针对硝酸盐对地下水污染的严重性 ,介绍了用 Ca O除去 CO2 和 H2 O的测定氮同位素比值的燃烧管方法和利用 Ag NO3+C(石墨 )生成 CO2 的测定 NO-3 中氧同位素比值的燃烧法 ;研究了用 15N和 18O同位素分析地下水中 NO-3 的来源和判断硝化...针对硝酸盐对地下水污染的严重性 ,介绍了用 Ca O除去 CO2 和 H2 O的测定氮同位素比值的燃烧管方法和利用 Ag NO3+C(石墨 )生成 CO2 的测定 NO-3 中氧同位素比值的燃烧法 ;研究了用 15N和 18O同位素分析地下水中 NO-3 的来源和判断硝化作用和反硝化作用的发生机理。展开更多
Seawater samples were collected in the water column from the Canada Basin aboard RV Xuelong in August 1999. Concentrations of δ; D, δ;18 O, nutrients (NO3 -, PO4 3-, SiO3 2-) and dissolved oxygen were measured, alon...Seawater samples were collected in the water column from the Canada Basin aboard RV Xuelong in August 1999. Concentrations of δ; D, δ;18 O, nutrients (NO3 -, PO4 3-, SiO3 2-) and dissolved oxygen were measured, along with hydrographic parameters (salinity and temperature). Our results showed that the upper layer of the water column was characterized by the occurrence of the upper halocline water (UHW) and the lower halocline water (LHW). The UHW was associated with a salinity of 33.1 (～150m depth) and maximums of nutrients, NO and PO*, whereas minimums of NO and PO* (PO* = PO4 3?+ O2/175?1.95 μmol/dm3) occurred at the depth of LHW (~300m depth). Two tracer systems, S-δ;18O-PO* and S-δ D-SiO3 3-, were used to estimate the fractions of the Atlantic water, Pacific water, river runoff and sea ice meltwater in water samples. Combined with the nutrient ratio NO/PO, it was suggested that the UHW was derived from the in-flow of the Pacific water through the Bering Strait. These waters were modified to obtain the high salinity and nutrients in the Chukchi shelf or/and the east Siberian shelf. The LHW was maintained by inflow of the Atlantic water through Barents Sea and subsequent mixing with freshwater in the shelf region to produce the signals of NO and PO* minimums. In study basin, the river runoff signals were confined to water depths less than 300 m and the fractions of river runoff decreased with the increasing depth. Water column inventories of river runoff and sea ice meltwater were calculated between the surface and 300m. The river runoff inventories in the Canada Basin were higher than those in other sea areas, suggesting that the Canada basin is a major storage region for Arctic river water. The sea ice meltwater signals suggested that the Canada Basin is a region of net sea ice formation and the inventories of net sea ice in the upper water column increasing from the south to the north.展开更多
A"once-in-a-millennium"super rainstorm battered Zhengzhou,central China,from 07/17/2021 to 07/22/2021(named"7.20"Zhengzhou rainstorm).It killed 398 people and caused billions of dollars in damage.A...A"once-in-a-millennium"super rainstorm battered Zhengzhou,central China,from 07/17/2021 to 07/22/2021(named"7.20"Zhengzhou rainstorm).It killed 398 people and caused billions of dollars in damage.A pressing question is whether rainstorms of this intensity can be effectively documented by geological archives to understand better their historical variabilities beyond the range of meteorological data.Here,four land snail shells were collected from Zhengzhou,and weekly to daily resolved snail shellδ^(18)O records from June to September of 2021 were obtained by gas-source mass spectrometry and secondary ion mass spectrometry.The daily resolved records show a dramatic negative shift between 06/18/2021 and 09/18/2021,which has been attributed to the"7.20"Zhengzhou rainstorm.Moreover,the measured amplitude of this shift is consistent with the theoretical value estimated from the flux balance model and instrumental data for the"7.20"Zhengzhou rainstorm.Our results suggest that the ultra-high resolutionδ^(18)O of land snail shells have the potential to reconstruct local synoptic scale rainstorms quantitatively,and thus fossil snail shells in sedimentary strata can be valuable material for investigating the historical variability of local rainstorms under different climate backgrounds.展开更多
