The Southern Ocean is an important carbon sink pool and plays a critical role in the global carbon cycling.The Amundsen Sea was reported to be highly productive in inshore area in the Southern Ocean.In order to invest...The Southern Ocean is an important carbon sink pool and plays a critical role in the global carbon cycling.The Amundsen Sea was reported to be highly productive in inshore area in the Southern Ocean.In order to investigate the influence of transparent exopolymer particles(TEP)on the behavior of dissolved organic carbon(DOC)in this region,a comprehensive study was conducted,encompassing both open water areas and highly productive polynyas.It was found that microbial heterotrophic metabolism is the primary process responsible for the production of humic-like fluorescent components in the open ocean.The relationship between apparent oxygen utilization and the two humic-like components can be accurately described by a power-law function,with a conversion rate consistent with that observed globally.The presence of TEP was found to have little impact on this process.Additionally,the study revealed the accumulation of DOC at the sea surface in the Amundsen Sea Polynya,suggesting that TEP may play a critical role in this phenomenon.These findings contribute to a deeper understanding of the dynamics and surface accumulation of DOC in the Amundsen Sea Polynya,and provide valuable insights into the carbon cycle in this region.展开更多
The distributions of partial pressure of carbon dioxide （pCO2） in the surface waters of the Changjiang River Estuary and adjacent Hangzhou Bay were examined in the summer of 2010. Surface water pCO2 ranged from 751-...The distributions of partial pressure of carbon dioxide （pCO2） in the surface waters of the Changjiang River Estuary and adjacent Hangzhou Bay were examined in the summer of 2010. Surface water pCO2 ranged from 751-2 095/zatm （1 atm=101 325 Pa） in the inner estuary, 177-1 036/zatm in the outer estuary, and 498-1 166 μatm in Hangzhou Bay. Overall, surface pCO2 behaved conservatively during the estuary mixing. In the inner estuary, surface pCO2 was relatively high due to urbanized pollution and a high respiration rate. The lowest pCO2 was observed in the outer estuary, which was apparently induced by a phytoplankton bloom because the dissolved oxygen and chlorophyll a were very high. The Changjiang River Estuary was a significant source of atmospheric CO2 and the degassing fluxes were estimated as 0-230 mmol/（m2.d） [61 mmol/（m2.d） on average] in the inner estuary. In contrast, the outer estuary acted as a CO2 sink.展开更多
To understand the response of transparent exopolymer particles(TEP)to the changes in phytoplankton communities caused by melting sea ice,we collected samples from the polynya and open ocean affected by the Antarctic c...To understand the response of transparent exopolymer particles(TEP)to the changes in phytoplankton communities caused by melting sea ice,we collected samples from the polynya and open ocean affected by the Antarctic circumpolar current in the Amundsen Sea.TEP,pigments,and other environmental factors were analyzed.The results showed that high TEP content was mainly found in the polynya,and was higher in the surface layer than in the deep layer.The main factor that affected TEP distribution was the phytoplankton community.In the polynya area,the phytoplankton were dominated by low-iron Haptophyta.In the Antarctic circumpolar current region affected by ice-melting water,the dominant species was diatom type II.Our results revealed that low-iron Haptophyta may be the main contributors to TEP content.展开更多
