『Abstract
　We present evidence of inhibition of calcite dissolution by dissolved magnesium through direct observation of the (104) surface using force microscopy (AFM) and vertical scanning interferometry (VSI). Far from equilibrium, the pattern of magnesium inhibition is dependent on solution composition and specific to surface step geometry. In CO2-free solutions (pH 8.8), dissolved magnesium brings about little inhibition even at concentrations of 0.8×10^-3 molal. At the same pH, magnesium concentrations of less than 0.05×10^-3 molal in carbonate -buffered solutions generate significant inhibition, although no changes in surface and etch pit morphology are observed. As concentrations exceed magnesite saturation, the dissolution rate shows little additional decrease; however, selective pinning of step edges results in unique etch pit profiles, seen in both AFM and VSI datasets. Despite the decrease in step velocity, magnesium addition in carbonated solutions also appears to activate the surface by increasing the nucleation rate of new defects. These relationships suggest that the modest depression of the bulk rate measured by VSI reflects a balance between competing reaction mechanisms that simultaneously depress the rate through selective inhibition of step movement, but also enhance reactivity on terraces by lowering the energy barrier to new etch pit formation.』

1. Introduction
2. Methods
3. Results
　3.1. VSI experiments
　3.2. AFM experiments
4. Discussion
　4.1. Control of step morphology
　4.2. Step velocities and enhanced defect nucleation rates
5. Summary and conclusions
Acknowledgments
References