2011 Vol. 33, No. 2
Display Method:
2011, 33(2): 1-10.
Abstract:
Using the high resolution CTD data between 1982 and 2008,we investigate the property and inter-annual variations of the summer cold water on the northern shelf of the Bering Sea. The results indicate that the waters in this area can be divided into four masses by the differences in temperature and salinity: Bering Shelf Cold Water (BSW_C), Bering Slope Current Water (BSCW),Mixing Modified Water(MW) and Bering Shelf Surface Water(BSW_S).-1 ℃,2 ℃ and 4 ℃ isolines can be used properly to identify the boundary of the different water masses. In summer, the cold water(T<-1 ℃) is generally located on the bottom of the shelf with depth less than 70 m north of 61.5°N. But in some years on the southern side of the cold water a phenomenon called "cold intermediate" may appear and it is related to the interaction of the Bering Slope Current Water and the Bering Shelf Water. Based on the historical data, we define two different physical parameters, which are called "the lowest temperature on the edge" and "the lowest temperature in the core", to investigate the inter-annual variations of the cold water: the long-term average temperature of the cold bottom water on the northern shelf in summer is -1.61 ℃ which is less than 0.2 ℃ compared to the average freezing point, fully demonstrating that the cold pool in summer still keeps the winter shelf waters characteristics of low-temperature; The distribution range of the cold pool in the year of 1989,1994,2002,2003,2004 and 2005 is smaller than the long-term average level, and this situation is called "warm year". Such changes of the cold pool in summer between "warm year" and "cold year" took place on the whole Bering Shelf over the past ten years.
Using the high resolution CTD data between 1982 and 2008,we investigate the property and inter-annual variations of the summer cold water on the northern shelf of the Bering Sea. The results indicate that the waters in this area can be divided into four masses by the differences in temperature and salinity: Bering Shelf Cold Water (BSW_C), Bering Slope Current Water (BSCW),Mixing Modified Water(MW) and Bering Shelf Surface Water(BSW_S).-1 ℃,2 ℃ and 4 ℃ isolines can be used properly to identify the boundary of the different water masses. In summer, the cold water(T<-1 ℃) is generally located on the bottom of the shelf with depth less than 70 m north of 61.5°N. But in some years on the southern side of the cold water a phenomenon called "cold intermediate" may appear and it is related to the interaction of the Bering Slope Current Water and the Bering Shelf Water. Based on the historical data, we define two different physical parameters, which are called "the lowest temperature on the edge" and "the lowest temperature in the core", to investigate the inter-annual variations of the cold water: the long-term average temperature of the cold bottom water on the northern shelf in summer is -1.61 ℃ which is less than 0.2 ℃ compared to the average freezing point, fully demonstrating that the cold pool in summer still keeps the winter shelf waters characteristics of low-temperature; The distribution range of the cold pool in the year of 1989,1994,2002,2003,2004 and 2005 is smaller than the long-term average level, and this situation is called "warm year". Such changes of the cold pool in summer between "warm year" and "cold year" took place on the whole Bering Shelf over the past ten years.
2011, 33(2): 11-19.
Abstract:
The phenomena of near surface temperature maximum (NSTM) occurred continually in the Canada Basin from 2004, which is one of the responses to the rapid change of the arctic. The fine structures of the NSTM are studied using the CTD data by the third National Arctic Research expedition of China(CHINARE) and the joint west arctic climate study (JWACS) and the Beaufort Gyre exploration project (BGEP) and ITP18 data collected in 2008 in the Canada Basin. The vertical properties of the NSTM are related to the sea ice. In the sea ice covered area there is little difference of the NSTM. But the differences of the maximum of temperature and the vertical structures of the NSTM are obvious in the marginal ice zone and the open water. The maximum temperature and the corresponding depth are related to not only the period of the NSTM, but the latitude of stations. The higher the latitude, the deeper the corresponding depth of the maximum temperature of the NSTM. The annual period of the NSTM is shown by ITP data, which occurrs in summer and disappears in spring in next year.
The phenomena of near surface temperature maximum (NSTM) occurred continually in the Canada Basin from 2004, which is one of the responses to the rapid change of the arctic. The fine structures of the NSTM are studied using the CTD data by the third National Arctic Research expedition of China(CHINARE) and the joint west arctic climate study (JWACS) and the Beaufort Gyre exploration project (BGEP) and ITP18 data collected in 2008 in the Canada Basin. The vertical properties of the NSTM are related to the sea ice. In the sea ice covered area there is little difference of the NSTM. But the differences of the maximum of temperature and the vertical structures of the NSTM are obvious in the marginal ice zone and the open water. The maximum temperature and the corresponding depth are related to not only the period of the NSTM, but the latitude of stations. The higher the latitude, the deeper the corresponding depth of the maximum temperature of the NSTM. The annual period of the NSTM is shown by ITP data, which occurrs in summer and disappears in spring in next year.
2011, 33(2): 20-26.
Abstract:
As the integrator of both the surface heat budget and the ocean heat flux, the mass balance of sea ice is a key climate-change indicator. A set of IMB (Ice Mass-balance Buoy) was deployed in the central Arctic Ocean during the 3rd arctic research expedition of China.Analysis of 11 months’data from August 2008 to July 2009 shows that aseasonal cycle is obvious on the temperature of sea ice. With the air temperature decreases, a cold front propagates down through the ice in the fall. The growth/ablation rate of sea ice bottom is mainly controled by water temperature below, and reaches its maximum 1.7 cm/d in the early February. Growth season of sea ice bottom lasts from the middle October in 2008 to the end June in 2009, with an average bottom growth rate of 0.6 cm/d and total sea ice growth of 160.3 cm.Bottom melting begins in the early July, being one-month lag when comparing with surface melting. Correlation analysis between the daily ice drift and the 10m wind gives a correlation coefficient of 0.14(99% significance), ice moves at 2.13% of the wind speed.
