Dr. Chappaz is an Associate Professor at Central Michigan University
- Postdoctoral Researcher, University of California - Riverside, 2008-2011
- Ph.D., Aquatic Geochemistry, INRS-ETE, University of Quebec, 2008
- M.Sc., Chemistry and Microbiology of Water, Universities of Poitiers and Pau, 2002
- B.Sc., Chemistry, University of Joseph Fourier, 2001
Research InterestsI define myself as a molecular geochemist indicating that I am particularly interested in exploring how molecular reactions control global biogeochemical cycles. My research interests aim to characterize the processes controlling the fate and reactivity of trace elements within modern and ancient aquatic systems. All my on-going funded projects are designed to answer crucial questions related to the biogeochemistry of trace elements either in ancient geological settings or modern environmental systems.
They can be divided in two groups: (1) a paleo angle that deals with studying trace element molecular geochemistry within sedimentary records with the objectives to improve our understanding of Earth History, oil and gas reservoir formation, climate changes, and exobiology; (2) a modern aspect tailored to identify pollution sources and predict either bioavailability of micro-nutriments or trace element toxicity, that contributes to reduce the impact of human activities on natural biogeochemical cycles in modern aquatic systems within a context of climate change.
To achieve these goals, I have developed a unique expertise consisting in characterizing geological and environmental samples by determining their trace element molecular geochemistry. The first studies of the Earth’s early oxygenation and life development, based on trace element geochemistry, only determined their concentrations in ancient sedimentary records. This basic approach allowed some major breakthroughs but it also presents significant weaknesses. With the availability of MC-ICP-MS allowing the determination of trace element isotopic signatures, the community thought a new golden age was arising. But several recent studies highlighted some problematic issues when using non-traditional isotope techniques.
Determining trace element speciation, i.e. identifying the predominant chemical species present in the matrix, is critically important if isotopic and concentration signatures are to be accurately interpreted in environmental archives. Molecular geochemistry consists in combining these three approaches for studying Earth History.
- Rico, K.I.*, Sheldon, N.D., Gallagher, T.M. and
Chappaz, A. Molybdenum availability, productivity, and atmospheric oxygen in the Mesoproterozoic.
Geophysical Research Letters. doi.org/10.1029/2019GL083316.
- Babos, H.B.*; Stuart, S., Pluskowski, A., Brown, A., Rohrssen, M.K. and
Chappaz, A. Evidence for the onset of mining activities during the 13th century in Poland using lead isotopes from lake sediment cores.
Science of the Total Environment. 683, 589-599.
- Tessin, A.*,
Chappaz, A, Hendy, I.L. and Sheldon, N.D. Molybdenum speciation as a paleo-redox proxy: a case study from Late Cretaceous Western Interior Seaway black shales.
Geology. 47, 59-62.
- Vorlicek, T.P., Helz, G.R.,
Chappaz, A., Vue, P., Vezina, A. and Hunter, W. Molybdenum Burial Mechanism in Sulfidic Sediments: Iron-Sulfide Pathway.
ACS Earth and Space Chemistry. 2, 565-576.
- Nedrich, S.M.*,
Chappaz, A., Hudson, M.L., Brown, S.S and Burton, A.G. Jr. Biogeochemical controls on the speciation and aquatic toxicity of Vanadium and other metals in sediments from a river reservoir.
Science of the Total Environment. 612, 313-320.
- Wagner, M.*,
Chappaz, A. and Lyons, T.W. Molybdenum speciation and burial pathway in weakly sulfidic environments: Insights from XAFS.
Geochimica et Cosmochimica Acta. 206, 18-29.
- Dahl, T.W.,
Chappaz, A., Canfield, D.E., Hoek, J., McKenzie, C., Svane, S and Canfield, D.E. Evidence of molybdenum association with particulate organic matter under sulfidic conditions.
Geobiology. DOI: 10.1111/gbi.12220.
- Ardakani, O.H.‡,
Chappaz, A.‡, Sanei, H. and Mayer. B. Effect of thermal maturity on remobilization of molybdenum in black shales.
Earth and Planetary Science Letters. 449, 311-320. ‡Joint first authors.
- Tessin, A.*, Sheldon, N.D., Hendy, I and
Chappaz, A. Iron limitation in the Western Interior Seaway during the Late Cretaceous OAE 3 and its role in phosphorus recycling and enhanced organic matter preservation.
Earth and Planetary Science Letters. 449, 135-144.
- Vorlicek, T.P. ‡,
Chappaz, A‡, Groskreutz, L.M.*, Young, N. and Lyons. T.W. A new analytical approach to determining Mo and Re speciation in sulfidic waters.
Chemical Geology. 403, 52-57. ‡Joint first authors.
Chappaz, A., Lyons, T.W., Gregory, D.D., Reinhard, C.T., Gill, B.C., Chao, L. and Large, R.R. Does pyrite act as an important host for molybdenum in modern and ancient euxinic sediments?
Geochimica et Cosmochimica Acta. 126: 112-122.