Soils in ice-free areas in Antarctica are recognized for their high salt concentrations and persistent arid conditions. While previous studies have investigated the distribution of salts and potential sources in the McMurdo Dry Valleys, logistical constraints have limited our investigation and understanding of salt dynamics within the Transantarctic Mountains. We focused on the Shackleton Glacier (85° S, 176° W), a major outlet glacier of the East Antarctic Ice Sheet located in the Central Transantarctic Mountains (CTAM), and collected surface soil samples from 10 ice-free areas. Concentrations of water-soluble nitrate (NO₃^–) and sulfate (SO₄^2–) ranged from <0.2 to ∼150 μmol g^–1 and <0.02 to ∼450 μmol g^–1, respectively. In general, salt concentrations increased with distance inland and with elevation. However, concentrations also increased with distance from current glacial ice position. To understand the source and formation of these salts, we measured the stable isotopes of dissolved water-soluble NO₃^– and SO₄^2–, and soil carbonate (HCO₃ + CO₃). δ¹⁵N-NO₃ values ranged from −47.8 to 20.4‰ and, while all Δ¹⁷O-NO₃ values are positive, they ranged from 15.7 to 45.9‰. δ³⁴S-SO₄ and δ¹⁸O-SO₄ values ranged from 12.5 and 17.9‰ and −14.5 to −7.1‰, respectively. Total inorganic carbon isotopes in bulk soil samples ranged from 0.2 to 8.5‰ for δ¹³C and −38.8 to −9.6‰ for δ¹⁸O. A simple mixing model indicates that NO₃^– is primarily derived from the troposphere (0–70%) and stratosphere (30–100%). SO₄^2– is primarily derived from secondary atmospheric sulfate (SAS) by the oxidation of reduced sulfur gases and compounds in the atmosphere by H₂O₂, carbonyl sulfide (COS), and ozone. Calcite and perhaps nahcolite (NaHCO₃) are formed through both slow and rapid freezing and/or the evaporation/sublimation of HCO₃ + CO₃-rich fluids. Our results indicate that the origins of salts from ice-free areas within the CTAM represent a complex interplay of atmospheric deposition, chemical weathering, and post-depositional processes related to glacial history and persistent arid conditions. These findings have important implications for the use of these salts in deciphering past climate and atmospheric conditions, biological habitat suitability, glacial history, and can possibly aid in our future collective understanding of salt dynamics on Mars.

南极无冰地区的土壤因其高盐含量和持续干旱条件而闻名。虽然先前的研究已经调查了麦克默多干旱谷中盐的分布和潜在来源，但后勤限制限制了我们对跨南极山脉内盐动态的调查和了解。我们将重点放在位于南极中部山脉（CTAM）的东南极冰盖的主要出口冰川Shackleton冰川（85°S，176°W）上，并从10个无冰区收集了地表土壤样品。水溶性硝酸盐（NO ₃ ^–）和硫酸盐（SO ₄ ^2–）的浓度范围从<0.2到〜150μmolg ^–1和<0.02到〜450μmolg ^–1， 分别。通常，盐浓度随内陆距离和海拔的升高而增加。但是，浓度也随着距当前冰川冰位置的距离增加而增加。为了理解这些盐的来源和形成，我们测量溶解水溶性NO的稳定同位素₃ ^-和SO ₄ ^2-，以及土壤碳酸盐（HCO ₃ + CO ₃）。δ ¹⁵ N-NO _3个值介于-47.8至20.4‰和，而所有Δ ¹⁷ -O-NO ₃的值是正的，它们从15.7不等45.9‰。δ ³⁴ S-SO ₄和δ ¹⁸ O形SO ₄值分别在12.5和17.9‰和-14.5至-7.1‰之间。散装土壤样品中总的无机碳同位素范围从0.2至8.5‰，δ ¹³ C和-38.8 -9.6到为‰δ ¹⁸ O.一个简单的混合模型表明，NO ₃ ^-主要由对流层衍生的（0-70％ ）和平流层（30-100％）。SO ₄ ^2–主要来自次级大气硫酸盐（SAS），它是通过H ₂ O ₂，羰基硫（COS）和臭氧将大气中还原的硫气和化合物氧化而形成的。通过缓慢和快速冷冻和/或HCO ₃的蒸发/升华形成方解石，也许还有石碳酸（NaHCO ₃）+富含CO _3的流体。我们的结果表明，CTAM内无冰地区的盐分起源代表了大气沉积，化学风化以及与冰川历史和持续干旱条件有关的沉积后过程的复杂相互作用。这些发现对这些盐在解释过去的气候和大气条件，生物栖息地的适宜性，冰川历史方面的应用具有重要意义，并且可能有助于我们对火星上盐动力学的未来集体理解。