What is the Real ΔG_r Function of Albite Dissolution?

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• 作者：C. Gruber^a ; ^{chengrub@post.bgu.ac.il} ; I. Kutuzov^a ; Y. Zakon^b ; J. Ganor^a
• 关键词：weathering ; dissolution ; silicon isotopes ; albite ; feldspar ; kinetics
• 刊名：Procedia Earth and Planetary Science
• 出版年：2017
• 出版时间：2017
• 年：2017
• 卷：17
• 期：Complete
• 页码：148-152
• 全文大小：271 K
• 卷排序：17

文摘

One of the most significant environmental variables that affect albite dissolution rate is deviation from equilibrium (ΔGr). Most of the studies that describe the effect of ΔGr on albite dissolution rate were conducted under alkline pH (8.8-9.2), elvetad temperatures (80-300 °C) and for Amelia Courthouse (USA) albite. Comparison of the f(ΔGr) derived from those studies to the only f(ΔGr) from low temperature (25 °C), circum neutral pH and EVJE (Norway) albite leads to different ΔGr functions. Yet, except for the study of1, rate laws for silicate minerals dissolution, which are based on experiments conducted under ambient conditions, are lacking. Here we present new experimental results of single point batch experiments (SPBE) of albite dissolution in a isotopically spiked solution. The novel method that use Si isotopes2 enables detecting rates that otherwise can’t be detected under ambient conditions. Albite dissolution rates were determined under neutral-acidic pH, temperatures of 3.6, 25 and 50 °C, and a wide range of undersaturation conditions. The dependency of the dissolution rate on deviation from equilibrium (f(ΔGr)) was in agreement with the prediction of previous studies. However, the value of ΔGcrit was found to be significantly different, suggesting an effect of extrinsic properties of the environment.