The study provides one of the first lines of evidence showing linkages between Antarctic phytoplankton abundance and composition in response to ENSO, based on historical reconstruction of sediment biomarkers. In addit...The study provides one of the first lines of evidence showing linkages between Antarctic phytoplankton abundance and composition in response to ENSO, based on historical reconstruction of sediment biomarkers. In addition to sediment biomarkers, field measured and remote sensing data of phytoplankton abundance were also recorded from Prydz Bay, Eastern Antarctica. Com-munity structure of field measured phytoplankton showed significant El Ni？o/La Ni？a-related succession during 1990 to 2002. In general, the number of algae species decreased during El Ni？o and La Ni？a years compared to normal years. Austral summer monthly variation of remotely sensed chlorophyll-a （Chl-a）, particulate organic carbon （POC）, and sea surface temperature （SST） indicated that ENSO impacted the timing of phytoplankton blooms during 2007 to 2011. Phytoplankton blooms （indicated by Chl-a and POC） preceded the increases in SST during El Ni？o years, and lagged behind the SST increases during La Ni？a years. Stratigraphic record of marine sedimentary lipid （brassicasterol, dinosterol and alkenones） biomarkers inferred that the proportions of different algae （diatoms, dinoflagellates and haptophytes） changed significantly between El Ni？o and La Ni？a events. The relative proportion of diatoms increased, with that of dinoflagellates being decreased during El Ni？o years, while it was reversed during La Ni？a years.展开更多
Concentrations ofbiogenic barium were investigated in surface sediments of Prydz Bay, Antarctica, during the 21st and 27th CHINARE cruises. Factors controlling the observed distribution are explored. Biogenic barium c...Concentrations ofbiogenic barium were investigated in surface sediments of Prydz Bay, Antarctica, during the 21st and 27th CHINARE cruises. Factors controlling the observed distribution are explored. Biogenic barium concentrations obtained from a sequential extraction procedure are compared with total concentrations obtained from the normative calculation based on a total digestion, and differences in the results are examined. Concentrations of biogenic barium, calculated by the normative calculation, were much higher than the concentrations obtained through sequential extraction; this discrepancy is the result of the occurrence of barium associated with Mn/Fe oxides, which represents an important component of total barium in these sediments. Concentrations of biogenic barium obtained from the sequential extraction range from 104 to 445 ktg.g1, and the average concentration was 227 p.g.g-~. The highest concentrations of biogenic barium occur in the central area of the bay, where the seawater is more stable, while lower values occur in the bank and the ice shelf. Biogenic barium is significantly linearly correlated with biogenic barium and organic carbon, and similar in distribution of Chl a, which may indicate that primary productivity of phytoplankton in the surface water column is the main environmental factor regulating barium concentration and distribution.展开更多
Biomarkers including brassicasterol, dinosterol and alkenone in sediments are used as indicators to reconstruct changes to the phytoplankton community in surface and sub-aerial sediments of Prydz Bay, Antarctica. The ...Biomarkers including brassicasterol, dinosterol and alkenone in sediments are used as indicators to reconstruct changes to the phytoplankton community in surface and sub-aerial sediments of Prydz Bay, Antarctica. The results indicate that the bio- marker records in surface and core sediment samples changed with time and space. The total content of phytoplankton biomarkers ranges from 391.0--1 470.6 ng.g-l. The phytoplankton biomass has increased in Prydz Bay over the past 100 years. This variation may be mainly related with climate change in the region. The total biomarker contents in surface sediments from 5 stations in Prydz Bay are in the range of 215.8--1 294.3 ng.g4. The phytoplankton biomass in Prydz Bay is higher than that outside of the bay. This is similar to the distributions of chlorophyll a, organic carbon and biogenic silica in surface waters determined through in situ investigation. Such consistency indicates a coupling between the bottom of the ocean and biogeochemical processes in the upper water.展开更多
