A three-dimensional coupled sea ice-ice shelf-ocean numerical model is developed for the Prydz Bay,Antarctica,using the Regional Ocean Modeling System with a grid resolution of approximately 2 km.The influence of the ...A three-dimensional coupled sea ice-ice shelf-ocean numerical model is developed for the Prydz Bay,Antarctica,using the Regional Ocean Modeling System with a grid resolution of approximately 2 km.The influence of the grounding giant iceberg D15 on the distribution of sea ice and polynyas in the Prydz Bay is analyzed through two numerical experiments.Iceberg D15,grounded off the western edge of the West Ice Shelf(WIS),obstructs the southwestward transport of sea ice along the east coast of Prydz Bay,causing sea ice to accumulate to the east of the iceberg and form multi-year fast ice.Grounding of Iceberg D15 also decreases sea ice coverage off its south edge and creates ice-free openings in spring near Davis Station and Zhongshan Station,facilitating the accessibility of vessels to the research stations.These simulated sea ice patterns closely match current satellite observations.When Iceberg D15 is removed,the previously blocked sea ice north of the iceberg,which moved westward,shifts southwesterly along the coastline,leading to a reduction in sea ice thickness during winter and spring,as well as lower sea ice concentrations in spring across large areas north and west of the iceberg.In contrast,the sea ice thickness increases considerably southwest of the WIS,extending to the front of the Amery Ice Shelf during seasons covered by sea ice.The increase in sea ice concentration can also extend to as far as 75°E in spring.Without Iceberg D15,which previously contributed to the ice barrier of Barrier Polynya(BP),the shape of BP changes,the area of BP and Davis Polynya(DP)decreases,and the polynya off the northwest edge of the WIS near 83°E expands.These polynya patterns are much similar to the satellite remote sensing observations before Iceberg D15 was grounded.From April to October,the total area of BP and DP decreases by 2.83×10^(4)km^(2)(60%)and 2.20×10^(3)km^(2)(20%),respectively,while the total sea ice production decreases by 4.11×10^(10)m^(3)(66%)and 1.52×10^(10)m^(3)(52%)compared to the experiment with iceberg.These results indicate the substantial effects of grounding giant icebergs on the spatio-temporal distribution of sea ice,the area of polynyas,and sea ice production.High-resolution Antarctic coastal numerical models,typically with grid scales of kilometers,are sufficient to represent large icebergs,and adding the grounding giant icebergs is crucial for producing realistic simulations of sea ice and polynyas.展开更多
The characteristics of modified Circumpolar Deep Water(mCDW)on the continental shelf in Prydz Bay,East Antarctica,are studied based on hydrographic data obtained by the Chinese National Antarctic Research Expeditions ...The characteristics of modified Circumpolar Deep Water(mCDW)on the continental shelf in Prydz Bay,East Antarctica,are studied based on hydrographic data obtained by the Chinese National Antarctic Research Expeditions across 14 summers from 1999 to 2022.In austral summer,the mCDW upwells along the upper continental slope then intrudes on the continental shelf across the shelf break in a warm tongue that gradually upwells poleward.The mCDW intrusion at the 73°E section is relatively weaker in December and stronger in February while showing significant interannual variability.During strong intrusions(January 2000 and February 2003),the mCDW extends southward to 68°S and upwells to 50 m,whereas the mCDW only reaches the shelf break during weak intrusions(December 2004,January 2006,January 2011,and February 2015).The intensity of the mCDW intrusions correlates strongly with the accumulated wind stress curl(30 days prior)north of the shelf break(73.5°-78.0°E,64.5°-66.0°S).The summertime westerly winds play a key role in regulating the interannual variability of mCDW intrusion onto the continental shelf.A southward shift of the westerly winds promotes the upwelling and southward intrusion of mCDW across the shelf break.In addition,mCDW at 73°E can reach as far as 68°S due to the southward flow of mCDW being hindered by a northward outflowing branch of the coastal current at the Amery Ice Shelf(AIS)front.In austral summer,the mCDW had never been observed at the section along the AIS front;thus,it cannot directly contribute to the basal melting of the ice shelf.展开更多
The melting of seasonal sea ice in Antarctica plays a pivotal role in the region’s carbon cycle,influencing global carbon storage and the exchange of carbon between the atmosphere and the ocean.However,the impact of ...The melting of seasonal sea ice in Antarctica plays a pivotal role in the region’s carbon cycle,influencing global carbon storage and the exchange of carbon between the atmosphere and the ocean.However,the impact of variability in the timing of seasonal sea ice retreat on the flux and composition of sinking particulate matter remains to be elucidated.In this study,we deployed sediment traps in Prydz Bay during the austral summers of 2019/2020 and 2020/2021,noting that sea ice melting occurred approximately one and a half months earlier in the former summer compared to the latter.We analyzed sediment trap data,which included total mass flux(TMF),particulate organic carbon(POC),biogenic silica(BSi),particulate inorganic carbon,and lithogenic particle(Litho)fluxes,as well as the stable isotopesδ^(13)C andδ^(15)N of particulate organic matter(POM).Additionally,we incorporated remote sensing data on sea ice concentration and chlorophyll a.This dramatic delay in sea ice melting timing could result in a significant increase in TMF,BSi and POC fluxes in the summer of 2020/2021 compared to 2019/2020.Elevated BSi fluxes and more ^(13)C-depleted POC in the austral summer of 2020/2021 suggest that the delayed melting of sea ice may have stimulated the productivity of centric diatoms.Furthermore,the higher BSi/POC ratio and more negativeδ^(15)N values of POM,along with a reduced presence of krill in the traps,indicate a diminished grazing pressure from zooplankton,which collectively enhanced the sedimentation efficiency of POC during the austral summer of 2020/2021.These findings highlight the critical role of sea ice melting timing in regulating productivity,flux and composition of sinking particulate matter in the Prydz Bay ecosystem,with significant implications for carbon cycling in polar oceans.展开更多
The global ocean is a major source of the climate-relevant atmospheric trace gas nitrous oxide(N_(2)O).However,an accurate assessment of the global oceanic emissions of N_(2)O is hampered by missing data on dissolved ...The global ocean is a major source of the climate-relevant atmospheric trace gas nitrous oxide(N_(2)O).However,an accurate assessment of the global oceanic emissions of N_(2)O is hampered by missing data on dissolved N_(2)O from large regions such as the Southern Ocean.To address this deficit,N_(2)O was measured in the Prydz Bay in February 2015 during the 31st Chinese National Antarctic Research Expedition.N_(2)O concentrations(saturation)in the surface layer were generally low(undersaturation with respect to atmospheric equilibrium)and ranged from 13.3 nmol/L to 16.1 nmol/L(83%–102%)at the time of sampling.A comparison of our observations with archived data revealed that no discernible trend in N_(2)O concentrations in the surface waters of Prydz Bay could be detected for the period between 2006 and 2015.Temperature and salinity changes driven by meltwater input were the predominant controls on N_(2)O concentrations in surface waters.At depth,the distribution of N_(2)O concentrations was dominated by production via nitrification in offshore deep waters and vertical convection in the shelf waters,where concentrations were lower and gradients were less steep.Our results suggest a rather unusual pattern of N_(2)O distribution in the Prydz Bay(low N_(2)O in shelf waters compared with the open ocean),providing important insights into the coastal dynamics of N_(2)O in high-latitude polar regions.展开更多
