What have we discovered? A laboratory investigation of the mechanisms of molybdenum accumulation in the solid phase: The influence of organic molecules Jennifer L. Morford, Franklin & Marshall College, Lancaster, PA Molybdenum (Mo) might be a useful tracer for past changes in organic carbon burial in marine sediments However, the mechanism(s) for how Mo gets into marine sediments is not well understood, although it may begin with the transition from MoO42- to MoS42- in the presence of sulfide. The role of organic molecules, which are ubiquitous in the environment as aqueous species and bound to solid surfaces, in Mo cycling has not been thoroughly investigated. What have we discovered? MoO42- interacts in solution with aromatic molecules that have two phenolic functional groups on adjacent ring carbons Both MoO42-and MoS42-adsorb to aluminum oxide and pyrite under acidic conditions, whereas adsorption is negligible above pH 6 Future research will investigate the possibility of MoS42- interactions with organic molecules in solution. Adsorption experiments will explore whether the presence of organic molecules enhances or inhibits MoO42- or MoS42- adsorption to solid surfaces.