滨海湿地具有较强的碳汇能力,不同植被类型会对沉积物中有机碳的来源和储量产生重要影响。在茅埏岛无植被、老红树林、幼红树林和互花米草等4种淤泥质潮滩各采集1根沉积物柱状样品(柱样长度均为1 m,按10 cm间隔分样),测定沉积物粒度、...滨海湿地具有较强的碳汇能力,不同植被类型会对沉积物中有机碳的来源和储量产生重要影响。在茅埏岛无植被、老红树林、幼红树林和互花米草等4种淤泥质潮滩各采集1根沉积物柱状样品(柱样长度均为1 m,按10 cm间隔分样),测定沉积物粒度、总有机碳(TOC)、总氮(TN)等参数,分析和讨论沉积物有机碳来源、储量及其影响因素。结果显示:1)无植被潮滩、老红树林潮滩、幼红树林潮滩和互花米草潮滩沉积物中TOC平均含量依次为0.71%±0.03%,0.76%±0.16%,0.69%±0.12%,0.83%±0.09%。在0~20 cm层,有植被潮滩TOC含量显著高于无植被潮滩;在20~100 cm层,互花米草潮滩沉积物TOC含量高于其它潮滩类型。2)茅埏岛潮滩中互花米草潮滩沉积物有机碳储量最高,达5.79 kg m^(2),其次是老红树林潮滩(5.61 kg m^(2)),幼红树林潮滩(4.95 kg m^(2))和无植被潮滩(4.84 kg m^(2))有机碳储量较低。互花米草潮滩和红树林的覆盖均在一定程度上增强了潮滩的储碳能力。3)互花米草潮滩沉积物中的有机碳主要以陆源为主,占比57.75%;本地植物贡献在老红树林潮滩沉积物中占比最大,占比32.65%;幼红树林潮滩和无植被潮滩沉积物中有机碳均以海源贡献为主,分别占比61.47%和50.45%。展开更多
潮间带是连接陆地生态系统与海洋生态系统的关键带状区域,其中,淤泥质潮滩是重要而容易被忽视的CO 2自然汇集生境,该生境中不同门类的大型底栖动物在促进碳的输入、传递和存储过程中发挥核心作用。本文以夏季浙江东部沿海隘顽湾淤泥质...潮间带是连接陆地生态系统与海洋生态系统的关键带状区域,其中,淤泥质潮滩是重要而容易被忽视的CO 2自然汇集生境,该生境中不同门类的大型底栖动物在促进碳的输入、传递和存储过程中发挥核心作用。本文以夏季浙江东部沿海隘顽湾淤泥质潮滩断面作为切入点,研究大型底栖动物群落结构及生物碳库。结果显示,隘顽湾淤泥质潮滩大型底栖动物平均丰度为105.2±37.2 ind m^(2),平均生物量为46.9±6.4 g m^(2),其生境内主要类群组成为甲壳类动物和软体动物,生态系统健康程度整体表现为优秀。隘顽湾潮滩中大型底栖动物有机碳含量由高到低分别为其他类(包括鱼类、纽虫)动物(40.95%)、多毛类动物(22.98%)、甲壳类动物(17.24%)、棘皮动物(15.90%)和软体动物(10.76%)。估算研究区域大型底栖动物碳库约为163.90 Mg,其中甲壳类动物为最大贡献者,占比59.80%。淤泥质潮滩大型底栖动物群落结构与生物碳库大小的探究,可作为我国蓝碳调查体系构建的重要科学依据,也可为进一步量化沿海生境整体碳库大小提供基础数据。展开更多
Lipid biomarkers in AD2 penguin droppings-amend soil core from the Ardley Island,Western Antarctic,were dated using 210Pb.Changes in the fatty acid ratios of nC18:2/nC18:0 from the penguin droppings reflect climate ch...Lipid biomarkers in AD2 penguin droppings-amend soil core from the Ardley Island,Western Antarctic,were dated using 210Pb.Changes in the fatty acid ratios of nC18:2/nC18:0 from the penguin droppings reflect climate changes coincident with ENNO events during 1931-2006.The occurrence of the minimum values in the depth of 2-3 and 6-7 cm are consistent with the end of ENSO in 1958 and 1983,respectively,reflecting a lag of the biomarker records in AD2 penguin droppings-amend soil in climatic signatures.This study also reveals that the changes in the relative concentration of n-alkanes nC23,the ratios of nC23/nC17 and nC21 /nC22+,and carbon preferential index(CPI) values collectively indicate the variations of soil microor-ganism and lower plant,which are closely related to climate changes.The ratios of bacterial fatty acids iC15:0/aC15:0 reflect the increasing significance of microorganism activities during the two periods that occurred at the end years of ENSO.Decrease in CPIA value and increase in nC21 /nC22+ indicate that low molecular weight fatty acids are derived from microorganism;and their insignificant correlation with Pr/Ph suggests microorganisms play an important role in the relatively simply ecosystem in the Antarctic and are closely linked to climatic conditions.In addition,the observed penguin community indicates the popula-tion of penguin can largely reflect the impacts of global climate changes on the ecosystem.展开更多
The historical data of phytoplankton and chlorophyll a(Chl a)(1990–2002)obtained during the Chinese National Antarctic Research Expedition(CHINARE)in the Prydz Bay have been integrated.The results showed that the tem...The historical data of phytoplankton and chlorophyll a(Chl a)(1990–2002)obtained during the Chinese National Antarctic Research Expedition(CHINARE)in the Prydz Bay have been integrated.The results showed that the temperature,salinity,nutrients,and oxygen of seawater changed when El Nino/La Nina occurred.The variation of biological communities reflected the response of ecosystem to environmental changes.During El Ni?o period,Chl a concentration and phytoplankton community structure changed significantly,and the relative proportion of diatoms increased while dinoflagellates decreased.During La Ni?a period,the proportion of diatoms decreased,but the golden-brown algae and blue-green algae increased significantly.The variation of phytoplankton population directly affected the