A theoretical evaluation of mineral stability in Don Juan Pond, Wright Valley, Victoria Land
A theoretical evaluation of mineral stability in Don Juan Pond, Wright Valley, Victoria Land
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DOI：
10.1017/s0954102097000114
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发表时间：
1997-03-01
影响因子：
1.6
通讯作者：
Marion, GM
中科院分区：
文献类型：
--
作者：
Marion, GM
唐璜池塘，位于赖特谷，维多利亚土地，是独特的几个原因。它是南极洲最咸的湖泊，是一种接近饱和的氯化钙溶液。由于这种高盐度，唐璜池塘通常在冬季保持不结冰，即使温度低于-50摄氏度。唐璜池塘是一个地方，安山岩（CaCl 2。6 H（2）O）是首次发现的天然产物。本文的目的是证明一个化学热力学模型（FREZCHEM）的实用性，通过开发冰，岩盐（NaCl），水岩盐（NaCl）的理论稳定性图。2 H（2）O）和唐璜池塘中的南极岩，使用1961年至1983年间34天收集的实验数据。在计算出的低共熔温度（-51.8 ℃）下，唐璜池的组成为CaCl 2 = 3.72 mol kg（-1）和NaCl = 0.50 mol kg（-1），这与纯NaCl-CaCl 2-H2O系统相似但不相同。唐璜池塘的低共熔温度和高CaCl 2浓度是冬季不结冰的原因。该模型与实验数据是兼容的，并预测在罕见的高水期，岩盐和安山岩冰的形成。这些固相都是从Don Juan Pond报道的。该模型还预测了在零度以下的温度下形成的水卤石;水卤石从来没有在唐璜池塘观察到，但这可能只是反映了大多数采样是在夏天，当岩盐在化学上比水卤石更稳定。FREZCHEM模型可能有助于阐明南极湖泊的物理化学行为，盐度的起源和演变。
Don Juan Pond, located in the Wright Valley, Victoria Land, is unique for several reasons. It is the most saline of the Antarctic lakes, being a near-saturated CaCl2 solution. As a consequence of this high salinity, Don Juan Pond generally remains unfrozen in winter, even at temperatures below -50 degrees C. Don Juan Pond is the site where antarcticite (CaCl2 . 6H(2)O) was first identified forming naturally. The objective of this paper is to demonstrate the utility of a chemical thermodynamic model (FREZCHEM) by developing theoretical stability diagrams for ice, halite (NaCl), hydrohalite (NaCl . 2H(2)O), and antarcticite in Don Juan Pond, using experimental data collected on 34 days between 1961 and 1983. The composition of Don Juan Pond at the calculated eutectic temperature (-51.8 degrees C) was CaCl2 = 3.72 mol kg(-1) and NaCl = 0.50 mol kg(-1), which is similar but not identical to a pure NaCl-CaCl2-H2O system. The low eutectic temperature and high CaCl2 concentrations of Don Juan Pond account for lack of freezing during winter. The model is compatible with the experimental data, and predicts the formation of ice during rare high water periods, halite, and antarcticite. These solid phases have all been reported from Don Juan Pond. The model also predicts the formation of hydrohalite at subzero temperatures; hydrohalite has never been observed at Don Juan Pond, but this may simply reflect that most sampling was done during the summer when halite is thermodynamically more stable than hydrohalite. The FREZCHEM model may prove useful in elucidating the physicochemical behaviour, the origin of salinity, and the evolution of Antarctic lakes.