The fractions of river runoff and sea-ice melted water in the Canada Basin in summer 2003 were determined by the salinity-δ18O system. The fraction of river runoff （fR） was high in the upper 50 m of the water colum...The fractions of river runoff and sea-ice melted water in the Canada Basin in summer 2003 were determined by the salinity-δ18O system. The fraction of river runoff （fR） was high in the upper 50 m of the water column and decreased with depth and latitude. The signals of the river runoffwere confined to water depths above 200 m. The total amount of river runoff in the Canada Basin was higher than that in other arctic seas, indicating that the Canada Basin is a main storage region for river runoff. The penetration depth of the sea-ice melted water was less than 50 m to the south of 78°N, while it was about 150 m to the north of 78°N. The total amount of sea-ice melted water was much higher to the north of 78°N than to the south of 78°N, indicating the sea-ice melted waters accumulated on the ice edge. The abundant sea-ice melted water on the ice edge was attributed to the earlier melted water in the southern Canada Basin and transported by the Beaufort Gyre or the reinforced melting of sea ice by solar radiation in the polynya.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
In this paper, the 18 O distribution of surface water from the central sea areas of the Bering Sea and the Chukchi Sea was studied. The δ 18 O value of surface water from the Bering Sea is averagely -0.5...In this paper, the 18 O distribution of surface water from the central sea areas of the Bering Sea and the Chukchi Sea was studied. The δ 18 O value of surface water from the Bering Sea is averagely -0.5‰; the δ 18 O contents of the Chukchi Sea are distributionally lower in northeast and higher in southwest; the δ 18 O value at the margin of Canadian Basin is -2.8‰, and averagely -0.8‰ in the southern area of the Chukchi Sea. The δ 18 O vertical distribution in some deep water stations from the Chukchi Sea and the Bering Sea is also studied. In the southern margin of Canadian Basin, the δ 18 O value is -2‰ -3‰ for surface layer and rises to 0 at 100 m depth layer. In the Bering Sea, the δ 18 O is about -0.5‰ for surface layer and increases to 0 at the depth of 300 m. The NO tracer can reflect obviously three water masses vertically distributed in the central Bering Sea: the upper Bering water mass, the middle Bering water mass and the deep Pacific water mass. The distributive ranges of NO and temperature for the various water masses are T<7℃, NO>780 μmol/dm 3 and T≥7℃, NO>650 μmol/dm 3 for upper Bering water mass, T<4℃, 550<NO<780 μmol/dm 3 for middle Bering water mass, and T<4℃, 330<NO<550 μmol/dm 3 for deep Pacific water mass. It is found from δ 18 O-S relation diagram and δ 18 O vertical profiles that the δ 18 O is about +0.3‰ from halocline layer till sea bottom. Its isotopic characteristics are the same as the Atlantic water, showing that the sea water comes from the north Atlantic. The freshwater end member of the Chukchi Sea in the survey period is also explored.展开更多
Oxygen and hydrogen isotopic compositions have been determined of three coexistent mineral triplets of alkali feldspar, quartz, arfvedsonite of 11 samples collected from the Tasigake alkali granite pluton, Ulungur Riv...Oxygen and hydrogen isotopic compositions have been determined of three coexistent mineral triplets of alkali feldspar, quartz, arfvedsonite of 11 samples collected from the Tasigake alkali granite pluton, Ulungur River region, northern Xinjiang. Isotopic exchange with meteoric water during subsolidus cooling caused strong 18O-D depletion and the remarkable nonequilibrium <sup>18</sup>O/<sup>16</sup>O relation between coexistent minerals. <sup>18</sup>O/<sup>16</sup>O exchange kinetic effects of the three minerals are simultaneously and consistently modelled. Exsolution and microtextural reorganization of alkali feldspar, and infiltration of water have been mutually facilitated by each other. Shallow intrusion, and circulation of meteoric water throughout the pluton cool it effectively. As a result, the "heat engine" is rapidly extinguished, and the nonequilibrium <sup>18</sup>O/<sup>16</sup>O relation is frosen.展开更多
文摘针对硝酸盐对地下水污染的严重性 ,介绍了用 Ca O除去 CO2 和 H2 O的测定氮同位素比值的燃烧管方法和利用 Ag NO3+C(石墨 )生成 CO2 的测定 NO-3 中氧同位素比值的燃烧法 ;研究了用 15N和 18O同位素分析地下水中 NO-3 的来源和判断硝化作用和反硝化作用的发生机理。
基金This work was supported by the Chinese First Arctic Expedition Foundation.
