CHEMISTRY OF ANTARCTIC SNOW AND ICE
We have studied 1000 samples of snow and ice from East and West Antarctica (coastal as well as central areas). These samples cover different time periods up to 30,000 years B.P. In the meltwater, we have measured major ions (i.e. Na+, NH4+, K+, Ca++, Mg++, H+, Cl-, NO3-, and SO4--) using stringent c...
| Main Author: | |
|---|---|
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
HAL CCSD
1987
|
| Subjects: | |
| Online Access: | https://hal.science/jpa-00226251 https://hal.science/jpa-00226251/document https://hal.science/jpa-00226251/file/ajp-jphyscol198748C111.pdf https://doi.org/10.1051/jphyscol:1987111 |
| Summary: | We have studied 1000 samples of snow and ice from East and West Antarctica (coastal as well as central areas). These samples cover different time periods up to 30,000 years B.P. In the meltwater, we have measured major ions (i.e. Na+, NH4+, K+, Ca++, Mg++, H+, Cl-, NO3-, and SO4--) using stringent contamination free tehniques. A very close balance between anions and cations is observed, making it possible to draw up the list of chemical compounds present in antarctic snow and ice. In coastal areas, snow contains essentially sea salt (14 µEq. l-1) and two acids : HNO3 (0.8) and H2SO4 (1.2). In more central areas, the sea salt contribution decreases strongly (30 % of the total ionic budget). Acids represent the preponderant part (HNO3, H2SO4 and sometimes HCl being present in variable proportions depending on the location). These soluble species represent the greatest part of total impurities (90 to 95 % by mass). The chemistry of the ice deposited during the late glacial age (18,000 years B.P.) is more intricate. Indeed, insoluble species (i.e. aluminosilicates) content is enhanced (50 % by mass, against 5 to 10 % during the Holocene). Besides, marine (sea salt) and terrestrial (CaSO4, MgSO4) contributions increase whereas acids contribution remains stable. Sea salt (55 %), terrestrial species (25 %) and acids (20 %) is a typical composition of soluble impurities in this aged ice. The dependence of deposition fluxes with the accumulation rate demonstrates that particulate impurities (i.e. sea salt and H2O-H2SO4) in the atmosphere are incorporated in snow both by wet and dry deposition. Typically dry deposition represents 60-70 % of the total deposition in central areas. On the other hand, this fraction seems to be weaker for HNO3 (present in gaseous phase in the Antarctic atmosphere). However, the incorporation of HNO3 in snow remains poorly understood. |
|---|