As the integrator of both the surface heat budget and the ocean heat flux, the mass balance of sea ice is a key climate-change indicator. A set of IMB (Ice Mass-balance Buoy) was deployed in the central Arctic Ocean during the 3rd arctic research expedition of China.Analysis of 11 months’data from August 2008 to July 2009 shows that aseasonal cycle is obvious on the temperature of sea ice. With the air temperature decreases, a cold front propagates down through the ice in the fall. The growth/ablation rate of sea ice bottom is mainly controled by water temperature below, and reaches its maximum 1.7 cm/d in the early February. Growth season of sea ice bottom lasts from the middle October in 2008 to the end June in 2009, with an average bottom growth rate of 0.6 cm/d and total sea ice growth of 160.3 cm.Bottom melting begins in the early July, being one-month lag when comparing with surface melting. Correlation analysis between the daily ice drift and the 10m wind gives a correlation coefficient of 0.14(99% significance), ice moves at 2.13% of the wind speed.
2011, 33(2): 27-35.
Abstract:
Turbulent flux near surface layer and its characteristic parameters on an drifting ice over Arctic Ocean (84°27'N,143°37'W 85°13'N,147°20'W) are presented using eddy correlation and related experiment data obtained from the Chinese 3th Arctic Scientific Expedition in 21—29 August, 2008. The results show that the inversion layer of temperature and humidity exist in most time of observational period. This phenomenon is also observed over the 75°N and 78°N area. The average sensible and latent heat fluxes are 0.5W/m2 and 2.4W/m2, which account for 18% and 86% of absorbed net radiation respectively. To compare with the results observed over 75°N and 78°N area, it shows different the latent heat flux plays important during the sea ice melting over the 84° 85°N area. The near surface atmosphere over the sea-ice is almost neutrally stratified, accounting for 91% of samples during the observation period. The drag coefficients of momentum (CDN) are about 1.64×10-3 in the near neutral stratification calculated by the relationships between CD and wind speed in the height of 10 m, and between CD and stability (z/L). Adaptability of the new parameterization scheme proposed from SHEBA is examined by our data and demonstrated that the similarity function in the new scheme is useful applied in the weak stable stratification over the floating ice area of Arctic Ocean, but it needs more measurement data to modify while it uses in climate modeling.
Turbulent flux near surface layer and its characteristic parameters on an drifting ice over Arctic Ocean (84°27'N,143°37'W 85°13'N,147°20'W) are presented using eddy correlation and related experiment data obtained from the Chinese 3th Arctic Scientific Expedition in 21—29 August, 2008. The results show that the inversion layer of temperature and humidity exist in most time of observational period. This phenomenon is also observed over the 75°N and 78°N area. The average sensible and latent heat fluxes are 0.5W/m2 and 2.4W/m2, which account for 18% and 86% of absorbed net radiation respectively. To compare with the results observed over 75°N and 78°N area, it shows different the latent heat flux plays important during the sea ice melting over the 84° 85°N area. The near surface atmosphere over the sea-ice is almost neutrally stratified, accounting for 91% of samples during the observation period. The drag coefficients of momentum (CDN) are about 1.64×10-3 in the near neutral stratification calculated by the relationships between CD and wind speed in the height of 10 m, and between CD and stability (z/L). Adaptability of the new parameterization scheme proposed from SHEBA is examined by our data and demonstrated that the similarity function in the new scheme is useful applied in the weak stable stratification over the floating ice area of Arctic Ocean, but it needs more measurement data to modify while it uses in climate modeling.
2011, 33(2): 36-41.
Abstract:
Surface layer parameters over 85°N drifting ice in the Arctic Ocean in summer are estimated using eddy correlation method with observational data of August 20 28,2008 during the 3rd Chinese National Arctic Research Expedition.The results show that the average sensible heat flux,latent heat flux and net radiation are 0.2,1.2 and 9.9 W/m2 respectively indicating that the majority of energy received by the underlying surface is used to melt ice and transfer downward,only a small portion for air heating by the way of sensible heat and latent heat.Surface albedo of drifting ice ranges from 0.68 to 0.82 with an average of 0.76.The drag coefficient is 1.65×10-3 under the near neutral stratification,which is bigger than the estimates obtained by the 1st and 2nd CHINARE.Carbon dioxide flux ranges from －0.09 to +0.06 mg/(m2·s)with an average of －0.015 mg/(m2·s),which means the drifting ice area in the Arctic Ocean in summer is a sink for atmospheric CO2.
Surface layer parameters over 85°N drifting ice in the Arctic Ocean in summer are estimated using eddy correlation method with observational data of August 20 28,2008 during the 3rd Chinese National Arctic Research Expedition.The results show that the average sensible heat flux,latent heat flux and net radiation are 0.2,1.2 and 9.9 W/m2 respectively indicating that the majority of energy received by the underlying surface is used to melt ice and transfer downward,only a small portion for air heating by the way of sensible heat and latent heat.Surface albedo of drifting ice ranges from 0.68 to 0.82 with an average of 0.76.The drag coefficient is 1.65×10-3 under the near neutral stratification,which is bigger than the estimates obtained by the 1st and 2nd CHINARE.Carbon dioxide flux ranges from －0.09 to +0.06 mg/(m2·s)with an average of －0.015 mg/(m2·s),which means the drifting ice area in the Arctic Ocean in summer is a sink for atmospheric CO2.
2011, 33(2): 42-47.
Abstract:
The surface albedo was observed at the Ice Camp during the Chinese National Arctic Research Expedition (CHINARE) at the end of melting season in 2008. The in situ data were investigated in this paper. Several albedo parameterizations were incorporated into a one-dimensional high-resolution thermodynamic snow/ice model (HIGHTSI) to simulate local surface albedo. The observed albedo varies between 0.75 0.85 during the observation period with a slightly decreasing trend, the local change of albedo was strongly linked with snowfall/sleet and snow drift events. The trend of observed surface albedo can be captured by an albedo scheme taken snow and ice thicknesses into account. Albedo schemes with the current complexity, however, are difficult to reconstruct the short-term variability.
