In spite of significant progress in the development and calibration of new proxies, major challenges still limit our ability to use these indicators to fully understand past environmental changes. Over the past two decades, both field and laboratory experiments have shed light on the importance of trace metals in controlling –through limitation or toxicity - the growth and composition of phytoplankton communities. Nonetheless, there is still a lack of reliable tools to evaluate trace metals–phytoplankton interactions during past environmental and climatic perturbations. In this work, we evaluated the use of the Zn content of silicate shells (frustules) of fossil diatoms to track past changes in Zn bioavailable concentrations of surface waters. This essential element is delivered to both continental and ocean waters via natural and/or anthropogenic inputs. Our approach combined laboratory and field experiments.