METAL SORPTION ONTO HALOPHILIC ARCHAEA

Identifying and quantifying the controls on metal mobilities in geologic systems is critical in order to understand processes such as global elemental cycling, metal transport in near-surface water-rock systems, sedimentary diagenesis, and soil formation. Archaea are ubiquitous in near-surface water-rock systems and numerous laboratory and field studies have demonstrated that Archaea can facilitate the formation and dissolution of minerals, potentially enhancing or inhibiting contaminant transport. However, despite the growing evidence that Archaea play a key role in many geologic processes in low temperature systems, our understanding of the rates and mechanisms of archaeal effects remains rudimentary. Experimental studies of metal (Cd,Pb,proton)-archaeal interactions were conducted in batch reactors as a function of pH, and solid-solute interactions. Surface complexation models (SCM) for metal-archaeal adsorption reactions were developed by combining sorption data with the results of acid-base titrations of the bacterial surface. The resulting SCM were robust and could be utilized to determine metal mass distribution in more complex multi-component systems. Notably archaeal sorption and buffering capacity are much higher then previously studied bacterial species and may indicate an important role for Archaea in biomineralization processes.