Iron sources and cycling in the Peruvian oxygen minimum zone assessed using iron isotopes
Our results show lowest δ56Fe down to -1.5‰ within the OMZ and close to the seafloor coinciding with elevated dFe concentrations. Dissolved Fe concentrations decreased and δ56Fe values increased with distance from the coast. These findings are in accordance with negative δ56Fe signatures resulting from reductive dissolution in sediments and indicate a preferential removal of lighter isotopes or mixing with heavier dFe from other sources. δ56Fe observations in pore waters will allow us to further constrain the sediment source contribution to the overall Fe budget in this region. Comparison with concentrations of Fe(II) and other trace metals, alongside biological and physical parameters collected during the same cruises will help to improve our understanding of Fe source and cycling processes in this region and their effect on Fe isotope fractionation.