The surface albedo was observed at the Ice Camp during the Chinese National Arctic Research Expedition (CHINARE) at the end of melting season in 2008. The in situ data were investigated in this paper. Several albedo parameterizations were incorporated into a one-dimensional high-resolution thermodynamic snow/ice model (HIGHTSI) to simulate local surface albedo. The observed albedo varies between 0.75 0.85 during the observation period with a slightly decreasing trend, the local change of albedo was strongly linked with snowfall/sleet and snow drift events. The trend of observed surface albedo can be captured by an albedo scheme taken snow and ice thicknesses into account. Albedo schemes with the current complexity, however, are difficult to reconstruct the short-term variability.
2011, 33(2): 48-59.
Abstract:
The vertical structure of troposphere over the Arctic Ocean floating ice region (79 85.5°N,144° 170°W) is presented by using the GPS radiosonde data obtained from the 3rd Chinese Arctic Expedition 2008. The results show that: the average temperature lapse rate of the middle troposphere is 6.47 ℃/km. The tropopause height (temperature) changes within 8.0 10.7 km(-59.4 -43.5 ℃), with a mean of 9.3 km(-50.5 ℃). The bottom height, strength of the stronger inversion in the boundary layer and the planetary boundary layer height all presents an obvious diurnal variation. The stronger inversion bottom height and the planetary boundary layer height are left to 850 and 1 000 m above at noon from 700 and 800 m at night, respectively. While the intensity of temperature inversion remarkably weakened from night to daytime.
The vertical structure of troposphere over the Arctic Ocean floating ice region (79 85.5°N,144° 170°W) is presented by using the GPS radiosonde data obtained from the 3rd Chinese Arctic Expedition 2008. The results show that: the average temperature lapse rate of the middle troposphere is 6.47 ℃/km. The tropopause height (temperature) changes within 8.0 10.7 km(-59.4 -43.5 ℃), with a mean of 9.3 km(-50.5 ℃). The bottom height, strength of the stronger inversion in the boundary layer and the planetary boundary layer height all presents an obvious diurnal variation. The stronger inversion bottom height and the planetary boundary layer height are left to 850 and 1 000 m above at noon from 700 and 800 m at night, respectively. While the intensity of temperature inversion remarkably weakened from night to daytime.
2011, 33(2): 60-68.
Abstract:
Aerosol black carbon concentration measured at deck level on board the R/V "Xuelong", with an in-situ aethalometer, during the cruise of the Third National Arctic Research Expedition of China from 12 July to 22 September, 2008. The cruise starts and ends at Shanghai, at the northern most point of 85°13.57'N.The result shows that the surface concentration of black carbon in the Arctic Ocean is the lowest throughout the course, with the mean of (5.3±3.7)ng/m3. There is little meridional gradient of black carbon concentration observed in the Arctic Ocean north of 70°N. Back trajectory analysis indicates that the transportation from low latitude to the Arctic Ocean north of 70°N in summer results not only in low surface concentrations of black carbon, but also in a small variation and a very weak meridional gradient. The black carbon concentrations in surfaces of Huanghai Sea and the Sea of Japan are very close each other in both July and September. The black carbon concentration in September is in range of 400 500 ng/m3, which is 3 times of that in July, 140 160 ng/m3. The terrigencus transport from the northeast Asia land and Alaska is a crucial element to influence the level of black carbon concentration in the ocean.
Aerosol black carbon concentration measured at deck level on board the R/V "Xuelong", with an in-situ aethalometer, during the cruise of the Third National Arctic Research Expedition of China from 12 July to 22 September, 2008. The cruise starts and ends at Shanghai, at the northern most point of 85°13.57'N.The result shows that the surface concentration of black carbon in the Arctic Ocean is the lowest throughout the course, with the mean of (5.3±3.7)ng/m3. There is little meridional gradient of black carbon concentration observed in the Arctic Ocean north of 70°N. Back trajectory analysis indicates that the transportation from low latitude to the Arctic Ocean north of 70°N in summer results not only in low surface concentrations of black carbon, but also in a small variation and a very weak meridional gradient. The black carbon concentrations in surfaces of Huanghai Sea and the Sea of Japan are very close each other in both July and September. The black carbon concentration in September is in range of 400 500 ng/m3, which is 3 times of that in July, 140 160 ng/m3. The terrigencus transport from the northeast Asia land and Alaska is a crucial element to influence the level of black carbon concentration in the ocean.
2011, 33(2): 69-76.
Abstract:
Radium isotopes in the water column along 64.3°N in the Bering Strait were determined to reveal the northward flow of the Pacific water. The specific activities of 226Ra and 228Ra, and the 228Ra/226Ra)A.R. show a longitudinal variation in the Bering Strait, depicting the pathways of Pacific inflow. Based on the distributions of temperature, salinity and radium isotopes in the Bering Strait, three water masses were identified: the Anadyr Water in the western channel, the Alaskan Coastal Water in the eastern channel, and the Bering Shelf Water in the central strait. A subseasonal variation of radium isotopes in the Bering Strait was observed.The specific activities of 226Ra and 228Ra, and 228Ra/226Ra)A.R. in September are higher than those observed in July, indicating water in the western Bering Strait is influenced by the southward flow of the Siberia Coastal Current in September.
Radium isotopes in the water column along 64.3°N in the Bering Strait were determined to reveal the northward flow of the Pacific water. The specific activities of 226Ra and 228Ra, and the 228Ra/226Ra)A.R. show a longitudinal variation in the Bering Strait, depicting the pathways of Pacific inflow. Based on the distributions of temperature, salinity and radium isotopes in the Bering Strait, three water masses were identified: the Anadyr Water in the western channel, the Alaskan Coastal Water in the eastern channel, and the Bering Shelf Water in the central strait. A subseasonal variation of radium isotopes in the Bering Strait was observed.The specific activities of 226Ra and 228Ra, and 228Ra/226Ra)A.R. in September are higher than those observed in July, indicating water in the western Bering Strait is influenced by the southward flow of the Siberia Coastal Current in September.