biodiversity of the bay,which were also quite sensitive to the marine environment changes.Meanwhile,the satellite remote sensing data of 2002–2011(December–March)have been used to study the temporal connection change of Chl a and phytoplankton in the Prydz Bay.We found that there were significant differences in the monthly variation characteristics of satellite remote sensing Chl a and sea surface temperature(SST),which had some links with sea ice melting and El Ni?o/La Ni?a events.We found that the start time of bloom advanced,lagged or synchronized with the changes of the SST,and we also found the occurrence time of phytoplankton bloom corresponded with the sea ice melting inner bay.To some extent,this study will help us understand the relationships between ENSO events and the phytoplankton bloom in the Southern Ocean.展开更多
Two records of the crust laminae from the Marcus-Wake Seamounts and the Magellan Seamount were biostratigraphically studied. Based on biological imprints of the calcareous nannofossils, the geological ages of the two ...Two records of the crust laminae from the Marcus-Wake Seamounts and the Magellan Seamount were biostratigraphically studied. Based on biological imprints of the calcareous nannofossils, the geological ages of the two records were determined, with CM1D03 from the Marcus-Wake Seamounts being of late Paleocene to Pleistocene and CM3D06 from the Magellan Seamount of Late Cretaceous （more than 70.0 Ma）. There are the obvious temporal-spatial differences in the initial formation period and enrichment characteristics of the cobalt-rich crusts of the two seamount chains and differences in the combination and distribution of microfossils in the inner crust layers between the seamounts. These differences are due to the adaptabilities of oceanic species in different environments. Ecological research was carried out in terms of population size of the calcareous nannofossi｜s preserved in the crustal layers to discern the relation of the geological events at the Eocene-Oligocene （E/O） tran- sition. The results show the transitions and recombination of species in the biotic community during the E/O transition obvi- ously corresponded to 25 mm depth in the CM1D03 crust and 58 mm depth in the CM3D06 crust. The changes in biological species and the formation of particular ecological structures indicate the adaptive response of the paleo-biological community in the western Pacific Ocean to the global cold-climate events and the close correlation between the formation of the crust and the global climate change.展开更多
基金funded by the National Natural Science Foundation of China(Grant nos.42276255 and 41976227)project“Impact and Response of Antarctic Seas to Climate Change,IRASCC 2020-2022”(Grant nos.01-01-02A and 02-02-05).
文摘The Southern Ocean is an important carbon sink pool and plays a critical role in the global carbon cycling.The Amundsen Sea was reported to be highly productive in inshore area in the Southern Ocean.In order to investigate the influence of transparent exopolymer particles(TEP)on the behavior of dissolved organic carbon(DOC)in this region,a comprehensive study was conducted,encompassing both open water areas and highly productive polynyas.It was found that microbial heterotrophic metabolism is the primary process responsible for the production of humic-like fluorescent components in the open ocean.The relationship between apparent oxygen utilization and the two humic-like components can be accurately described by a power-law function,with a conversion rate consistent with that observed globally.The presence of TEP was found to have little impact on this process.Additionally,the study revealed the accumulation of DOC at the sea surface in the Amundsen Sea Polynya,suggesting that TEP may play a critical role in this phenomenon.These findings contribute to a deeper understanding of the dynamics and surface accumulation of DOC in the Amundsen Sea Polynya,and provide valuable insights into the carbon cycle in this region.
