Effect of Ionic Strength on H2O and Si-Species Stability Field Geometry in pH-Eh Space

IF 1.7 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Aquatic Geochemistry Pub Date : 2023-11-03 DOI:10.1007/s10498-023-09417-0

Samuel Bowman, Arkajyoti Pathak, Vikas Agrawal, Shikha Sharma

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Abstract

Speciation diagrams in pH-Eh space at some pressure, temperature, and composition are highly useful in indicating the thermodynamic behavior expected in a system. While these diagrams are found frequently throughout geochemical literature, they often overlook the geometric behavior of stability fields and fail to address the specific impacts of ionic strength and fluid composition. Modeling results from the Salton Sea and Krafla geothermal sites suggest a positive correlation between ionic strength and the H₂O_(l) stability field area or reactivity domain. In addition, the Si-bearing species (selected due to the propensity of adverse scale occurrence) within the Salton Sea brine are shifted farther apart than the centroids of the same Si species in the comparatively dilute Krafla. These modeling observations imply that geothermal brines at equilibrium accommodate a larger H₂O reactive field in pH-Eh space, allowing for the possibility that water–rock interactions could occur at pH-Eh conditions that would conventionally be unexpected if ionic strength is not considered.

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离子强度对pH-Eh空间中H2O和si物质稳定性场几何的影响

pH-Eh空间在一定压力、温度和组成下的形态图对于指示系统中预期的热力学行为非常有用。虽然这些图在地球化学文献中经常发现，但它们往往忽略了稳定场的几何行为，并且无法解决离子强度和流体成分的具体影响。Salton海和Krafla地热站点的模拟结果表明，离子强度与H2O(l)稳定场面积或反应性域呈正相关。此外，在Salton Sea卤水中，含硅物种(由于不利水垢发生的倾向而选择)比在相对稀释的Krafla中相同Si物种的质心偏移得更远。这些模拟观察表明，在平衡状态下的地热盐水在pH-Eh空间中容纳了更大的H2O反应场，这就允许水岩相互作用在pH-Eh条件下发生的可能性，如果不考虑离子强度，这是通常无法预料的。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Aquatic Geochemistry 地学-地球化学与地球物理

CiteScore

4.30

自引率

0.00%

发文量

审稿时长

1 months

期刊介绍： We publish original studies relating to the geochemistry of natural waters and their interactions with rocks and minerals under near Earth-surface conditions. Coverage includes theoretical, experimental, and modeling papers dealing with this subject area, as well as papers presenting observations of natural systems that stress major processes. The journal also presents `letter''-type papers for rapid publication and a limited number of review-type papers on topics of particularly broad interest or current major controversy.