Alain Manceau

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Alain Manceau
ENS-Lyon, Lyon
ESRF, Grenoble
Doctoral advisorGeorges Calas
Websiteperso.ens-lyon.fr/alain.manceau/

Alain Manceau, born September 19, 1955, is a French environmental

marine sediments, and on the structural biogeochemistry of mercury in natural organic matter, animals (fish, birds, mammals), and humans
.

Biography

Manceau is a former pupil of the

École Normale Supérieure de Lyon) in 1977.[1] He obtained the agrégation in natural sciences in 1981, then his doctorate in 1984 at the University Paris VII (now Université Paris Cité) under the direction of George Calas.[2] He spent his entire academic career at the French National Centre for Scientific Research (CNRS), first as a research fellow from 1984, then as a research director from 1993 to 2022.[1]
From 1984 to 1992, he worked at the
ENS-Lyon in 2022,[4] and research scientist at the European Synchrotron Radiation Facility (ESRF) in 2023.[5] In 1997, he was a visiting professor at the University of Illinois Urbana-Champaign, then Adjunct professor until 2001.[1] He was a visiting professor at the University of California, Berkeley from 2001 to 2002.[1]

Scientific works

Environmental mineralogy and geochemistry

Minerals play a key role in the biogeochemical cycling of the elements at the Earth's surface, sequestering and releasing them as they undergo precipitation, crystal growth, and dissolution in response to chemical and biological processes. Manceau's research in this field focuses on the structure of disordered minerals (clays, iron (Fe) and manganese (Mn) oxides, including ferrihydrite and birnessite), on chemical reactions at their surface in contact with aqueous solutions, and on the crystal chemistry of trace metals in these phases.

In 1993, he established in collaboration with Victor Drits a structural model for ferrihydrite based on the modeling of the X-ray diffraction pattern.[6] This model was confirmed in 2002 by Rietveld refinement of the neutron diffraction pattern,[7] and in 2014 by simulation of the pair distribution function measured by high-energy X-ray scattering.[8]

Electron image of d-MnO2 nanoparticles viewed parallel (a) and perpendicular (b) to the layer plane.[8]
Structure of a cylindrically bent layer of d-MnO2 nanosheet.[8]

In 1997, he and Victor Drits led the synthesis and resolution of the structure of

ferromanganese deposits compared to seawater.[16]

From 2002 to 2012, he applied the knowledge base acquired on the crystal chemistry of trace metals and biogeochemical processes at mineral surfaces and the root-soil interface (rhizosphere) to the phytoremediation of contaminated soils and sediments, and abandoned mine sites.[17][18][19] He contributed to improving the Jardins Filtrants® (Filtering Gardens) process for treating wastewater and solid matrices by phytolixiviation, phytoextraction, and rhizofiltration developed by the Phytorestore company.

In 2022, he extended his research on the

manganese nodules and crusts.[21]

Structural biogeochemistry of mercury

Binding site of mercury (Hg) in selenoprotein P of grebe bird.[22][23]

Mercury (Hg) is a global pollutant that is generated both by natural sources, such as volcanic eruptions and wildfires, and human activities, such as coal combustion, gold mining, and the incineration of industrial waste. In aquatic and terrestrial food chains, mercury accumulates as methylmercury (MeHg), a potent toxin that affects the function of animal's and human's brain and reproductive system. Understanding the internal detoxification processes of MeHg in living organisms is essential for protecting wildlife and humans, and designing treatments against mercury poisoning.

In 2015, Manceau led foundational studies on the structural

animals, and humans using X-ray emission spectroscopy at the ESRF. In 2021, he found that the Clark's grebe (Aechmophorus clarkii) and the Forster's tern (Sterna forsteri) from California, the southern giant petrel (Macronectes giganteus) and the south polar skua (Stercorarius maccormicki) from the Southern Ocean, and the Indo-Pacific blue marlin (Makaira mazera) from French Polynesia, detoxify the organic methylmercury-cysteine complex (MeHgCys) in inorganic mercury-selenocysteine complex (Hg(Sec)4).[22][23][24][25] A few months later, he extended this result to long-finned pilot whale from the analysis of 89 tissues (liver, kidney, muscle, heart, brain) from 28 individuals stranded on the coasts of Scotland and the Faroe Islands.[26]

This body of work shed light on how birds, cetacea, and fishes manage to get rid of methylmercury toxicity. Demethylation of the MeHgCys complex to Hg(Sec)4 and very poorly soluble inorganic HgSe is catalyzed by selenoprotein P (SelP) within which nucleate clusters of Hgx(Sec,Se)y that grow, likely by self-assembly of mercurial proteins as is common in biomineralization processes, to form in fine inert, non-toxic mercury selenide (HgSe) crystals.