2011, 33(2): 77-84.
Abstract:
Surface water in the Bering Sea was collected in July-September 1999 for 228Ra measurements and used as a tracer for the cross-shelf exchange of nutrients. The specific activity of surface 228Ra ranges from below detection to 0.81 Bq/m3, which is lower than that reported in the western shelves of the Arctic Ocean. The spatial distribution of 228Ra and 228Ra/226Ra)A.R. shows an increase from the central basin to the northeastern shelf. The relationship between 228Ra/226Ra)A.R. and salinity indicates the influence of the Bering gyre, the Bering Slope Current and the Alaska Coastal Current on 228Ra and 228Ra/226Ra)A.R.. Based on a one-dimensional steady state model of 228Ra, the horizontal eddy diffusion coefficient in study areas was calculated to be 1.9×108 m2/d. The horizontal exchange fluxes of nutrients from the central basin to the northeastern shelf were estimated by combining the horizontal eddy diffusion coefficient and the spatial gradients of nutrients. The surface horizontal input of nitrate to the northeastern shelf only contributed a small fraction to the new production in the northeastern Bering Sea shelf waters, indicating the importance of other nutrient input pathways in supporting new production on the northeastern Bering shelf.
Surface water in the Bering Sea was collected in July-September 1999 for 228Ra measurements and used as a tracer for the cross-shelf exchange of nutrients. The specific activity of surface 228Ra ranges from below detection to 0.81 Bq/m3, which is lower than that reported in the western shelves of the Arctic Ocean. The spatial distribution of 228Ra and 228Ra/226Ra)A.R. shows an increase from the central basin to the northeastern shelf. The relationship between 228Ra/226Ra)A.R. and salinity indicates the influence of the Bering gyre, the Bering Slope Current and the Alaska Coastal Current on 228Ra and 228Ra/226Ra)A.R.. Based on a one-dimensional steady state model of 228Ra, the horizontal eddy diffusion coefficient in study areas was calculated to be 1.9×108 m2/d. The horizontal exchange fluxes of nutrients from the central basin to the northeastern shelf were estimated by combining the horizontal eddy diffusion coefficient and the spatial gradients of nutrients. The surface horizontal input of nitrate to the northeastern shelf only contributed a small fraction to the new production in the northeastern Bering Sea shelf waters, indicating the importance of other nutrient input pathways in supporting new production on the northeastern Bering shelf.
2011, 33(2): 85-95.
Abstract:
Nutrients were analyzed for Bering Strait and Chukchi shelf water samples collected during the 1999, 2003 and 2008 arctic expedition of China. Concentrations of nutrients are the highest in the west part of the strait and decrease dramatically to the east part in summer. These spatial distributions of nutrients are depend on water masses (mixed layer, halocline waters, the Anadyr Current, the Alaskan coastal Current, Bering Shelf Current and Anadyr River water), primary production and cyclone. Because of phytoplankton uptake and dilution effect of ice melt water, the concentration of nutrients in the mixed layer (10 m) is lower than the deep layer of the meridian section along 170°W. Below 10 m, nutrients concentrations are higher in the north of 70°N than the southern part of Chukchi Sea because of the Herald shoal and different water mass. Besides physical transport, the variation of organic matter re-mineralization may be another important factor for the nutrients distribution patterns. parameter N*｛N*= ×0.87｝ was applied to discussing the loss of fixed nitrogen to N2 via denitrification or anammox processes. The values of N* in the Bering Strait region are less negative than that in waters of Chukchi Sea, suggested that the Pacific inflow transforms fixed nitrogen to N2 on the Bering Sea shelf.From the negative N* value and lower concentration ratio of(nitrate plus nitrite plus ammonium) to phosphate in th Chukchi Sea that it is inferre the loss of fixed nitrogen in the water-sediment interface will increase nitrogen limitation to the Arctic Ocean phytoplankton growth.
Nutrients were analyzed for Bering Strait and Chukchi shelf water samples collected during the 1999, 2003 and 2008 arctic expedition of China. Concentrations of nutrients are the highest in the west part of the strait and decrease dramatically to the east part in summer. These spatial distributions of nutrients are depend on water masses (mixed layer, halocline waters, the Anadyr Current, the Alaskan coastal Current, Bering Shelf Current and Anadyr River water), primary production and cyclone. Because of phytoplankton uptake and dilution effect of ice melt water, the concentration of nutrients in the mixed layer (10 m) is lower than the deep layer of the meridian section along 170°W. Below 10 m, nutrients concentrations are higher in the north of 70°N than the southern part of Chukchi Sea because of the Herald shoal and different water mass. Besides physical transport, the variation of organic matter re-mineralization may be another important factor for the nutrients distribution patterns. parameter N*｛N*= ×0.87｝ was applied to discussing the loss of fixed nitrogen to N2 via denitrification or anammox processes. The values of N* in the Bering Strait region are less negative than that in waters of Chukchi Sea, suggested that the Pacific inflow transforms fixed nitrogen to N2 on the Bering Sea shelf.From the negative N* value and lower concentration ratio of(nitrate plus nitrite plus ammonium) to phosphate in th Chukchi Sea that it is inferre the loss of fixed nitrogen in the water-sediment interface will increase nitrogen limitation to the Arctic Ocean phytoplankton growth.
2011, 33(2): 96-102.
