Physicochemical Model of Silver Behavior in a Weathering Profile

Abstract—A weathering profile of phyllite shales with an original Ag concentration of 10–5 wt % (the average Ag concentration in the Earth’s crust is 7 × 10–6 wt %) was numerically simulated with the SELECTOR program package. Under oxidizing conditions, Ag occurs in the solutions dominantly in the form of the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{Ag}}_{{({\text{aq}}{\text{.}})}}^{ + }$$\end{document} cation and a few percent of the anion , at a total Ag concentration of ×10–6.4 mol/L. Under reduced conditions, the dominant ion is \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{Ag}}_{{({\text{aq}}{\text{.}})}}^{0}$$\end{document}, whose concentration is 10–8.19 mol/L. The mineral form of Ag throughout the whole vertical section is native silver.