文摘Seawater samples were collected in the water column from the Canada Basin aboard RV Xuelong in August 1999. Concentrations of δ; D, δ;18 O, nutrients (NO3 -, PO4 3-, SiO3 2-) and dissolved oxygen were measured, along with hydrographic parameters (salinity and temperature). Our results showed that the upper layer of the water column was characterized by the occurrence of the upper halocline water (UHW) and the lower halocline water (LHW). The UHW was associated with a salinity of 33.1 (～150m depth) and maximums of nutrients, NO and PO*, whereas minimums of NO and PO* (PO* = PO4 3?+ O2/175?1.95 μmol/dm3) occurred at the depth of LHW (~300m depth). Two tracer systems, S-δ;18O-PO* and S-δ D-SiO3 3-, were used to estimate the fractions of the Atlantic water, Pacific water, river runoff and sea ice meltwater in water samples. Combined with the nutrient ratio NO/PO, it was suggested that the UHW was derived from the in-flow of the Pacific water through the Bering Strait. These waters were modified to obtain the high salinity and nutrients in the Chukchi shelf or/and the east Siberian shelf. The LHW was maintained by inflow of the Atlantic water through Barents Sea and subsequent mixing with freshwater in the shelf region to produce the signals of NO and PO* minimums. In study basin, the river runoff signals were confined to water depths less than 300 m and the fractions of river runoff decreased with the increasing depth. Water column inventories of river runoff and sea ice meltwater were calculated between the surface and 300m. The river runoff inventories in the Canada Basin were higher than those in other sea areas, suggesting that the Canada basin is a major storage region for Arctic river water. The sea ice meltwater signals suggested that the Canada Basin is a region of net sea ice formation and the inventories of net sea ice in the upper water column increasing from the south to the north.
基金supported by the National Natural Science Foundation of China(42221003,4202530442103084)the Research Projects from the Chinese Academy of Sciences(XDB40000000)+1 种基金the Science and Technology Innovation Project of Laoshan Laboratory(LSKJ202203300)the CAS Youth Interdisciplinary Team。
文摘A"once-in-a-millennium"super rainstorm battered Zhengzhou,central China,from 07/17/2021 to 07/22/2021(named"7.20"Zhengzhou rainstorm).It killed 398 people and caused billions of dollars in damage.A pressing question is whether rainstorms of this intensity can be effectively documented by geological archives to understand better their historical variabilities beyond the range of meteorological data.Here,four land snail shells were collected from Zhengzhou,and weekly to daily resolved snail shellδ^(18)O records from June to September of 2021 were obtained by gas-source mass spectrometry and secondary ion mass spectrometry.The daily resolved records show a dramatic negative shift between 06/18/2021 and 09/18/2021,which has been attributed to the"7.20"Zhengzhou rainstorm.Moreover,the measured amplitude of this shift is consistent with the theoretical value estimated from the flux balance model and instrumental data for the"7.20"Zhengzhou rainstorm.Our results suggest that the ultra-high resolutionδ^(18)O of land snail shells have the potential to reconstruct local synoptic scale rainstorms quantitatively,and thus fossil snail shells in sedimentary strata can be valuable material for investigating the historical variability of local rainstorms under different climate backgrounds.