The cell density, species composition and distribution of phytoplankton, and their relations to environmental factors in Prydz Bay and its adjacent sea area, Antarctica (69degrees-77degrees E, 62degrees-70degrees S) d...The cell density, species composition and distribution of phytoplankton, and their relations to environmental factors in Prydz Bay and its adjacent sea area, Antarctica (69degrees-77degrees E, 62degrees-70degrees S) during the austral summer of 1998/1999 were investigated. A total of 48 taxa belonging to 21 genera of phytoplankton in the sea area were identified. The average cell density of phytoplankton was 22.46 x 10(3) cells/dm(3), of which diatoms were predominant (84.51%). The highest cell density of phytoplankton occurred in Prydz Bay and the adjacent continental shelf where the average cell density was 46.03 x 10(3) cells/dm(3). The lowest cell density (3.34 x 10(3) cells/dm(3)) occurred in deep sea area. The dominant species of phytoplankton was Fragilariopsis curta. The vertical distribution of phytoplankton density was highest in the upper part of 0-50 in depth, lower in 100 in and lowest in 150 in. The species composition and cell density of phytoplankton were influenced by water circulation. The cell density was positively correlated with water temperature and salinity, and negatively correlated with the concentration of nutrients.展开更多
In order to better understand the spatial and temporal distribution of dissolved cadmium in Prydz Bay, east Antarctica, seawaters were sampled by CTD during the CHINARE-25 cruise （Oct. 2008 - Apr. 2009） and the conc...In order to better understand the spatial and temporal distribution of dissolved cadmium in Prydz Bay, east Antarctica, seawaters were sampled by CTD during the CHINARE-25 cruise （Oct. 2008 - Apr. 2009） and the concentrations of cadmium were analyzed by AAS （Atomic Absorption Spectrometry） in the clean laboratory. Together with the data of macronutrients and chl.a from the same cruise, the relationship between cadmium and biological process was studied. The results showed that the concentrations of Cd in the surface water had a good relationship with chl.a and biologicl process was the important factor that influenced the distribution of dissolved Cd in the surface water. Linear relationship was found between dissolved Cd and phosphate in the surface water and the high ratio of Cd/P at the edge of ice shelf was most probably due to ice melting, vertical distribution of Cd was similar to those of macronutrient such as phosphate and was affected by decomposition of organic particals. The temporal change of dissolved Cd in upper layer was slight and tide probably had influence on the change.展开更多
The Prydz Bay in the Antarctic is an important area in the Southern Ocean due to its unique geographic feature. It plays an important role in the carbon cycle in the Southern Ocean. To investigate the distributions of...The Prydz Bay in the Antarctic is an important area in the Southern Ocean due to its unique geographic feature. It plays an important role in the carbon cycle in the Southern Ocean. To investigate the distributions of carbon dioxide in the atmosphere and surface seawater and its air-sea exchange rates in this region, the Chinese National Antarctic Research Expedition （CHINARE） had set up several sections in the Prydz Bay. Here we present the results from the CHINARE-XVI cruises were presented onboard R/V Xue/ong from November 1999 to April 2000 and the main driving forces were discussed controlling the distributions of partial pressure of carbon dioxide. According to the partial pressure of carbon dioxide distributions, the Prydz Bay can be divided into the inside and outside regions. The partial pressure of carbon dioxide was low in the inside region but higher in the outside region during the measurement period. This distribution had a good negative correlation with the concentrations of ehlorophyll-a in general, suggesting that the partial pressure of carbon dioxide was substantially affected by biological production. The results also indicate that the biological produetion is most likely the main driving force in the marginal ice zone in the Southern Ocean in summer. However, in the Antarctic divergence sector of the Prydz Bay （about 64°S）, the hydrological processes become the controlling factor as the sea surface partial pressure of carbon dioxide is much higher than the atmospheric one due to the upwelling of the high DIC CDW, and this made the outside of Prydz Bay a source of carbon dioxide. On the basis of the calculations, the CO2 flux in January （austral summer） was -3.23 mmol/（m^2 · d） in the inner part of Prydz Bay, i.e. , a sink of atmospheric CO2, and was 0.62 mmol/（m^2 · d） in the outside part of the bay, a weak source of atmospheric CO2. The average air-sea flux of CO2 in the Prydz Bay was 2.50 mmol/（m^2 · d）.展开更多
Dissolved and particulate thorium-234, particulate organic carbon in the upper 150 m of water columns from five stations in the Prydz Bay, the Southern Ocean were determined during the 22nd Chinese National Antarctic ...Dissolved and particulate thorium-234, particulate organic carbon in the upper 150 m of water columns from five stations in the Prydz Bay, the Southern Ocean were determined during the 22nd Chinese National Antarctic Research Expedition （from November 2005 to March 2006 ）. The disequilibria between thorium-234 and its parent uranium-238 in upper layer was used to derive the averaged residence time of thorium-234, which decreased along with the latitude to the south and a minimum value, 1 - 8 d for particulate thorium-234 and 29 - 48 d for dissolved thorium-234, appeared at the medium latitude station, and the export fluxes of thorium-234 were calculated too and ＇a maximum value, 0. 35 -0. 63 Bq/（m^3 · d） for the particulate thorium-234 and 0. 44 -0. 65 Bq/ （m^3 ·d） for the dissolved thorium-234, appeared at the same station. The export fluxes of particulate organic carbon at different water columns were derived by two methods with irreversible scavenging model, and the averaged values were 104. 7 mmol/ （ m2 · d ） （ E method） and 120. 6 mmol/（ m2·d ） （ B method ）, respectively, indicating that a relatively high new production would exist in summer in the Prydz Bay where it will play a potential significant role in sequestering the absorption CO2 to deeper ocean.展开更多
Thermohaline features, spatial extensions, and depths of the antarctic circumpolar deep water, the antarctic bottom water, and the upper layer water near the Prydz Bay （ including the Prydz Bay s.mmer surface water, ...Thermohaline features, spatial extensions, and depths of the antarctic circumpolar deep water, the antarctic bottom water, and the upper layer water near the Prydz Bay （ including the Prydz Bay s.mmer surface water, the antarctic winter water, and the Prydz Bay shelf water ） are analyzed and studied by use of the full depth CTD data obtained in the Southern Ocean near the Prydz Bay during the 1998/1999 austral summer. The northward extension of the shelf water, the thickness of the temperature inversion layer, the minima in the vertical temperature profile and the vertical temperature gradient are interpreted. On the basis of analysis of gravitational potential field, the geostrophic current and the geostrophic volume transport are calculated to determine the location of the strongest current in the zonal circulation near the Prydz Bay and to find the spatial variability of the volume transport in the64° -66.5°S zone. In addition, the central location, the frontal strength, the vertical depth and thickness of the continental water boundary （CWB） are estimated from the CTD data to expound the spatial variability of CWB in the study area （64° -66.5°S, 70° -75°E）.展开更多
Supercooled water with temperatures below freezing point, was identified from hydrographic data obtained by Chinese and Australian expeditions to Prydz Bay, Antarctica, during the austral summer. The study shows that ...Supercooled water with temperatures below freezing point, was identified from hydrographic data obtained by Chinese and Australian expeditions to Prydz Bay, Antarctica, during the austral summer. The study shows that most supercooled waters occurred at depths of 63-271 m in the region north of the Amery Ice Shelf （AIS） front. The maximum supercooling was 0.16℃ below the in-situ freezing point. In temperature and salinity ranges of-2.14 - -1.96℃ and 34.39-34.46, respectively, the water was colder and fresher than peripheral shelf water. The supercooled water had less variability in the vertical profiles compared to shelf water. Based on analysis of their thermohaline features and spatial distribution, as well as the circulation pattern in Prydz Bay, we conclude that these supercooled waters originated from a cavity beneath the AIS and resulted from upwelling just outside of the AIS front. Water emerging from the ice shelf cools to an extremely low temperature （about -2.0℃） by additional cooling from the ice shelf, and becomes buoyant with the addition of melt water from the ice shelf base. When this water flows out of the ice shelf front, its upper boundary is removed, and thus it rises abruptly. Once the temperature of this water reaches below the freezing point, supercooling takes place. In summer, the seasonal pycnocline at -100 m water depth acts as a barrier to upwelling and supercooling. The upwelling of ice shelf outflow water illuminates a unique mid-depth convection of the polar ocean.展开更多
