Abstract:

As a major chemical component in Antarctic snow and ice, nitrate (NO– 3) has been widely investigated, as these data can potentially deliver information on the past climate. Unlike other chemical ions (e.g., Na+ and K+), NO– 3 is not irreversibly deposited into snowpacks, as it will undergo post-depositional processing, which will significantly affect the initial atmospheric information and hamper the interpretation of ice-core records. The isotopic composition of NO– 3 can deliver more information than possible with determinations of the concentration alone; that is, the nitrogen and oxygen isotopes can suggest the sources of NOx and the oxidation capability of the atmosphere. Owing to limited amounts in samples, especially ice cores, and the low concentrations of NO– 3 in Antarctic snow and ice, investigations on isotopes of NO– 3 are rare, and the isotopes of NO– 3 in Antarctica are far from understood. We discuss the spatial distribution patterns of NO– 3 isotopes and possible influencing factors across the Antarctic ice sheet. Furthermore, we summarize the post-depositional processes of NO– 3 in snowpack, and its main mechanisms, and review the available reports on NO– 3 isotope records in Antarctic snow pit and ice cores. Lastly, the main shortcomings of available studies are discussed, and potential research directions on NO– 3 isotopes in Antarctic snow and ice are pointed out.

Key words: Antarctic snow, nitrate, stable isotopes