基金The Marine Public Welfare Project of China under contract Nos200805029,200905012,200905025,and 201005034the Scientific Research Fund of the Second Institute of Oceanography,SOA under contract Nos JG0821 and JG1021
文摘The distributions of partial pressure of carbon dioxide （pCO2） in the surface waters of the Changjiang River Estuary and adjacent Hangzhou Bay were examined in the summer of 2010. Surface water pCO2 ranged from 751-2 095/zatm （1 atm=101 325 Pa） in the inner estuary, 177-1 036/zatm in the outer estuary, and 498-1 166 μatm in Hangzhou Bay. Overall, surface pCO2 behaved conservatively during the estuary mixing. In the inner estuary, surface pCO2 was relatively high due to urbanized pollution and a high respiration rate. The lowest pCO2 was observed in the outer estuary, which was apparently induced by a phytoplankton bloom because the dissolved oxygen and chlorophyll a were very high. The Changjiang River Estuary was a significant source of atmospheric CO2 and the degassing fluxes were estimated as 0-230 mmol/（m2.d） [61 mmol/（m2.d） on average] in the inner estuary. In contrast, the outer estuary acted as a CO2 sink.
基金financially supported by National Polar Special Program “Impact and Response of Antarctic Seas to Climate Change” (Grant nos. IRASCC 02-02-01, 02-02-03, 02-02-04, and 02-02-05)。
文摘To understand the response of transparent exopolymer particles(TEP)to the changes in phytoplankton communities caused by melting sea ice,we collected samples from the polynya and open ocean affected by the Antarctic circumpolar current in the Amundsen Sea.TEP,pigments,and other environmental factors were analyzed.The results showed that high TEP content was mainly found in the polynya,and was higher in the surface layer than in the deep layer.The main factor that affected TEP distribution was the phytoplankton community.In the polynya area,the phytoplankton were dominated by low-iron Haptophyta.In the Antarctic circumpolar current region affected by ice-melting water,the dominant species was diatom type II.Our results revealed that low-iron Haptophyta may be the main contributors to TEP content.
基金financially supported by the National Natural Science Foundation of China (NSFC) (40876104, 41306202, 41376193, 41076134 and 41006118)the scientific research fund of Second Institute of Oceanography, SOA (JT1208 and JG1218)+1 种基金Chinese Arctic and Antarctic Administration Foundation (20110208)the special fund for polar environment comprehensive investigation and assessment (CHINARE 2014-04-04, 2014-01-04 and 2014-04-01)
文摘The study provides one of the first lines of evidence showing linkages between Antarctic phytoplankton abundance and composition in response to ENSO, based on historical reconstruction of sediment biomarkers. In addition to sediment biomarkers, field measured and remote sensing data of phytoplankton abundance were also recorded from Prydz Bay, Eastern Antarctica. Com-munity structure of field measured phytoplankton showed significant El Ni？o/La Ni？a-related succession during 1990 to 2002. In general, the number of algae species decreased during El Ni？o and La Ni？a years compared to normal years. Austral summer monthly variation of remotely sensed chlorophyll-a （Chl-a）, particulate organic carbon （POC）, and sea surface temperature （SST） indicated that ENSO impacted the timing of phytoplankton blooms during 2007 to 2011. Phytoplankton blooms （indicated by Chl-a and POC） preceded the increases in SST during El Ni？o years, and lagged behind the SST increases during La Ni？a years. Stratigraphic record of marine sedimentary lipid （brassicasterol, dinosterol and alkenones） biomarkers inferred that the proportions of different algae （diatoms, dinoflagellates and haptophytes） changed significantly between El Ni？o and La Ni？a events. The relative proportion of diatoms increased, with that of dinoflagellates being decreased during El Ni？o years, while it was reversed during La Ni？a years.
基金supported by the National Natural Science Foundation of China(Grant nos.41006118 and 41076134)the Chinese Polar Environment Comprehensive Investigation & Assessment Programmes(Grant no.CHINARE2012-04-04)
文摘Concentrations ofbiogenic barium were investigated in surface sediments of Prydz Bay, Antarctica, during the 21st and 27th CHINARE cruises. Factors controlling the observed distribution are explored. Biogenic barium concentrations obtained from a sequential extraction procedure are compared with total concentrations obtained from the normative calculation based on a total digestion, and differences in the results are examined. Concentrations of biogenic barium, calculated by the normative calculation, were much higher than the concentrations obtained through sequential extraction; this discrepancy is the result of the occurrence of barium associated with Mn/Fe oxides, which represents an important component of total barium in these sediments. Concentrations of biogenic barium obtained from the sequential extraction range from 104 to 445 ktg.g1, and the average concentration was 227 p.g.g-~. The highest concentrations of biogenic barium occur in the central area of the bay, where the seawater is more stable, while lower values occur in the bank and the ice shelf. Biogenic barium is significantly linearly correlated with biogenic barium and organic carbon, and similar in distribution of Chl a, which may indicate that primary productivity of phytoplankton in the surface water column is the main environmental factor regulating barium concentration and distribution.