Abstract:
Sm-Nd isotopes were measured on the clay-size fraction of thirty-four surface sediments to clarify sediment provenance and transport mechanism in the western Arctic Ocean, the Chukchi Sea, the Chukchi Borderland and the Canadian Basin. Spatial variations of Sm and Nd isotopes of surface sediments indicate there are multiple provenances in the study area. In the Chukchi Sea, three isotope-inferred sediment provenances,which have gradually decreasing c(147Sm) to c(144Nd), epsilon values of Nd and model ages from west to east, indicate the northward transport paths of the three branches of the Pacific inflows. Due to the transport of the clockwise Beaufort Gyre, sediments are mainly derived from the Mackenzie River and have lower epsilon value Nd of (-13.28 -11.76) and older model age in the Canadian Basin and on the Chukchi Plateau in the north of the study area. Meanwhile, relatively larger model age deviations indicate there are strong water mass and sediment mixing due to co-actions of the Pacific water, the Atlantic water and the Beaufort Gyre on the Chuckchi Rise and continental slope.
Sm-Nd isotopes were measured on the clay-size fraction of thirty-four surface sediments to clarify sediment provenance and transport mechanism in the western Arctic Ocean, the Chukchi Sea, the Chukchi Borderland and the Canadian Basin. Spatial variations of Sm and Nd isotopes of surface sediments indicate there are multiple provenances in the study area. In the Chukchi Sea, three isotope-inferred sediment provenances,which have gradually decreasing c(147Sm) to c(144Nd), epsilon values of Nd and model ages from west to east, indicate the northward transport paths of the three branches of the Pacific inflows. Due to the transport of the clockwise Beaufort Gyre, sediments are mainly derived from the Mackenzie River and have lower epsilon value Nd of (-13.28 -11.76) and older model age in the Canadian Basin and on the Chukchi Plateau in the north of the study area. Meanwhile, relatively larger model age deviations indicate there are strong water mass and sediment mixing due to co-actions of the Pacific water, the Atlantic water and the Beaufort Gyre on the Chuckchi Rise and continental slope.
2011, 33(2): 103-114.
Abstract:
Biogenic and terrigenous coarse fractions in the surface sediments from the western Arctic Ocean, which were collected in the First, the Second and the Third Chinese National Arctic Expeditions, were measured by different means in this paper, revealing the surface productivity changes, source of organic matter and input patterns of terrigenous coarse matters in the study area. The surface productivity indicated by the biogenic sediments in the area is closely related to the three Pacific Ocean currents entering into the Chukchi Sea through Bering Strait. High surface productivity in the western Chukchi Sea is resulted from the hyperhaline and hypertrophic Anadyr Stream, whereas low planktonic siliceous productivity in its eastern part is caused by the hypohaline and hypotrophic Alaska Coastal Stream.High planktonic calcareous productivity in the Chukchi Sea Plateau and Alpha Ridge is ascribed to the impact of the northern Atlantic water mass. Low planktonic calcareous productivity in the Chukchi Sea shelf is attributed to the terrigenous matter dilution and life depth of calcareous microorganism. Low calcareous planktonic productivity in the Canada Basin is responded to the strong CaCO3 dissolution. Distribution of terrigenous coarse fraction (ice-rafted detritus-IRD) in the western Arctic Ocean is influenced mainly by sea ice and iceberg transport, terrestrial ice input, river and Pacific currents. The terrigenous coarse fraction in the Bering Strait is impacted by the Pacific currents entering into the Chukchi Sea through Bering Strait. The terrigenous coarse fraction near Alaska coastal area is transported by the terrestrial ice and river. The high IRD in the Northwind Ridge is contributed by the massive sea ice and icebergs conveyed by the Beaufort Circulation, and deposited at the seafloor when the sea ice and icebergs melt.
Biogenic and terrigenous coarse fractions in the surface sediments from the western Arctic Ocean, which were collected in the First, the Second and the Third Chinese National Arctic Expeditions, were measured by different means in this paper, revealing the surface productivity changes, source of organic matter and input patterns of terrigenous coarse matters in the study area. The surface productivity indicated by the biogenic sediments in the area is closely related to the three Pacific Ocean currents entering into the Chukchi Sea through Bering Strait. High surface productivity in the western Chukchi Sea is resulted from the hyperhaline and hypertrophic Anadyr Stream, whereas low planktonic siliceous productivity in its eastern part is caused by the hypohaline and hypotrophic Alaska Coastal Stream.High planktonic calcareous productivity in the Chukchi Sea Plateau and Alpha Ridge is ascribed to the impact of the northern Atlantic water mass. Low planktonic calcareous productivity in the Chukchi Sea shelf is attributed to the terrigenous matter dilution and life depth of calcareous microorganism. Low calcareous planktonic productivity in the Canada Basin is responded to the strong CaCO3 dissolution. Distribution of terrigenous coarse fraction (ice-rafted detritus-IRD) in the western Arctic Ocean is influenced mainly by sea ice and iceberg transport, terrestrial ice input, river and Pacific currents. The terrigenous coarse fraction in the Bering Strait is impacted by the Pacific currents entering into the Chukchi Sea through Bering Strait. The terrigenous coarse fraction near Alaska coastal area is transported by the terrestrial ice and river. The high IRD in the Northwind Ridge is contributed by the massive sea ice and icebergs conveyed by the Beaufort Circulation, and deposited at the seafloor when the sea ice and icebergs melt.
2011, 33(2): 115-123.
Abstract:
Kongsfjorden being close to two tidewater glaciers at the high-latitudes of arctic, is an established reference site for study of the marine-glacial sedimentary processes and sedimentary environments. Fifty-four surface sediment samples were collected from Kongsfjorden during the summer scientific expedition of Chinese Arctic Huanghe River Station, in2007—2008. The grain-size characteristics of the sediment samples were studied and compared with modern moraine sediments of Europe, North America and China using the methods of discrete map for standard deviation and mean grain size. The marine-glacial deposits in Kongsfjorden can be divided into two major types according to the division of glacial-marine deposits types: residual paratill and compound paratill. The source of glacial-marine deposits and processes of glacial marine sedimentation were preliminarily discussed.