Using a combination of stable isotope(15N) and radionuclide(226Ra) analyses, we examine possible controls on the interactions between melting ice and the uptake of nitrogen in the Prydz Bay during the 2006 austral sum...Using a combination of stable isotope(15N) and radionuclide(226Ra) analyses, we examine possible controls on the interactions between melting ice and the uptake of nitrogen in the Prydz Bay during the 2006 austral summer.We find that specific rates of uptake for nitrate and ammonium correlate positively to their concentrations, thus suggesting a substrate effect. In the study area, we observe that regions along open, oceanic water have high fratios(nitrate uptake/nitrate+ammonium uptake), while areas near the Amery Ice Shelf have significantly low fratios. Further analysis reveals a negative correlation between the f-ratio and the melt water fraction, thus implying that the melting of ice plays an essential role in regulating pelagic N dynamics in the Southern Ocean(SO). Stratification, produced by melting ice, should profoundly affect the efficiency of the SO’s biological pump and consequently affect the concentration of CO2 in the atmosphere. Results presented in this study add information to an already significant base of understanding of the controls on pelagic C and N dynamics in the SO. This provides unique insights for either interpreting past changes in geologic records or for predicting future climate change trends.展开更多
In this study, we investigated the distributions of sea-surface suspended particulate organic carbon （POC） and its stable isotope （δ13C POC） in Prydz Bay, Antarctica, and examined the factors influencing their di...In this study, we investigated the distributions of sea-surface suspended particulate organic carbon （POC） and its stable isotope （δ13C POC） in Prydz Bay, Antarctica, and examined the factors influencing their distribution, sources, and transport. We used measurements collected from 61 stations in Prydz Bay during the 29th Chinese National Antarctic Research Expedition, in combination with remote sensing data on sea surface temperature （SST）, chlorophyll a concentration, and sea ice coverage. The POC concentration in the surface waters of Prydz Bay was 0.28-0.84 mg.L-1, with an average concentration of 0.48 mg.L-1. The δ13C POC value ranged from -29.68‰ to -26.30‰, with an average of-28.01‰. The concentration of suspended POC was highest in near-shore areas and in western Prydz Bay. The POC concentration was correlated with chlorophyll a concentration and sea ice coverage, suggesting that POC was associated with phytoplankton production in local water columns, while the growth of phytoplankton was obviously affected by sea ice coverage. The δ13C poc value in suspended particles decreased gradually towards the outer waters of Prydz Bay, while in eastern Prydz Bay the δ13Cpoc value become gradually more negative from nearshore to deep-water areas, suggesting that δ13C poc was mainly influenced by CO2 fixation by phytoplankton. The δ13C POC value in suspended particles near Zhongshan Station was significantly negative, possibly as a result of the input of terrigenous organic matter and changes in the phytoplankton species composition in the nearshore area.展开更多
Considering the complex topographic features of the southeast of Prydz Bay where China's Zhongshan Station is located,three types of geomorphologic units can be identified,i.e., submarine slopes,canyons,and terrai...Considering the complex topographic features of the southeast of Prydz Bay where China's Zhongshan Station is located,three types of geomorphologic units can be identified,i.e., submarine slopes,canyons,and terrains.The major topographic features in the study area are the submarine canyon and trough system outside the calving ice front of Dalk Glacier.A 3.8 km×80 m fissure is found on the submarine terrain at Zhongshan Anchorage,which,once triggered by geological hazards such as earthquakes and ice falls,would be a threat to the usage and maintenance of the anchorage.展开更多
In 2013, the 29th Chinese National Antarctic Research Expedition（CHINARE） prospected the Prydz Bay on the Antarctic continental shelf, and the Chinese R/V Xuelong icebreaker sampled all of the examined locations. Th...In 2013, the 29th Chinese National Antarctic Research Expedition（CHINARE） prospected the Prydz Bay on the Antarctic continental shelf, and the Chinese R/V Xuelong icebreaker sampled all of the examined locations. The nature of Antarctic fish diversity in the high-latitude Prydz Bay is virtually unknown, and the accuracy of relevant estimates has not been established. Thus, it is necessary to evaluate this diversity and propose protective measures. In total, ninety-nine specimens were collected from various locations. To overcome uncertainties associated with identifying species based on morphology, DNA barcoding（COI gene） was employed to reconstruct phylogenetic relationships with delimited references from NCBI. Twenty-two species representing six families were unambiguously identified from a neighbor-joining（NJ） tree and barcoding gaps. With the morphological identification, thirteen species were identified correctly, five species were identified correctly at the genus level, and four species were identified at the close sister species level. Notothenioid dominance was not evident in the Prydz Bay, in contrast to other published studies. The low species diversity and catch biomass during this CHINARE were severely constrained by limited fishing methods and localized sites, which led to biased underestimation. Our analyses indicate that DNA barcoding is an effective tool for the identification of fish species in the Prydz Bay. The identification and distribution of Antarctic fish should be an integral component of understanding Antarctic fish biodiversity and biogeography, and large-scale studies are necessary for the further taxonomic identification of Antarctic fish.展开更多
In this paper, CTD observational data obtained during the 15th Chinese National Antarctic Research Expedition (CHINARE-15) in the Southern Ocean are used to analyse and study water mass distribution in the Prydz Bay a...In this paper, CTD observational data obtained during the 15th Chinese National Antarctic Research Expedition (CHINARE-15) in the Southern Ocean are used to analyse and study water mass distribution in the Prydz Bay and its adjacent seas. The area, depth, and the thermohaline characteristics are identified for the Prydz Bay summer coastal surface water, the Prydz Bay winter water, the Prydz Bay shelf water, and the circumpolar deep water. Based on the above discussion, the northward extention of the Prydz Bay shelf water are found. Then the thermodynamic and the dynamic characteristics are further discussed, dealing with the inversion layer depth of the water temperature, the locations of the minima of the vertical temperature distribution and the temperature vertical gradient in the water column, the baraclinicity, and the effect of Coriolis deflection force.展开更多
In this paper, we present measurements of velocity, temperature, salinity, and turbulence collected in Prydz Bay, Antarctica, during February, 2005. The dissipation rates of turbulent kinetic energy （e） and diapycna...In this paper, we present measurements of velocity, temperature, salinity, and turbulence collected in Prydz Bay, Antarctica, during February, 2005. The dissipation rates of turbulent kinetic energy （e） and diapycnal diffusivities （Ks） were estimated along a section in front of the Amery Ice Shelf. The dissipation rates and diapycnal diffusivities were spatially non-uniform, with higher values found in the western half of the section where E reached 10.7 W/kg and Kz reached 10.2 mVs, about two and three orders of magnitude higher than those in the open ocean, respectively. In the western half of the section both the dissipation rates and diffusivities showed a high-low-high vertical structure. This vertical structure may have been determined by internal waves in the upper layer, where the ice shelf draft acts as a possible energy source, and by bottom-generated internal waves in the lower layer, where both tides and geostrophic currents are possible energy sources. The intense diapycnal mixing revealed in our observations could contribute to the production of Antarctic Bottom Water in Prydz Bay.展开更多
