Alain Manceau is a Researcher Emeritus at the French National Center for Scientific Research (CNRS). He studied earth sciences and biology at École Normale Supérieure de Saint-Cloud (today ENS-Lyon) and obtained the agrégation in natural sciences in 1981 before receiving his Ph. D. in 1984 from the Université Paris VII (today Université Paris Cité). The same year he joined the CNRS in Paris, then, in 1992, moved to the Université Grenoble Alpes (UGA) where he established environmental mineralogy and geochemistry at the Institute for Earth Sciences (ISTerre), a component of the Earth and Planetary Sciences Observatory (OSUG). He was appointed CNRS Researcher Emeritus at the École Normale Supérieure de Lyon (ENS-Lyon) in 2022, and a research scientist at the European Synchrotron Radiation Facility (ESRF) in 2023. In 1997, he was a visiting professor at the University of Illinois Urbana-Champaign, then Adjunct Professor until 2001. He was a visiting professor at the University of California, Berkeley in 2001 and 2002.

Manceau's research focuses on environmental mineralogy and biogeochemistry of metal contaminants and trace elements using X-ray absorption spectroscopy, X-ray diffraction, and quantum chemistry. He and collaborators have made notable contributions to understanding the structure and reactivity of nanoparticulate iron and manganese oxides (ferrihydrite, birnessite) and clay minerals, and on the structural biogeochemistry of mercury in natural organic matter, animals (fish, birds, mammals), and humans.

In the mid-90s, he pioneered the application of synchrotron radiation techniques for determining the speciation of heavy metals in natural bioinorganic systems, and was a co-lead PI of the French Absorption spectroscopy beamline in Material and Environmental sciences (FAME) at the European Synchrotron Radiation Facility (ESRF) in Grenoble. In 2002-2003, he was a key developer of a new generation of X-ray microprobe dedicated to the study of environmental materials at the Advanced Light Source (ALS) of the Lawrence Berkeley National Laboratory, while a visiting professor at the University of California at Berkeley. He used this instrument to improve phytoremediation techniques aimed to contain, remove, or degrade contaminants in soils, sediments, and waters, in collaboration with the Phytorestore company.

From 2011 through 2021, he was the lead-PI of the EcoX consortium project at the ESRF funded by the Equipex program of the French government for new infrastructures of scientific excellence. EcoX initiated the construction of three high resolution and luminosity X-ray spectrometers: FAME-UHD, TEXS, and a mobile micro spectrometer. He used these instruments to study the atomic-scale biochemistry of mercury in plants, animals, and humans. A highlight of the research on mercury is the discovery of the biomineralization pathway of toxic methylmercury into non-toxic mercury selenide in birds, through a sequence of demethylation reactions involving selenoprotein P, and the finding of the antagonistic role of selenium in controlling mercury toxicity. In 2022, he was awarded an Advanced Grant from the European Research Council to fathom the sequestration and enrichment of critical metals and rare-earth elements (REEs) in marine deposits using the ESRF's new flagship ID24-DCM beamline for micro emission spectroscopy.

Alain Manceau has authored over 200 articles in the world's leading mineralogy, geochemisty, environmental, and materials science journals, and has received several national and international awards and honors for his research in molecular environmental science. He was awarded the CNRS Silver Medal in 2010, after receiving the Bronze Medal in 1989, he won the ES&T 2021 Best Paper Award in 2022 for his work on the mercury-selenium antagonism, and he received in 2023 the Léon Lutaud Price and the Georges Millot Medal from the French Academy of Sciences. In 2020, he was ranked 111th out of a total of 70,197 researchers in Geochemistry/Geophysics in a bibliometric study by scientists from the Stanford University based on the Elsevier Scopus database.