The new Hg(Sec)4 species identified by Manceau and his collaborators was the main “missing intermediate” in the chemical reaction that helps animals to survive high levels of mercury. However, because Hg(Sec)4 has a molar ratio of selenium to mercury of 4:1, four selenium atoms are required to detoxify just one mercury atom. Thus, Hg(Sec)4 severely depletes the amount of bioavailable selenium. Selenium deficiency can affect the function of animals’ brain and reproductive system, as selenoproteins serve critical antioxidant functions in the brain and testes.[27] His works on the Hg-Se antagonism won him the ES&T 2021 Best Paper Award.

The stepwise MeHgCys → Hg(Sec)4 + HgSe demethylation reaction is accompanied by the fractionation of the 202Hg and 198Hg isotopes, denoted δ202Hg. The δ202Hg fractionation measured on whole animal tissues (δ202Hgt) is the sum of the fractionations of the MeHgCys, Hg(Sec)4, and HgSe species, weighted by their relative abundance:


               δ202Hgt = f(Spi)t × δ202Spi

where δ202Spi is the fractionation of each chemical species, and f(Spi) their relative abundance, or mole fraction. Manceau and his co-authors found that δ202Spi can be obtained by mathematical inversion of macroscopic isotopic and microscopic spectroscopic data.[26][28]

The combination of isotopic and spectroscopic data on birds and cetacea revealed that dietary methylmercury and the Hg(Sec)4-SelP complex are distributed to all tissues (liver, kidney, sketetal muscle, brain) via the circulatory system with, however, a hierarchy in the tissular percentage of each species. Most of the detoxification process is carried out in the liver, whereas the brain, which is particularly sensitive to the neurotoxic effects of mercury, is distinguished from other tissues by a low mercury concentration and a high proportion of inert HgSe. These results appear to be transposable to humans.[29]

Publications

Manceau has published more than 200 scientific papers in Science Citation Index journals totalizing more than 24,000 citations and garnering an h-index over 90.[30] In 2020, he was ranked 111th out of a total of 70,197 researchers in Geochemistry/Geophysics in a bibliometric study by scientists of the Stanford University based on the Elsevier Scopus database.[31]

Awards and honors

Online conference and research highlight

References

  1. ^ a b c d "Alain Manceau | Curriculum Vitae". Retrieved 2023-11-20.
  2. ^ "Alain Manceau | Ph.D. supervisor" (PDF). Retrieved 2023-11-20.
  3. ^ "Alain Manceau |IMPMC" (PDF). Retrieved 2023-11-20.
  4. ^ "Alain Manceau |ENS Lyon". Retrieved 2023-11-20.
  5. ^ "Alain Manceau | ESRF". 4 April 2023. Retrieved 2023-11-20.
  6. S2CID 11345105
    .
  7. S2CID 55727756
    .
  8. ^
    S2CID 56356250
    .
  9. S2CID 56030552
    .
  10. S2CID 55969753
    .
  11. S2CID 53443294
    .
  12. PMID 33436628
    .
  13. S2CID 54923713
    .
  14. S2CID 251086409
    .
  15. S2CID 259292146
    .
  16. ISBN 9780080983004
  17. doi:10.2138/gsrmg.49.1.341
    .
  18. S2CID 1771467
    .
  19. doi:10.1021/es9505154
    .
  20. S2CID 250572338
    .
  21. doi:10.1021/acsearthspacechem.1c00447
    .
  22. ^
    S2CID 231679875
    .
  23. ^
    S2CID 231680173
    .
  24. S2CID 234874204
    .
  25. S2CID 233601869
    .
  26. ^
    S2CID 236302944
    .
  27. PMID 25974694
    .
  28. S2CID 238238141
    .
  29. PMID 22826746
    .
  30. ^ "h-index".
  31. PMID 33064726
    .
  32. ^ "List of MSA fellows".
  33. ^ "Recipients of the George W. Brindley Clay Science Lecture award".
  34. ^ "Recipients of the George Brown Lecture award".
  35. ^ "Equipex projects at ESRF".
  36. ^ "Academy of Europe: Manceau Alain". www.ae-info.org.
  37. ^ "List of ERC Grantees at ESRF".
  38. ISSN 0013-936X
    .
  39. ^ "Prix thématiques de l'Académie des Sciences, relatifs aux Sciences de l'univers".
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