During the 29 th Chinese National Antarctic Research Expedition,spatial variations in nitrogen isotopic composition of particulate nitrogen(δ15NPN)and their controlling factors were examined in detail with regard to ...During the 29 th Chinese National Antarctic Research Expedition,spatial variations in nitrogen isotopic composition of particulate nitrogen(δ15NPN)and their controlling factors were examined in detail with regard to nitrate drawdown by phytoplankton and particulate nitrogen(PN)remineralization in the Prydz Bay and its adjacent areas.To better constrain the nitrogen transformations,the physical and chemical parameters,including temperature,salinity,nutrients,PN andδ15NPN in seawater column were measured from surface to bottom.In addition,the nitrogen isotopic fractionation factor of nitrate assimilation by phytoplankton in the mixed layer,and the nitrogen isotopic fractionation factor of PN remineralization below the mixed layer were estimated using Rayleigh model and Steady State model,respectively.Our results showed that suspended particles had its lowestδ15NPN in the surface layer,which was due to the preferential assimilation of 14 N in nitrate by phytoplankton.Theδ15NPN in the mixed layer of the Prydz Bay and its adjacent areas decreased from the inner shelf to the outer basin,ascribing to the effect of isotope fractionation during phytoplankton assimilation.In mixed layer,the spatial distribution ofδ15NPN associated with particulate organic matter(POM)production can be well interpreted according to Rayleigh model and Steady State model.The nitrogen isotope fractionation factor during phytoplankton assimilating nitrate was estimated as 10.0‰by Steady State model,which was more reasonable than that calculated by Rayleigh model.These results validate the previous reports of fractionation factor during nitrate assimilation by phytoplankton.Increasingδ15NPN with depth below the euphotic zone correlated with the decreasing PN contents,and it was attributed to preferential remineralization of 14 N in PN by bacteria.In subsurface and deep layer,theδ15NPN distributions also conformed to Rayleigh model and Steady State model during PN remineralization,with a fractionation factor of about 3.6‰and 3.2‰,respectively.It is the first time to estimate the fractionation factor during POM production and remineralization in the Prydz Bay and its adjacent areas.Such fractionation may provide a useful tool for the follow-up study of the nitrogen dynamics in the Southern Ocean.展开更多
Nano- and microalgae samples were collected from 34 stations in the Prydz Bay and its adjacent Southern indian Ocean, Antarctica during a Period from December 1990 to January 1991. 122 taxa belonging to 40 genera 5 ph...Nano- and microalgae samples were collected from 34 stations in the Prydz Bay and its adjacent Southern indian Ocean, Antarctica during a Period from December 1990 to January 1991. 122 taxa belonging to 40 genera 5 phyla were identified. Among them diatom occupy 73%,dinoflagellates 20. 5%, the other species 6. 5 %. The average cell abundance of nano- and microalgae was 2551×104 cells/m3 in surface waters. The concentration of nano- and microalgae occurred in the Prydz Bay and its adjacent continental station Ⅳ 7 and northern water area between West Ice Shelf and Shackleton Ice Shelf (Stations Ⅶ 3, Ⅷ 1, Ⅷ 2, Ⅷ 3, Ⅸ 1, Ⅺ 1); and minimal abundance occurred in northwestern area of the Prydz Bay (some stations of section Ⅲ and Station Ⅳ 1-5). The average cell abundance of planktonic nano- and microalgae from net sample was 811. 62×104 cells/m3, and the concentration area occurred in the adjacent continent waters of the Prydz Bay (Stations Ⅳ 2, Ⅳ 4, Ⅳ 5, Ⅳ 7, Ⅴ 4 and Ⅴ 5) and northern area of the West Ice Shelf(Stations Ⅶ 1 and Ⅶ 3); low abundance occurred in eastern area of the Shackleton Ice Shelf (at each station of sections Ⅹ and Ⅺ ). For the vertical distribution of planktonic nano- and microalgae, the maximum value was usually found at the surface and above 50 m depth, and gradually decreased with the water depth from 100 m to 200 m. The relationship between planktonic nano-and microalgal abundance and Euphausia superba density and nutrient (nitrate,phosphate and silicate) contents were negative significance.展开更多
During the 16th Chinese National Antarctic Research Expedition (CHINARE) (from November 1999 to April 2000) seawater samples were collected for (DOC) determination in the Prydz Bay and its nearby sea areas. DOC concen...During the 16th Chinese National Antarctic Research Expedition (CHINARE) (from November 1999 to April 2000) seawater samples were collected for (DOC) determination in the Prydz Bay and its nearby sea areas. DOC concentrations were determined-by high temperature catalytic oxidation (HTCO) method. The results shows that DOC concentrations, in the upper water column (0 similar to 100 in) range from 14.3 to 181.1 mumol/dm(3), with averaging 52.5 mumol/dm(3) (n = 55). These values are slightly higher than those reported for the Ross Sea, the Pacific Ocean and others. Profiles of DOC concentration in the study areas show a decreasing concentration with increasing depth in the upper 100 m, which is related to biological activities in the water column. DOC concentrations below 100 in are relatively constant with a mean of 40.4 gammamol/dm(3). These DOC are unactive for physical and biological activities and are called refractory DOC. Concentration of the refractory DOC in the study area is consistent with the previous reported values for the Southern Ocean, which is about 41 mumol/dm(3). Based on the difference between the measured DOC concentration and the refractory concentration, the excess DOC concentration in the upper column can be calculated at every station. The excess DOC shows a spatial variability with a higher excess in the north of 64degreesS and little excess in the south of 64degreesS. In conclusion, DOC concentrations in the Prydz Bay and its nearby sea areas,are, consistent with the previous reported values in the Southern Ocean, which show a low DOC concentration with respect to the other oceans. Distribution of surface DOC concentrations in the study areas shows an increase from the southwestern to the northeastern, which is ascribed to the northern spread of continental shelf water from the Prydz Bay in summer. Contents of DOC and their distribution in the Prydz Bay and its nearby sea areas are mainly controlled by physical and biological processes.展开更多
Antarctic krill (Euphausia superba) were collected from the Prydz Bay region during the austral summer of 1999/2000. The sample - collection was made at 15 sites in 3 longitudinal transects. Although krill were encoun...Antarctic krill (Euphausia superba) were collected from the Prydz Bay region during the austral summer of 1999/2000. The sample - collection was made at 15 sites in 3 longitudinal transects. Although krill were encountered at 14 sites, the abundance was comparatively low in general. The main component of the krill population was of post -larval stages. The mean numerical and weight density of krill integrated for all sampling stations in the survey area were 16. 17 ind. 1000 m -3and 12.02 g 1000 m -3 , respectively. In the survey area, stations with larger krill density are mainly located in the slope zone, except that the largest sample was collected in the open sea zone. No krill occurred in the only station of the shelf zone during our investigation. Krill collected from the slope zone were under better growth condition than those from the open sea zone, but when the survey area is considered as a whole, the growth condition is normal. The results of the comprehensive analysis of the environmental factors show that the three large sample stations seem to be related with the cold water mass at 75 m depth and the confluence area between the high and low Chla centers at the depth of 25 m.展开更多
基金The National Natural Science Foundation of China under contract Nos 41976217 and 42306249the National Key Research and Development Program of China under contract No.2018YFA0605701.
