南极雪冰中硝酸根稳定同位素研究进展

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 NO_x 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.