As a conservative tracer, oxygen isotopes in seawater are widely used for water mass analysis, along with temperature and salinity. In this study, seawater oxygen-18 datasets in the Canada Basin during 1967-2010 were ...As a conservative tracer, oxygen isotopes in seawater are widely used for water mass analysis, along with temperature and salinity. In this study, seawater oxygen-18 datasets in the Canada Basin during 1967-2010 were obtained from the four cruises of the Chinese National Arctic Research Expedition （1999, 2003, 2008, and 2010） and the NASA database. Fractions of sea ice meltwater and river runoffwere determined from the salinity-5180 system. Our results showed that the river runoff decreased from the south to the north in the Canada Basin. The enhanced amount of river runoff observed in the southern Canada Basin may originate from the Mackenzie River, transported by the Beaufort Gyre. The river runoff component showed maximum fractions during 1967-1969, 1978-1979, 1984-1985, 1993-1994, and 2008-2010, indicating the refresh time of the river runoffwas 5.0-16.0 a in the Canada Basin. The temporal variation of the river runoffwas related to the change of the Arctic Oscillation （AO） index, suggesting the freshwater stored in the Canada Basin was affected by surface sea ice drift and water mass movement driven by atmospheric circulation.展开更多
A combination of 5180 and salinity data was employed to explore the freshwater balance in the Canada Basin in summer 2008. The Arctic river water and Pacific river water were quantitatively distinguished by using diff...A combination of 5180 and salinity data was employed to explore the freshwater balance in the Canada Basin in summer 2008. The Arctic river water and Pacific river water were quantitatively distinguished by using different saline end-members. The fractions of total river water, including the Arctic and Pacific river water, were high in the upper 50 m and decreased with depth as well as increasing latitude. In contrast, the fraction of Pacific river water increased gradually with depth but decreased toward north. The inventory of total river water in the Canada Basin was higher than other arctic seas, indicating that Canada Basin was a main storage region for river water in the Arctic Ocean. The fraction of Arctic river water was higher than Pacific river water in the upper 50 m while the opposite was true below 50 m. As a result, the inventories of Pacific river water were higher than those of Arctic river water, demonstrating that the Pacific inflow through the Bering Strait is the main source of freshwater in the Canada Basin. Both the river water and sea-ice melted water in the permanent ice zone were more abundant than those in the region with sea-ice just melted. The fractions of total river water, Arctic river water, Pacific river water increased northward to the north of 82°N, indicating an additional source of river water in the permanent ice zone of the northern Canada Basin. A possible reason for the extra river water in the permanent ice zone is the lateral advection of shelf waters by the Trans-Polar Drift. The penetration depth of sea-ice melted waters was less than 30 m in the southern Canada Basin, while it extended to 125 m in the northern Canada Basin. The inventory of sea- ice melted water suggested that sea-ice melted waters were also accumulated in the permanent ice zone, attributing to the trap of earlier melted waters in the permanent ice zone via the Beaufort Gyre.展开更多
Stable carbon and nitrogen isotopic composition of particulate organic matter （POM） were measured for samples collected from the Bering Sea in 2010 summer. Particulate organic carbon （POC） and particulate nitrogen...Stable carbon and nitrogen isotopic composition of particulate organic matter （POM） were measured for samples collected from the Bering Sea in 2010 summer. Particulate organic carbon （POC） and particulate nitrogen （PN） showed high concentrations in the shelf and slope regions and decreased with depth in the slope and basin, indicating that biological processes play an important role on POM distribution. The low C/N ratio and heavy isotopic composition of POM, compared to those from the Alaska River, suggested a predominant contribution of marine biogenic organic matter in the Bering Sea. The fact thatδ^13Candδ^15Ngenerally increased with depth in the Bering Sea basin demonstrated that organic components with light carbon or nitrogen were decomposed preferentially during their transport to deep water. However, the highδ^13Candδ^15Nobserved in shelf bottom water were mostly resulted from sediment resuspension.展开更多
210pb was measured during the 3rd Chinese National Arctic Research Expedition cruise to investigate its spa- tial pattern in the western Arctic Ocean, as well as its relation with the thermocline in the Canadian Basin...210pb was measured during the 3rd Chinese National Arctic Research Expedition cruise to investigate its spa- tial pattern in the western Arctic Ocean, as well as its relation with the thermocline in the Canadian Basin. The specific activities varied from 0.04 to 2.72, 〈0.013 to 4.37, and 0.1 to 4.85 Bq/m3 for dissolved, particu- late, and bulk 210pb, respectively, corresponding to respective averages of 0.65, 0.43, and 1.08 Bq/m3. In the Canadian Basin, the minimum 210pb activities occurred in the thermocline, which was characterized by low temperature of-1.52℃ and salinity of 33.1. Combining the spatial distribution of 210pb and hydrographical characteristics in the western Arctic Ocean, this scenario was ascribed to the effective scavenging of 210pb when the Pacific water flowed across the Chukchi Shelf. Quantitatively, this interpretation was supported by both the shorter residence times and higher scavenging efficiencies （SE） of dissolved 210pb over the Chukchi Shelf. The highest SE values were observed in the Herald Shoal and bottom waters over the slope.展开更多