文摘A three-dimensional coupled sea ice-ice shelf-ocean numerical model is developed for the Prydz Bay,Antarctica,using the Regional Ocean Modeling System with a grid resolution of approximately 2 km.The influence of the grounding giant iceberg D15 on the distribution of sea ice and polynyas in the Prydz Bay is analyzed through two numerical experiments.Iceberg D15,grounded off the western edge of the West Ice Shelf(WIS),obstructs the southwestward transport of sea ice along the east coast of Prydz Bay,causing sea ice to accumulate to the east of the iceberg and form multi-year fast ice.Grounding of Iceberg D15 also decreases sea ice coverage off its south edge and creates ice-free openings in spring near Davis Station and Zhongshan Station,facilitating the accessibility of vessels to the research stations.These simulated sea ice patterns closely match current satellite observations.When Iceberg D15 is removed,the previously blocked sea ice north of the iceberg,which moved westward,shifts southwesterly along the coastline,leading to a reduction in sea ice thickness during winter and spring,as well as lower sea ice concentrations in spring across large areas north and west of the iceberg.In contrast,the sea ice thickness increases considerably southwest of the WIS,extending to the front of the Amery Ice Shelf during seasons covered by sea ice.The increase in sea ice concentration can also extend to as far as 75°E in spring.Without Iceberg D15,which previously contributed to the ice barrier of Barrier Polynya(BP),the shape of BP changes,the area of BP and Davis Polynya(DP)decreases,and the polynya off the northwest edge of the WIS near 83°E expands.These polynya patterns are much similar to the satellite remote sensing observations before Iceberg D15 was grounded.From April to October,the total area of BP and DP decreases by 2.83×10^(4)km^(2)(60%)and 2.20×10^(3)km^(2)(20%),respectively,while the total sea ice production decreases by 4.11×10^(10)m^(3)(66%)and 1.52×10^(10)m^(3)(52%)compared to the experiment with iceberg.These results indicate the substantial effects of grounding giant icebergs on the spatio-temporal distribution of sea ice,the area of polynyas,and sea ice production.High-resolution Antarctic coastal numerical models,typically with grid scales of kilometers,are sufficient to represent large icebergs,and adding the grounding giant icebergs is crucial for producing realistic simulations of sea ice and polynyas.
基金supported by the National Natural Science Foundation of China(No.41976217)the National Key R&D Program of China(No.2018YFA0605701).
文摘The characteristics of modified Circumpolar Deep Water(mCDW)on the continental shelf in Prydz Bay,East Antarctica,are studied based on hydrographic data obtained by the Chinese National Antarctic Research Expeditions across 14 summers from 1999 to 2022.In austral summer,the mCDW upwells along the upper continental slope then intrudes on the continental shelf across the shelf break in a warm tongue that gradually upwells poleward.The mCDW intrusion at the 73°E section is relatively weaker in December and stronger in February while showing significant interannual variability.During strong intrusions(January 2000 and February 2003),the mCDW extends southward to 68°S and upwells to 50 m,whereas the mCDW only reaches the shelf break during weak intrusions(December 2004,January 2006,January 2011,and February 2015).The intensity of the mCDW intrusions correlates strongly with the accumulated wind stress curl(30 days prior)north of the shelf break(73.5°-78.0°E,64.5°-66.0°S).The summertime westerly winds play a key role in regulating the interannual variability of mCDW intrusion onto the continental shelf.A southward shift of the westerly winds promotes the upwelling and southward intrusion of mCDW across the shelf break.In addition,mCDW at 73°E can reach as far as 68°S due to the southward flow of mCDW being hindered by a northward outflowing branch of the coastal current at the Amery Ice Shelf(AIS)front.In austral summer,the mCDW had never been observed at the section along the AIS front;thus,it cannot directly contribute to the basal melting of the ice shelf.
基金The National Key Research and Development Program of China under contract No.2022YFE0136500the Scientific Research Fund of the Second Institute of Oceanography,Ministry of Natural Resources,under contract Nos JG2212 and JG2211+2 种基金the National Natural Science Foundation of China under contract Nos 42276255,41976228,and 42176227the National Polar Special Program“Impact and Response of Antarctic Seas to Climate Change”under contract Nos IRASCC 01-01-02 and IRASCC 02-02the China Scholarship Council under contract No.201704180017.
文摘The melting of seasonal sea ice in Antarctica plays a pivotal role in the region’s carbon cycle,influencing global carbon storage and the exchange of carbon between the atmosphere and the ocean.However,the impact of variability in the timing of seasonal sea ice retreat on the flux and composition of sinking particulate matter remains to be elucidated.In this study,we deployed sediment traps in Prydz Bay during the austral summers of 2019/2020 and 2020/2021,noting that sea ice melting occurred approximately one and a half months earlier in the former summer compared to the latter.We analyzed sediment trap data,which included total mass flux(TMF),particulate organic carbon(POC),biogenic silica(BSi),particulate inorganic carbon,and lithogenic particle(Litho)fluxes,as well as the stable isotopesδ^(13)C andδ^(15)N of particulate organic matter(POM).Additionally,we incorporated remote sensing data on sea ice concentration and chlorophyll a.This dramatic delay in sea ice melting timing could result in a significant increase in TMF,BSi and POC fluxes in the summer of 2020/2021 compared to 2019/2020.Elevated BSi fluxes and more ^(13)C-depleted POC in the austral summer of 2020/2021 suggest that the delayed melting of sea ice may have stimulated the productivity of centric diatoms.Furthermore,the higher BSi/POC ratio and more negativeδ^(15)N values of POM,along with a reduced presence of krill in the traps,indicate a diminished grazing pressure from zooplankton,which collectively enhanced the sedimentation efficiency of POC during the austral summer of 2020/2021.These findings highlight the critical role of sea ice melting timing in regulating productivity,flux and composition of sinking particulate matter in the Prydz Bay ecosystem,with significant implications for carbon cycling in polar oceans.
基金The National Natural Science Foundation of China under contract No.41906193the Scientific Research Foundation of Third Institute of Oceanography,Ministry of Natural Resources,under contract No.2019033+2 种基金the Natural Science Foundation of Fujian Province under contract No.2019J05147the Federal Ministry of Education and Research of Germany under contract No.FKZ 03F03F0783Athe National Polar Special Program under contract Nos IRASCC 01-01-02 and IRASCC 02-02.
文摘The global ocean is a major source of the climate-relevant atmospheric trace gas nitrous oxide(N_(2)O).However,an accurate assessment of the global oceanic emissions of N_(2)O is hampered by missing data on dissolved N_(2)O from large regions such as the Southern Ocean.To address this deficit,N_(2)O was measured in the Prydz Bay in February 2015 during the 31st Chinese National Antarctic Research Expedition.N_(2)O concentrations(saturation)in the surface layer were generally low(undersaturation with respect to atmospheric equilibrium)and ranged from 13.3 nmol/L to 16.1 nmol/L(83%–102%)at the time of sampling.A comparison of our observations with archived data revealed that no discernible trend in N_(2)O concentrations in the surface waters of Prydz Bay could be detected for the period between 2006 and 2015.Temperature and salinity changes driven by meltwater input were the predominant controls on N_(2)O concentrations in surface waters.At depth,the distribution of N_(2)O concentrations was dominated by production via nitrification in offshore deep waters and vertical convection in the shelf waters,where concentrations were lower and gradients were less steep.Our results suggest a rather unusual pattern of N_(2)O distribution in the Prydz Bay(low N_(2)O in shelf waters compared with the open ocean),providing important insights into the coastal dynamics of N_(2)O in high-latitude polar regions.