基金supported by the National Nature Science Foundation of China under contract (Grant nos.40876104, 41006118 and 41076134)
文摘Biomarkers including brassicasterol, dinosterol and alkenone in sediments are used as indicators to reconstruct changes to the phytoplankton community in surface and sub-aerial sediments of Prydz Bay, Antarctica. The results indicate that the bio- marker records in surface and core sediment samples changed with time and space. The total content of phytoplankton biomarkers ranges from 391.0--1 470.6 ng.g-l. The phytoplankton biomass has increased in Prydz Bay over the past 100 years. This variation may be mainly related with climate change in the region. The total biomarker contents in surface sediments from 5 stations in Prydz Bay are in the range of 215.8--1 294.3 ng.g4. The phytoplankton biomass in Prydz Bay is higher than that outside of the bay. This is similar to the distributions of chlorophyll a, organic carbon and biogenic silica in surface waters determined through in situ investigation. Such consistency indicates a coupling between the bottom of the ocean and biogeochemical processes in the upper water.
文摘滨海湿地具有较强的碳汇能力,不同植被类型会对沉积物中有机碳的来源和储量产生重要影响。在茅埏岛无植被、老红树林、幼红树林和互花米草等4种淤泥质潮滩各采集1根沉积物柱状样品(柱样长度均为1 m,按10 cm间隔分样),测定沉积物粒度、总有机碳(TOC)、总氮(TN)等参数,分析和讨论沉积物有机碳来源、储量及其影响因素。结果显示:1)无植被潮滩、老红树林潮滩、幼红树林潮滩和互花米草潮滩沉积物中TOC平均含量依次为0.71%±0.03%,0.76%±0.16%,0.69%±0.12%,0.83%±0.09%。在0~20 cm层,有植被潮滩TOC含量显著高于无植被潮滩;在20~100 cm层,互花米草潮滩沉积物TOC含量高于其它潮滩类型。2)茅埏岛潮滩中互花米草潮滩沉积物有机碳储量最高,达5.79 kg m^(2),其次是老红树林潮滩(5.61 kg m^(2)),幼红树林潮滩(4.95 kg m^(2))和无植被潮滩(4.84 kg m^(2))有机碳储量较低。互花米草潮滩和红树林的覆盖均在一定程度上增强了潮滩的储碳能力。3)互花米草潮滩沉积物中的有机碳主要以陆源为主,占比57.75%;本地植物贡献在老红树林潮滩沉积物中占比最大,占比32.65%;幼红树林潮滩和无植被潮滩沉积物中有机碳均以海源贡献为主,分别占比61.47%和50.45%。
文摘潮间带是连接陆地生态系统与海洋生态系统的关键带状区域,其中,淤泥质潮滩是重要而容易被忽视的CO 2自然汇集生境,该生境中不同门类的大型底栖动物在促进碳的输入、传递和存储过程中发挥核心作用。本文以夏季浙江东部沿海隘顽湾淤泥质潮滩断面作为切入点,研究大型底栖动物群落结构及生物碳库。结果显示,隘顽湾淤泥质潮滩大型底栖动物平均丰度为105.2±37.2 ind m^(2),平均生物量为46.9±6.4 g m^(2),其生境内主要类群组成为甲壳类动物和软体动物,生态系统健康程度整体表现为优秀。隘顽湾潮滩中大型底栖动物有机碳含量由高到低分别为其他类(包括鱼类、纽虫)动物(40.95%)、多毛类动物(22.98%)、甲壳类动物(17.24%)、棘皮动物(15.90%)和软体动物(10.76%)。估算研究区域大型底栖动物碳库约为163.90 Mg,其中甲壳类动物为最大贡献者,占比59.80%。淤泥质潮滩大型底栖动物群落结构与生物碳库大小的探究,可作为我国蓝碳调查体系构建的重要科学依据,也可为进一步量化沿海生境整体碳库大小提供基础数据。
基金supported by National Natural Science Foundation of Chi-na (Grant Nos.40876104 and 41006118)
文摘Lipid biomarkers in AD2 penguin droppings-amend soil core from the Ardley Island,Western Antarctic,were dated using 210Pb.Changes in the fatty acid ratios of nC18:2/nC18:0 from the penguin droppings reflect climate changes coincident with ENNO events during 1931-2006.The occurrence of the minimum values in the depth of 2-3 and 6-7 cm are consistent with the end of ENSO in 1958 and 1983,respectively,reflecting a lag of the biomarker records in AD2 penguin droppings-amend soil in climatic signatures.This study also reveals that the changes in the relative concentration of n-alkanes nC23,the ratios of nC23/nC17 and nC21 /nC22+,and carbon preferential index(CPI) values collectively indicate the variations of soil microor-ganism and lower plant,which are closely related to climate changes.The ratios of bacterial fatty acids iC15:0/aC15:0 reflect the increasing significance of microorganism activities during the two periods that occurred at the end years of ENSO.Decrease in CPIA value and increase in nC21 /nC22+ indicate that low molecular weight fatty acids are derived from microorganism;and their insignificant correlation with Pr/Ph suggests microorganisms play an important role in the relatively simply ecosystem in the Antarctic and are closely linked to climatic conditions.In addition,the observed penguin community indicates the popula-tion of penguin can largely reflect the impacts of global climate changes on the ecosystem.
