In a paper published in Chemical Geology entitled: “Molybdenum isotope fractionation and speciation in a euxinic lake—Testing ways to discern isotope fractionation processes in a sulfidic setting”, we compare molybdenum isotope and speciation data from lake sediments deposited under euxinic (anoxic and sulfidic) waters. We conclude that the chemical Mo species present in sediments did not form in the water column, but rather was a product of later diagenesis – dissolution and re-precipitation.

This process complicates the use of molybdenum speciation data to discern molybdenum isotope fractionation process occurring in the water column, since the Mo speciation can be “reset” inside the sediments. 

As this is the first combined molybdenum isotope-speciation data from euxinic sediments, we can now explore if this process also occurs in marine euxinic settings.

http://www.sciencedirect.com/science/article/pii/S0009254117302127