文摘The cell density, species composition and distribution of phytoplankton, and their relations to environmental factors in Prydz Bay and its adjacent sea area, Antarctica (69degrees-77degrees E, 62degrees-70degrees S) during the austral summer of 1998/1999 were investigated. A total of 48 taxa belonging to 21 genera of phytoplankton in the sea area were identified. The average cell density of phytoplankton was 22.46 x 10(3) cells/dm(3), of which diatoms were predominant (84.51%). The highest cell density of phytoplankton occurred in Prydz Bay and the adjacent continental shelf where the average cell density was 46.03 x 10(3) cells/dm(3). The lowest cell density (3.34 x 10(3) cells/dm(3)) occurred in deep sea area. The dominant species of phytoplankton was Fragilariopsis curta. The vertical distribution of phytoplankton density was highest in the upper part of 0-50 in depth, lower in 100 in and lowest in 150 in. The species composition and cell density of phytoplankton were influenced by water circulation. The cell density was positively correlated with water temperature and salinity, and negatively correlated with the concentration of nutrients.
基金supported by the National Natural Science Foundation of China No. 41076134
文摘In order to better understand the spatial and temporal distribution of dissolved cadmium in Prydz Bay, east Antarctica, seawaters were sampled by CTD during the CHINARE-25 cruise （Oct. 2008 - Apr. 2009） and the concentrations of cadmium were analyzed by AAS （Atomic Absorption Spectrometry） in the clean laboratory. Together with the data of macronutrients and chl.a from the same cruise, the relationship between cadmium and biological process was studied. The results showed that the concentrations of Cd in the surface water had a good relationship with chl.a and biologicl process was the important factor that influenced the distribution of dissolved Cd in the surface water. Linear relationship was found between dissolved Cd and phosphate in the surface water and the high ratio of Cd/P at the edge of ice shelf was most probably due to ice melting, vertical distribution of Cd was similar to those of macronutrient such as phosphate and was affected by decomposition of organic particals. The temporal change of dissolved Cd in upper layer was slight and tide probably had influence on the change.
基金The National Natural Science Foundation of China under contract Nos40276001,40406014,40676062 and 40531007the Polar StrategyFoundation of under contract No.20070224+3 种基金the National Key Technology Reaserch and Development Program for the11th Five-year Plan of China undercontract No.2006BAB18B04the Fujian Province Youth Technological Creation of China under contract No.2004J056Fujian Province Natural Science Foundation of China under contract No.Z0513027TIOSOA Foundation
文摘The Prydz Bay in the Antarctic is an important area in the Southern Ocean due to its unique geographic feature. It plays an important role in the carbon cycle in the Southern Ocean. To investigate the distributions of carbon dioxide in the atmosphere and surface seawater and its air-sea exchange rates in this region, the Chinese National Antarctic Research Expedition （CHINARE） had set up several sections in the Prydz Bay. Here we present the results from the CHINARE-XVI cruises were presented onboard R/V Xue/ong from November 1999 to April 2000 and the main driving forces were discussed controlling the distributions of partial pressure of carbon dioxide. According to the partial pressure of carbon dioxide distributions, the Prydz Bay can be divided into the inside and outside regions. The partial pressure of carbon dioxide was low in the inside region but higher in the outside region during the measurement period. This distribution had a good negative correlation with the concentrations of ehlorophyll-a in general, suggesting that the partial pressure of carbon dioxide was substantially affected by biological production. The results also indicate that the biological produetion is most likely the main driving force in the marginal ice zone in the Southern Ocean in summer. However, in the Antarctic divergence sector of the Prydz Bay （about 64°S）, the hydrological processes become the controlling factor as the sea surface partial pressure of carbon dioxide is much higher than the atmospheric one due to the upwelling of the high DIC CDW, and this made the outside of Prydz Bay a source of carbon dioxide. On the basis of the calculations, the CO2 flux in January （austral summer） was -3.23 mmol/（m^2 · d） in the inner part of Prydz Bay, i.e. , a sink of atmospheric CO2, and was 0.62 mmol/（m^2 · d） in the outside part of the bay, a weak source of atmospheric CO2. The average air-sea flux of CO2 in the Prydz Bay was 2.50 mmol/（m^2 · d）.
基金The Scientific Research Foundation of Third Institute of Oceanography,State Oceanic Administration under contract NoTIO2007003the Natural Science Foundation of Fujian Province of China under contract No2006J0287+1 种基金the National Natural Science Foundation of China fromkey program under contract No 40531007 and from general program under contract Nos40406014 and 40276001the State Social Commonweal Foundationof China under contract No 2004DIB5178
文摘Dissolved and particulate thorium-234, particulate organic carbon in the upper 150 m of water columns from five stations in the Prydz Bay, the Southern Ocean were determined during the 22nd Chinese National Antarctic Research Expedition （from November 2005 to March 2006 ）. The disequilibria between thorium-234 and its parent uranium-238 in upper layer was used to derive the averaged residence time of thorium-234, which decreased along with the latitude to the south and a minimum value, 1 - 8 d for particulate thorium-234 and 29 - 48 d for dissolved thorium-234, appeared at the medium latitude station, and the export fluxes of thorium-234 were calculated too and ＇a maximum value, 0. 35 -0. 63 Bq/（m^3 · d） for the particulate thorium-234 and 0. 44 -0. 65 Bq/ （m^3 ·d） for the dissolved thorium-234, appeared at the same station. The export fluxes of particulate organic carbon at different water columns were derived by two methods with irreversible scavenging model, and the averaged values were 104. 7 mmol/ （ m2 · d ） （ E method） and 120. 6 mmol/（ m2·d ） （ B method ）, respectively, indicating that a relatively high new production would exist in summer in the Prydz Bay where it will play a potential significant role in sequestering the absorption CO2 to deeper ocean.
基金This study was jointly supported by the National National Science Foundation of China under contract Nos 40376009,40231013 and 49836010the Ministry of Science and Technology of China under contact Nos 2003DIB4J135,2005DIB3J114 and 2006BAC06B02.
文摘Thermohaline features, spatial extensions, and depths of the antarctic circumpolar deep water, the antarctic bottom water, and the upper layer water near the Prydz Bay （ including the Prydz Bay s.mmer surface water, the antarctic winter water, and the Prydz Bay shelf water ） are analyzed and studied by use of the full depth CTD data obtained in the Southern Ocean near the Prydz Bay during the 1998/1999 austral summer. The northward extension of the shelf water, the thickness of the temperature inversion layer, the minima in the vertical temperature profile and the vertical temperature gradient are interpreted. On the basis of analysis of gravitational potential field, the geostrophic current and the geostrophic volume transport are calculated to determine the location of the strongest current in the zonal circulation near the Prydz Bay and to find the spatial variability of the volume transport in the64° -66.5°S zone. In addition, the central location, the frontal strength, the vertical depth and thickness of the continental water boundary （CWB） are estimated from the CTD data to expound the spatial variability of CWB in the study area （64° -66.5°S, 70° -75°E）.
