Precipitation of molybdenum from euxinic waters and the role of organic matter

Molybdenum preserved in organic-rich shales is a key archive employed in studying Earth's past oxygenation and Life's evolution. In these shales, positive correlations between Mo and Corg are common and have been attributed to Mo scavenging from seawater by organic shuttles. Here, we argue that known organic ligands are too weak or too scarce to capture more than minor amounts of Mo from seawater, especially in competition with sulfide....