.The identification of the river diversion events in the shelf sediments would not only provide the definite ages for the sediments,but also give a clue for better understanding of the sedimentation in that area.In this study,210 Pb,grain size,geochemical element,and foraminiferal data in core H205 from the north Yellow Sea were systematically investigated.A high-resolution sedimentary record was established,which was coupled with the Yellow River diversion and runoff changes.The results show that the foraminiferal composition and foraminiferal abundance of the sediments from the north Yellow Sea had good response to the Yellow River diversion in 1855.Before the change,shallow water assemblages dominated the foraminifera,and the abundance of each foraminiferal species was very low.After the diversion event,the abundance of most foraminifera increased sharply,with a maximum increase of 16 times,and the assemblage was still dominated by shallow water species.Furthermore,the changes in foraminiferal abundance in the core sediments corresponded well with the discharge fluctuation of the Yellow River since 1855.When the Yellow River began entering the Bohai Sea,the Yellow River water,which is rich in nutrients,along with the coastal currents affected the north Yellow Sea,increased the primary productivity in the north Yellow Sea,which is the main reason for the abrupt increase and fluctuation of foraminiferal abundance in this area.At the meantime,the East Asian winter monsoon could also promote the development of nearshore foraminiferal species by enhancing the coastal currents.
基金the National Natural Science Foundation of China(NSFC)who organized the public survey cruise in the Yangtze River Estuary in March 2015,with special thanks to the crew of the R/V Run Jiang No.1 for kindly assisting in sediment sampling on the cruiseThis study was funded by the NSFC(No.41676036)and the National Key R&D Program of China(No.2016YFA0600904).
文摘For a long time,most studies about pyrite have focused on sediments while only a few have focused on pyrite in water.In this study,a method that combines the scanning electron microscopy(SEM)and the energy dispersive X-ray spectrometry(EDS)was used to compare pyrite particles suspended in water to those in associated bottom sediments,both obtained from the mixing zone of the Yangtze Estuary.It was found that the pyrite particles in the two media have similar morphologies and size distributions.The particle morphology mainly includes two types,single crystal and aggregate,and the particle size mainly ranges from 0.5 to 2μm.The pyrite particles in water exhibit an increase in relative content towards the sea,and their transport and deposit processes are mainly affected by hydrodynamic conditions.It is concluded that the pyrite particles in the suspended matter mainly derived from the resuspension of sediments,which are products of the early diagenesis.Precursor minerals may appear during the formation of pyrite,but are generally restricted by the diagenetic environment and local microenvironment.
基金supported by National Basic Research Program of China (Grant No. 2010CB428901)National Natural Science Foundation of China (Grant Nos. 40976036 and40676032)Open Foundation of the State Key Laboratory of Loess and Quaternary Geology (Grant No. SKLLQG1107)
文摘Three cores(ZY-1,ZY-2 and ZY-3) retrieved from the Central Yellow Sea mud(CYSM) were analyzed in sensitive grain size and AMS 14 C dating to reconstruct the history of the East Asian Winter Monsoon(EAWM) since the Middle Holocene in the study area.The results show that these data provide a continuous history of the EAWM over the past 7.2 ka and that the EAWM can be divided into three periods:strong and highly fluctuating during 7.2-4.2 ka BP;moderate and relatively stable during 4.2-1.8 ka BP;and weakened during 1.8-0 ka BP.Compared with the East Asian Summer Monsoon(EASM) recorded in the previous studies,the evolutionary history of the EAWM broadly follows the orbital-derived winter insolation with a similar long-term step-decreased trend as the EASM.At the centennial scale,however,the EAWM intensified events correlate well with the EASM weakened events and the North Atlantic climatic variations(Bond events 0 to 5) within the dating error,most likely forced by the reduction of solar irradiance through changes in the oceanic-atmospheric circulation patterns.
基金supported by the National Basic Research Program of China (2010CB428901)the National Natural Science Foundation of China (90211022 and 41020164005)
文摘Sea surface temperature (SST) records in the South Yellow Sea during the last 6200 years are reconstructed by the unsaturation index of long-chain alkenones (K 37 U ') in sediment core ZY2 from the central mud area.The SST records varied between 14.1 and 16.5°C (15.6°C on average),with 3 phases:(1) A high SST phase at 6.2-5.9 cal ka BP;(2) A low and intensely fluctuating SST phase at 5.9-2.3 cal ka BP;and (3) A high and stable SST phase since 2.3 cal ka BP.Variation of the SST records is similar to intensity of the Kuroshio Current (KC),and corresponds well in time to global cold climate events.However,the amplitude of the SST response to cooling events was significantly different in different phases.The SST response to global cooling event was weak while the KC was strong;and the SST response was strong while the KC was weak.The difference in amplitude of the SST response is possibly caused by the modulation effect of the Yellow Sea Warm Current which acts as a shelf branch of the KC and a compensating current induced by the East Asia winter monsoon.The warm waters brought by the Yellow Sea Warm Current cushion the SST decrease induced by climate cooling,and both the Kuroshio and East Asian winter monsoon play important roles in the modulation mechanism.The SST records display a periodicity of 1482 years.The same period was found in the KC records,indicating that variation of the SST records in the central South Yellow Sea is strongly affected by KC intensity.The same period was also found in Greenland ice cores and North Atlantic and Arabian Sea sediment cores,showing a regional response of marine environmental variability in the East China Seas to that in the global oceans.