基金Supported by the National Natural Science Foundation of China (No. 40676011)the Key Technologies Research and Development Program of China (No. 2006BAB18B02)China’s Program for New Century Excellent Talents in University (No. NCET-10-0720)
文摘Supercooled water with temperatures below freezing point, was identified from hydrographic data obtained by Chinese and Australian expeditions to Prydz Bay, Antarctica, during the austral summer. The study shows that most supercooled waters occurred at depths of 63-271 m in the region north of the Amery Ice Shelf （AIS） front. The maximum supercooling was 0.16℃ below the in-situ freezing point. In temperature and salinity ranges of-2.14 - -1.96℃ and 34.39-34.46, respectively, the water was colder and fresher than peripheral shelf water. The supercooled water had less variability in the vertical profiles compared to shelf water. Based on analysis of their thermohaline features and spatial distribution, as well as the circulation pattern in Prydz Bay, we conclude that these supercooled waters originated from a cavity beneath the AIS and resulted from upwelling just outside of the AIS front. Water emerging from the ice shelf cools to an extremely low temperature （about -2.0℃） by additional cooling from the ice shelf, and becomes buoyant with the addition of melt water from the ice shelf base. When this water flows out of the ice shelf front, its upper boundary is removed, and thus it rises abruptly. Once the temperature of this water reaches below the freezing point, supercooling takes place. In summer, the seasonal pycnocline at -100 m water depth acts as a barrier to upwelling and supercooling. The upwelling of ice shelf outflow water illuminates a unique mid-depth convection of the polar ocean.
基金The National Natural Science Foundation of China under contract No.41676174the Foundation for Innovative Research Groups of the National Natural Science Foundation of China under contract No.41721005the Science and Technology Basic Resources Investigation Program of China under contract No.2017FY201403
文摘Using a combination of stable isotope(15N) and radionuclide(226Ra) analyses, we examine possible controls on the interactions between melting ice and the uptake of nitrogen in the Prydz Bay during the 2006 austral summer.We find that specific rates of uptake for nitrate and ammonium correlate positively to their concentrations, thus suggesting a substrate effect. In the study area, we observe that regions along open, oceanic water have high fratios(nitrate uptake/nitrate+ammonium uptake), while areas near the Amery Ice Shelf have significantly low fratios. Further analysis reveals a negative correlation between the f-ratio and the melt water fraction, thus implying that the melting of ice plays an essential role in regulating pelagic N dynamics in the Southern Ocean(SO). Stratification, produced by melting ice, should profoundly affect the efficiency of the SO’s biological pump and consequently affect the concentration of CO2 in the atmosphere. Results presented in this study add information to an already significant base of understanding of the controls on pelagic C and N dynamics in the SO. This provides unique insights for either interpreting past changes in geologic records or for predicting future climate change trends.
基金supported by the Chinese Polar Environment Comprehensive Investigation and Assessment Program (Grant nos. CHINARE2012-01-02, CHINARE2013-01-02, CHINARE201301-07, CHINARE2013-04-01)
文摘In this study, we investigated the distributions of sea-surface suspended particulate organic carbon （POC） and its stable isotope （δ13C POC） in Prydz Bay, Antarctica, and examined the factors influencing their distribution, sources, and transport. We used measurements collected from 61 stations in Prydz Bay during the 29th Chinese National Antarctic Research Expedition, in combination with remote sensing data on sea surface temperature （SST）, chlorophyll a concentration, and sea ice coverage. The POC concentration in the surface waters of Prydz Bay was 0.28-0.84 mg.L-1, with an average concentration of 0.48 mg.L-1. The δ13C POC value ranged from -29.68‰ to -26.30‰, with an average of-28.01‰. The concentration of suspended POC was highest in near-shore areas and in western Prydz Bay. The POC concentration was correlated with chlorophyll a concentration and sea ice coverage, suggesting that POC was associated with phytoplankton production in local water columns, while the growth of phytoplankton was obviously affected by sea ice coverage. The δ13C poc value in suspended particles decreased gradually towards the outer waters of Prydz Bay, while in eastern Prydz Bay the δ13Cpoc value become gradually more negative from nearshore to deep-water areas, suggesting that δ13C poc was mainly influenced by CO2 fixation by phytoplankton. The δ13C POC value in suspended particles near Zhongshan Station was significantly negative, possibly as a result of the input of terrigenous organic matter and changes in the phytoplankton species composition in the nearshore area.
基金Supported by the ~(15)th Chinese National Antarctic Research Expedition
文摘Considering the complex topographic features of the southeast of Prydz Bay where China's Zhongshan Station is located,three types of geomorphologic units can be identified,i.e., submarine slopes,canyons,and terrains.The major topographic features in the study area are the submarine canyon and trough system outside the calving ice front of Dalk Glacier.A 3.8 km×80 m fissure is found on the submarine terrain at Zhongshan Anchorage,which,once triggered by geological hazards such as earthquakes and ice falls,would be a threat to the usage and maintenance of the anchorage.
基金Chinese Polar Environment Comprehensive Investigation and Assessment Program under contract Nos CHINARE2012-2015-01-05,CHINARE 2012-2015-04-01 and CHINARE 2017-04-03
文摘In 2013, the 29th Chinese National Antarctic Research Expedition（CHINARE） prospected the Prydz Bay on the Antarctic continental shelf, and the Chinese R/V Xuelong icebreaker sampled all of the examined locations. The nature of Antarctic fish diversity in the high-latitude Prydz Bay is virtually unknown, and the accuracy of relevant estimates has not been established. Thus, it is necessary to evaluate this diversity and propose protective measures. In total, ninety-nine specimens were collected from various locations. To overcome uncertainties associated with identifying species based on morphology, DNA barcoding（COI gene） was employed to reconstruct phylogenetic relationships with delimited references from NCBI. Twenty-two species representing six families were unambiguously identified from a neighbor-joining（NJ） tree and barcoding gaps. With the morphological identification, thirteen species were identified correctly, five species were identified correctly at the genus level, and four species were identified at the close sister species level. Notothenioid dominance was not evident in the Prydz Bay, in contrast to other published studies. The low species diversity and catch biomass during this CHINARE were severely constrained by limited fishing methods and localized sites, which led to biased underestimation. Our analyses indicate that DNA barcoding is an effective tool for the identification of fish species in the Prydz Bay. The identification and distribution of Antarctic fish should be an integral component of understanding Antarctic fish biodiversity and biogeography, and large-scale studies are necessary for the further taxonomic identification of Antarctic fish.
基金National Science Foundation ofChina(No.4 983 60 1 0 )
文摘In this paper, CTD observational data obtained during the 15th Chinese National Antarctic Research Expedition (CHINARE-15) in the Southern Ocean are used to analyse and study water mass distribution in the Prydz Bay and its adjacent seas. The area, depth, and the thermohaline characteristics are identified for the Prydz Bay summer coastal surface water, the Prydz Bay winter water, the Prydz Bay shelf water, and the circumpolar deep water. Based on the above discussion, the northward extention of the Prydz Bay shelf water are found. Then the thermodynamic and the dynamic characteristics are further discussed, dealing with the inversion layer depth of the water temperature, the locations of the minima of the vertical temperature distribution and the temperature vertical gradient in the water column, the baraclinicity, and the effect of Coriolis deflection force.