基金supported by the National Natural Science Foundation of China(Grant Nos.40876104,41076134,41306202,and 41376193)the Scientific Research Fund of the Second Institute,SOA(Grant Nos.JT1208,JG1217 and JG1218)
文摘The historical data of phytoplankton and chlorophyll a(Chl a)(1990–2002)obtained during the Chinese National Antarctic Research Expedition(CHINARE)in the Prydz Bay have been integrated.The results showed that the temperature,salinity,nutrients,and oxygen of seawater changed when El Nino/La Nina occurred.The variation of biological communities reflected the response of ecosystem to environmental changes.During El Ni?o period,Chl a concentration and phytoplankton community structure changed significantly,and the relative proportion of diatoms increased while dinoflagellates decreased.During La Ni?a period,the proportion of diatoms decreased,but the golden-brown algae and blue-green algae increased significantly.The variation of phytoplankton population directly affected the biodiversity of the bay,which were also quite sensitive to the marine environment changes.Meanwhile,the satellite remote sensing data of 2002–2011(December–March)have been used to study the temporal connection change of Chl a and phytoplankton in the Prydz Bay.We found that there were significant differences in the monthly variation characteristics of satellite remote sensing Chl a and sea surface temperature(SST),which had some links with sea ice melting and El Ni?o/La Ni?a events.We found that the start time of bloom advanced,lagged or synchronized with the changes of the SST,and we also found the occurrence time of phytoplankton bloom corresponded with the sea ice melting inner bay.To some extent,this study will help us understand the relationships between ENSO events and the phytoplankton bloom in the Southern Ocean.
基金supported by the National Natural Science Foundation of China(Grant Nos.41076072 and 40676025)
文摘Two records of the crust laminae from the Marcus-Wake Seamounts and the Magellan Seamount were biostratigraphically studied. Based on biological imprints of the calcareous nannofossils, the geological ages of the two records were determined, with CM1D03 from the Marcus-Wake Seamounts being of late Paleocene to Pleistocene and CM3D06 from the Magellan Seamount of Late Cretaceous （more than 70.0 Ma）. There are the obvious temporal-spatial differences in the initial formation period and enrichment characteristics of the cobalt-rich crusts of the two seamount chains and differences in the combination and distribution of microfossils in the inner crust layers between the seamounts. These differences are due to the adaptabilities of oceanic species in different environments. Ecological research was carried out in terms of population size of the calcareous nannofossi｜s preserved in the crustal layers to discern the relation of the geological events at the Eocene-Oligocene （E/O） tran- sition. The results show the transitions and recombination of species in the biotic community during the E/O transition obvi- ously corresponded to 25 mm depth in the CM1D03 crust and 58 mm depth in the CM3D06 crust. The changes in biological species and the formation of particular ecological structures indicate the adaptive response of the paleo-biological community in the western Pacific Ocean to the global cold-climate events and the close correlation between the formation of the crust and the global climate change.