Kongsfjorden being close to two tidewater glaciers at the high-latitudes of arctic, is an established reference site for study of the marine-glacial sedimentary processes and sedimentary environments. Fifty-four surface sediment samples were collected from Kongsfjorden during the summer scientific expedition of Chinese Arctic Huanghe River Station, in2007—2008. The grain-size characteristics of the sediment samples were studied and compared with modern moraine sediments of Europe, North America and China using the methods of discrete map for standard deviation and mean grain size. The marine-glacial deposits in Kongsfjorden can be divided into two major types according to the division of glacial-marine deposits types: residual paratill and compound paratill. The source of glacial-marine deposits and processes of glacial marine sedimentation were preliminarily discussed.
2011, 33(2): 124-133.
Abstract:
Investigations of the size-fractionated chlorophyll a and primary productivity were carried out in the western Arctic Ocean during the 3nd national arctic research expedition of China during the summer of 2008. The results show that the surface chlorophyll a concentrations are 0.013 19.367 μg/dm3 and the average value is (0.677±2.2661)μg/dm3 in the surveyed area. Chlorophyll a concentrations in the subsurface water are higher than these at the surface layer and in the deep depth water. The distribution of chlorophyll a is obviously areal characteristics, the areal arrange order of the water-column chlorophyll a is the Chukchi shelf, the Beaufout Sea, the Chukchi Plateau, the Mendeleev Ride and the Canada Basin. The chlorophyll a concentrations decrease in two sequential samplings on Section R, with water-column average values of (3.083±3.009) and (0.797±0.774)g/dm3, respectively. The primary productivity at the surveyed stations is 0.050 2.453 mg/(μm3·h). The primary productivity of the Chukchi shelf is higher than that of the Chukchi Plateau,the Canada Basin,the Beaufout Sea and the Mendeleev Ride.The results of the size-fractionated chlorophyll a and primary productivity show that microplankton accounts for the majority of the total chlorophyll a (51.75%) and primary productivity(50.89%) on the Chukchi shelf and the Beaufout sea Shelf. The contributions of the picoplankton account for the majority of the total chlorophyll a (68.25%) and primary productivity (56.13%) in the Beaufout Sea,on the Chukchi Plateau, the Mendeleev Ride and in the Canada Basin.
Investigations of the size-fractionated chlorophyll a and primary productivity were carried out in the western Arctic Ocean during the 3nd national arctic research expedition of China during the summer of 2008. The results show that the surface chlorophyll a concentrations are 0.013 19.367 μg/dm3 and the average value is (0.677±2.2661)μg/dm3 in the surveyed area. Chlorophyll a concentrations in the subsurface water are higher than these at the surface layer and in the deep depth water. The distribution of chlorophyll a is obviously areal characteristics, the areal arrange order of the water-column chlorophyll a is the Chukchi shelf, the Beaufout Sea, the Chukchi Plateau, the Mendeleev Ride and the Canada Basin. The chlorophyll a concentrations decrease in two sequential samplings on Section R, with water-column average values of (3.083±3.009) and (0.797±0.774)g/dm3, respectively. The primary productivity at the surveyed stations is 0.050 2.453 mg/(μm3·h). The primary productivity of the Chukchi shelf is higher than that of the Chukchi Plateau,the Canada Basin,the Beaufout Sea and the Mendeleev Ride.The results of the size-fractionated chlorophyll a and primary productivity show that microplankton accounts for the majority of the total chlorophyll a (51.75%) and primary productivity(50.89%) on the Chukchi shelf and the Beaufout sea Shelf. The contributions of the picoplankton account for the majority of the total chlorophyll a (68.25%) and primary productivity (56.13%) in the Beaufout Sea,on the Chukchi Plateau, the Mendeleev Ride and in the Canada Basin.
2011, 33(2): 134-145.
Abstract:
The abundance, cell size (cellular carbon content), and cellular pigments of picophytoplankton on the shelf area of the north Bearing Sea(61°29' 64°21'N, 168°00' 174°32'W) were analyzed by flow cytometry(FCM).A statistical analysis was used to study the response of the picophytoplankton to environmental changes. Synechococcus and picoeukaryotes were the only type of the picophytoplankton community; and their respective cell abundance was 0.01×106 2.69×106 and 0.47×106 13.20×106 cells/dm3. The chlorophyll a, phycoerythrin, and the cell size (cellular carbon content) had the same changing trend with the change of environmental factors. Comparatively, the chlorophylls a and the cell abundance, and the carotenoids and the cell size (cellular carbon content) of the picoeukaryotes had the same changing trends, respectively. Both salinity and nutrients had significant influence on the cellular carbon content and the ratio of carotinoids to chlorophylls a of picoeukaryotes. High nutrient concentration was prone to induce high ratio of cellular carbon content to chlorophylls a. Both synechococcus and picoeukaryotes preferred relatively high temperature and low salinity; and were easily to form high cell abundance in oligotrophic water, whereas in seawaters with relatively high nutrient concentration were prone to form cells with high cellular carbon content.The cell abundance of picoeukaryotes decreased intensely when the nitrogen-phosphorus ratio greater than 7. The cell abundance was relatively high, whereas the cell size (cellular carbon content) and the phycoerythrin-chlorophyll a ratio were relatively small. Comparatively, the cell size (cellular carbon content) and the phycoerythrin-chlorophyll a ratio were relatively large and the cell abundance was relatively low when the picophytoplankton was at relatively deep water layers and high latitudes. The ascending of the water temperature and the increase of the inflows of freshwater from the continent can increase both the abundance and the variety of picophytoplankton on the continental shelf of the north Bering Sea.