基金Supported by the National Natural Science Foundation of China(Nos.40906004,40890153,41176008,and 91028008)the National High Technology Research and Development Program of China(863 Program)(No.2008AA09A402)+2 种基金the Polar Science Strategic Foundation of China(No.20080206)the Key Lab Open Research Foundation of China(No.KP201006)the National Key Technology Research and Development Program of China(No.2006BAB18B02)
文摘In this paper, we present measurements of velocity, temperature, salinity, and turbulence collected in Prydz Bay, Antarctica, during February, 2005. The dissipation rates of turbulent kinetic energy （e） and diapycnal diffusivities （Ks） were estimated along a section in front of the Amery Ice Shelf. The dissipation rates and diapycnal diffusivities were spatially non-uniform, with higher values found in the western half of the section where E reached 10.7 W/kg and Kz reached 10.2 mVs, about two and three orders of magnitude higher than those in the open ocean, respectively. In the western half of the section both the dissipation rates and diffusivities showed a high-low-high vertical structure. This vertical structure may have been determined by internal waves in the upper layer, where the ice shelf draft acts as a possible energy source, and by bottom-generated internal waves in the lower layer, where both tides and geostrophic currents are possible energy sources. The intense diapycnal mixing revealed in our observations could contribute to the production of Antarctic Bottom Water in Prydz Bay.
基金The National Natural Science Foundation of China under contract No.41721005the COMRA Program of China under contract No.DY135-E2-2-03the Polar Environment Comprehensive Investigation&Assessment Program of China under contract Nos CHINARE2017-01-04-03 and CHINARE2017-04-01-06
文摘During the 29 th Chinese National Antarctic Research Expedition,spatial variations in nitrogen isotopic composition of particulate nitrogen(δ15NPN)and their controlling factors were examined in detail with regard to nitrate drawdown by phytoplankton and particulate nitrogen(PN)remineralization in the Prydz Bay and its adjacent areas.To better constrain the nitrogen transformations,the physical and chemical parameters,including temperature,salinity,nutrients,PN andδ15NPN in seawater column were measured from surface to bottom.In addition,the nitrogen isotopic fractionation factor of nitrate assimilation by phytoplankton in the mixed layer,and the nitrogen isotopic fractionation factor of PN remineralization below the mixed layer were estimated using Rayleigh model and Steady State model,respectively.Our results showed that suspended particles had its lowestδ15NPN in the surface layer,which was due to the preferential assimilation of 14 N in nitrate by phytoplankton.Theδ15NPN in the mixed layer of the Prydz Bay and its adjacent areas decreased from the inner shelf to the outer basin,ascribing to the effect of isotope fractionation during phytoplankton assimilation.In mixed layer,the spatial distribution ofδ15NPN associated with particulate organic matter(POM)production can be well interpreted according to Rayleigh model and Steady State model.The nitrogen isotope fractionation factor during phytoplankton assimilating nitrate was estimated as 10.0‰by Steady State model,which was more reasonable than that calculated by Rayleigh model.These results validate the previous reports of fractionation factor during nitrate assimilation by phytoplankton.Increasingδ15NPN with depth below the euphotic zone correlated with the decreasing PN contents,and it was attributed to preferential remineralization of 14 N in PN by bacteria.In subsurface and deep layer,theδ15NPN distributions also conformed to Rayleigh model and Steady State model during PN remineralization,with a fractionation factor of about 3.6‰and 3.2‰,respectively.It is the first time to estimate the fractionation factor during POM production and remineralization in the Prydz Bay and its adjacent areas.Such fractionation may provide a useful tool for the follow-up study of the nitrogen dynamics in the Southern Ocean.
文摘Nano- and microalgae samples were collected from 34 stations in the Prydz Bay and its adjacent Southern indian Ocean, Antarctica during a Period from December 1990 to January 1991. 122 taxa belonging to 40 genera 5 phyla were identified. Among them diatom occupy 73%,dinoflagellates 20. 5%, the other species 6. 5 %. The average cell abundance of nano- and microalgae was 2551×104 cells/m3 in surface waters. The concentration of nano- and microalgae occurred in the Prydz Bay and its adjacent continental station Ⅳ 7 and northern water area between West Ice Shelf and Shackleton Ice Shelf (Stations Ⅶ 3, Ⅷ 1, Ⅷ 2, Ⅷ 3, Ⅸ 1, Ⅺ 1); and minimal abundance occurred in northwestern area of the Prydz Bay (some stations of section Ⅲ and Station Ⅳ 1-5). The average cell abundance of planktonic nano- and microalgae from net sample was 811. 62×104 cells/m3, and the concentration area occurred in the adjacent continent waters of the Prydz Bay (Stations Ⅳ 2, Ⅳ 4, Ⅳ 5, Ⅳ 7, Ⅴ 4 and Ⅴ 5) and northern area of the West Ice Shelf(Stations Ⅶ 1 and Ⅶ 3); low abundance occurred in eastern area of the Shackleton Ice Shelf (at each station of sections Ⅹ and Ⅺ ). For the vertical distribution of planktonic nano- and microalgae, the maximum value was usually found at the surface and above 50 m depth, and gradually decreased with the water depth from 100 m to 200 m. The relationship between planktonic nano-and microalgal abundance and Euphausia superba density and nutrient (nitrate,phosphate and silicate) contents were negative significance.
文摘During the 16th Chinese National Antarctic Research Expedition (CHINARE) (from November 1999 to April 2000) seawater samples were collected for (DOC) determination in the Prydz Bay and its nearby sea areas. DOC concentrations were determined-by high temperature catalytic oxidation (HTCO) method. The results shows that DOC concentrations, in the upper water column (0 similar to 100 in) range from 14.3 to 181.1 mumol/dm(3), with averaging 52.5 mumol/dm(3) (n = 55). These values are slightly higher than those reported for the Ross Sea, the Pacific Ocean and others. Profiles of DOC concentration in the study areas show a decreasing concentration with increasing depth in the upper 100 m, which is related to biological activities in the water column. DOC concentrations below 100 in are relatively constant with a mean of 40.4 gammamol/dm(3). These DOC are unactive for physical and biological activities and are called refractory DOC. Concentration of the refractory DOC in the study area is consistent with the previous reported values for the Southern Ocean, which is about 41 mumol/dm(3). Based on the difference between the measured DOC concentration and the refractory concentration, the excess DOC concentration in the upper column can be calculated at every station. The excess DOC shows a spatial variability with a higher excess in the north of 64degreesS and little excess in the south of 64degreesS. In conclusion, DOC concentrations in the Prydz Bay and its nearby sea areas,are, consistent with the previous reported values in the Southern Ocean, which show a low DOC concentration with respect to the other oceans. Distribution of surface DOC concentrations in the study areas shows an increase from the southwestern to the northeastern, which is ascribed to the northern spread of continental shelf water from the Prydz Bay in summer. Contents of DOC and their distribution in the Prydz Bay and its nearby sea areas are mainly controlled by physical and biological processes.
基金This study was supported by the CAS know ledge innov ation program KZCX2-303.
文摘Antarctic krill (Euphausia superba) were collected from the Prydz Bay region during the austral summer of 1999/2000. The sample - collection was made at 15 sites in 3 longitudinal transects. Although krill were encountered at 14 sites, the abundance was comparatively low in general. The main component of the krill population was of post -larval stages. The mean numerical and weight density of krill integrated for all sampling stations in the survey area were 16. 17 ind. 1000 m -3and 12.02 g 1000 m -3 , respectively. In the survey area, stations with larger krill density are mainly located in the slope zone, except that the largest sample was collected in the open sea zone. No krill occurred in the only station of the shelf zone during our investigation. Krill collected from the slope zone were under better growth condition than those from the open sea zone, but when the survey area is considered as a whole, the growth condition is normal. The results of the comprehensive analysis of the environmental factors show that the three large sample stations seem to be related with the cold water mass at 75 m depth and the confluence area between the high and low Chla centers at the depth of 25 m.