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a special scientific research project for public welfare supported by the State Oceanic Administration under contract No.201105022-4the 4th Chinese Arctic Research Program
文摘The fractions of river runoff and sea-ice melted water in the Canada Basin in summer 2003 were determined by the salinity-δ18O system. The fraction of river runoff （fR） was high in the upper 50 m of the water column and decreased with depth and latitude. The signals of the river runoffwere confined to water depths above 200 m. The total amount of river runoff in the Canada Basin was higher than that in other arctic seas, indicating that the Canada Basin is a main storage region for river runoff. The penetration depth of the sea-ice melted water was less than 50 m to the south of 78°N, while it was about 150 m to the north of 78°N. The total amount of sea-ice melted water was much higher to the north of 78°N than to the south of 78°N, indicating the sea-ice melted waters accumulated on the ice edge. The abundant sea-ice melted water on the ice edge was attributed to the earlier melted water in the southern Canada Basin and transported by the Beaufort Gyre or the reinforced melting of sea ice by solar radiation in the polynya.
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.
文摘In this paper, the 18 O distribution of surface water from the central sea areas of the Bering Sea and the Chukchi Sea was studied. The δ 18 O value of surface water from the Bering Sea is averagely -0.5‰; the δ 18 O contents of the Chukchi Sea are distributionally lower in northeast and higher in southwest; the δ 18 O value at the margin of Canadian Basin is -2.8‰, and averagely -0.8‰ in the southern area of the Chukchi Sea. The δ 18 O vertical distribution in some deep water stations from the Chukchi Sea and the Bering Sea is also studied. In the southern margin of Canadian Basin, the δ 18 O value is -2‰ -3‰ for surface layer and rises to 0 at 100 m depth layer. In the Bering Sea, the δ 18 O is about -0.5‰ for surface layer and increases to 0 at the depth of 300 m. The NO tracer can reflect obviously three water masses vertically distributed in the central Bering Sea: the upper Bering water mass, the middle Bering water mass and the deep Pacific water mass. The distributive ranges of NO and temperature for the various water masses are T<7℃, NO>780 μmol/dm 3 and T≥7℃, NO>650 μmol/dm 3 for upper Bering water mass, T<4℃, 550<NO<780 μmol/dm 3 for middle Bering water mass, and T<4℃, 330<NO<550 μmol/dm 3 for deep Pacific water mass. It is found from δ 18 O-S relation diagram and δ 18 O vertical profiles that the δ 18 O is about +0.3‰ from halocline layer till sea bottom. Its isotopic characteristics are the same as the Atlantic water, showing that the sea water comes from the north Atlantic. The freshwater end member of the Chukchi Sea in the survey period is also explored.
文摘Oxygen and hydrogen isotopic compositions have been determined of three coexistent mineral triplets of alkali feldspar, quartz, arfvedsonite of 11 samples collected from the Tasigake alkali granite pluton, Ulungur River region, northern Xinjiang. Isotopic exchange with meteoric water during subsolidus cooling caused strong 18O-D depletion and the remarkable nonequilibrium <sup>18</sup>O/<sup>16</sup>O relation between coexistent minerals. <sup>18</sup>O/<sup>16</sup>O exchange kinetic effects of the three minerals are simultaneously and consistently modelled. Exsolution and microtextural reorganization of alkali feldspar, and infiltration of water have been mutually facilitated by each other. Shallow intrusion, and circulation of meteoric water throughout the pluton cool it effectively. As a result, the "heat engine" is rapidly extinguished, and the nonequilibrium <sup>18</sup>O/<sup>16</sup>O relation is frosen.
