The 1990 International Trans-Antarctica Expedition covered a total distance of 5 896 km and lasted 220 days, during the traverse the author carried out observations of snow-pit stratigraphyand surface characteristics ...The 1990 International Trans-Antarctica Expedition covered a total distance of 5 896 km and lasted 220 days, during the traverse the author carried out observations of snow-pit stratigraphyand surface characteristics along the Trans-Antarctica route and analyses of stable isotope and glaciochemistry of the selected samples. These studies have provided a batch of the latest and extensive data on the present climate and environment in the Antarctica, which is of great significance to the global change research. From the analysis of this batch of data, a group of achievements have been gained,which are helpful to our understanding comprehensively and systematically on the surface topography of Antarctic Ice Sheet, precipitation distribution, temperature difference, snowfall deposition processes,stable isotope distribution, distribution of main anions and canons and heavy-metal element and their sources in main geographic regions of the Antarctica.The stratigraphy profiles of total 106 snow-pits showed that in West Antarctica the meltwater infiltration-congelation is obvious and the annual precipitation is larger than that in East Antarctica, which implies that the climate in West Antarctica is warmer, more humid and influenced more greatly by the South Ocean than that in East Antarctica. Radiation ice-glazes found frequently in snow profiles indicate that even in inland of East Antarctica, surface 'melting' occurs in summer due to the long-time solar radiation.The distribution of δD in the surface 25 cm snow along the traverse showed that the δD decreases in general with increasing latitudes, and the minimum value occurs between 80° S and 85° S (around the Vostok Station). In the top area of the East Antarctic Plateau, ex d value is higher to other regions by 40%, which is tentatively attributed to the difference in vapor sources.The distribution of NO, along the traverse demonstrates a general feature of higher concentration in the inland than in the outer regions, but the NO3 flux is lower in inland region than that in coastal regions. At both sides of the South Pole, the NO3 concentration and flux peaks occur, which are just in the shield zone of aurora australis, which suggested that the high flux of NO3 may be largely attributed by photoelectricity in the upper atmosphere.The Pb content increases from west to east along the traverse. If the average value over the Larsen Ice Sheet and the Antarctic Peninsula is regarded as the background in modern precipitation, the average value over the section of the traverse between Vostok and Mirnyy Stations is 2～3 times higher than the background, suggesting that the environment in this region has been polluted by human activities.On the other hand, the distribution of Ph content may also be affected by the bio-geochemical processes in the surface water of the South Oceans.展开更多
This research aimed to identify and characterize individual spherical fly ash particles extracted from surface snow at Urumqi Glacier No.1 (UG1), Eastern Tien Shan, central Asia. Characterization of the spherical part...This research aimed to identify and characterize individual spherical fly ash particles extracted from surface snow at Urumqi Glacier No.1 (UG1), Eastern Tien Shan, central Asia. Characterization of the spherical particles (i.e. morphology, chemical composition and genesis) was obtained by scanning electron microscopy coupled with energy dispersive X-ray spectrometer (SEM-EDX). This method enabled the characterization of submicroscopic spherical particles, which were present in very small quantities. Spherical particles and agglomerates were identified according to their morphology in five snow samples. Prevalent particle types in all samples were granular spherical particles, hollow spherical particles, irregularly shaped carbonaceous particles and agglomerates. The vast majority of spherical particles in our samples had mostly smooth and glossy surfaces, although these particles varied in diameter and elemental composition. The diameter of fly ash particles ranged from 0.76 to 16.7 m, with an average of 3.79 m (median: 3.21 m). Individual particle analyses of elemental composition showed that particles formed in combustion were mainly composed of carbon, silicon, aluminum and trace elements (e.g. Na, K, Ca, Fe). Some spherical fly ash particles contained toxic heavy metals (e.g. Pb, Cr, As, Zn), and indicated that fly ash particles acted as the main possible carriers of toxic heavy metals deposited in snow and ice of glaciers in high altitudes of central Asia. On the basis of chemical information obtained from EDX, the fly ash particles deposited in the snow could be classified into four types. Namely, Si-dominant particles, with average diameters of 3.24 m were formed by industrial coal combustion via high temperature processes in typical coal-fired heating stations and thermal power plants. Moreover, Fe-dominant particles, with average diameters of 3.82 m, and Ti-dominant spherical particles formed by lower temperature processes in foundry and iron or steel plants. In addition, C-dominant particles, with average diameters of 8.43 m, formed from unburned coal. Fe-dominant particles had larger average diameters than Sidominant particles, indicating that the former were easier to form and developed earlier in the furnace because of their differential melting points of compositional oxide. Backward air mass trajectory analysis suggests that the developed urban regions of central Asia contributed the primary fly ash particles from industrial combustion to the study site through the high-level westerlies jet steam.展开更多