Seawater samples were collected around Prydz Bay in summer of 2014,dissolved and particulate^(210)Po and^(210)Pb were measured to reveal the disequilibrium characteristics and particle dynamics.Our results show that t...Seawater samples were collected around Prydz Bay in summer of 2014,dissolved and particulate^(210)Po and^(210)Pb were measured to reveal the disequilibrium characteristics and particle dynamics.Our results show that the distribution of^(210)Po and^(210)Po/^(210)Pb activity ratio in the upper water is mainly affected by biological absorption or particle adsorption.An abnormal excess of^(210)Po relative to^(210)Pb was observed in the surface water at stations P1-2 and P2-2,which is likely to be the horizontal transport of water mass with high DPo/DPb)_(A.R.)and TPo/TPb)_(A.R.).In this study,the removal of particulate^(210)Po is mainly controlled by the scavenging of dissolved^(210)Po and the two have a linear positive correlation with the salinity,a negative linear correlation with the content of dissolved oxygen and a reciprocal relationship with the content of POC.The export flux of POC at 100 m is estimated to be 1.8-4.4 mmol·m^(−2)·d^(−1)(avg.2.9 mmol·m^(−2)·d^(−1))based on^(210)Po/^(210)Pb disequilibria,with the highest value in the shelf,which is consistent with the distribution of biological productivity.展开更多
基金The Chinese Polar Environment Comprehensive Investigation and Assessment Programs under contract Nos CHINARE2014-03-04-03 and CHINARE2013-04-03-05the National Natural Science Foundation of China under contract No.41125020+1 种基金the 4th Chinese Arctic Research Programa special scientific research project for public welfare supported by the State Oceanic Administration under contract No.201105022-4
文摘As a conservative tracer, oxygen isotopes in seawater are widely used for water mass analysis, along with temperature and salinity. In this study, seawater oxygen-18 datasets in the Canada Basin during 1967-2010 were obtained from the four cruises of the Chinese National Arctic Research Expedition （1999, 2003, 2008, and 2010） and the NASA database. Fractions of sea ice meltwater and river runoffwere determined from the salinity-5180 system. Our results showed that the river runoff decreased from the south to the north in the Canada Basin. The enhanced amount of river runoff observed in the southern Canada Basin may originate from the Mackenzie River, transported by the Beaufort Gyre. The river runoff component showed maximum fractions during 1967-1969, 1978-1979, 1984-1985, 1993-1994, and 2008-2010, indicating the refresh time of the river runoffwas 5.0-16.0 a in the Canada Basin. The temporal variation of the river runoffwas related to the change of the Arctic Oscillation （AO） index, suggesting the freshwater stored in the Canada Basin was affected by surface sea ice drift and water mass movement driven by atmospheric circulation.
基金The Chinese Polar Environment Comprehensive Investigation&Assessment Program under contract Nos CHINARE2017-03-04-03 and CHINARE2017-04-03-05the Natural Science Foundation of China under contract No.41125020
文摘A combination of 5180 and salinity data was employed to explore the freshwater balance in the Canada Basin in summer 2008. The Arctic river water and Pacific river water were quantitatively distinguished by using different saline end-members. The fractions of total river water, including the Arctic and Pacific river water, were high in the upper 50 m and decreased with depth as well as increasing latitude. In contrast, the fraction of Pacific river water increased gradually with depth but decreased toward north. The inventory of total river water in the Canada Basin was higher than other arctic seas, indicating that Canada Basin was a main storage region for river water in the Arctic Ocean. The fraction of Arctic river water was higher than Pacific river water in the upper 50 m while the opposite was true below 50 m. As a result, the inventories of Pacific river water were higher than those of Arctic river water, demonstrating that the Pacific inflow through the Bering Strait is the main source of freshwater in the Canada Basin. Both the river water and sea-ice melted water in the permanent ice zone were more abundant than those in the region with sea-ice just melted. The fractions of total river water, Arctic river water, Pacific river water increased northward to the north of 82°N, indicating an additional source of river water in the permanent ice zone of the northern Canada Basin. A possible reason for the extra river water in the permanent ice zone is the lateral advection of shelf waters by the Trans-Polar Drift. The penetration depth of sea-ice melted waters was less than 30 m in the southern Canada Basin, while it extended to 125 m in the northern Canada Basin. The inventory of sea- ice melted water suggested that sea-ice melted waters were also accumulated in the permanent ice zone, attributing to the trap of earlier melted waters in the permanent ice zone via the Beaufort Gyre.
