Enhanced Dissolution of Cinnabar (Mercuric Sulfide)

by Dissolved Organic Matter

Isolated from the Everglades, FL

M. Ravichandran¹, G.R. Aiken², M.M. Reddy², J.N. Ryan¹

¹Department of Civil, Environmental, and Architectural Engineering

University of Colorado, Boulder, CO 80309

²USGS, 3215 Marine Street, Boulder, CO 80303

Introduction

Dissolved organic matter (DOM), particularly the humic fractions, are known to increase the solubilitiy of several oxide, hydroxide, and sulfide minerals. Despite the ubiquitous presence of DOM in natural waters and the toxic nature of mercury (Hg) to organisms, the role of DOM in the dissolution of cinnabar (HgS), a major ore mineral and a sink of Hg in contaminated sediments, has not been studied before. In this study we show that DOM enhances the release of Hg from cinnabar, a solid with limited solubility (solubility product, log K_sp = 52.4).