The abundance, cell size (cellular carbon content), and cellular pigments of picophytoplankton on the shelf area of the north Bearing Sea(61°29' 64°21'N, 168°00' 174°32'W) were analyzed by flow cytometry(FCM).A statistical analysis was used to study the response of the picophytoplankton to environmental changes. Synechococcus and picoeukaryotes were the only type of the picophytoplankton community; and their respective cell abundance was 0.01×106 2.69×106 and 0.47×106 13.20×106 cells/dm3. The chlorophyll a, phycoerythrin, and the cell size (cellular carbon content) had the same changing trend with the change of environmental factors. Comparatively, the chlorophylls a and the cell abundance, and the carotenoids and the cell size (cellular carbon content) of the picoeukaryotes had the same changing trends, respectively. Both salinity and nutrients had significant influence on the cellular carbon content and the ratio of carotinoids to chlorophylls a of picoeukaryotes. High nutrient concentration was prone to induce high ratio of cellular carbon content to chlorophylls a. Both synechococcus and picoeukaryotes preferred relatively high temperature and low salinity; and were easily to form high cell abundance in oligotrophic water, whereas in seawaters with relatively high nutrient concentration were prone to form cells with high cellular carbon content.The cell abundance of picoeukaryotes decreased intensely when the nitrogen-phosphorus ratio greater than 7. The cell abundance was relatively high, whereas the cell size (cellular carbon content) and the phycoerythrin-chlorophyll a ratio were relatively small. Comparatively, the cell size (cellular carbon content) and the phycoerythrin-chlorophyll a ratio were relatively large and the cell abundance was relatively low when the picophytoplankton was at relatively deep water layers and high latitudes. The ascending of the water temperature and the increase of the inflows of freshwater from the continent can increase both the abundance and the variety of picophytoplankton on the continental shelf of the north Bering Sea.
2011, 33(2): 146-156.
Abstract:
Based on the species composition and abundance of zooplankton from 43 stations in the western Arctic Ocean, community structures and geographic distributions, as well as relations between zooplankton communities and environmental conditions were investigated. The species composition and abundance were compared with the previously published results to examine possible changes an community level. Three zooplankton communities were identified with a cluster analysis: a high latitude deep ocean community located in the Canadian Basin and Chuchi Plateau;a shelf community located in the central Chukchi Sea;a neritic transition community including station along the Alaska coast and in the north of Chukchi Sea. The deep ocean community was less in total zooplankton abundance, and dominated by copepods. The most important dominant species include Oithona spp., Scolethricella minor, Calanus hyperboreus and Metridia longa. Barnache cypris, Calanus glacialis and Pseudocalanus newmani were the most important dominant species in the shelf community, and P.newmani, banarcle nauplii and Acartia longiremis were of the most importance in the neritic transition community.Barnacle cypris was recorded as dominant taxon in all communities, with the highest average density of 573.2 ind/m-3 observed in the shelf community. The deep ocean community inhabited in high latitude area characterized by low temperature and low chlorophyll a concentration. The shelf community distributed mainly in the central Chukchi Sea with high temperature and low chlorophyll a concentration and at several stations with low temperature and high chlorophyll a concentration.The stations from all these three habitats were included in the neritic transition community. It was indicated that zooplankton community is rather steady in high latitude areas, but varies significantly in the Chukchi Sea due to both environmental influences and local development. Though the species composition was different from the previous results, it was induced mainly by various sampling date and gears, rather than long-term changes.
Based on the species composition and abundance of zooplankton from 43 stations in the western Arctic Ocean, community structures and geographic distributions, as well as relations between zooplankton communities and environmental conditions were investigated. The species composition and abundance were compared with the previously published results to examine possible changes an community level. Three zooplankton communities were identified with a cluster analysis: a high latitude deep ocean community located in the Canadian Basin and Chuchi Plateau;a shelf community located in the central Chukchi Sea;a neritic transition community including station along the Alaska coast and in the north of Chukchi Sea. The deep ocean community was less in total zooplankton abundance, and dominated by copepods. The most important dominant species include Oithona spp., Scolethricella minor, Calanus hyperboreus and Metridia longa. Barnache cypris, Calanus glacialis and Pseudocalanus newmani were the most important dominant species in the shelf community, and P.newmani, banarcle nauplii and Acartia longiremis were of the most importance in the neritic transition community.Barnacle cypris was recorded as dominant taxon in all communities, with the highest average density of 573.2 ind/m-3 observed in the shelf community. The deep ocean community inhabited in high latitude area characterized by low temperature and low chlorophyll a concentration. The shelf community distributed mainly in the central Chukchi Sea with high temperature and low chlorophyll a concentration and at several stations with low temperature and high chlorophyll a concentration.The stations from all these three habitats were included in the neritic transition community. It was indicated that zooplankton community is rather steady in high latitude areas, but varies significantly in the Chukchi Sea due to both environmental influences and local development. Though the species composition was different from the previous results, it was induced mainly by various sampling date and gears, rather than long-term changes.
2011, 33(2): 157-165.
Abstract:
Distribution features and structural conditions of nutrients in the Bering Sea were observed during the third arctic research expedition of China in the summer of 2008. The results showed that the distribution and structural condition of nutrients in the Bering Sea were obviously areal characteristics. The surface average concentrations (9.73, 0.94, 11.06 μmol/dm3 respectively) of DIN, phosphate and silicate in the Bering Basin were much higher than those (0.60, 0.43, 3.74 μmol/dm3 respectively) in the continental shelf waters. The high surface concentrations of nutrients appeared mainly in the southern area of the Bering Basin and the low values occurred on the slope break and in the eastern waters of the continental shelf. The concentrations of DIN, phosphate and silicate were generally high, while chlorophyll a concentrations were low in the euphotic zone of the Bering Basin, showing typically characteristics of high-nutrients, low-chlorophyll a (HNLC). The results suggested that the biological process were not the main controlling factor for nutrient distributions in the Bering Basin, while the distributions and variations of nutrients in the continental shelf waters were not only controlled by the transport of physical process, but also affected by phytoplankton productivity and consumption of nutrient during summer. The surface average ratios of N/P, Si/P on the slope break and in continental shelf waters were 1.8, 9.9 and 3.2, 2.2 respectively. DIN-deficiency in the continental shelf waters and Si-deficiency on the slope break were apparently characteristics in summer. The concentration of phosphate was generally high and it was not possible to be a limiting-factor for the phytoplankton growth in the Bering Sea. N was limiting factor for the phytoplankton productivity in the most of continental shelf waters due to deficiency of DIN and low ratios of N/P in the surface waters, whereas Si-limitation was sporadic, only on the slope break during growth of diatom.
