Acid drainage from unused mines (AMD) is a global problem. In these environments understanding the role of microbes is critical to predict its remediation as well as creation, but is also important due to its recent use as an analogue for the surface of Mars. Measuring microbial activity using isotopic signatures is a well-established idea used for AMD production, however, is typically only applicable to the metabolism of specific microbes. In contrast, fractionation in phosphate that is required by all forms of life, has been shown to be a viable tracer for biological activity in near neutral environments by Prof. Blake at Yale University. At acidic conditions different speciations of phosphate play an important role in O fractionation but the signatures associated with minerals such as Fe-oxides and microbial metabolism is unknown. Thus, the proposed project will use a synergy of experimental, analytical and computational techniques to test whether the isotopic fractionation of oxygen in phosphate can be used as an isotopic tracer in acidic systems. To do this fractionation associated with relevant microbes and Fe-minerals will be examined using experiments, analysed by state of the art Thermo-Chemical Elemental Analysis and compared to natural AMD samples in the outgoing phase at Yale University. To predict whether these signatures can be retained within the Fe-minerals computational simulations, conducted at the return host University College London with Prof. de Leeuw, will be used to examine phosphate adsorption to different Fe-minerals and the competition of other molecules for adsorption sites. The proposed project offers the European scientific community the opportunity to transfer unique skills whilst simultaneously generating cross disciplinary collaborations that have a high potential to produce long term projects and is the perfect project for the researcher to establish the skills required for a career in environmental remediation research.