Anthropogenic greenhouse gas emissions may be offset by sequestering carbon dioxide (CO2 ) through the carbonation of silicate minerals. In the natural environment, microbes can aid in silicate dissolution and carbonate precipitation, and therefore, can potentially be used to catalyze carbonation reactions. The hydromagnesite playas of Atlin, British Columbia, Canada provide a natural model to examine mineral carbonation on a watershed scale. At near surface conditions, microorganisms are involved in weathering of bedrock and precipitation of carbonate minerals, which results in CO 2 sequestration. Regions with ultramafic bedrock, such as Atlin, represent the best potential sources of feedstocks for mineral carbonation. Experimental [...]