基金The Chinese Polar Environment Comprehensive Investigation and Assessment Programs under contract Nos CHIN-ARE2014-03-04-03 and CHINARE2014-04-03-05the National Natural Science Foundation of China under contract No.41125020+1 种基金the 5th Chinese Arctic Research Programthe Polar Science Strategic Research Foundation of China under contract No.20120307
文摘Stable carbon and nitrogen isotopic composition of particulate organic matter （POM） were measured for samples collected from the Bering Sea in 2010 summer. Particulate organic carbon （POC） and particulate nitrogen （PN） showed high concentrations in the shelf and slope regions and decreased with depth in the slope and basin, indicating that biological processes play an important role on POM distribution. The low C/N ratio and heavy isotopic composition of POM, compared to those from the Alaska River, suggested a predominant contribution of marine biogenic organic matter in the Bering Sea. The fact thatδ^13Candδ^15Ngenerally increased with depth in the Bering Sea basin demonstrated that organic components with light carbon or nitrogen were decomposed preferentially during their transport to deep water. However, the highδ^13Candδ^15Nobserved in shelf bottom water were mostly resulted from sediment resuspension.
基金The Chinese Polar Environment Comprehensive Investigation and Assessment Programs under contract No.CHINARE2014-03-04-03the National Natural Science Foundation of China under contract No.41125020+1 种基金the 4th Chinese Arctic Research Programthe Polar Science Strategic Research Foundation of China under contract No.20120307
文摘210pb was measured during the 3rd Chinese National Arctic Research Expedition cruise to investigate its spa- tial pattern in the western Arctic Ocean, as well as its relation with the thermocline in the Canadian Basin. The specific activities varied from 0.04 to 2.72, 〈0.013 to 4.37, and 0.1 to 4.85 Bq/m3 for dissolved, particu- late, and bulk 210pb, respectively, corresponding to respective averages of 0.65, 0.43, and 1.08 Bq/m3. In the Canadian Basin, the minimum 210pb activities occurred in the thermocline, which was characterized by low temperature of-1.52℃ and salinity of 33.1. Combining the spatial distribution of 210pb and hydrographical characteristics in the western Arctic Ocean, this scenario was ascribed to the effective scavenging of 210pb when the Pacific water flowed across the Chukchi Shelf. Quantitatively, this interpretation was supported by both the shorter residence times and higher scavenging efficiencies （SE） of dissolved 210pb over the Chukchi Shelf. The highest SE values were observed in the Herald Shoal and bottom waters over the slope.
基金financially supported by National Polar Special Program “Impact and Response of Antarctic Seas to Climate Change” (Grant nos. IRASCC 01-01-02C, 02-01-01)supported by National Natural Science Foundation of China (Grant no. 41721005)the program funded by China Ocean Mineral Resources R & D Association (Grant no. DY135-13-E2-03)。
文摘Seawater samples were collected around Prydz Bay in summer of 2014,dissolved and particulate^(210)Po and^(210)Pb were measured to reveal the disequilibrium characteristics and particle dynamics.Our results show that the distribution of^(210)Po and^(210)Po/^(210)Pb activity ratio in the upper water is mainly affected by biological absorption or particle adsorption.An abnormal excess of^(210)Po relative to^(210)Pb was observed in the surface water at stations P1-2 and P2-2,which is likely to be the horizontal transport of water mass with high DPo/DPb)_(A.R.)and TPo/TPb)_(A.R.).In this study,the removal of particulate^(210)Po is mainly controlled by the scavenging of dissolved^(210)Po and the two have a linear positive correlation with the salinity,a negative linear correlation with the content of dissolved oxygen and a reciprocal relationship with the content of POC.The export flux of POC at 100 m is estimated to be 1.8-4.4 mmol·m^(−2)·d^(−1)(avg.2.9 mmol·m^(−2)·d^(−1))based on^(210)Po/^(210)Pb disequilibria,with the highest value in the shelf,which is consistent with the distribution of biological productivity.