Distribution features and structural conditions of nutrients in the Bering Sea were observed during the third arctic research expedition of China in the summer of 2008. The results showed that the distribution and structural condition of nutrients in the Bering Sea were obviously areal characteristics. The surface average concentrations (9.73, 0.94, 11.06 μmol/dm3 respectively) of DIN, phosphate and silicate in the Bering Basin were much higher than those (0.60, 0.43, 3.74 μmol/dm3 respectively) in the continental shelf waters. The high surface concentrations of nutrients appeared mainly in the southern area of the Bering Basin and the low values occurred on the slope break and in the eastern waters of the continental shelf. The concentrations of DIN, phosphate and silicate were generally high, while chlorophyll a concentrations were low in the euphotic zone of the Bering Basin, showing typically characteristics of high-nutrients, low-chlorophyll a (HNLC). The results suggested that the biological process were not the main controlling factor for nutrient distributions in the Bering Basin, while the distributions and variations of nutrients in the continental shelf waters were not only controlled by the transport of physical process, but also affected by phytoplankton productivity and consumption of nutrient during summer. The surface average ratios of N/P, Si/P on the slope break and in continental shelf waters were 1.8, 9.9 and 3.2, 2.2 respectively. DIN-deficiency in the continental shelf waters and Si-deficiency on the slope break were apparently characteristics in summer. The concentration of phosphate was generally high and it was not possible to be a limiting-factor for the phytoplankton growth in the Bering Sea. N was limiting factor for the phytoplankton productivity in the most of continental shelf waters due to deficiency of DIN and low ratios of N/P in the surface waters, whereas Si-limitation was sporadic, only on the slope break during growth of diatom.
2011, 33(2): 166-174.
Abstract:
The abundance, cell size (cellular carbon content), and cellular pigments of picophytoplankton on the shelf area of the north Bearing Sea(61°29' 64°21'N, 168°00' 174°32'W) were analyzed by flow cytometry(FCM).A statistical analysis was used to study the response of the picophytoplankton to environmental changes. Synechococcus and picoeukaryotes were the only type of the picophytoplankton community; and their respective cell abundance was 0.01×106 2.69×106 and 0.47×106 13.20×106 cells/dm3. The chlorophyll a, phycoerythrin, and the cell size (cellular carbon content) had the same changing trend with the change of environmental factors. Comparatively, the chlorophylls a and the cell abundance, and the carotenoids and the cell size (cellular carbon content) of the picoeukaryotes had the same changing trends, respectively. Both salinity and nutrients had significant influence on the cellular carbon content and the ratio of carotinoids to chlorophylls a of picoeukaryotes. High nutrient concentration was prone to induce high ratio of cellular carbon content to chlorophylls a. Both synechococcus and picoeukaryotes preferred relatively high temperature and low salinity; and were easily to form high cell abundance in oligotrophic water, whereas in seawaters with relatively high nutrient concentration were prone to form cells with high cellular carbon content.The cell abundance of picoeukaryotes decreased intensely when the nitrogen-phosphorus ratio greater than 7. The cell abundance was relatively high, whereas the cell size (cellular carbon content) and the phycoerythrin-chlorophyll a ratio were relatively small. Comparatively, the cell size (cellular carbon content) and the phycoerythrin-chlorophyll a ratio were relatively large and the cell abundance was relatively low when the picophytoplankton was at relatively deep water layers and high latitudes. The ascending of the water temperature and the increase of the inflows of freshwater from the continent can increase both the abundance and the variety of picophytoplankton on the continental shelf of the north Bering Sea.
The abundance, cell size (cellular carbon content), and cellular pigments of picophytoplankton on the shelf area of the north Bearing Sea(61°29' 64°21'N, 168°00' 174°32'W) were analyzed by flow cytometry(FCM).A statistical analysis was used to study the response of the picophytoplankton to environmental changes. Synechococcus and picoeukaryotes were the only type of the picophytoplankton community; and their respective cell abundance was 0.01×106 2.69×106 and 0.47×106 13.20×106 cells/dm3. The chlorophyll a, phycoerythrin, and the cell size (cellular carbon content) had the same changing trend with the change of environmental factors. Comparatively, the chlorophylls a and the cell abundance, and the carotenoids and the cell size (cellular carbon content) of the picoeukaryotes had the same changing trends, respectively. Both salinity and nutrients had significant influence on the cellular carbon content and the ratio of carotinoids to chlorophylls a of picoeukaryotes. High nutrient concentration was prone to induce high ratio of cellular carbon content to chlorophylls a. Both synechococcus and picoeukaryotes preferred relatively high temperature and low salinity; and were easily to form high cell abundance in oligotrophic water, whereas in seawaters with relatively high nutrient concentration were prone to form cells with high cellular carbon content.The cell abundance of picoeukaryotes decreased intensely when the nitrogen-phosphorus ratio greater than 7. The cell abundance was relatively high, whereas the cell size (cellular carbon content) and the phycoerythrin-chlorophyll a ratio were relatively small. Comparatively, the cell size (cellular carbon content) and the phycoerythrin-chlorophyll a ratio were relatively large and the cell abundance was relatively low when the picophytoplankton was at relatively deep water layers and high latitudes. The ascending of the water temperature and the increase of the inflows of freshwater from the continent can increase both the abundance and the variety of picophytoplankton on the continental shelf of the north Bering Sea.
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