文摘The 1990 International Trans-Antarctica Expedition covered a total distance of 5 896 km and lasted 220 days, during the traverse the author carried out observations of snow-pit stratigraphyand surface characteristics along the Trans-Antarctica route and analyses of stable isotope and glaciochemistry of the selected samples. These studies have provided a batch of the latest and extensive data on the present climate and environment in the Antarctica, which is of great significance to the global change research. From the analysis of this batch of data, a group of achievements have been gained,which are helpful to our understanding comprehensively and systematically on the surface topography of Antarctic Ice Sheet, precipitation distribution, temperature difference, snowfall deposition processes,stable isotope distribution, distribution of main anions and canons and heavy-metal element and their sources in main geographic regions of the Antarctica.The stratigraphy profiles of total 106 snow-pits showed that in West Antarctica the meltwater infiltration-congelation is obvious and the annual precipitation is larger than that in East Antarctica, which implies that the climate in West Antarctica is warmer, more humid and influenced more greatly by the South Ocean than that in East Antarctica. Radiation ice-glazes found frequently in snow profiles indicate that even in inland of East Antarctica, surface 'melting' occurs in summer due to the long-time solar radiation.The distribution of δD in the surface 25 cm snow along the traverse showed that the δD decreases in general with increasing latitudes, and the minimum value occurs between 80° S and 85° S (around the Vostok Station). In the top area of the East Antarctic Plateau, ex d value is higher to other regions by 40%, which is tentatively attributed to the difference in vapor sources.The distribution of NO, along the traverse demonstrates a general feature of higher concentration in the inland than in the outer regions, but the NO3 flux is lower in inland region than that in coastal regions. At both sides of the South Pole, the NO3 concentration and flux peaks occur, which are just in the shield zone of aurora australis, which suggested that the high flux of NO3 may be largely attributed by photoelectricity in the upper atmosphere.The Pb content increases from west to east along the traverse. If the average value over the Larsen Ice Sheet and the Antarctic Peninsula is regarded as the background in modern precipitation, the average value over the section of the traverse between Vostok and Mirnyy Stations is 2～3 times higher than the background, suggesting that the environment in this region has been polluted by human activities.On the other hand, the distribution of Ph content may also be affected by the bio-geochemical processes in the surface water of the South Oceans.
基金supported by the National Natural Science Foundation of China (40871046, 40571038 and 4081019001) the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-YW-146)
文摘This research aimed to identify and characterize individual spherical fly ash particles extracted from surface snow at Urumqi Glacier No.1 (UG1), Eastern Tien Shan, central Asia. Characterization of the spherical particles (i.e. morphology, chemical composition and genesis) was obtained by scanning electron microscopy coupled with energy dispersive X-ray spectrometer (SEM-EDX). This method enabled the characterization of submicroscopic spherical particles, which were present in very small quantities. Spherical particles and agglomerates were identified according to their morphology in five snow samples. Prevalent particle types in all samples were granular spherical particles, hollow spherical particles, irregularly shaped carbonaceous particles and agglomerates. The vast majority of spherical particles in our samples had mostly smooth and glossy surfaces, although these particles varied in diameter and elemental composition. The diameter of fly ash particles ranged from 0.76 to 16.7 m, with an average of 3.79 m (median: 3.21 m). Individual particle analyses of elemental composition showed that particles formed in combustion were mainly composed of carbon, silicon, aluminum and trace elements (e.g. Na, K, Ca, Fe). Some spherical fly ash particles contained toxic heavy metals (e.g. Pb, Cr, As, Zn), and indicated that fly ash particles acted as the main possible carriers of toxic heavy metals deposited in snow and ice of glaciers in high altitudes of central Asia. On the basis of chemical information obtained from EDX, the fly ash particles deposited in the snow could be classified into four types. Namely, Si-dominant particles, with average diameters of 3.24 m were formed by industrial coal combustion via high temperature processes in typical coal-fired heating stations and thermal power plants. Moreover, Fe-dominant particles, with average diameters of 3.82 m, and Ti-dominant spherical particles formed by lower temperature processes in foundry and iron or steel plants. In addition, C-dominant particles, with average diameters of 8.43 m, formed from unburned coal. Fe-dominant particles had larger average diameters than Sidominant particles, indicating that the former were easier to form and developed earlier in the furnace because of their differential melting points of compositional oxide. Backward air mass trajectory analysis suggests that the developed urban regions of central Asia contributed the primary fly ash particles from industrial combustion to the study site through the high-level westerlies jet steam.
