The Lambert Glacier basin is one of particular regions in East Antarctica, because of its distinctive topography. During the repeat inland traverses carried out in recent several years, surface 2 m snow samples and sh...The Lambert Glacier basin is one of particular regions in East Antarctica, because of its distinctive topography. During the repeat inland traverses carried out in recent several years, surface 2 m snow samples and shallow (10～27 m deep) cores were collected at several ten stations and at near ten stations, respectively. The stable isotopic ratios of these samples and cores were measured in order to investigate the relation of isotopes with temperature and to study the climatic change in recent decades over this area. The correlation between isotopic ratios and mean annual temperature gives that δ-temperature gradient is relatively close to that along a traverse route between Vostok and Mirnyy stations. The inconsistency of δ18O profiles of these cores makes it difficult to distinguish an overall trend of climatic change in past decades. After incorporating the result of snow accumulation variability and temperature record over 30 years at the coast station, it is believed that climate was in a little cooling and drying from 1950s to 1980s and has been in a warming period since then.展开更多
In order to reduce the cohesive force between pavement and ice, the approach of pavement surface coating with hydrophobic admixtures is investigated. The deicing effect of this approach is examined by the contact angl...In order to reduce the cohesive force between pavement and ice, the approach of pavement surface coating with hydrophobic admixtures is investigated. The deicing effect of this approach is examined by the contact angle test and the shear test. The durability of the approach is examined by the accelerated abrasion test, and the skid resistance of the pavement with surface coating is examined by the British pendulum test and the surface texture depth test. In the contact angle test, the contact angle between hydrophobic admixture and water is 100.2°. In the shear test, the maximum shear stress is 0.06 MPa for the specimen coated with hydrophobic admixture, which is much lower than that of the specimen without hydrophobic admixture coating, 3.5 MPa. Furth- ermore, the ice and asphalt surface are completely separated for the coated specimen while not for the uncoated specimen. Based on the accelerated abrasion test, the residual hydro- phobic admixture in the veins of the pavement after abrasion still has a deicing effect. From the skid resistance tests, the British pendulum number （BPN） and the texture depth （TD） of the specimen coated with hydrophobic admixtures are larger than those of the standard requirements. The overall experi-mental observation indicates that the approach can effectively reduce close contact between asphalt pavement and ice; therefore, it can be a promising solution to road icing problems in winter.展开更多
The exchanges of NOx between snow and air have significant impact on the atmospheric components and photochemical processes in the overlying boundary layer. Such exchanges increase the oxidizing capacity of the atmosp...The exchanges of NOx between snow and air have significant impact on the atmospheric components and photochemical processes in the overlying boundary layer. Such exchanges increase the oxidizing capacity of the atmosphere and may have a crucial impact on the air signals that are retrieved from ice cores. In the recent years, sunlit snow and ice have been demonstrated to be important NOx sources in the polar atmospheric boundary layer. This paper makes a thorough review on the release of NOx from snow and ice, including field observations and experimental evidences, release mechanisms and influential parameters that affect such a release process, polar NOx concentrations and fluxes, and environmental impacts of the chemical processes of NOx in the polar atmospheric boundary layer. In the Tibetan Plateau, the released NOx observed recently in the sunlit snow/ice-cover is 1-order magnitude more than that in polar regions, but further scientific research is still needed to reveal its impact on the atmospheric oxidizing capacity.展开更多
文摘The Lambert Glacier basin is one of particular regions in East Antarctica, because of its distinctive topography. During the repeat inland traverses carried out in recent several years, surface 2 m snow samples and shallow (10～27 m deep) cores were collected at several ten stations and at near ten stations, respectively. The stable isotopic ratios of these samples and cores were measured in order to investigate the relation of isotopes with temperature and to study the climatic change in recent decades over this area. The correlation between isotopic ratios and mean annual temperature gives that δ-temperature gradient is relatively close to that along a traverse route between Vostok and Mirnyy stations. The inconsistency of δ18O profiles of these cores makes it difficult to distinguish an overall trend of climatic change in past decades. After incorporating the result of snow accumulation variability and temperature record over 30 years at the coast station, it is believed that climate was in a little cooling and drying from 1950s to 1980s and has been in a warming period since then.
文摘In order to reduce the cohesive force between pavement and ice, the approach of pavement surface coating with hydrophobic admixtures is investigated. The deicing effect of this approach is examined by the contact angle test and the shear test. The durability of the approach is examined by the accelerated abrasion test, and the skid resistance of the pavement with surface coating is examined by the British pendulum test and the surface texture depth test. In the contact angle test, the contact angle between hydrophobic admixture and water is 100.2°. In the shear test, the maximum shear stress is 0.06 MPa for the specimen coated with hydrophobic admixture, which is much lower than that of the specimen without hydrophobic admixture coating, 3.5 MPa. Furth- ermore, the ice and asphalt surface are completely separated for the coated specimen while not for the uncoated specimen. Based on the accelerated abrasion test, the residual hydro- phobic admixture in the veins of the pavement after abrasion still has a deicing effect. From the skid resistance tests, the British pendulum number （BPN） and the texture depth （TD） of the specimen coated with hydrophobic admixtures are larger than those of the standard requirements. The overall experi-mental observation indicates that the approach can effectively reduce close contact between asphalt pavement and ice; therefore, it can be a promising solution to road icing problems in winter.
基金supported by the Fund of Polar Scientific Research(No.20080216) of State Ocean Administration, Chinaby Chinese Natural Science Foundation(No. 20407001,No.40701170)
文摘The exchanges of NOx between snow and air have significant impact on the atmospheric components and photochemical processes in the overlying boundary layer. Such exchanges increase the oxidizing capacity of the atmosphere and may have a crucial impact on the air signals that are retrieved from ice cores. In the recent years, sunlit snow and ice have been demonstrated to be important NOx sources in the polar atmospheric boundary layer. This paper makes a thorough review on the release of NOx from snow and ice, including field observations and experimental evidences, release mechanisms and influential parameters that affect such a release process, polar NOx concentrations and fluxes, and environmental impacts of the chemical processes of NOx in the polar atmospheric boundary layer. In the Tibetan Plateau, the released NOx observed recently in the sunlit snow/ice-cover is 1-order magnitude more than that in polar regions, but further scientific research is still needed to reveal its impact on the atmospheric oxidizing capacity.
